Tesis: "Reservoirs"

1

AlBinHassan, Nasher M. "Reservoir properties prediction in carbonate reservoirs". Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/5922.

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Prediction of fluid pressure before drilling, using geophysical methods helps the industry a lot in saving human life, drilling hazards, and equipments.There are several geophysical methods available to predict the fluid pressure before drilling but the most commonly used in the industry are those based on seismic velocities. However, seismic velocities methods are applied on clastic reservoirs with the assumptions that the pressure mechanism is due to mechanical compaction. A major exploration challenge is to successfully predict the presence of high pressure zones in the carbonate reservoirs. Carbonate reservoirs have a more complicated internal structure than clastic reservoirs. The main objective of this study is to predict the carbonate reservoir properties such as porosity and fluid pressure. The new prediction methods that I used in this thesis are called the artificail intelligent algorithms. These algorithms are better than the conventional geophysical methods because of their ability to explore complex relationships between the input seismic attributes and the predicted properties. The algorithms include artificial neural networks and group methods of data handling. Empirical equations from seismic prediction methods were used to transform velocities to fluid pressure. High resolution velocites (wavefrom tomography) proved that better prediction can be achieved when using better input velocity. The velocity methods performed a nice prediction when used with clastic seismic data but proved to give unreliable results when used with the carbonate seismic data. This was because of the difficult internal structure of carbonate reservoirs. The neural network methods proved that they are robust in clustering and segmenting the input carbonate seismic data. The usage of more input seismic attributes made the neural network methods better than the conventional velocity methods. Also, this gave the neural network methods more information about the same physical reservoir property. Among the different seismic attributes used in the experiment, seismic inversion and coherence attributes showed good reaction to high pressure zones. Porosity results from the supervised neural network method were used as a guide to the unsupervised neural network method to predict fluid pressure. The group method of data handling algorithm is performed here for the first time with seismic data to predict the reservoir properties. The new method showed faster and easier prediction than the neural network methods. The automation of the new method yields to better porosity and pore pressure prediction.

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2

Whaballa, Ala. "Reservoir simulation and well testing of compartmentalized reservoirs". Thesis, Heriot-Watt University, 1991. http://hdl.handle.net/10399/1493.

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3

Dickey, Richard Jason Bayne David Roberge. "Oligotrophication effects following diversion of waste effluent from an embayment of Lake Martin, Alabama". Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Fall/Theses/DICKEY_RICHARD_7.pdf.

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4

Seth, Siddhartha. "Increase in surface energy by drainage of sandstone and carbonate". Laramie, Wyo. : University of Wyoming, 2006. http://proquest.umi.com/pqdweb?did=1221730011&sid=4&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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5

Duruewuru, Anthony U. "Thermodynamic analysis of transient two-phase flow in oil and gas reservoirs /". Full-text version available from OU Domain via ProQuest Digital Dissertations, 1985.

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6

PETER, COSTANZO. "Capturing reservoir production uncertainty for channelized reservoirs using channel amalgamation indexes". Doctoral thesis, Politecnico di Torino, 2016. http://hdl.handle.net/11583/2644036.

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One of the main concerns in reservoir studies is to accurately define the internal architecture and the geological characteristics of the reservoir so as to estimate the amount of hydrocarbons that could be recovered for a given development strategy. This can represent a major challenge especially during the appraisal stage of a reservoir, because the information available is still very limited, or in the presence of geological heterogeneities, which increase the architectural complexity and the uncertainty associated to the internal description, such as in channelized depositional settings. At the appraisal stage of a reservoir study, all the uncertainties affecting the quantity and distribution of hydrocarbons in the reservoir should be captured and accounted for in the evaluation of the final hydrocarbon recovery to properly assess the viability of any development plan. A typical modeling workflow accounting for geological uncertainties consists in creating a large set of 3-D stochastic geological (static) models from a set of geological input parameters. Subsequently, a few representative reservoir realizations are selected out of this set based on the calculated hydrocarbons originally in place and simulated to estimate future production so as to propagate the uncertainty onto the final recovery factors. However, even in homogeneous reservoirs, the estimation of the hydrocarbon stored in the reservoir can be affected by uncertainties because it is calculated mostly from local petrophysical parameters, which might not be representative of the rock properties at the reservoir scale. This especially applies to channelized reservoirs characterized by depositional elements with high geological heterogeneity, both in the lateral and in the vertical directions. Thus for these depositional settings a more attractive criterion for the model selection is offered by the study of the connectivity layout of the reservoir elements. In the technical literature, connectivity is defined through numerical indexes that account for geological connectivity between reservoir elements, which might not be indicative of reservoir production performance. In fact, the latter is influenced by the degree of connectivity among sand bodies and only deep merging of the channels guarantees that the reservoir can be efficiently drained by just a few wells. Therefore, in the first place, the present study was aimed at thoroughly investigating the validity of the indexes previously proposed in the technical literature by evaluating the reservoir production uncertainty associated to sets of synthetic equi-probable models of channelized oil reservoirs. Secondly, the goal of the research was to develop new indexes to express the channel connectivity, capable of incorporating information on the quality of the connectivity through the evaluation of channel amalgamation. When applied to the same set of reservoir equi-probable realizations, these indexes proved that a more effective selection of the geological realizations can be made to capture the uncertainty affecting the forecasted reservoir production performance.

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7

Seetha, Ram Katakam V. "Conjunctive And Multipurpose Operation Of Reservoirs Using Genetic Algorithms". Thesis, Indian Institute of Science, 2000. https://etd.iisc.ac.in/handle/2005/222.

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Optimal operation of reservoir systems is necessary for better utilizing the limited water resources and to justify the high capital investments associated with reservoir projects. However, finding optimal policies for real-life problems of reservoir systems operation (RSO) is a challenging task as the available analytical methods can not handle the arbitrary functions of the problem and almost all methods employed are numerical or iterative type that are computer dependent. Since the computer resources in terms of memory and CPU time are limited, a limit exists for the size of the problem, in terms of arithmetic and memory involved, that can be handled. This limit is approached quickly as the dimension and the nonlinearity of the problem increases. In encountering the complex aspects of the problem all the traditionally employed methods have their own drawbacks. Linear programming (LP), though very efficient in dealing with linear functions, can not handle nonlinear functions which is the case mostly in real-life problems. Attempting to approximate nonlinear functions to linear ones results in the problem size growing enormously. Dynamic programming (DP), though suitable for most of the RSO problems, requires exponentially increasing computer resources as the dimension of the problem increases and at present many high dimensional real-life problems can not be solved using DP. Nonlinear programming (NLP) methods are not known to be efficient in RSO problems due to slow rate of convergence and inability to handle stochastic problems. Simulation methods can, practically, explore only a small portion of the search region. Many simplifications in formulations and adoption of approximate methods in literature still fall short in addressing the most critical aspects, namely multidimensionality, stochasticity, and additional complexity in conjunctive operation, of the problem. As the problem complexity increases and the possibility of arriving at the solution recedes, a near optimal solution with the best use of computational resources can be very valuable. In this context, genetic algorithms (GA) can be a promising technique which is believed to have an advantage in terms of efficient use of computer resources. GA is a random search method which find, in general, near optimal solutions using evolutionary mechanism of natural selection and natural genetics. When a pool of feasible solutions, represented in a coded form, are given fitness according to a objective function and explored by genetic operators for obtaining new pools of solutions, then the ensuing trajectories of solutions come closer and closer to the optimal solution which has the greatest fitness associated with it. GA can be applied to arbitrary functions and is not excessively sensitive to the dimension of the problem. Though in general GA finds only the near optimal solutions trapping in local optima is not a serious problem due to global look and random search. Since GA is not fully explored for RSO problems two such problems are selected here to study the usefulness and efficiency of GA in obtaining near optimal solutions. One problem is conjunctive operation of a system consisting of a surface reservoir and an aquifer, taken from the literature for which deterministic and stochastic models are solved. Another problem is real-time operation of a multipurpose reservoir, operated for irrigation (primary purpose) and hydropower production, which is in the form of a case study. The conjunctive operation problem consists of determining optimal policy for a combined system of a surface reservoir and an aquifer. The surface reservoir releases water to an exclusive area for irrigation and to a recharge facility from which it reaches the aquifer in the following period. Another exclusive area is irrigated by water pumped from the aquifer. The objective is to maximize the total benefit from the two irrigated areas. The inflow to the surface reservoir is treated as constant in deterministic model and taken at 6 different classes in stochastic model. The hydrological interactions between aquifer and reservoir are described using a lumped parameter model in which the average aquifer water table is arrived at based on the quantity of water in the aquifer, and local drawdown in pumping well is neglected. In order to evaluate the GA solution both deterministic and stochastic models are solved using DP and stochastic DP (SDP) techniques respectively. In the deterministic model, steady state (SS) cyclic (repetitive) solution is identified in DP as well as in GA. It is shown that the benefit from GA solution converges to as near as 95% of the benefit from exact DP solution at a highly discounted CPU time. In the stochastic model, the steady state solution obtained with SDP consists of converged first stage decisions, which took a 8-stage horizon, for any combination of components of the system state. The GA solution is obtained after simplifying the model to reduce the number of decision variables. Unlike SDP policy which gives decisions considering the state of the system in terms of storages, at reservoir, aquifer, and recharge facility, and previous inflow at the beginning of that period, GA gives decisions for each period of the horizon considering only the past inflow state of the period. In arriving at these decisions the effect of neglected state information is approximately reflected in the decisions by the process of refinement of the decisions, to conform to feasibility of storages in reservoir and aquifer, carried out in a simplified simulation process. Moreover, the validity of the solution is confirmed by simulating the operation with all possible inflow sequences for which the 8-stages benefit converged up to 90 % of the optimum. However, since 8 stages are required for convergence to SS, a 16-stage process is required for GA method in which the first 8 stages policy is valid. Results show that GA convergence to the optimum is satisfactory, justifying the approximations, with significant savings in CPU time. For real-time operation of a multipurpose reservoir, a rule curve (RC) based monthly operation is formulated and applied on a real-life problem involving releases for irrigation as well as power production. The RC operation is based on the target storages that have to be maintained, at each season of the year, in the reservoir during normal hydrological conditions. Exceptions to target storages are allowed when the demands have to be met or for conserving water during the periods of high inflows. The reservoir in the case study supplies water to irrigation fields through two canals where a set of turbines each at the canal heads generate hydropower. A third set of turbines operate on the river bed with the water let out downstream from the dam. The problem consists of determining the the RC target storages that facilitate maximum power production while meeting the irrigation demands up to a given reliability level. The RC target storages are considered at three different levels, corresponding to dry, normal, and wet conditions, according to the system state in terms of actual (beginning of period) storage of the reservoir. That is, if the actual beginning storage of the reservoir is less than some coefficient, dry-coe, times the normal target storage the target for the end of the period storage is taken at the dry storage target (of the three sets of storages). Similarly the wet level is taken for the end of the period target if the actual beginning storage is greater than some coefficient, wet-coe, times the normal storage. For other conditions the target is the normal storage level. The dry-coe and wet-coe parameters are obtained by trial and error analysis working on a small sequence of inflows. The three sets of targets are obtained from optimization over a 1000 year generated inflow sequence. With deterministic DP solutions, for small sequences of inflows, the optimization capability of GA-RC approach, in terms of objective function convergence, and generalization or robustness capability of GA-RC approach, for which the GA-RC benefit is obtained by simulating the reservoir operation using the previously obtained GA-RC solution, are evaluated. In both the cases GA-RC approach proves to be promising. Finally a 15 year real-time simulation of the reservoir is carried out using historical inflows and demands and the comparison with the historical operation shows significant improvement in benefit, i.e. power produced, without compromising irrigation demands throughout the simulation period.

