Дисертації з теми "Gas production rate"

Decay and accumulation of blanket peat in the Northern Pennine region of England are considered, both in quantitative and qualitative terms. Productivity on the surface of these peat bogs is not unusually high, suggesting that a low decay rate may be responsible for the accumulation of the peat. Considerable study has formerly been made of the aerobic decay processes, at the expense of the parallel anaerobic processes, which have largely hitherto been considered negligible. Yet a current mathematical model of peat accumulation suggests that it is likely to be the anaerobic decay rate which determines the total depth of peat which may accumulate. Further, such models intimate that a very small absolute change in the anaerobic decay rate will have an unexpectedly large effect on the potential steady state depth of peat. The present study concentrates on obtaining measurements of anaerobic decay rates, and on identifying the possible limiting environmental factors of the decay. The design of a sampler to collect gas samples in situ from blanket peat is described. The components of particular interest in the samples are CH4 and C02. Gas concentrations down eight peat profiles at two sites are monitored over two seasons. Simultaneous surface flux measurements above pool, lawn and hummock microhabitats are also made. Water level, temperature, pH, redox potential, depth of the sulphide zone and total sulphide concentration are recorded on each field visit. The results from the gas sample analyses are discussed in relation to the environmental factors and in relation to our present understanding of peat decay rates and their consequences on peat accumulation. The anaerobic decay rate is calculated, and is confirmed to be several orders of magnitude less than that in the overlying aerobic peat. It is shown that the methane is not fossil, but is continually being produced at all depths. Rates of gas production are calculated. Annual methane and carbon dioxide losses from entire peat bogs are calculated to contribute a significant amount to carbon cycling, on a site-specific and global scale.

The International Energy Agency (IEA) expects total natural gas output in the EU to decrease from 216 billion cubic meters per year (bcm/year) in 2006 to 90 bcm/year in 2030. For the same period, EU demand for natural gas is forecast to increase rapidly. In 2006 demand for natural gas in the EU amounted to 532 bcm/year. By 2030, it is expected to reach 680 bcm/year. As a consequence, the widening gap between EU production and consumption requires a 90% increase of import volumes between 2006 and 2030. The main sources of imported gas for the EU are Russia and Norway. Between them they accounted for 62% of the EU’s gas imports in 2006. The objective of this thesis is to assess the potential future levels of gas supplies to the EU from its two main suppliers, Norway and Russia. Scenarios for future natural gas production potential for Norway and Russia have been modeled utilizing a bottom-up approach, building field-by-field, and individual modeling has been made for giant and semi- giant gas fields. In order to forecast the production profile for an individual giant natural gas field a Giant Gas Field Model (GGF-model) has been developed. The GGF-model has also been applied to production from an aggregate of fields, such as production from small fields and undiscovered resources. Energy security in the EU is heavily dependent on gas supplies from a relatively small number of giant gas fields. In Norway almost all production originates from 18 fields of which 9 can be considered as giant fields. In Russia 36 giant fields account for essentially all gas production. There is limited potential for increased gas exports from Norway to the EU, and all of the scenarios investigated show Norwegian gas production in decline by 2030. Norwegian pipeline gas exports to the EU may even be, by 2030, 20 bcm/year lower than today’s level. The maximum increase in exports of Russian gas supplies to the EU amount to only 45% by 2030. In real numbers this means a mere increase of about 70 bcm In addition, there are a number of potential downside factors for future Russian gas supplies to the European markets. Consequently, a 90% increase of import volumes to the EU by 2030 will be impossible to achieve. From a European energy security perspective the dependence of pipeline gas imports is not the only energy security problem to be in the limelight, the question of physical availability of overall gas supplies deserves serious attention as well. There is a lively discussion regarding the geopolitical implications of European dependence on imported gas from Russia. However, the results of this thesis suggest that when assessing the future gas demand of the EU it would be of equal importance to be concerned about diminishing availability of global gas supplies.

For enhancing anaerobic sludge digestion and biogas recovery, an increase in organic load rate (OLR) from 1.0 to 3.0kgVS/(m3·day) was imposed upon a new anaerobic digestion process combined with a sludge recirculation. The new setup requires a traditional mesophilic anaerobic digester coupled with a centrifuge for maintaining relatively high solid content within the digester. The hypothesis of this study was that increasing continuously OLR from 1.0 to 3.0kgVS/(m3·day) in a pilot-scale anaerobic digester with recycled sludge would not badly influence the digester stability, based on which biogas production would be enhanced. To test this hypothesis, a continuous 73-day study with laboratory experiment was conducted. Due to scarcity of original feeding sludge and its deteriorating quality, OLR had to be increased relied on introduction of extra sludge followed by measurement of total solid (TS) and volatile solid (VS) contents in both feeding sludge and digester sludge, for calculating OLR and examining its variations. To assess the relationship between biogas production and OLR, a measurement of gas yield and methane content was a necessity, performed by applying a biogas flow meter and MSA AUER EX-METER II (P). Moreover, temperature, pH value, volatile fatty acid (VFA) and alkalinity must be tested frequently, for the purpose of preventing system failure. The results demonstrate that the digester succeeded in withstanding an OLR up to 3.15kgVS/(m3·day). Furthermore, an enhancement in biogas yield and methane content were observed after increasing the OLR by introducing extra sludge. Biogas production measurement performed during this study indicated that biogas yield was enhanced by 73%, with a maximum production of 14.5m3/day, when OLR was increased from 2.05 to 3.15kgVS/(m3·day). However, methane content was merely promoted by 10.5%, to the highest value of 63%, with the same increase in OLR. Specific gas production (SGP), as another means of evaluating the relationship between biogas production and OLR, was observed to be 0.65Nm3/kg VSin averagely.

