Letteratura scientifica selezionata sul tema "Fractures"
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Articoli di riviste sul tema "Fractures"
1
Schoenberg, Michael, e Colin M. Sayers. "Seismic anisotropy of fractured rock". GEOPHYSICS 60, n. 1 (gennaio 1995): 204–11. http://dx.doi.org/10.1190/1.1443748.
Testo completoAbstract (sommario):
A simple method for including the effects of geologically realistic fractures on the seismic propagation through fractured rocks can be obtained by writing the effective compliance tensor of the fractured rock as the sum of the compliance tensor of the unfractured background rock and the compliance tensors for each set of parallel fractures or aligned fractures. The compliance tensor of each fracture set is derivable from a second rank fracture compliance tensor. For a rotationally symmetric set of fractures, the fracture compliance tensor depends on only two fracture compliances, one controlling fracture compliance normal, the other, tangential, to the plane of the fractures. The stiffness tensor, which is more useful in the consideration of elastic wave propagation through rocks, can then be obtained by inversion. The components of the excess fracture compliance tensor represent the maximum amount of information that can be obtained from seismic data. If the background rock is isotropic and the normal and shear compliance of each fracture are equal, although different from those of other fractures, the effective elastic behavior of the fractured rock is orthorhombic for any orientation distribution of fractures. A comparison of the theory with recent ultrasonic experiments on a simulated fractured medium shows near equality of the normal and shear compliance for the case of air‐filled fractures.
2
Wang, Yueying, Jun Yao, Shuaishi Fu, Aimin Lv, Zhixue Sun e Kelvin Bongole. "Simulation of counter-current imbibition in water-wet fractured reservoirs based on discrete-fracture model". Open Physics 15, n. 1 (3 agosto 2017): 536–43. http://dx.doi.org/10.1515/phys-2017-0061.
Testo completoAbstract (sommario):
AbstractIsolated fractures usually exist in fractured media systems, where the capillary pressure in the fracture is lower than that of the matrix, causing the discrepancy in oil recoveries between fractured and non-fractured porous media. Experiments, analytical solutions and conventional simulation methods based on the continuum model approach are incompetent or insufficient in describing media containing isolated fractures. In this paper, the simulation of the counter-current imbibition in fractured media is based on the discrete-fracture model (DFM). The interlocking or arrangement of matrix and fracture system within the model resembles the traditional discrete fracture network model and the hybrid-mixed-finite-element method is employed to solve the associated equations. The Behbahani experimental data validates our simulation solution for consistency. The simulation results of the fractured media show that the isolated-fractures affect the imbibition in the matrix block. Moreover, the isolated fracture parameters such as fracture length and fracture location influence the trend of the recovery curves. Thus, the counter-current imbibition behavior of media with isolated fractures can be predicted using this method based on the discrete-fracture model.
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Zhang, Qinghe, Bing Zhang, Chen Chen, Ling Li, Xiaorui Wang, Bowen Jiang e Tianle Zheng. "A Test Method for Finding Early Dynamic Fracture of Rock: Using DIC and YOLOv5". Sensors 22, n. 17 (23 agosto 2022): 6320. http://dx.doi.org/10.3390/s22176320.
Testo completoAbstract (sommario):
Intelligent monitoring and early warning of rock mass failure is vital. To realize the early intelligent identification of dynamic fractures in the failure process of complex fractured rocks, 3D printing of the fracture network model was used to produce rock-like specimens containing 20 random joints. An algorithm for the early intelligent identification of dynamic fractures was proposed based on the YOLOv5 deep learning network model and DIC cloud. The results demonstrate an important relationship between the overall strength of the specimen with complex fractures and dynamic fracture propagation, and the overall specimen strength can be judged semi-quantitatively by counting dynamic fracture propagation. Before the initiation of each primary fracture, a strain concentration area appears, which indicates new fracture initiation. The dynamic evolution of primary fractures can be divided into four types: primary fractures, stress concentration areas, new fractures, and cross fractures. The cross fractures have the greatest impact on the overall strength of the specimen. The overall identification accuracy of the four types of fractures identified by the algorithm reached 88%, which shows that the method is fast, accurate, and effective for fracture identification and location, and classification of complex fractured rock masses.
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Alemi, Dr Mehrdad, e Hossein Jalalifar. "Advanced Concepts in Naturally Fractured Reservoirs with Analysis of Field Data". Indian Journal of Petroleum Engineering 2, n. 1 (30 maggio 2022): 1–5. http://dx.doi.org/10.54105/ijpe.b1912.052122.