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8

Seetha, Ram Katakam V. "Conjunctive And Multipurpose Operation Of Reservoirs Using Genetic Algorithms". Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/222.

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Optimal operation of reservoir systems is necessary for better utilizing the limited water resources and to justify the high capital investments associated with reservoir projects. However, finding optimal policies for real-life problems of reservoir systems operation (RSO) is a challenging task as the available analytical methods can not handle the arbitrary functions of the problem and almost all methods employed are numerical or iterative type that are computer dependent. Since the computer resources in terms of memory and CPU time are limited, a limit exists for the size of the problem, in terms of arithmetic and memory involved, that can be handled. This limit is approached quickly as the dimension and the nonlinearity of the problem increases. In encountering the complex aspects of the problem all the traditionally employed methods have their own drawbacks. Linear programming (LP), though very efficient in dealing with linear functions, can not handle nonlinear functions which is the case mostly in real-life problems. Attempting to approximate nonlinear functions to linear ones results in the problem size growing enormously. Dynamic programming (DP), though suitable for most of the RSO problems, requires exponentially increasing computer resources as the dimension of the problem increases and at present many high dimensional real-life problems can not be solved using DP. Nonlinear programming (NLP) methods are not known to be efficient in RSO problems due to slow rate of convergence and inability to handle stochastic problems. Simulation methods can, practically, explore only a small portion of the search region. Many simplifications in formulations and adoption of approximate methods in literature still fall short in addressing the most critical aspects, namely multidimensionality, stochasticity, and additional complexity in conjunctive operation, of the problem. As the problem complexity increases and the possibility of arriving at the solution recedes, a near optimal solution with the best use of computational resources can be very valuable. In this context, genetic algorithms (GA) can be a promising technique which is believed to have an advantage in terms of efficient use of computer resources. GA is a random search method which find, in general, near optimal solutions using evolutionary mechanism of natural selection and natural genetics. When a pool of feasible solutions, represented in a coded form, are given fitness according to a objective function and explored by genetic operators for obtaining new pools of solutions, then the ensuing trajectories of solutions come closer and closer to the optimal solution which has the greatest fitness associated with it. GA can be applied to arbitrary functions and is not excessively sensitive to the dimension of the problem. Though in general GA finds only the near optimal solutions trapping in local optima is not a serious problem due to global look and random search. Since GA is not fully explored for RSO problems two such problems are selected here to study the usefulness and efficiency of GA in obtaining near optimal solutions. One problem is conjunctive operation of a system consisting of a surface reservoir and an aquifer, taken from the literature for which deterministic and stochastic models are solved. Another problem is real-time operation of a multipurpose reservoir, operated for irrigation (primary purpose) and hydropower production, which is in the form of a case study. The conjunctive operation problem consists of determining optimal policy for a combined system of a surface reservoir and an aquifer. The surface reservoir releases water to an exclusive area for irrigation and to a recharge facility from which it reaches the aquifer in the following period. Another exclusive area is irrigated by water pumped from the aquifer. The objective is to maximize the total benefit from the two irrigated areas. The inflow to the surface reservoir is treated as constant in deterministic model and taken at 6 different classes in stochastic model. The hydrological interactions between aquifer and reservoir are described using a lumped parameter model in which the average aquifer water table is arrived at based on the quantity of water in the aquifer, and local drawdown in pumping well is neglected. In order to evaluate the GA solution both deterministic and stochastic models are solved using DP and stochastic DP (SDP) techniques respectively. In the deterministic model, steady state (SS) cyclic (repetitive) solution is identified in DP as well as in GA. It is shown that the benefit from GA solution converges to as near as 95% of the benefit from exact DP solution at a highly discounted CPU time. In the stochastic model, the steady state solution obtained with SDP consists of converged first stage decisions, which took a 8-stage horizon, for any combination of components of the system state. The GA solution is obtained after simplifying the model to reduce the number of decision variables. Unlike SDP policy which gives decisions considering the state of the system in terms of storages, at reservoir, aquifer, and recharge facility, and previous inflow at the beginning of that period, GA gives decisions for each period of the horizon considering only the past inflow state of the period. In arriving at these decisions the effect of neglected state information is approximately reflected in the decisions by the process of refinement of the decisions, to conform to feasibility of storages in reservoir and aquifer, carried out in a simplified simulation process. Moreover, the validity of the solution is confirmed by simulating the operation with all possible inflow sequences for which the 8-stages benefit converged up to 90 % of the optimum. However, since 8 stages are required for convergence to SS, a 16-stage process is required for GA method in which the first 8 stages policy is valid. Results show that GA convergence to the optimum is satisfactory, justifying the approximations, with significant savings in CPU time. For real-time operation of a multipurpose reservoir, a rule curve (RC) based monthly operation is formulated and applied on a real-life problem involving releases for irrigation as well as power production. The RC operation is based on the target storages that have to be maintained, at each season of the year, in the reservoir during normal hydrological conditions. Exceptions to target storages are allowed when the demands have to be met or for conserving water during the periods of high inflows. The reservoir in the case study supplies water to irrigation fields through two canals where a set of turbines each at the canal heads generate hydropower. A third set of turbines operate on the river bed with the water let out downstream from the dam. The problem consists of determining the the RC target storages that facilitate maximum power production while meeting the irrigation demands up to a given reliability level. The RC target storages are considered at three different levels, corresponding to dry, normal, and wet conditions, according to the system state in terms of actual (beginning of period) storage of the reservoir. That is, if the actual beginning storage of the reservoir is less than some coefficient, dry-coe, times the normal target storage the target for the end of the period storage is taken at the dry storage target (of the three sets of storages). Similarly the wet level is taken for the end of the period target if the actual beginning storage is greater than some coefficient, wet-coe, times the normal storage. For other conditions the target is the normal storage level. The dry-coe and wet-coe parameters are obtained by trial and error analysis working on a small sequence of inflows. The three sets of targets are obtained from optimization over a 1000 year generated inflow sequence. With deterministic DP solutions, for small sequences of inflows, the optimization capability of GA-RC approach, in terms of objective function convergence, and generalization or robustness capability of GA-RC approach, for which the GA-RC benefit is obtained by simulating the reservoir operation using the previously obtained GA-RC solution, are evaluated. In both the cases GA-RC approach proves to be promising. Finally a 15 year real-time simulation of the reservoir is carried out using historical inflows and demands and the comparison with the historical operation shows significant improvement in benefit, i.e. power produced, without compromising irrigation demands throughout the simulation period.

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9

Raza, Arshad. "Reservoir Characterization for CO2 Injectivity and Flooding in Petroleum Reservoirs, offshore Malaysia". Thesis, Curtin University, 2017. http://hdl.handle.net/20.500.11937/57524.

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Reservoir characterization of the Malaysian gas reservoir for CO2 storage is carried out at preliminary and comprehensive level to provide insight into the storage capacity, injectivity, trapping mechanisms (structural, capillary, dissolution, and mineral), and containment. Screening tools are proposed in this study for the selections of reservoir, injection well, and injection zone along with CO2 residual trapping novel method, experimental assessment of compaction effect and numerical modeling scheme to improve the reservoir characterization.

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10

Cantero, Pérez Jon. "Papel de las células inmunes residentes en la mucosa cervicovaginal ante las infecciones de transmisión sexua". Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/669603.