An investigation was undertaken to determine the feasibility of increasing the hydrogen production rate by coupling the water gas shift (WGS) process to the hybrid sulphur process (HyS). This investigation also involved the technical and economical analysis of the water gas shift and the H2 separation by means of Pressure swing adsorption (PSA) process. A technical analysis of the water gas shift reaction was determined under the operating conditions selected on the basis of some information available in the literature. The high temperature system (HTS) and low temperature system (LTS) reactors were assumed to be operated at temperatures of 350°C and 200°C, respectively. The operating pressure for both reactors was assumed to be 30 atmospheres. The H2 production rate of the partial oxidation (POX) and the WGS processes was 242T/D, which is approximately two times the amount produced by the HyS process alone. The PSA was used for the purification process leading to a hydrogen product with a purity of 99.99%. From the total H2 produced by the POX and the WGS processes only 90 percent of H2 is recovered in the PSA. The unrecovered H2 leaves the PSA as a purge gas together with C02 and traces of CH4, CO, and saturated H20. The estimated capital cost of the WGS plant with PSA is about US$50 million. The production cost is highly dependent on the cost of all of the required raw materials and utilities involved. The production cost obtained was US $1.41/kg H2 based on the input cost of synthesis gas as produced by the POX process. In this case the production cost of synthesis gas based on US $6/GJ for natural gas and US $0/Ton for oxygen was estimated to be US $0.154/kg. By increasing the oxygen and natural gas cost, the corresponding increase in synthesis gas has resulted in an increase in H2 production cost of US $1.84/kg.
Thesis (M.Sc. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2009.

The interruption cost for one hour of a petrochemical plant is 33 times higher than that of the average interruption cost for industrial plants across all industries. In addition to the high cost of loss of production, interruptions to the operations of petrochemical and gas-toliquid plants pose safety and environmental hazards. Thus it is necessary to better understand the reliability requirements of petrochemical and gas-to-liquid plants. This study investigated the reliability of electrical distribution networks used in petrochemical and gas-to-liquid plants compared to those used in other industrial plants. A model was developed that can be used to establish the adequacy of the reliability of a distribution network in terms of the components and network topologies used. This model was validated against data that had been collected by the IEEE and applied to an actual petrochemical plant. Over 19 years’ worth of data regarding the trips that have occurred on the distribution network of an existing petrochemical plant was collected and manipulated in order to calculate the reliability indices associated with the equipment used to make up thisRecommended Practice for the Design of Reliable Industrial and Commercial Power Systems. The cost of loss of production and the capital costs associated with increased reliability were calculated for a section of the existing petrochemical plant. The reliability associated with different network topologies that could possibly be used to supply power to this section of the plant were modelled using an appropriate software package. The resulting total cost of ownership over the life of the plant associated with each topology was then calculated in order to establish which network topology is the most appropriate for petrochemical and gas-to-liquid plants. It was concluded the components that affect the reliability of an industrial distribution network are different to those that affect a utility distribution network. These components were listed and compared. It was found that the reliability indices that were calculated for the components that affect the reliability of a petrochemical plant were similar to those provided by the IEEE. 17 out of 20 of the indices that were calculated were within the required factor of deviation. Generally the failure rates of components used in petrochemical plants were very similar to those given in the IEEE Gold Book, while the MTTR’s for the components used in petrochemical plants were found to be slightly better than those given in the IEEE Gold Book. The effect of network topology was found to be significant, with small changes in the topology of a network resulting in large variations in the reliability of the network. It was also found that the most appropriate type of network topology to use in the design of the electrical distribution network of a petrochemical plant is the dual radial network. This is the most conservative of the commonly used network topologies and is the one that is currently used in the existing plant that was studied. Due to the high cost of loss of production in petrochemical plants it was established that any incremental improvement in the reliability of the dual radial network would be beneficial to the total cost of ownership of such a plant. Such incremental improvement of the reliability of the distribution network could be cost effectively achieved by adopting a conservative maintenance strategy and the establishment of a conservative spares inventory. Before this study was undertaken, there was no literature around the reliability of electrical distribution networks that focused specifically on petrochemical and gas-to-liquid plants. This study produced a set of reliability indices and a model that electrical engineers can use in the reliability analysis of petrochemical and gas-to-liquid plants. Furthermore it shows that, because the cost of loss of production in petrochemical plants is so high, the most conservative distribution network design and maintenance philosophies should always be used. distribution network. These reliability indices were compared to those given by the IEEE
Dissertation (MEng)--University of Pretoria, 2013.
gm2014
Electrical, Electronic and Computer Engineering
unrestricted

This thesis is a study of naturally occurring radioactive materials (NORM) activity concentration, gamma dose rate and radon (222Rn) exhalation from the waste streams of large-scale onshore petroleum operations. Types of activities covered included; sludge recovery from separation tanks, sludge farming, NORM storage, scaling in oil tubulars, scaling in gas production and sedimentation in produced water evaporation ponds. Field work was conducted in the arid desert terrain of an operational oil exploration and production region in the Sultanate of Oman. The main radionuclides found were 226Ra and 210Pb (238U - series), 228Ra and 228Th (232Th - series), and 227Ac (235U - series), along with 40K. All activity concentrations were higher than the ambient soil level and varied over several orders of magnitude. The range of gamma dose rates at a 1 m height above ground for the farm treated sludge had a range of 0.06 0.43 µSv h 1, and an average close to the ambient soil mean of 0.086 ± 0.014 µSv h 1, whereas the untreated sludge gamma dose rates had a range of 0.07 1.78 µSv h 1, and a mean of 0.456 ± 0.303 µSv h 1. The geometric mean of ambient soil 222Rn exhalation rate for area surrounding the sludge was mBq m 2 s 1. Radon exhalation rates reported in oil waste products were all higher than the ambient soil value and varied over three orders of magnitude. This study resulted in some unique findings including: (i) detection of radiotoxic 227Ac in the oil scales and sludge, (ii) need of a new empirical relation between petroleum sludge activity concentrations and gamma dose rates, and (iii) assessment of exhalation of 222Rn from oil sludge. Additionally the study investigated a method to determine oil scale and sludge age by the use of inherent behaviour of radionuclides as 228Ra:226Ra and 228Th:228Ra activity ratios.