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Las infecciones de transmisión sexual (ITS) tienen una alta prevalencia a nivel mundial y pueden causar graves consecuencias tanto a hombres como a mujeres, incluyendo infertilidad, abortos y malformaciones del recién nacido. La principal vía de entrada de estas infecciones es la mucosa genital, la cual está vigilada por las células inmunitarias que allí residen. En la presente tesis hemos caracterizado in situ el papel de estas células frente a dos ITS: clamidia y VIH, utilizando para ello el modelo de explante cervicovaginal, consistente en la manipulación y el cultivo de tejido cervical de donantes. En el caso de la clamidia, hemos estudiado compuestos sintéticos derivados de la α-galactosilceramida (αGC, glicolípidos) con el objetivo de identificar aquellos más prometedores como adyuvantes en una futura vacuna contra este patógeno, centrándonos para ello en la generación de una respuesta inmunitaria tipo Th1, caracterizada por la secreción de interferón-γ. Estos glicolípidos activan las células iNKT, una pequeña población capaz de iniciar la respuesta inmune al interactuar con diferentes tipos celulares tanto innatos como adaptativos. Tras caracterizar el efecto de estos compuestos sobre diferentes poblaciones inmunitarias de la mucosa genital femenina, examinamos su papel protector frente a la infección por clamidia en células HeLa (línea celular originaria del epitelio cervical). Paralelamente, también analizamos su efecto durante la infección ex vivo del tejido con VIH. Pese a todos estos enfoques, no hemos identificado ningún compuesto que suponga una mejora con respecto a la αGC en el control de estas infecciones. En el caso del VIH, hemos estudiado el papel de los linfocitos T CD4+ de memoria residentes (TRM) en el tejido cervical como reservorios del VIH. Tras fenotipar en detalle esta población, caracterizada por la expresión de CD69, hemos visto que se encuentra enriquecida en algunos marcadores asociados con una mayor susceptibilidad al virus (especialmente la fracción que también expresa CD32), por lo que podría ser una de sus primeras dianas. La infección ex vivo del tejido mostró que las células TRM presentaban mayores niveles de infección productiva (p24) y de ADN viral que las CD69-. Además, dentro de estas TRM, las CD32+ contenían todavía mayores cantidades de ADN viral. El análisis de tejido cervical de pacientes VIH+ en tratamiento antirretroviral reveló una disminución de la población CD4+ TRM en comparación al tejido de donantes sanas. Con respecto a la sangre, el tejido de estas pacientes presentó entre 4 y 200 veces más cantidad de ADN viral, confirmando que se trata de un importante reservorio del virus. Dicho ADN se encontró mayoritariamente en las células TRM (>93%), y en algunos casos contenía incluso genomas intactos del virus. Por último, detectamos ARN viral en el cérvix de pacientes VIH+ tanto virémicas como virológicamente suprimidas, que en algunos casos se localizaba en regiones enriquecidas en CD69 o en el epitelio (y, por tanto, TRM). Así, podemos concluir que las TRM suponen un importante reservorio viral en el tejido cervicovaginal, por lo que cabe esperar que suceda lo mismo en diferentes tejidos debido a su amplia distribución por el organismo. Por este motivo, las nuevas estrategias dirigidas a eliminar los reservorios del virus deberían prestar especial atención a esta población.
Sexually transmitted infections (STI) have a high prevalence globally and affect both men and women, causing serious consequences like infertility, aborts or newborn malformations. These diseases are mainly acquired during sexual intercourses through the genital mucosal. For this reason, we analysed the role of mucosal resident immune cells against them, focusing in two of the most prevalent infections: chlamydia and HIV. To perform an in situ analysis, we established the cervicovaginal explant model, which consists in the manipulation and culture of cervical tissue and allows to perform several immunological readouts. Concerning chlamydia, we studied several synthetic derivatives from a glycolipid known as α-galactosylceramide (αGC) in order to identify the most promising ones according to their capacities as adjuvants in a future vaccine against this pathogen. To do so, we focused in the generation of a Th1 response as it is well described that this profile, characterized by interferon-γ (IFN-γ) secretion, is the most effective in controlling Chlamydia trachomatis infection. These glycolipids activate iNKT cells, a small subset that causes a general activation of the immune system by interacting with both innate and adaptive immune populations. After an extensive characterization of the effect of these compounds over different cervical immune subsets, we evaluated the protection that these compounds offer against chlamydial infection in HeLa cells (an epithelial cell line obtained from cervical tissue). Also, we studied their effect during the ex vivo HIV infection of the tissue. Despite all these approaches, we did not identify any compound better than the original αGC in controlling these infections. Concerning HIV, we analysed the role of resident memory T CD4+ lymphocytes (TRM) present at the cervicovaginal mucosa as HIV-1 reservoirs. After an extensive phenotyping analysis we concluded that this subset, characterized by the expression of CD69, is enriched in several markers associated with a higher susceptibility to HIV infection (especially the fraction that also expresses CD32), indicating that it could be a preferential target of the virus. Ex vivo infection of the tissue showed that TRM cells harboured higher levels of productive infection (measured in terms of p24 antigen) and viral DNA than the CD69- fraction. Indeed, CD32-expressing TRM displayed even higher DNA levels. CD4+ TRM cells were diminished in cervical tissue from HIV+ patients under antiretroviral treatment in comparison to healthy donors. This tissue exhibited 4- to 200-fold more viral DNA compared to contemporary blood, confirming that it represents an important HIV reservoir. Specifically, TRM cells accounted for more than 93% of the viral DNA and moreover, in some cases we were able to detect intact genomes. Finally, we were also able to detect viral ARN in cervical tissue from viremic and aviremic HIV+ patients, which occasionally was located in CD69-enriched regions or in the epithelium (corresponding to TRM phenotypes). In conclusion, we showed that TRM cells represent an important HIV reservoir in cervicovaginal tissue, so they should be taken into account when designing strategies to eliminate HIV reservoirs as they are widely distributed through different tissues.

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11

Vasilikou, Foteini. "Modeling CO2 Sequestration and Enhanced Gas Recovery in Complex Unconventional Reservoirs". Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/64320.

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Geologic sequestration of CO2 into unmineable coal seams is proposed as a way to mitigate the greenhouse gas effect and potentially contribute to economic prosperity through enhanced methane recovery. In 2009, the Virginia Center for Coal and Energy Research (VCCER) injected 907 tonnes of CO2 into one vertical coalbed methane well for one month in Russell County, Virginia (VA). The main objective of the test was to assess storage potential of coal seams and to investigate the potential of enhanced gas recovery. In 2014, a larger scale test is planned where 20,000 tonnes of CO2 will be injected into three vertical coalbed methane wells over a period of a year in Buchanan County, VA. During primary coalbed methane production and enhanced production through CO2 injection, a series of complex physical and mechanical phenomena occur. The ability to represent the behavior of a coalbed reservoir as accurately as possible via computer simulations yields insight into the processes taking place and is an indispensable tool for the decision process of future operations. More specifically, the economic viability of projects can be assessed by predicting production: well performance can be maximized, drilling patterns can be optimized and, most importantly, associated risks with operations can be accounted for and possibly avoided. However, developing representative computer models and successfully simulating reservoir production and injection regimes is challenging. A large number of input parameters are required, many of which are uncertain even if they are determined experimentally or via in-situ measurements. Such parameters include, but are not limited to, seam geometry, formation properties, production constraints, etc. Modeling of production and injection in multi-seam formations for hydraulically fractured wells is a recent development in coalbed methane/enhanced coalbed methane (CBM/ECBM) reservoir modeling, where models become even more complex and demanding. In such cases model simulation times become important. The development of accurate simulation models that correctly account for the behavior of coalbeds in primary and enhanced production is a process that requires attention to detail, data validation, and model verification. A number of simplifying assumptions are necessary to run these models, where the user should be able to balance accuracy with computational time. In this thesis, pre- and post-injection simulations for the site in Russell County, VA, and preliminary reservoir simulations for the Buchanan County, VA, site are performed. The concepts of multi-well, multi-seam, explicitly modeled hydraulic fractures and skin factors are incorporated with field results to provide accurate modeling predictions.
Ph. D.

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12

LIMA, BIANCA FERNANDES. "NATURALLY FRACTURED RESERVOIRS SIMULATION". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2013. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=34826@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
A presença de fraturas naturais em reservatórios de petróleo pode gerar grandes impactos no deslocamento de fluidos em seu interior. Os maiores problemas estão na irregularidade da área varrida pelo fluido injetado, por exemplo, a água, e a antecipação dos breakthroughs, ou seja, a chegada precoce da água aos poços produtores. De modo a analisar o efeito promovido pela presença de fraturas no meio, foram simulados os dois modelos de simulação de fluxo em reservatórios fraturados: o modelo de dupla-porosidade (DP) e o modelo de dupla-porosidade e dupla-permeabilidade (DPDK), bem como outros dois modelos derivados do modelo DP, o modelo de Subdomínios (SD) e o modelo MINC (Multiple Interacting Continua). Também foram realizadas análises paramétricas para compreender o impacto de propriedades, como as permeabilidades tanto da matriz quanto da fratura e o espaçamento das fraturas, no comportamento do fluxo em reservatórios fraturados. A presença de corredores de fraturas (fracture swarms) foi, igualmente, avaliada, assim como seu efeito associado à presença de camadas de altíssima permeabilidade (super-K). Por fim, foi simulado um modelo mais complexo, denominado GTEP, o qual foi construído a partir de uma seção aplicada à simulação de um reservatório carbonático gigante do Oriente Médio, com o intuito de exemplificar a irregularidade da área varrida em reservatórios naturalmente fraturados.
The presence of natural fractures in oil reservoirs can generate major impacts on the fluid displacement inside them. The greatest problems are irregularity in the area swept by the injected fluid, e.g. water, and breakthroughs anticipation, or early arrival of water to the producing wells. In order to analyze the effect of the presence of fractures in the medium, two flow models of fractured reservoirs were constructed: the dual-porosity model (DP) and the dual-porosity and dual permeability model (DPDK), as well as two other models derived from the DP model, Subdomains model (SD) and MINC model (Multiple Interacting Continua). Parametric analyzes were also conducted to comprehend the impact of properties, such as the matrix permeability, the fracture permeability and the fracture spacing, on the flow behavior in fractured reservoirs. The presence of fracture corridors (fracture swarms) was also evaluated in three models, as well as its effect associated with the presence of layers of high permeability, denoted super-K. Finally, a more complex model, called GTEP Field, was simulated, which was constructed from a section applied to the simulation of a giant carbonate reservoir in the Middle East, in order to illustrate the irregularity of the swept area in natural fractured reservoirs.

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13

Sagar, Rajiv K. "Reservoir description by integration of well test data and spatial statistics /". Access abstract and link to full text, 1993. http://0-wwwlib.umi.com.library.utulsa.edu/dissertations/fullcit/9416603.

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14

Ahmed, Elfeel Mohamed. "Improved upscaling and reservoir simulation of enhanced oil recovery processes in naturally fractured reservoirs". Thesis, Heriot-Watt University, 2014. http://hdl.handle.net/10399/2755.

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Naturally fractured reservoirs (NFR) contain a significant amount of remaining petroleum reserves and are now considered for Enhanced Oil Recovery (EOR) schemes that involve three-phase flow such as water-alternating-gas (WAG) injection. Accurate numerical simulation of flow in NFR is essential for sound reservoir management decisions to maximise oil recovery and minimise the cost of field development. In this thesis, two important issues related to flow simulation in NFR are investigated. First, a step-wise upscaling approach is developed to evaluate the accuracy of dual porosity models in estimating matrix-fracture transfer duringWAG injection. It was found that the classical dual porosity models generally overestimate recovery from matrix blocks. Hence, a double block model was developed and extended to a multi-rate dual porosity (MRDP). The multi-rate double block model showed significant improvements in matching detailed fine grid simulations of three-phase matrix-fracture transfer. Second, the accuracy of upscaling discrete fracture networks (DFN) is assessed and its impact on history matching was investigated on a real fractured reservoir. A new method to upscale the shape factors needed for MRDP models from DFN is presented. This method is a notable step towards more accurate but still efficient reservoir simulation in NFR.

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15

Dominick, Nehemiah Eliezer. "Reservoir heterogeneity of the sandstone reservoirs within the Pletmos basin, block11a, offshore South Africa". Thesis, University of the Western Cape, 2014. http://hdl.handle.net/11394/3901.

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>Magister Scientiae - MSc
This study is aimed at illustrating the reservoir heterogeneity in the BCII - BCI interval of the Ga-field, offshore South Africa. This was achieved by generating a conceptual static model as a predictive tool for the BCII - BCI interval. The reservoir zones between BCII - BCI were sub divided into two major zones, viz: zone A and zone B. Petrophysical analysis was conducted on the three wells Ga-A3, Ga-Q1 and Ga-Q2. The application of the sequential gaussian algorithm ensured that all of the available data was honoured to the highest extent in generating the realisations to display the heterogeneity of the BCII – BCI sandstone reservoir. Sampling values from the well logs were extrapolated into the 3D grid. Each reservoir contained a percentage of shale or clay of about 45% -50%. Small scaled reservoir heterogeneity has been construed to the influence of the sedimentary structures. Large scaled reservoir heterogeneity has been identified, due to the lateral extent of the claystones which is widely distributed throughout the study area

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16

Tran, Nam Hong Petroleum Engineering Faculty of Engineering UNSW. "Characterisation and modelling of naturally fractured reservoirs". Awarded by:University of New South Wales. Petroleum Engineering, 2004. http://handle.unsw.edu.au/1959.4/20559.

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Naturally fractured reservoirs are generally extremely complex. The aim of characterisation and modelling of such reservoirs is to construct numerical models of rock and fractures, preparing input data for reliable stimulation and fluid flow simulation analyses. This requires the knowledge of different fracture heterogeneities and their correlations at well locations and inter-well regions. This study addresses the issues of how to integrate different information from various field data sources and construct comprehensive discrete fracture networks for naturally fractured reservoir. The methodology combines several mathematical and artificial intelligent techniques, which include statistics, geostatistics, fuzzy neural network, stochastic simulation and simulated annealing global optimisation. The study has contributed to knowledge in characterisation and modelling of naturally fractured reservoirs in several ways. It has developed: .An effective and data-dependant fracture characterisation procedure. It examines all the conventional reservoir data sources and their roles towards characterisation of different fracture properties. The procedure has the advantage of being both comprehensive and flexible. It is able to integrate all multi-scaled and diverse fracture information from the different data sources. .An improved hybrid stochastic generation algorithm for modelling discrete fracture networks. The stochastic simulation is able to utilise both discrete and continuum fracture information. It could simulate not only complicated distributions for fracture properties (e.g. multimodal circular statistics and non-parametric distributions) but also their correlations. In addition, with the incorporation of artificial fuzzy neural simulation, discrete multifractal geometry of fracture size and fracture density distribution map could be evaluated and modelled. Compared to most of the previous fracture modelling approach, this model is more flexible and comprehensive. .An improved conditional global optimisation model for modelling discrete fracture networks. The hybrid model takes full advantages of the advanced fracture characterisation using geostatistical and fuzzy neural analyses. Discrete fractures are treated individually and yet continuum information could be modelled. Compared to the stochastic simulation approach, this model produces more representative fracture networks. Compared to the conventional optimisation programs, this model is more versatile and contains superior objective function.

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17

Sawadogo, Ousmane. "Coupled fully three-dimensional mathematical modelling of sediment deposition and erosion in reservoirs". Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96707.

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Thesis (PhD)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: The investigation of reservoir sedimentation has become an important and valuable research topic in engineering practice. Sediment deposition in reservoirs can affect ood levels, drainage for agriculture land, pumpstation and hydropower operation and navigation. An extensive review of the technical literature pertaining to suspended sediment transports as well as deposited sediment ushing from reservoirs has shown that most studies on sediment are still based on empirical formulas and experimental work, despite the availability of sophisticated computers. This is because sediment transport and particularly sediment deposition and erosion are complex processes, that involve the interaction of many physical factors which are not easily modelled numerically. In addition, most of the existing three-dimensional numerical models are not coupled hydrodynamic and sediment transport models. They first simulate the velocity field and water depth and then the concentration and bed change are calculated. Furthermore, they are not fully three-dimensional models for using layer-averaged approaches in conjunction with Saint-Venant equations. The key objective of the present research was to develop a coupled fully three-dimensional (3D) numerical model based on Navier-Stokes equations which includes both the sediment transport component and hydrodynamic parameters. In this regard, a physical model was set up in a laboratory ume in order to investigate the bottom outlet sediment ushing under pressure in a controlled environment. The proposed coupled fully 3D numerical model was used to simulate the experimental tests. Results from these simulations were in good agreement with the measurements. The geometric features of the scour hole (temporal and spatial hole development) upstream of the bottom outlet were reasonably well predicted compared to the experimental data. Furthermore, the velocity field upstream of the bottom outlet was in good agreement with measurements. The proposed numerical model can be considered reliable provided that the model is correctly set up to reflect the condition of a particular case study. Finally, the coupled fully 3D numerical model for turbulent suspended sediment transport in reservoirs was validated against a range of typical reservoir sediment transport and deposition laboratory flume cases. The proposed suspended sediment transport model successfully predicted both sediment deposition and entrainment processes and therefore, it can be used for turbulent suspended sediment transport assessments in reservoirs.
AFRIKAANSE OPSOMMING: Die ondersoek van damtoeslikking het 'n belangrike navorsing onderwerp in ingenieurswese praktyk geword. Sedimentdeponering in damme kan vloed vlakke, dreinering van landbo grond sowel as pompstasie en hidrokrag werking en navigasie benvloed. 'n Omvattende ontleding van die tegniese literatuur met betrekking tot gesuspendeerde sedimentvervoer asook die spoel van gedeponeerde sediment uit reservoirs het getoon dat die meeste studies oor sediment steeds op empiriese formules en eksperimentele werk gebaseer is, ten spyte van die beskikbaarheid van gesofistikeerde rekenaars. Dit is omdat sedimentvervoer en veral sedimentafsetting en -erosie komplekse prosesse is, wat die interaksie van baie fisiese faktore behels en nie moeiteloos numeries gemodelleer kan word nie. Daarbenewens, in die meeste van die bestaande drie -dimensionele numeriese modelle is die hidrodinamika en sedimentvervoer modelle nie gekoppel nie. Die numeriese modelle simuleer eerstens die snelheid veld en waterdiepte en dan word die sedimentkonsentrasie en bedverandering bereken. Verder is die bestaande modelle nie ten volle driedimensioneel nie, en gebruik laag-gemiddelde benadering in samewerking met Saint- Venant vergelykings. Die hoofdoelwit van die huidige navorsing was om 'n gekoppelde volle drie -dimensionele (3D) numeriese model gebaseer op Navier -Stokes-vergelykings wat beide die sediment vervoer komponent en hidrodinamiese parameters insluit, te ontwikkel. In hierdie verband is 'n fisiese model opgestel in 'n laboratorium kanaal om die bodem uitlaat spoel van sediment onder druk in 'n beheerde omgewing te ondersoek. Die voorgestelde gekoppelde 3D numeriese model is gebruik om die eksperimentele toetse na te boots. Resultate van hierdie simulasies het goed ooreengestem met die metings. Die geometriese eienskappe van die erosie gat (tyd en ruimtelike gatontwikkeling) stroomop van die bodemuitlaat was redelik goed voorspel vergeleke met die eksperimentele data. Verder is die snelheid veld stroomop van die bodem uitlaat ook goed voorspel. Die voorgestelde numeriese model kan beskou word as betroubaar met die wete dat die model korrek opgestel is om die toestand van 'n bepaalde gevallestudie te weerspiel. Ten slotte, is n gekoppelde 3D numeriese model vir turbulente gesuspendeerde sediment vervoer in reservoirs ontwikkel en getoets teen 'n reeks laboratorium kanaal eksperimente. Die voorgestelde gesuspendeerde sediment vervoer model voorspel suksesvol beide die sediment afsetting- en erosieprosesse en daarom kan dit gebruik word vir die simulasie van turbulente gesuspendeerde sediment vervoer in damme.