This thesis is a study of naturally occurring radioactive materials (NORM) activity concentration, gamma dose rate and radon (222Rn) exhalation from the waste streams of large-scale onshore petroleum operations. Types of activities covered included; sludge recovery from separation tanks, sludge farming, NORM storage, scaling in oil tubulars, scaling in gas production and sedimentation in produced water evaporation ponds. Field work was conducted in the arid desert terrain of an operational oil exploration and production region in the Sultanate of Oman. The main radionuclides found were 226Ra and 210Pb (238U - series), 228Ra and 228Th (232Th - series), and 227Ac (235U - series), along with 40K. All activity concentrations were higher than the ambient soil level and varied over several orders of magnitude. The range of gamma dose rates at a 1 m height above ground for the farm treated sludge had a range of 0.06 0.43 µSv h 1, and an average close to the ambient soil mean of 0.086 ± 0.014 µSv h 1, whereas the untreated sludge gamma dose rates had a range of 0.07 1.78 µSv h 1, and a mean of 0.456 ± 0.303 µSv h 1. The geometric mean of ambient soil 222Rn exhalation rate for area surrounding the sludge was mBq m 2 s 1. Radon exhalation rates reported in oil waste products were all higher than the ambient soil value and varied over three orders of magnitude. This study resulted in some unique findings including: (i) detection of radiotoxic 227Ac in the oil scales and sludge, (ii) need of a new empirical relation between petroleum sludge activity concentrations and gamma dose rates, and (iii) assessment of exhalation of 222Rn from oil sludge. Additionally the study investigated a method to determine oil scale and sludge age by the use of inherent behaviour of radionuclides as 228Ra:226Ra and 228Th:228Ra activity ratios.

AD is regarded as a sustainable technology that could assist the UK Government meet internationally agreed GHG emission targets by 2050. However, the mature status of the technology is based on expensive systems that rely on high energy feedstock to be profitable. Meanwhile, the natural biodegradation of cow slurry is a recognised contributor to climate change despite having a relatively low CH4 potential because of the large volumes produced. Economic mixing is essential to the cost-effectiveness of farm AD but techniques applied are not always appropriate as slurry is a shear thinning thixotropic Herschel-Bulkley fluid and therefore challenging to mix. The apparent viscosity of slurry and the shear stress induced was most influenced by solids content (exponential change) followed by temperature (linear). Most shear thinning occurred before a rising shear rate of 20s-1 was achieved with the fluid acting near-Newtonian above. Thixotropic recovery occurred within 1 hour of resting. Rheological values were also much higher than previously reported. Highest CH4 production occurred in the first 10 days of the batch process using a range of mixing regimes with different shear rates and rest periods. During fed-batch operations, changing shear rate had a minimal effect on CH4 production using a 30-day HRT whereas shorter rest periods increased production. Specific CH4 production rate was highest when feeding and mixing coincided. However, when HRT was reduced (OLR increased) the CH4 produced by all mixed regimes significantly increased with highest values being achieved using high intensity mixing rested for short periods. Lower HRTs also requires smaller digesters. Parasitic mixing energy invariably had the most influence on net energy production. Signs of instability were evident after 20 days using the low HRT. Significant microbial adaptation was also observed as the experiments progressed. The research outcomes demonstrate that mixing regime and HRT can be managed to maximise net energy production whilst reducing capital expenditure.

This work examines the isotopic composition and abundance of helium in a number of different crustal environments with a view to understanding its production and transport in the crust. The work was largely carried out using existing instrumentation, but a dedicated interface was also built to allow computer control of a quadrupole mass spectrometer for rare gas abundance pattern determination. Conventional calculations of the radiogenic ³He/⁴He production ratio based on the assumption of a chemically homogeneous composition cannot adequately account for the ³He/⁴He ratio in waters from the Carnmenellis Granite of SW England. Alpha tracking and back-scattered electron microscopy show that the majority of the U and Th are concentrated in volumetrically insignificant accessory minerals. A new model has been devised, taking this heterogeneity into account, to explain the Carnmenellis data. Helium isotopic analysis of the granite itself revealed isotopic disequilibrium with the circulating waters. This may be related to differential release of ³He and ⁴He associated with different formation sites. A survey was made of the helium abundance and isotopic composition of groundwaters from the Pannonian Basin of Hungary in order to study the behaviour of mantle-derived fluids in an area of major recent crustal extension and volcanism. More than 80 samples were analysed covering most of the basin, and almost all contained a component of mantle-derived helium. Although ³He/⁴He ratio is not clearly correlated with the surface expression of volcanism, it may act as an indicator of intrusion at depth. The ³He flux through the Hungarian crust is ≈4 atoms.cm^-2.s^-2. If the mechanism of extraction is partial melting, then by analogy with melt production at mid-ocean ridges, addition of a 20-40 metre layer of basalt (for 5-10% partial melting) must be added to the Hungarian crust in a million years to support the present day ³He flux.