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18

Monn, Will D. "A multidisciplinary approach to reservoir characterization of the coastal Entrada erg-margin gas play, Utah". Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1211.pdf.

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19

Srinivasan, Balaji S. "The impact of reservoir properties on mixing of inert cushion and natural gas in storage reservoirs". Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4653.

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Thesis (M.S.)--West Virginia University, 2006.
Title from document title page. Document formatted into pages; contains vii, 88 p. : ill. (some col.), map (part col.). Includes abstract. Includes bibliographical references (p. 47-49).

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20

Malik, Kazim A. "An intelligent portfolio management approach to gas storage field deliverability maintenance and enhancement". Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4833.

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Thesis (M.S.)--West Virginia University, 2006.
Title from document title page. Document formatted into pages; contains vii, 105 p. : ill. (some col.) ; map (part col.). Includes abstract. Includes bibliographical references (p. 58-59).

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21

Belyadi, Abbas. "Analysis of single-point test to determine skin factor". Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4881.

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Thesis (M.S.)--West Virginia University, 2006.
Title from document title page. Document formatted into pages; contains ix, 52 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 25-28).

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22

Belyadi, Fatemeh. "Determining low permeability formation properties from absolute open flow potential". Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4879.

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Thesis (M.S.)--West Virginia University, 2006.
Title from document title page. Document formatted into pages; contains viii, 63 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 36-42).

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23

Crawley, P. D. "Optimum operating policies for multiple reservoir systems /". Title page, contents and synopsis only, 1990. http://web4.library.adelaide.edu.au/theses/09EN/09enc911.pdf.

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24

Chang, Yan. "Impacts of Climate Changeson Reservoirs in Northern Sweden : case study of Akkajaure reservoir by modelling". Thesis, Linköpings universitet, Tema vatten i natur och samhälle, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-68419.

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Since the middle of the 20th century, the average temperature of the atmosphere near Earthsurface has increased. The global warming causes many effects in hydrological systems, suchas changes in thermal structure, water quality, aquatic ecosystems, etc. This thesis studies theimpact of climate change on Akkajaure reservoir, the second largest regulated reservoir inSweden, by simulating a predicted temperature rise based on the climate and hydrologicalconditions of Akkajaure in 1998-2002. The congeal duration, ice thickness and the turbulentkinetic energy (TKE) in the lake were calculated by the catchment hydrological model and thelake model. The movement of phytoplankton and their mean net production (MeanNP) rateare simulated by the dispersion model and the photosynthesis model. By comparing thesimulation results of past situation and three predicted scenarios, it is obtained that theincreases of temperature shorten the congeal duration, which is a lead factor for shortening thetrough period and amplification of peak value of TKE. The comparison of plankton particlesposition illustrates that the particles stay in a deeper position for a longer time because of thechanges of TKE. Though the plankton stays in euphotic zone longer as the temperatureincreases, the comparison of the mean production rate between the real scenario and thepredicted scenarios concludes that the mean production rate grows as the temperatureincreases because the shortened ice cover period makes the duration of absorbed sunlightincreases in lake. The effects of global warming may influence the distribution of microalgaein on high latitude lakes and reservoirs. The phytoplankton will stay in deeper water layers fora longer time.

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25

Nejedlik, John. "Reservoir characterisation of Golden Beach Group reservoirs along the northern margin of the Gippsland Basin /". Title page, contents and acknowledgments only, 1998. http://web4.library.adelaide.edu.au/theses/09S.B/09s.bn417.pdf.

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26

Alp, Doruk. "Gas Production From Hydrate Reservoirs". Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606241/index.pdf.

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In this study
gas production by depressurization method from a hydrate reservoir containing free gas zone below the hydrate zone is numerically modeled through 3 dimensional, 3 phase, non-isothermal reservoir simulation. The endothermic nature of hydrate decomposition requires modeling to be non-isothermal
hence energy balance equations must be employed in the simulation process. TOUGH-Fx, the successor of the well known multipurpose reservoir simulator TOUGH2 (Pruess [24]) and its very first module TOUGH-Fx/Hydrate, both developed by Moridis et.al [23] at LBNL, are utilized to model production from a theoretical hydrate reservoir, which is first studied by Holder [11] and then by Moridis [22], for comparison purposes. The study involves 2 different reservoir models, one with 30% gas in the hydrate zone (case 1) and other one with 30% water in the hydrate zone (case 2). These models are further investigated for the effect of well-bore heating. The prominent results of the modeling study are: &
#8226
In case 1, second dissociation front develops at the top of hydrate zone and most substantial methane release from the hydrate occurs there. &
#8226
In case 2 (hydrate-water in the hydrate zone), because a second dissociation front at the top of hydrate zone could not fully develop due to high capillary pressure acting on liquid phase, a structure similar to ice lens formation is observed. &
#8226
Initial cumulative replenishment (first 5 years) and the replenishment rate (first 3.5 years) are higher for case 2 because, production pressure drop is felt all over the reservoir due to low compressibility of water and more hydrate is decomposed. Compared to previous works of Holder [11] and Moridis [22], amount of released gas contribution within the first 3 years of production is significantly low which is primarily attributed to the specified high capillary pressure function.

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27

Weiz, Bettina. "Water Reservoirs in South India". Diss., lmu, 2006. http://nbn-resolving.de/urn:nbn:de:bvb:19-80428.

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28

Amos, Gregory C. A. "Environmental reservoirs of antibiotic resistance". Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/58024/.

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Emerging antibiotic resistance mechanisms threatens the foundation of modern medicine. Growing evidence suggests anthropogenic inputs such as agriculture could form reservoirs of resistant bacteria which could directly or indirectly transfer to humans. Waste Water treatment plants (WWTPs) are an input which contains waste from several sources including that of human, animal and industry, providing a hot-spot for horizontal gene transfer to occur between bacteria from many origins. In this project we evaluated the role of WWTPs in creating environmental reservoirs of antibiotic resistance. An initial study investigated the impacts of WWTP effluent on the antibiotic resistant bacterial load in downstream rivers, particularly focusing on the class 1 integron as a marker for resistance. WWTP effluent was responsible for significantly higher levels of resistant bacteria in downstream river sediments compared to upstream, a result of the introduction and/ or selection for a diverse range of class 1 integrons. A second study investigated the effects of effluent on the clinically important antibiotic resistance gene blaCTX-M-15. Numerous examples of blaCTX-M-15 carried on new genetic contexts in association with new pathogenicity determinants were recovered, as was evidence for transfer of blaCTX-M-15 between diverse bacteria. The prevalence of blaCTX-M-15 as well as the diversity of its carriage were both increased greatly by WWTP effluent. The final study was on the Thames River basin in the UK, where we developed a model with the ability to predict antibiotic resistance load and exposure. This work suggests that WWTP effluent contributes to environmental reservoirs of resistant bacteria which could be of clinical importance. There is a danger that continued expansion of environmental reservoirs of antibiotic resistance will lead to increased therapeutic failure in the clinic and ultimately the end of the antibiotic era.

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29

Pongthunya, Potcharaporn. "Upscaling in polymer flooded reservoirs". Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/10733.

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Polymer flooding is one of the most successful techniques in Enhanced Oil Recovery. One of the obstacles to implementing the technique is the understanding of fluid flow in porous media at different length scales. Although many of the microscopic processes, in microns, in the reservoir are well understood, simulating fluid flow in the reservoir at the micron scale is completely impractical. Each project requires numerous simulations to cover a wide range of scenarios. To shorten the run time, the blocks in the reservoir model are generally coarsened from the core scale in centimetres to larger scales in metres or kilometres. This helps reduce the number of gridblocks for simulations from around 10 [to the power of 13] cells to at most 10 [to the power of 5] or 10 [to the power of 6] cells. Reservoir rock properties such as porosity and permeability are averaged from the small scales using various methods, known as upscaling. In practice, upscaled permeabilities are calculated using the techniques derived for water flooding. The same upscaled model is then used for studying a variety of fluid displacements and injection schemes. The impact of using upscaled models for simulations of non-Newtonian flow displacement, as in polymer flooding, is not well understood. This study investigates the effects of upscaling errors on production forecasts in non-Newtonian flow and recommends an approach to be applied in upscaled models for better production predictions. Two permeability distributions: a two-dimensional randomly generated lognormal permeability field and a fluvial system are investigated. These models are flooded by fluids governed by a power law rheological model that represents Newtonian, shear-thinning, and shear-thickening flow behaviour. The errors in production predictions and pressure profiles are analysed. We find considerably high errors in predictions when the properties of fluid displacement are changed. These significant errors can harm economic evaluations of projects. In addition, we prove that upscaled models manipulated for a perfect match to a fine scale model under water flooding should not be used for polymer flooded modelling. Furthermore, we discover that in addition to upscaling permeability, effective viscosity should be parameterised when injecting with non-Newtonian fluid. We recommend adjusting the power law exponent of the displacing fluid model for better results. We verify the new approach and conclude that a good agreement in predictions between fine and coarse scale models can be achieved by a single phase upscaling with an adjustment of the exponent in the power law rheological model.

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30

Liu, Yan. "Seismic characterisation of carbonate reservoirs". Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/61386.

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The characterisation of karstified carbonate reservoirs is a challenging task due to: (a) Complex fault systems; (b) Amplitude anomalies (karst features) and (c) Strong heterogeneity. To deal with these difficulties, I have developed three techniques targeting at the karstified carbonate reservoirs from Tarim basin: (a) Fracture detection based on seismic coherence can be affected by dipping reflectors and noise. A robust algorithm is developed, where dip is used to eliminate the impact of dipping reflectors and a pseudo-multichannel appraoch is employed to improve robustness (good performance for S/N ratio greater than 2). (b) In the presence of karst fractures (strong amplitudes), seismic facies classification based on seismic trace shape may not analyse the weak amplitudes in the background strata. To combat this difficulty, I use the amplitude variation pattern (normalised seismic segment) as the input to avoid the potential impact of strong amplitudes and help to analyse the weak amplitude. (c) It is difficult to honour the lateral variation due to the strong heterogeneity in the karstified carbonate reservoirs. I adopt a Fourier integral method (FIM) in the stochastic inversion where the lateral variation is honoured based on the seismic trace similarity. After I have successfully developed and verified these methods listed above, I apply them together to characterise another carbonate reservoir. This case study has less number of existing wells (five). Explicitly, I apply in order: seismic coherence, seismic facies classification, FIM-based stochastic inversion, and the lithofacies classification. I use seismic coherence as prior knowledge in the classification, enabling to honour the localised dolomitization along faults and fractures. Finally, I propose three well locations for potential oil/gas production based on the classified facies and lithofacies probability (over 40%). My study shows that the algorithms can be employed for reservoir characterisation and provide improved results comparing with conventional methods.

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31

Cherupally, Sai Kiran. "Hierarchical Random Boolean Network Reservoirs". PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4345.

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Reservoir Computing (RC) is an emerging Machine Learning (ML) paradigm. RC systems contain randomly assembled computing devices and can be trained to solve complex temporal tasks. These systems are computationally cheaper to train than other ML paradigms such as recurrent neural networks, and they can also be trained to solve multiple tasks simultaneously. Further, hierarchical RC systems with fixed topologies, were shown to outperform monolithic RC systems by up to 40% when solving temporal tasks. Although the performance of monolithic RC networks was shown to improve with increasing network size, building large monolithic networks may be challenging, for example because of signal attenuation. In this research, larger hierarchical RC systems were built using a network generation algorithm. The benefits of these systems are presented by evaluating their accuracy in solving three temporal problems: pattern detection, food foraging, and memory recall. This work also demonstrates the functionality of random Boolean networks being used as reservoirs. Networks with up to 5,000 neurons were used to 200 sequences from memory and to identify X or O patterns temporally. Also, a Genetic Algorithm (GA) was used to train different types of hierarchical RC networks, to find optimal solutions for food-foraging tasks. This research shows that about 80% of the possible different hierarchical configurations of RC systems can outperform monolithic RC systems by up to 60% while solving complex temporal tasks. These results suggest that hierarchical random Boolean network RC systems can be used to solve temporal tasks, instead of building large monolithic RC systems.

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32

Grassia, Gino Sebastian y n/a. "The isolation, growth and survival of thermophilic bacteria from high temperature petroleum reservoirs". University of Canberra. Applied Science, 1995. http://erl.canberra.edu.au./public/adt-AUC20060712.131412.

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The microbial ecology of 45 high temperature (> 50 ° C) petroleum reservoirs was investigated by isolating and characterizing bacteria that were present in their produced fluids. Initial work was aimed at selecting a suitable high temperature petroleum reservoir for the study of natural microbial populations. Experimental work then focussed on establishing the physico-chemical conditions that prevail in the selected reservoir and on developing media and enrichment conditions for the isolation of microorganisms indigenous to the reservoir. The ability of reservoir bacteria to grow and survive under the physical and chemical conditions found in the selected reservoir was used to assess the likelihood of an indigenous origin for these bacteria. The petroleum reservoir selected for study was the Alton petroleum reservoir (SW Queensland, Australia). It was established that most of the physico-chemical conditions in the Alton reservoir had remained unchanged since oil recovery began. The stability of redox conditions (90 mV) in the reservoir over its operating life was identified as an important factor in the coexistence of strict aerobic and strict anaerobic bacterial populations within the reservoir. An important change that has occurred in the Alton reservoir over its operating life because of oil recovery was an increase in water pH from 6.41 to 8.42 as a result of carbon dioxide loss (1.36 atm to 0.0134 atm) from the reservoir. Development of novel enrichment procedures that simulated Alton reservoir conditions led to the isolation of previously unreported aerobic and anaerobic populations of thermophilic bacteria. The aerobic bacteria isolated were identified as either endosporeforming heterotrophic bacteria from the genus Bacillus or nonspore-forming heterotrophic bacteria resembling members of the genus Thermoleophilum. All aerobes grew on carbon sources such as acetate and n-heptadecane that are normal constituents of the reservoir. The anaerobic bacteria isolated were characterized as sheathed fermentative bacteria from the order Thermotogales or non-sheathed fermentative bacteria. In parallel studies, the natural microbial populations in other reservoirs were investigated and I concluded that fermentative microorganisms were common inhabitants of high temperature petroleum reservoirs. The isolation of fermentative bacteria from these high temperature petroleum reservoirs established that fermentative bacteria are a fourth major microbial group, together with hydrocarbon-oxidizers, sulphate-reducers and methanogens, to be reported in petroleum reservoirs. The fermentative bacteria use organic nutrients and carbohydrates, but not contemporary crude oil as the principal nutrient source within reservoir waters. The thermophilic bacteria isolated from Alton petroleum reservoir demonstrated growth characteristics such as temperature (optima 50-70 ° C and range 37-85 ° C), pH (optima 6.0-9.0 and range 5.0-9.0 and salinity (optima 0-15 g per litre and range 0-30 g per litre), that were consistent with conditions encountered in the Alton reservoir (temperature 75 � C, pH 8.5 and TDS 2.7 g per litre). The isolated bacteria also demonstrated a number of characteristics that might enable them to survive adverse conditions that could be encountered in a petroleum reservoir environment. The characteristics that contribute to aerobic bacteria surviving in and overcoming periods of oxygen limitation include well-documented processes such as sporulation, by Bacillus spp., and microaerophily. The characteristics that contribute to fermentative bacteria surviving were: (1) a natural tolerance to reservoir physico-chemical fluctuations, (2) an ability to remain viable when metabolic activity was suppressed to very low rates by the growth-limiting conditions imposed, and (3) possible formation of viable ultramicrobacteria (UMB). Formation of UMB (bacteria smaller than 0.3 |im) by thermophilic bacteria has not been reported previously. The recovery of thermophilic UMB by filtration from the Alton reservoir water indicates that these bacteria occur in natural habitats. This study found the formation of thermophilic UMB and their survival characteristics differed considerably from that reported for the mesophilic, marine bacterium Vibrio sp. DWI. Unlike mesophilic marine bacteria, thermophilic bacteria did not always respond to nutrient deprivation by forming UMB and that these UMB did not show any increased ability to survive in the face of adverse conditions. Although the formation of UMB as part of routine cell growth and division was not demonstrated directly in this study, circumstantial evidence suggests that they form part of a natural life cycle. The exact conditions that result in UMB formation and their role in survival remain unresolved. The capacity of nonspore-forming indigenous populations from Alton to survive sudden shifts in environmental conditions that might result from common oilfield operations was poor. Such operations were demonstrated to be inhibitory or lethal to Alton reservoir bacteria. It also was concluded that such oilfield operations suppress indigenous microbiota. However, the impacts of most oilfield operations within a reservoir are likely to be confined to the immediate area surrounding injection and producing wells. Minimizing the localized effects of oilfield practices on indigenous reservoir populations will lead to the better management of undesirable microbial activity in reservoirs such as H2S formation (souring) and facilitate development of better microbially mediated oil recovery process. This study showed that selected reservoir isolates possess characteristics which are suitable for in situ biotechnological applications such as microbially enhanced oil recovery (MEOR). Characteristics favourable for enhanced oil recovery include a capability for UMB formation, which would enable better dispersion, and resistance to high concentrations of reservoir components such as calcium, magnesium, strontium, heavy metals and hydrocarbons.

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33

Kim, Young-Oh. "The value of monthly and seasonal forecasts in Bayesian stochastic dynamic programming /". Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/10142.

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34

Xie, Ming 1973. "Prediction of daily net inflows for management of reservoir systems". Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33043.

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Operational planning of water resource systems like reservoirs and hydropower plants calls for real-time forecasting of reservoir inflow. Reservoir daily inflow forecasts provide a warning of impending floods or drought conditions and help to optimize operating policies for reservoir management based on a fine time scale. The aim of this study was to determine the best model for daily reservoir inflow prediction through linear regression, exponential smoothing and artificial neural network (ANN) techniques. The Hedi reservoir, the third largest reservoir in south China with a 1.144 x 109 m 3, was selected as the study site. The performance of these forecasting models, in terms of forecasting accuracy, efficiency of model development and adaptability for future prediction, were compared to one another. All models performed well during the dry season (inflow with low variability), while the non-linear ANNs were superior to other models in frontal rainy season and typhoon season (inflow with high variability). The performance of ANN models were hardly affected by the high degree of uncertainty and variability inherent to the rainy season. Stepwise selection was very helpful in identifying significant variables for regression models and ANNs. This procedure reduced ANN's size and greatly improved forecasting accuracy for ANN models. The impact of training data series, model architecture and network internal parameters on ANNs performances were also addressed in this study. The overall evaluation indicates that ANNs are an effective and robust tool for input-output mapping under more extreme and variable conditions. ANNs provide an alternative forecasting approach to conventional time series forecasting models for daily reservoir inflow prediction.