Дисертація присвячена удосконаленню методів глинокислотного діяння на присвердловинну зону пласта з використанням борофтористоводневої кислоти. З цією метою проаналізовано сучасний стан використання глинокислотних розчинів на основі фтористоводневої, кремнійфтористоводневої та борофтористоводневої кислот. Для розроблення ефективних технологій глинокислотного діяння проведено дослідження основних властивостей розчинів борофтористоводневої кислоти -розчинності бентонітової глини залежно від різних чинників (концентрація різних кислот, неіоногенних та катіонактивних ПАР, водорозчинних полімерів тощо), диспергування глинистих нашарувань в глинокислотних розчинах різного складу, розчинності карбонатної породи, корозійної активності розчинів борофтористоводневої кислоти як самостійно, так і в суміші з інгібіторами кислотної корозії, впливу нагнітання глинокислотних розчинів на проникність порід-колекторів. На основі лабораторних досліджень запропоновано дев'ять базових рецептур глинокислотних розчинів на основі борофтористоводневої кислоти, які можна використовувати за трьома основними технологіями. Дослідно-промислові випробування та подальше впровадження розроблених технологій глинокислотного діяння у видобувних свердловинах ПАТ "Укрнафта" підтвердили правильність отриманих результатів та їх ефективність в промислових умовах. Технологічна ефективність розроблених технологій глинокислотного діяння підтверджена результатами гідродинамічних досліджень свердловин до і після проведеного оброблення.
Диссертация посвящена совершенствованию методов глинокислотного воздействия на прискважинную зону пласта с использованием борофтористоводородной кислоты. С этой целью проанализировано современное состояние использования глинокислотных растворов на основе фтористоводородной, кремнийфтористоводородной и борофтористоводородной кислот. Для разработки эффективных технологий глинокислотного воздействия проведены исследования основных свойств растворов борофтористоводородной кислоты - растворимости бентонитовой глины в зависимости от различных факторов (концентрация различных кислот, неионогенных и катионактивных ПАВ, водорастворимых полимеров и другое), диспергирования глинистых компонентов в глинокислотных растворах различного состава, растворимости карбонатной породы, коррозионной активности растворов борофтористоводородной кислоты как самостоятельно, так и в смеси с ингибиторами кислотной коррозии, влияния нагнетания глинокислотных растворов на проницаемость пород-коллекторов. В ходе исследований установлено, что дополнительный ввод в раствор борофтористоводородной кислоты фтористоводородной или соляной кислоты обеспечивает увеличение скорости растворения бентонита в 1,1 - 1,3 раза, а уксусной или фосфорной кислоты, поверхностно-активных веществ и водорастворимых полимеров - снижение растворимости бентонита в 1,2 - 17,5 раз. Способность борофтористоводородной кислоты (скорость разрушения бентонитовых образцов 630 - 1380 г/м2мин) в отличие от фтористоводородной (скорость разрушения 60 г/м2мин) к увеличению скорости разрушения глинистых образований может быть использована в технологиях разглинизации призабойной зоны пласта. Наиболее эффективными ингибиторами кислотной коррозии для использования в растворах борофтористо водородной кислоты являются ИКУ-118, Додикор-2725 та А1-600, которые при этом также обеспечивают незначительное снижение скорости растворения бентонита. Снижение скорости растворения глинистых минералов при использовании борофтористоводородной кислоты при концентрациях 1 - 10 % в условиях ее фильтрации через терригенный поровый коллектор обеспечивает снижение степени образования пелитовых частиц, которые в свою очередь не оказывают негативного влияния на проницаемость образцов горнах пород. Следует учитывать, что при самостоятельном использовании борофтористоводородной кислоты увеличение коэффициента проницаемости наблюдается только в образцах с карбонатностю до 2,5- 3 %. При большей карбонатности образцов горных пород необходимо применять дополнительные мероприятия для снижения карбонатности породы (ввод соляной или иной кислоты в раствор борофтористоводородной кислоты, предварительное нагнетание кислотного раствора. На основе лабораторных исследований рекомендованы девять основных рецептур глинокислотных растворов на основе борофтористоводородной кислоты, которые можно использовать за тремя основными технологиями. Опытнопромысловые испытания и последующее использование разработанных технологий глинокислотного воздействия в добывающих скважинах ОАО "Укрнафта" (на протяжении 2002 - 2010 гг. с использованием новых кислотных систем проведено 119 скважино-операций, что обеспечило дополнительную добычу 89,5 тыс. т нефти с конденсатом и 63,5 млн. м3 газа при успешности работ - 86,5 %) подтвердили правильность полученных результатов и их эффектавность в промысловых условиях. Технологическая эффективность разработанных технологий глинокислотного воздействия подтверждена результатами гидродинамических исследований скважин до и после проведенных обработок. Установлено, что в зависимости от технологии воздействия и состава глинокислотного раствора обеспечивается исключительное воздействие или на призабойную, или на отдаленную зону пласта, или одновременное воздействие на призабойную и отдаленную зону пласта.
The thesis is devoted to the problems of method advancement of mud-acid treatment of downhole and step-out well zones using boricfluorhydric acid. The modem use of mud-acid solutions based on hydrofluoric, silicafluorhydric and boricfluorhydric acids is analysed. The basic properties of boricfluorhydric acid solutions - solubility of bentonite clay depending on various factors (concentration of different acids, non-ionogen and cation-active surfactants, water-soluble polymers, etc.), dispersion of clay layers in mud-acid solutions of different composition, solubility of carbonate rocks, corrosion activity of boricfluorhydric acid solutions both independently and in mixture with inhibitors of acid corrosion, effect of mud-acid solutions injection on the permeability of reservoir rocks are studied to develop effective technologies of mud-acid treatment. Nine basic formulae of mud-acid solutions based on boricfluorhydric acid that can be used in three main technological schemes are offered on the basis of laboratory studies. Field testing and subsequent implementation of the developed technologies of mud-acid treatment of producing wells of public company "Ukrnafta" proved the results and their effectiveness in field conditions . Technological efficiency of the developed technologies of acid treatment confirmed the results of hydrodynamic investigations of wells before and after the treatment.

Thesis (Ph. D.)--Joint Program in Chemical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2007.
Includes bibliographical references (p. 215-225).
The five noble gases (helium, neon, argon, krypton, and xenon) are biologically and chemically inert, making them ideal oceanographic tracers. Additionally, the noble gases have a wide range of solubilities and molecular diffusivities, and thus respond differently to physical forcing. Tritium, an isotope of hydrogen, is useful in tandem with its daughter helium-3 as a tracer for water mass ages. In this thesis, a fourteen month time-series of the five noble gases, helium-3 and tritium was measured at the Bermuda Atlantic Time-series Study (BATS) site. The time-series of five noble gases was used to develop a parameterization of air-sea gas exchange for oligotrophic waters and wind speeds between 0 and 13 m s-1 that explicitly includes bubble processes and that constrains diffusive gas exchange to ± 6% and complete and partial air injection processes to ± 15%. Additionally, the parameterization is based on weeks to seasonal time scales, matching the time scales of many relevant biogeochemical cycles. The time-series of helium isotopes, tritium, argon, and oxygen was used to constrain upper ocean biological production. Specifically, the helium flux gauge technique was used to estimate new production, apparent oxygen utilization rates were used to quantify export production, and euphotic zone seasonal cycles of oxygen and argon were used to determine net community production. The concurrent use of these three methods allows examination of the relationship between the types of production and begins to address a number of apparent inconsistencies in the elemental budgets of carbon, oxygen, and nitrogen.
by Rachel H.R. Stanley.
Ph.D.

Une nouvelle famille de catalyseurs a été développée pour la déshydratation des alcools en C2-C4. Ces catalyseurs qui correspondent à des phosphates de terres rares, sont plus actifs et au moins aussi sélectifs que les catalyseurs traditionnels de déshydratation et ils ne montrent que des désactivations limitées en fonction du temps par dépôt de coke à leur surface. Plusieurs méthodes de préparation de ces catalyseurs ont été développées et les catalyseurs ont été caractérisés par DRX, spectroscopie IR, Raman, MET, EDX, XPS. L’acido-basicité des catalyseurs a été étudiée par TPD de NH3 et CO2 et adsorption de pyridine et de lutidine suivie par IR. Les études catalytiques ont permis de montrer que le mécanisme principal de déshydratation est de type E1 et que les principaux sites catalytiques sont des sites acides de Bronsted ou de Lewis. Les sites acides de Bronsted correspondent à des d’espèces (H2PO4)2- dont la présence est liée à un excès de phosphore en surface, les sites acides de Lewis correspondent aux ions terre rare. L’implication des deux types de sites a été étudiée en fonction de plusieurs paramètres. Les performances des catalyseurs ont été attribuées à une quantité importante de sites acides moyennement forts et à une très faible quantité de sites basiques faibles. Dans la déshydratation du 1-butanol, il apparaît clairement que les sites les plus actifs et les plus sélectifs en 2-butene sont des sites acides de Bronsted. Sur un plan plus appliqué la thèse a permis de mettre au point de nouveaux procédés de préparation de propène soit direct soit passant par une étape de métathèse (éthylène + 2-butène), de 1 et 2- butène et de butadiène (déshydratation du 3-butène-1-ol et du 2, 3-butanediol)
A new family of catalysts has been developed for the dehydration of C2-C5 alcohols. These performing catalysts, which correspond to lanthanides phosphates, are more active and at least as selective when compared to traditional efficient dehydration and show very limited deactivation under reaction flow due to coke deposition. Different methods of preparation of the catalysts have been developed and the catalysts have been characterized by various techniques like XRD, Raman spectroscopy, TEM with EDX analyses and XPS. The acid base properties of the solids have been studied by NH3 and CO2 TPD and by adsorption of lutidine and pyridine followed by IR. The catalytic studies allow showing that the main reaction mechanism on the solids was E1-type and the active sites are both Bronsted and Lewis sites. The Bronsted acid sites correspond to (H2PO4)2- species which presence is related to an excess of P at the surface and the Lewis acid sites correspond to the rare earth cations. The implication of both types of sites as a function of different parameters has been studied. The high efficiency has been attributed to a high amount of acid sites with a moderated acid strength and to a very low amount of basic sites with weak strength. In the dehydration of 1-butanol it appears clearly that the more active and selective sites are Brosnted acid sites. On an industrial point of view the, the thesis work allowed to design new processes of production of propene either direct or through a metathesis reaction (ethylene+ 2-butene), of 1 and 2-butene and of butadiene (dehydration of 3-butene-1-ol and 2, 3-butanediol

Clusters are finite ensembles of atoms or molecules with sizes in the nanometer regime (i.e. nanoparticles). This thesis present results on the geometric and electronic structure of homogeneous and heterogeneous combinations of atoms and molecules. The systems have been studied with synchrotron radiation and valence, core and Auger electron spectroscopic techniques.

The first theme of the thesis is that of mixed clusters. It is shown that by varying the cluster production technique both structures that are close to that predicted by equilibrium considerations can be attained as well as far from equilibrium structures.