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35

Tie, Hongguang. "Oil recovery by spontaneous imbibition and viscous displacement from mixed-wet carbonates". Laramie, Wyo. : University of Wyoming, 2006. http://proquest.umi.com/pqdweb?did=1212796311&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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36

Serrat-Capdevila, Aleix. "An Alternative Approach to the Operation of Multinational Reservoir Systems: Application to the Amistad & Falcon Reservoir System (Lower Rio Grande/Rio Bravo)". Thesis, The University of Arizona, 2004. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0249_sip1_w.pdf&type=application/pdf.

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37

Lohse, Walter H. "Separation of algae from growth media by CGA flotation". Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/50061.

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The efficiency of colloidal gas aphron (CGA) flotation for separation of algae from growth media was investigated. Anionic, cationic and non-ionic surfactants were used to generate CGAs. Preliminary batch studies showed that two CGA flotation procedures could be successfully used for algae flotation. CGA flotation without pretreatment of algae was only successful using cationic surfactants. All three types of surfactants yielded promising results while combining CGA flotation with alum flocculation as a pretreatment step. Observed removal efficiencies were above ninety percent for batch applications. “Pure CGA flotation” was studied in countercurrent continuous flow operations. Satisfactory removal of algae could be achieved even at substantially reduced volume ratios of CGAs to algae solution. However, TOC concentrations increased with higher volume ratios and higher flowrates due to carryover of CGA bubbles and diffusion of surfactant molecules into the bulk solution. The cationic surfactant Cetyl Pyrimidinium Chloride, present at very low concentrations in the raffinate and the froth algae mixture, exhibited biostatic and biocidal properties in the microbial activity test.
Master of Science
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38

Knudsen, Brage Rugstad. "Production Optimization in Shale Gas Reservoirs". Thesis, Norwegian University of Science and Technology, Department of Engineering Cybernetics, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-10035.

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Natural gas from organic rich shales has become an important part of the supply of natural gas in the United States. Modern drilling and stimulation techniques have increased the potential and profitability of shale gas reserves that earlier were regarded as unprofitable resources of natural gas. The most prominent property of shale gas reservoirs is the low permeability. This is also the reason why recovery from shale gas wells is challenging and clarifies the need for stimulation with hydraulic fracturing. Shale gas wells typically exhibit a high initial peak in the production rate with a successive rapid decline followed by low production rates. Liquid accumulation is common in shale wells and is detrimental on the production rates. Shut-ins of shale gas wells is used as a means to prevent liquid loading and boost the production. This strategy is used in a model-based production optimization of one and multiple shale gas well with the objective of maximizing the production and long-term recovery. The optimization problem is formulated using a simultaneous implementation of the reservoir model and the optimization problem, with binary variables to model on/off valves and an imposed minimal production rate to prevent liquid loading. A reformulation of the nonlinear well model is applied to transform the problem from a mixed integer nonlinear program to a mixed integer linear program. Four numerical examples are presented to review the potential of using model-based optimization on shale gas wells. The use of shut-ins with variable duration is observed to result in minimal loss of cumulative production on the long term recovery. For short term production planning, a set of optimal production settings are solved for multiple wells with global constraints on the production rate and on the switching capacity. The reformulation to a mixed integer linear program is shown to be effective on the formulated optimization problems and allows for assessment of the error bounds of the solution.

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39

Yacob, Shahrakbah y n/a. "Metal-reducing microorganisms in petroleum reservoirs". University of Canberra. Resource & Environmental Science, 2000. http://erl.canberra.edu.au./public/adt-AUC20061112.102729.

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Metal-reducing microorganisms reduce a variety of metals in metabolic processes coupled to the oxidation of organic compounds. These bacteria play an important role in the biogeochemical cycling of metals and organic matter in anaerobic aquatic and sediment ecosystems. It has been proposed recently that metal-reducing microorganisms also are active in deep subsurface environments such as petroleum reservoirs. Only two metal-reducing bacteria have been isolated from petroleum reservoir fluids, Shewanella putrefaciens and Deferribacter thermophilus. This project studied the occurrence and distribution of metal-reducing microorganisms in petroleum reservoirs. The research focused on the isolation, characterisation and identification of anaerobic bacteria from petroleum reservoirs that were capable of reducing metals and the potential roles of these isolates in the microbial ecology and biogeochemical cycling of petroleum reservoirs. Petroleum reservoirs were selected for this study on the basis of physio-chemical conditions such as temperature, salinity, pH and the presence of organic and inorganic compounds, that were likely to provide a suitable environment for anaerobic bacteria capable of reducing metals. Factors such as the stratigraphic features of the sedimentary basin, age of reservoir and past oil field practices also were considered in choosing the reservoir for study. Seven petroleum reservoirs in the USA and Azerbaijan were chosen for extensive investigations. The physico-chemical conditions in these reservoirs varied substantially. A systematic study of the production water from these petroleum reservoirs revealed a consistent presence of iron- and manganese-reducing microorganisms. It was found that salinity and temperature play a significant and defining role in the occurrence and distribution of these metal-reducing microorganisms. Biotic metal reduction was detected from production waters from all but one of the oil wells sampled. It was significant that the water from this well (Neftcala #1074) was the most saline (78 g/l NaCI). Metal-reducing activity was detected at temperatures up to 70°C. Two pure cultures, strains RED1 for Redwash petroleum reservoir (USA) and NEF1 from the Neftcala petroleum reservoir (Azerbaijan) were isolated and characterized. The strains had diverse physiological and metabolic properties including the ability to oxidize a wide range of carbon compounds and reduce a variety of metals. Their temperature, salinity and pH optima varied markedly. Phylogenetic analyses of the 16S rRNA of strain RED1 showed that the strain represented a new species of a new genus in the domain Bacteria. The bacterium most closely related to strain RED1 is the fermentative Fe(III)-reducer, Pelobacter acetylenicus (similarity value, 92.8%). Strain NEF1 possesses a unique combination of phenotypic traits and a low mol % G+C. From preliminary analyses and comparative biochemistry, NEF1 appears to be a novel metal-reducing bacterium of the Flexistipes group. The bacteria isolated in this study were able to grow at temperatures and salinities consistent with the reservoir from which they were isolated. This indicated that petroleum reservoirs are a new source of physiologically diverse, novel, metal-reducing microorganisms. The bacteria isolated also demonstrated a number of characteristics that would enable them to survive and persist in extreme subsurface conditions and develop a selective ecological advantage in petroleum reservoir environments. Significantly, the metal-reducing bacteria isolated were able to utilize an array of metabolic products produced by bacteria indigenous to petroleum reservoirs. This has resulted in a new proposed model for the ecological succession of bacteria in petroleum reservoirs.

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40

Rahman, N. M. Anisur. "Transient pressure analysis in compartmentalized reservoirs". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0001/NQ29096.pdf.

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41

Feitosa, Gilvan Soares. "Well test analysis for heterogenous reservoirs /". Access abstract and link to full text, 1993. http://0-wwwlib.umi.com.library.utulsa.edu/dissertations/fullcit/9330022.

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42

Angelakis, Dimitrios. "Atom-photon interactions in structured reservoirs". Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250165.

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43

Ouzzane, Djamel Eddine. "Phase behaviour in gas condensate reservoirs". Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417922.

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44

Kome, Melvin Njumbe. "Well testing in gas hydrate reservoirs". Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2015. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-160567.

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Reservoir testing and analysis are fundamental tools in understanding reservoir hydraulics and hence forecasting reservoir responses. The quality of the analysis is very dependent on the conceptual model used in investigating the responses under different flowing conditions. The use of reservoir testing in the characterization and derivation of reservoir parameters is widely established, especially in conventional oil and gas reservoirs. However, with depleting conventional reserves, the quest for unconventional reservoirs to secure the increasing demand for energy is increasing; which has triggered intensive research in the fields of reservoir characterization. Gas hydrate reservoirs, being one of the unconventional gas reservoirs with huge energy potential, is still in the juvenile stage with reservoir testing as compared to the other unconventional reservoirs. The endothermic dissociation hydrates to gas and water requires addressing multiphase flow and heat energy balance, which has made efforts to develop reservoir testing models in this field difficult. As of now, analytically quantifying the effect on hydrate dissociation on rate and pressure transient responses are till date a huge challenge. During depressurization, the heat energy stored in the reservoir is used up and due to the endothermic nature of the dissociation; heat flux begins from the confining layers. For Class 3 gas hydrates, just heat conduction would be responsible for the heat influx and further hydrate dissociation; however, the moving boundary problem could also be an issue to address in this reservoir, depending on the equilibrium pressure. To address heat flux problem, a proper definition of the inner boundary condition for temperature propagation using a Clausius-Clapeyron type hydrate equilibrium model is required. In Class 1 and 2, crossflow problems would occur and depending on the layer of production, convective heat influx from the free fluid layer and heat conduction from the cap rock of the hydrate layer would be further issues to address. All these phenomena make the derivation of a suitable reservoir testing model very complex. However, with a strong combination of heat energy and mass balance techniques, a representative diffusivity equation can be derived. Reservoir testing models have been developed and responses investigated for different boundary conditions in normally pressured Class 3 gas hydrates, over-pressured Class 3 gas hydrates (moving boundary problem) and Class 1 and 2 gas hydrates (crossflow problem). The effects of heat flux on the reservoir responses have been addressed in detail.