Electronic processes following ionization constitute the second theme. The post-collision interaction phenomenon, energy exchange between the photo- and the Auger electrons, is shown to be different in clusters of argon, krypton and xenon. A model is proposed that takes polarization screening in the final state into account. This result is of general character and should be applicable to the analysis of core level photoelectron and Auger electron spectra of insulating and semi-conducting bulk materials as well.

Interatomic Coloumbic Decay is a process that can occur in the condensed phases of weakly bonded systems. Results on the time-scale of the process in Ne clusters and mixed Ar/Ne clusters are herein discussed, as well observations of resonant contributions to the process. In analogy to Auger vis-à-vis Resonant Auger it is found that to the ICD process there is a corresponding Resonant ICD process possible. This has later been observed in other systems and by theoretical calculations as well in subsequent works by other groups.

Delocalization of dicationic valence final states in the hydrogen bonded ammonia clusters and aqueous ammonia has also been investigated by Auger electron spectroscopy. With those results it was possible to assign a previously observed feature in the Auger electron spectrum of solid ammonia.

The so-called "Arps" rate decline relations are by far the most widely used tool for assessing oil and gas reserves from rate performance. These relations (i.e., the exponential and hyperbolic decline relations) are empirical where the starting point for their derivation is given by the definitions of the "loss ratio" and the "derivative of the loss ratio", where the "loss ratio" is the ratio of rate data to derivative of rate data, and the "derivative of the loss ratio" is the "b-parameter" as defined by Arps [1945]. The primary goal of this work is the interpretation of the b-parameter continuously over time and thus the better understanding of its character. As is shown below we propose "monotonically decreasing functional forms" for the characterization of the b-parameter, in addition to the exponential and hyperbolic rate decline relations, where the b-parameter is assumed to be zero and constant, respectively. The proposed equations are as follow: b(t)=constant (Arps' hyperbolic rate-decline relation), []tbbtb10exp)(-bt= (exponential function), (power-law function), 10)(btbtb=)/(1)(10tbbtb+= (rational function). The corresponding rate decline relation for each case is obtained by solving the differential equation associated with the selected functional for the b-parameter. The next step of this procedure is to test and validate each of the rate decline relations by applying them to various numerical simulation cases (for gas), as well as for field data cases obtained from tight/shale gas reservoirs. Our results indicate that b-parameter is never constant but it changes continuously with time. The ultimate objective of this work is to establish each model as a potential analysis/diagnostic relation. Most of the proposed models yield more realistic estimations of gas reserves in comparison to the traditional Arps' rate decline relations (i.e., the hyperbolic decline) where the reserves estimates are inconsistent and over-estimated. As an example, the rational b-parameter model seems to be the most accurate model in terms of representing the character of rate data; and therefore, should yield more realistic reserves estimates. Illustrative examples are provided for better understanding of each b-parameter rate decline model. The proposed family of rate decline relations was based on the character of the b-parameter computed from the rate-time data and they can be applied to a wide range of data sets, as dictated by the character of rate data.

In oil or gas production wells, water can become trapped by capillary forces in the reservoir rock near to the wellbore or hydraulic fracture face. The trapped water dramatically reduces the production rate of oil or gas. The general term for wells suffering from productivity loss due to capillary trapped water is “water block”. The severity of the water block is the result of the combined effects of wettability, capillary forces, viscous forces, fluid compressibility, hydraulic fracture length and various other reservoir and well properties. A numerical model can be used to evaluate all the effects for particular scenarios. However, for most oil or gas reservoirs, there is great uncertainty in many of the reservoir parameters. Evaluating enough scenarios numerically to account for all the uncertainty can be extremely time-consuming. Analysing the sensitivity to uncertain parameters is substantially faster and better served by analytical models. Historically, the impact of the end effects in production wells have been neglected in analytical models as the target reservoirs have generally had high permeability. Now, the development of petroleum fields involves targeting much lower permeability reservoirs. These reservoirs can exhibit high capillary pressures. Despite the significant capillary pressure effects, analytical models have yet to be developed for gas or oil well performance accounting for capillary end effects. The goal of this thesis is to develop analytical models to include the effects of capillary forces near to the wellbore or the hydraulic fracture and to analyse the impact of fluid compressibility, wettability, capillary forces, viscous forces, porous media network characteristics and hydraulic fracture half-length. This thesis includes five journal papers, four of which have been published; the last one finished with intention to submit later this year. The thesis develops new analytical models to calculate the productivity index of gas wells. The new models account for viscous forces, capillary forces, inertial forces, wettability, compressibility, non-uniform flow into hydraulic fractures and capillary end effects near to the wellbore or hydraulic fracture. The analytical models are validated through matching with experimental data or numerical simulators. The forms of the capillary pressure and relative permeability curves are extremely important properties of the reservoir which impact the magnitude of the capillary end effect. The shape of the curves is significantly impacted by the characteristics of the pore network. A sophisticated mixed percolation model coupled with effective medium theory is developed in the thesis. The novelty of the new percolation model is that it applies mixed bond-site percolation for the first time to the water-hydrocarbon drainage problem, while only bond or site percolation was applied in previous models. This thesis integrates the complex interaction between the viscous, capillary and inertial forces, water cut, hydraulic fracture length and the topology of the pore network. The study quantifies the impact of each of the aforementioned characteristics of two phase flow on the productivity of gas wells. The results of this thesis are critical in screening for economic well candidates for intervention.
Thesis (Ph.D.) -- University of Adelaide, Australian School of Petroleum, 2020

There have been many attempts to use mathematical method in order to characterize shale gas/oil reservoirs with multi-transverse hydraulic fractures horizontal well. Many authors have tried to come up with a suitable and practical mathematical model. To analyze the production data of a shale reservoir correctly, an understanding and choosing the proper mathematical model is required. Therefore, three models (the homogeneous linear flow model, the transient linear dual porosity model, and the fully transient linear triple porosity model) will be studied and compared to provide correct interpretation guidelines for these models. The analytical solutions and interpretation guidelines are developed in this work to interpret the production data of shale reservoirs effectively. Verification and derivation of asymptotic and associated equations from the Laplace space for dual porosity and triple porosity models are performed in order to generate analysis equations. Theories and practical applications of the three models (the homogeneous linear flow model, the dual porosity model, and the triple porosity model) are presented. A simplified triple porosity model with practical analytical solutions is proposed in order to reduce its complexity. This research provides the interpretation guidelines with various analysis equations for different flow periods or different physical properties. From theoretical and field examples of interpretation, the possible errors are presented. Finally, the three models are compared in a production analysis with the assumption of infinite conductivity of hydraulic fractures.

The vast shale gas and tight oil reservoirs in North America cannot be economically developed without multi-stage hydraulic fracture treatments. Owing to the disparity in the density of natural fractures in addition to the disparate in-situ stress conditions in these kinds of formations, microseismic fracture mapping has shown that hydraulic fracture treatments develop a range of large-scale fracture networks in the shale plays. In this thesis, an approach is presented, where the fracture networks approximated with microseismic mapping are integrated with a commercial numerical production simulator that discretely models the network structure in both vertical and horizontal wells. A novel approach for reservoir simulation is used, where porosity (instead of permeability) is used as a scaling parameter for the fracture width. Two different fracture geometries have been broadly proposed for a multi stage horizontal well, orthogonal and transverse. The orthogonal pattern represents a complex network with cross cutting fractures orthogonal to each other; whereas transverse pattern maps uninterrupted fractures achieving maximum depth of penetration into the reservoir. The response for a vii single-stage fracture is further investigated by comparing the propagation of the stage to be dendritic versus planar. A dendritic propagation is bifurcation of the hydraulic fracture due to intersection with the natural fracture (failure along the plane of weakness). The impact of fracture spacing to optimize these fracture geometries is studied. A systematic optimization for designing the fracture length and width is also presented. The simulation is motivated by the oil window of Eagle Ford shale formation and the results of this work illustrate how different fracture network geometries impact well performance, which is critical for improving future horizontal well completions and fracturing strategies in low permeability shale and tight oil reservoirs. A rate transient analysis (RTA) technique employing a rate normalized pressure (RNP) vs. superposition time function (STF) plot is used for the linear flow analysis. The parameters that influence linear flow are analytically derived. It is found that picking a straight line on this curve can lead to erroneous results because multiple solutions exist. A new technique for linear flow analysis is used. The ratio of derivative of inverse production and derivative of square root time is plotted against square root time and the constant derivative region is seen to be indicative of linear flow. The analysis is found to be robust because different simulation cases are modeled and permeability and fracture half-length are estimated.
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New decline curve models have been developed to overcome the boundary-dominated flow assumption of the basic Arps’ models, which restricts their application in ultra-low permeability reservoirs exhibiting long-duration transient flow regimes. However, these new decline curve analysis (DCA) methods are still based only on production rate data, relying on the assumption of stable flowing pressure. Since this stabilized state is not reached rapidly in most cases, the applicability of these methods and the reliability of their solutions may be compromised. In addition, production performance predictions cannot be disassociated from the existing operation constraints under which production history was developed. On the other hand, DCA is often carried out without a proper identification of flow regimes. The arbitrary application of DCA models regardless of existing flow regimes may produce unrealistic production forecasts, because these models have been designed assuming specific flow regimes. The main purpose of this study was to evaluate the possible benefits provided by including flowing pressures in production decline analysis. As a result, it have been demonstrated that decline curve analysis based on pressure-normalized rates can be used as a reliable production forecasting technique suited to interpret unconventional wells in specific situations such as unstable operating conditions, limited availability of production data (short production history) and high-pressure, rate-restricted wells. In addition, pressure-normalized DCA techniques proved to have the special ability of dissociating the estimation of future production performance from the existing operation constraints under which production history was developed. On the other hand, it was also observed than more consistent and representative flow regime interpretations may be obtained as diagnostic plots are improved by including MBT, pseudovariables (for gas wells) and pressure-normalized rates. This means that misinterpretations may occur if diagnostic plots are not applied correctly. In general, an improved forecasting ability implies greater accuracy in the production performance forecasts and more reliable reserve estimations. The petroleum industry may become more confident in reserves estimates, which are the basis for the design of development plans, investment decisions, and valuation of companies’ assets.