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45

Sobbi, Farhad Aschar. "Well testing of naturally fractured reservoirs". Thesis, Heriot-Watt University, 1988. http://hdl.handle.net/10399/1481.

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46

CAMIZA, DANILLO DURAN. "SECONDARY RECOVERY IN NATURALLY FRACTURED RESERVOIRS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=26967@1.

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Todos os reservatórios de petróleo apresentam algum grau de fraturamento. Muitas vezes, a presença de fraturas afeta de forma significativa o fluxo dos fluidos nele contidos, seja por incrementarem a permeabilidade do meio, criando caminhos preferenciais de escoamento, seja por imporem algum tipo de barreira ao fluxo. Quando submetidos à injeção de água, reservatórios naturalmente fraturados podem apresentar graves problemas de produção prematura de água e baixíssimas eficiências de varrido. Os estudos realizados neste trabalho procuraram contribuir para o melhor entendimento dos processos de recuperação envolvidos na produção de reservatórios fraturados, bem como o impacto de cada um dos principais parâmetros que condicionam o fluxo no meio poroso fraturado. Foi realizada, ainda, uma análise de possíveis estratégias de drenagem para esse tipo de reservatório. Por fim, foram realizadas simulações para estudar possíveis ganhos da injeção de emulsão de óleo em água, como método de recuperação, em comparação com a injeção de água.
All oil reservoirs have some degree of fracturing. Often, the presence of fractures affects significantly the flow of the fluids contained in the reservoir, increasing the permeability and creating preferential flow paths or by imposing some barrier to the flow. When subjected to waterflooding, naturally fractured reservoirs may have serious problems like early production of water or very low swept efficiencies. The analyses conducted in this study contemplated the understanding of recovery processes involved in the production of fractured reservoirs and the impact of each of the main parameters that influence the flow in fractured porous media. Also, an analysis of possible draining strategies for this type of reservoir was performed. Finally, simulations were performed to study the possible gains of emulsion injection, as a recovery method, compared with water injection.

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47

VILLALOBOS, RAFAEL ANTONIO SANABRIA. "OBJECT-BASED MODELING OF FLUVIAL RESERVOIRS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=27516@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
O problema tratado nesta dissertação consiste em modelar reservatórios fluviais utilizando modelos geoestatísticos baseados em objetos. Este trabalho propõe um modelo baseado em objetos para sistemas fluviais que simula, conforme dados observados, duas das principais faces associadas aos reservatórios fluviais: o canal e o espraiamento de crevasse. O modelo proposto realiza uma simulação com condicionantes baseado na técnica Simulated Annealing.
The problem addressed in this work is to model fluvial reservoirs using geostatistical model based on objects. This work aims to create an object-based model for fluvial systems which simulates, given some observed data, two of the principal facies associated to the fluvial reservoirs: the channel sand and crevasse splay sand. Also, it applies a simulation with constraints based on the Simulated Annealing approach.

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48

DIAS, RODRIGO ARAUJO CARDOSO. "WELLS PRODUCTIVITY IN HIGH HETEROGENEITY RESERVOIRS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2017. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=32970@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
A previsão da produção de poços tem um papel crucial na engenharia de petróleo. Logo, a modelagem do escoamento no reservatório e no poço é fundamental em diversos problemas nessa área. Na maioria esmagadora dos problemas, a equação de Darcy é a escolha para prever o comportamento do fluxo em rochas petrolíferas. O grande sucesso do uso da equação de Darcy, infelizmente, levou sua aplicação para fora do âmbito dos problemas para os quais esta se aplica. A equação clássica de Darcy apresenta limitações quando aplicadas em meios porosos altamente heterogêneos, por exemplo com cavidades conectadas por redes de fraturas, com vugs e cavernas. Ao longo dos anos, outras modelagens foram propostas e derivadas de outros pontos de vista para tratar o escoamento em meios porosos, por exemplo, através do processo de média de volume ou através de teoria de mistura. O presente trabalho utiliza as equações médias em meios porosos. O modelo desenvolvido contabiliza termos adicionais para a equação de quantidade de movimento linear que são relevantes em várias situações práticas, e envolve a solução conjunta das equações de conservação. No modelo desenvolvido neste trabalho, o escoamento no reservatório é resolvido de forma acoplada ao escoamento ao longo do poço, considerando a possibilidade de utilização de diferentes tipos de completação. As previsões dos campos de pressão e velocidade, assim como a produtividade de poços de petróleo utilizando o modelo desenvolvido são comparadas com as previsões do modelo baseado na equação de Darcy. Mostra-se que para determinadas situações, em especial em reservatórios carbonáticos, altamente heterogêneos, grandes diferenças podem ser obtidas. A previsão da produtividade de um poço a partir da equação de Darcy pode ser significativamente super-estimada.
Predicting wellbore production plays a crucial role in petroleum engineering. Therefore, the modeling of the ow in reservoir and in wellbore is fundamental in several problems in this area. In the overwhelming majority problems, Darcy s equation is the choice to predict the behavior of ow in reservoirs. The great success of Darcy s equation, unfortunately, took its application out of the scope of the problems for which it applies. The classic Darcy s equation presents limitations when applied in highly heterogeneous porous media, for example with cavities connected by fracture networks, with vugs and caves. Over the years, other models have been proposed and derived from other points of view to treat ow in porous media, for example through the average volume process or through mixture theory. The present work considers the average volume process in porous media. The developed model includes additional terms for the linear momentum equation that are relevant in several practical situations, and involves the joint solution of conservation equations. In the model developed in this work, the ow in the reservoir is solved coupled to the wellbore ow, considering the possibility of using different completion types. The pressure and velocity fields predictions as well as the productivity of oil wellbores using the developed model are compared with the predictions of the model based on the Darcy s equation. It is shown that for certain situations, especially in highly heterogeneous carbonate reservoirs, large differences can be obtained. The prediction of the productivity of a wellbore from the Darcy s equation can be significantly overestimated.

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49

BELA, RENAN VIEIRA. "MODELING FALLOFF TESTS IN MULTILAYERED RESERVOIRS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=36012@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE EXCELENCIA ACADEMICA
O teste de injetividade é um procedimento que tem por objetivo extrair informações sobre um reservatório de petróleo a partir da injeção de um fluido (usualmente, água) no reservatório. Com base na resposta de pressão medida durante o tempo de teste, pode-se inferir uma série de características acerca do reservatório, tais como permeabilidade equivalente, condição de fronteira do reservatório e volume de óleo recuperável. O teste de injetividade é dividido em dois períodos: um de fluxo, durante o qual ocorre a injeção de água no reservatório; e o segundo de falloff, no qual o poço é fechado e o fluxo ao longo do reservatório cessa. Os modelos analíticos hoje existentes são capazes de descrever bem tanto o período de injeção quanto o de falloff apenas para reservatórios com uma camada. Nos reservatórios com múltiplas camadas, somente o período de injeção tem uma formulação conhecida. Portanto, esse trabalho tem como objetivo propor uma solução analítica para o período de falloff em reservatórios com múltiplas camadas. A precisão da solução proposta foi avaliada a partir da comparação com um simulador numérico de fluxo para uma série de casos. Os resultados mostraram boa concordância entre os dados numéricos e o modelo proposto. Além disso, os dados do falloff obtidos com a solução analítica foram usados para estimar a permeabilidade equivalente do reservatório. Os valores encontrados apresentaram precisão satisfatória para todos os casos.
The injectivity test is a procedure used to collect information over a petroleum reservoir by injecting a fluid (commonly, water) into the reservoir. According to the pressure response measured during the test, several reservoir features might be inferred, such as equivalent permeability, outer boundary condition and recoverable oil volume. Injectivity test consists of two different stages: the flow period and the falloff period. During the former, occurs the water injection into the rock formation. The latter stage is marked by the well shut-in and, hence, a zero-flow pulse propagates along the reservoir. Over the past years, accomplishments have been made regarding the pressure behavior in multilayer reservoirs under single-phase flow and injectivity tests in single-layer reservoirs. However, an analytical solution for pressure behavior in multilayer reservoirs is well known just during the flow period. Therefore, this work attempts to develop an analytical model for the falloff period in multilayer reservoirs. The accuracy of the proposed solution was assessed by comparison with a finite difference flow simulator. Results showed a close agreement between the analytical model and numerical data. Moreover, falloff data obtained by the analytical solution was used to estimate the reservoir equivalent permeability. Calculated values presented a satisfactory accuracy for all cases.

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50

Mtchedlishvili, George. "Inverse modeling of tight gas reservoirs". Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola&quot, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:105-5595821.

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In terms of a considerable increase the quality of characterization of tight-gas reservoirs, the aim of the present thesis was (i) an accurate representation of specific conditions in a reservoir simulation model, induced after the hydraulic fracturing or as a result of the underbalanced drilling procedure and (ii) performing the history match on a basis of real field data to calibrate the generated model by identifying the main model parameters and to investigate the different physical mechanisms, e.g. multiphase flow phenomena, affecting the well production performance. Due to the complexity of hydrocarbon reservoirs and the simplified nature of the numerical model, the study of the inverse problems in the stochastic framework provides capabilities using diagnostic statistics to quantify a quality of calibration and reliability of parameter estimates. As shown in the present thesis the statistical criteria for model selection may help the modelers to determine an appropriate level of parameterization and one would like to have as good an approximation of structure of the system as the information permits.

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