This thesis reveals atypical dynamic reservoir behaviour within Cooper Basin ultra-deep coal seams during gas production that calls for a paradigm shift in gas extraction technology, diametrically opposed to the evolutionary path of current drilling, wellbore completion, and reservoir stimulation practices. An anomalous geomechanical reservoir boundary condition is detected that is, by definition, mostly restricted to ultra-deep coal seams. The discovery has resulted in the formulation of a new coal seam reservoir concept - “Expanding Reservoir Boundary Theory”. Ultra-deep Permian coal seams of the Cooper Basin in central Australia represent a nascent thermogenic source rock reservoir play. Proof-of-concept gas flow occurred in 2007. The vast (100+ Tscf) potential resource is comparable in commercial significance, and technical challenge, to the shale gas plays of North America. As with shale, full-cycle, standalone commercial gas production from Cooper Basin ultra-deep coal seams requires a large, complex, permeable “stimulated reservoir volume” (SRV) domain having high fracture / fabric face surface area for gas desorption. This goal has not yet been achieved after 13 years of trials because, owing to the bipolar combination of coal-like geomechanical properties and shale-like reservoir properties, these poorly cleated, inertinitic coal seams exhibit “hybrid” characteristics. This is problematic for achieving effective reservoir stimulation, and poses the greatest immediate challenge. Stimulation techniques adopted from other play types are incompatible with the highly unfavourable combination of nanoDarcy-scale permeability, “ductility”, and high stress. The Cooper Basin Deep Coal Gas (CBDCG) Play commences 6,000 feet (1,830 metres) below the “commercial permeability depth limit” for most shallow coal seam gas (CSG) reservoirs but this does not reduce gas flow potential. Shale gas industry technologies have, in principle, eliminated the requirement for naturally occurring coal fabric permeability. Optimum reservoir conditions occur at depths beyond 9,000 feet (2,740 metres), driven by very low water saturation, high gas content, gas oversaturation, overpressure, rigid host rock strata, and high deviatoric stress. The limited literature does not yet adequately characterise the physical response of ultra-deep coal seams, and the surrounding host rock strata, to production pressure drawdown. It remains to be established how artificial fracture and coal fabric aperture width change as a consequence of the dynamic, diametric competition between gas desorption-induced coal matrix shrinkage and the omnipresent tendency for reservoir compaction caused by increasing production pressure drawdown-induced effective stress. This technical impasse, inhibiting commercialisation, is addressed by analysing the atypical flowback behaviour of hydraulically fracture stimulated coal seams within a dedicated vertical wellbore at 9,500 feet (2,900 metres). High-resolution, non-classical flowback analysis is performed on the pure dataset of Australia’s first ultra-deep coal gas well. Wellhead and fracture network pressures are recorded continuously for 8 1/2 years, at a 10-minute sample interval, while flowing to atmosphere. Natural flowback behaviour is analogous to that of a mechanical gas plunger artificial lift system. A low but gradually increasing quasi-steady state base gas flow, free of produced formation water, is overprinted by a non-steady state, cyclical pressure signature that is diagnostic of dynamic reservoir behaviour during gas production. A total of 114 high-rate, “geyser-like” gas surge events, gradually increasing in duration from 2 hours to 2 weeks, and in reservoir equivalent volume from 360 to 20,000 rcf (10 to 570 rcm), suggest the gas headspace compartment of a “down-hole void space domain” is steadily increasing in size. The gas surge events result from intermittent release of fracture network gas, hydrostatically compressed by flowback fluid slowly accumulating within the wellbore. A production “history match” for the gas surge event pressure profile is obtained by designing, fabricating, operating, and data logging a computer-controlled hydraulic apparatus within The University of Adelaide’s experimental wellbore, at a depth of 230 feet (70 metres). This physically simulates open-ended flowing manometer-like hydrodynamic behaviour of the wellbore-reservoir system. A postulated geological trigger mechanism for surge initiation is tested and validated; “wellbore hydrostatic back-pressure and reservoir stress-dependent leak-off”. Time-lapse pressure transient analysis (PTA) is performed on three extended wellbore pressure build-up tests, lasting 157, 259, and 295 days respectively. Increasing permeability is recognised within coal fabric surrounding the initial fracture network SRV domain. Time-lapse rate transient analysis (RTA) performed on the first two subsequent wellbore pressure “blow-down to atmosphere” (BDTA) gas flow rate decline profiles indicates that hydraulic fracture flow conductivity increased during the intervening 327-day flowback period. Interpreted dilation of hydraulic fracture apertures is supported by a 60% increase in the initial BDTA gas flow rates, from 7.5 to 12.0 MMscfd (212.4 to 340.0 Mscmd). Cooper Basin ultra-deep coal gas reservoirs behave differently to other deep, thermogenic source rock reservoirs, and require a paradigm shift in reservoir stimulation technology that does not rely exclusively upon hydraulic fracture stimulation and the “brittleness factor”. Pressure arching may fill this role by neutralising the omnipresent tendency for reservoir compaction caused by increasing production pressure drawdown-induced effective stress. The combined, mutually sustaining actions of desorption-induced coal matrix shrinkage and sympathetic pressure arch “stress shield” evolution generate an “expanding reservoir boundary and decreasing confining stress” condition that allows producing ultra-deep coal seams, and adjacent strata indirectly (which may include other reservoir types), to progressively de-stress and “self-fracture” in an overall state of endogenous tensile failure. As with underground coal mine excavations, pressure arching will deflect maximum stress vectors around the dilating “dispersed coal fabric void space” domain of a growing fracture network SRV domain that has developed reduced bulk structural integrity, and reduced bulk compressive strength, compared to the surrounding native coal seam and host rock strata. Size and effectiveness of pressure arching increases with depth. Cooper Basin ultra-deep coal seams, and adjacent “non-coal” reservoirs indirectly, may be effectively stimulated to flow gas on a large scale by harnessing this self-perpetuating, depth-resistant mechanism for creating coal fracture / fabric permeability and surface area for gas desorption. They may be induced to pervasively “shatter”, or “self-fracture”, naturally during gas production, independent of the lack of “brittleness”, analogous to the manner in which shrinkage crack networks slowly form, in a state of intrinsic, endogenous tension, within desiccating clay-rich surface sediment. Full-cycle, standalone commercial gas production is considered likely to occur when “Expanding Reservoir Boundary Theory” is applied, so as to replicate the very large, complex fracture network SRV domain of commercial shale gas reservoirs.
Thesis (Ph.D.) -- University of Adelaide, Australian School of Petroleum, 2020

Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2007.
"September 2007". "Joint Program in Oceanography/Applied Ocean Science and Engineering"--Cover. Title from Web page (viewed on Mar. 24, 2008). Includes bibliographical references (p. 215-225).