Testo completoAbstract (sommario):
Dual porosity reservoir is mainly defined as fractured reservoir. The Two porosities are included for fracture and matrix, Flow in the fractures, oil storage in the matrix. Dual Permeability reservoir are those pay zones with flow in both the fracture and matrix systems. Single porosity means matrix, dual porosity means both matrix and fractures and triple porosity means matrix, fractures and vugs. The description of displacement mechanisms in fractured reservoirs can be construed as: oil expansion, gravity forces, capillary forces, balance of gravity and capillary forces, diffusion and convection. Fractures are usually found in limestone and dolomites due to solution, re-crystallization. Two categories of fractures are available such as: Open Fractures and Closed Fractures which depend mainly on circulation water and precipitation. Fractures which are closed at surface conditions may be open in reservoir conditions. Fractures related to folding axis are such as: longitudinal fractures, along the folding axis and transverse fractures, perpendicular to the folding axis and diagonal fractures, in relation with the folding axis. There are some pivotal issues and expressions in fractured reservoirs that in this paper, an approach to the advanced concepts in Naturally Fractured Reservoirs has been studied.
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Guo, Jingjing, Haitao Wang, Liehui Zhang e Chengyong Li. "Pressure Transient Analysis and Flux Distribution for Multistage Fractured Horizontal Wells in Triple-Porosity Reservoir Media with Consideration of Stress-Sensitivity Effect". Journal of Chemistry 2015 (2015): 1–16. http://dx.doi.org/10.1155/2015/212901.
Testo completoAbstract (sommario):
Triple-porosity model is usually adopted to describe reservoirs with multiscaled pore spaces, including matrix pores, natural fractures, and vugs. Multiple fractures created by hydraulic fracturing can effectively improve the connectivity between existing natural fractures and thus increase well deliverability. However, little work has been done on pressure transient behavior of multistage fractured horizontal wells in triple-porosity reservoirs. Based on source/sink function method, this paper presents a triple-porosity model to investigate the transient pressure dynamics and flux distribution for multistage fractured horizontal wells in fractured-vuggy reservoirs with consideration of stress-dependent natural fracture permeability. The model is semianalytically solved by discretizing hydraulic fractures and Pedrosa’s transformation, perturbation theory, and integration transformation method. Type curves of transient pressure dynamics are generated, and flux distribution among hydraulic fractures for a fractured horizontal well with constant production rate is also discussed. Parametric study shows that major influential parameters on transient pressure responses are parameters pertinent to reservoir properties, interporosity mass transfer, and hydraulic fractures. Analysis of flux distribution indicates that flux density gradually increases from the horizontal wellbore to fracture tips, and the flux contribution of outermost fractures is higher than that of inner fractures. The model can also be extended to optimize hydraulic fracture parameters.
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Kuchuk, Fikri, e Denis Biryukov. "Pressure-Transient Tests and Flow Regimes in Fractured Reservoirs". SPE Reservoir Evaluation & Engineering 18, n. 02 (31 marzo 2015): 187–204. http://dx.doi.org/10.2118/166296-pa.
Testo completoAbstract (sommario):
Summary Fractures are common features in many well-known reservoirs. Naturally fractured reservoirs include fractured igneous, metamorphic, and sedimentary rocks (matrix). Faults in many naturally fractured carbonate reservoirs often have high-permeability zones, and are connected to numerous fractures that have varying conductivities. Furthermore, in many naturally fractured reservoirs, faults and fractures can be discrete (rather than connected-network dual-porosity systems). In this paper, we investigate the pressure-transient behavior of continuously and discretely naturally fractured reservoirs with semianalytical solutions. These fractured reservoirs can contain periodically or arbitrarily distributed finite- and/or infinite-conductivity fractures with different lengths and orientations. Unlike the single-derivative shape of the Warren and Root (1963) model, fractured reservoirs exhibit diverse pressure behaviors as well as more than 10 flow regimes. There are seven important factors that dominate the pressure-transient test as well as flow-regime behaviors of fractured reservoirs: (1) fractures intersect the wellbore parallel to its axis, with a dipping angle of 90° (vertical fractures), including hydraulic fractures; (2) fractures intersect the wellbore with dipping angles from 0° to less than 90°; (3) fractures are in the vicinity of the wellbore; (4) fractures have extremely high or low fracture and fault conductivities; (5) fractures have various sizes and distributions; (6) fractures have high and low matrix block permeabilities; and (7) fractures are damaged (skin zone) as a result of drilling and completion operations and fluids. All flow regimes associated with these factors are shown for a number of continuously and discretely fractured reservoirs with different well and fracture configurations. For a few cases, these flow regimes were compared with those from the field data. We performed history matching of the pressure-transient data generated from our discretely and continuously fractured reservoir models with the Warren and Root (1963) dual-porosity-type models, and it is shown that they yield incorrect reservoir parameters.
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Zhao, Kai, Runsen Li, Haoran Lei, Wei Gao, Zhenwei Zhang, Xiaoyun Wang e Le Qu. "Numerical Simulation of Influencing Factors of Hydraulic Fracture Network Development in Reservoirs with Pre-Existing Fractures". Processes 10, n. 4 (15 aprile 2022): 773. http://dx.doi.org/10.3390/pr10040773.
Testo completoAbstract (sommario):
The intersection behavior of hydraulic fractures and single natural fractures has been studied in detail; however, in fractured reservoirs, natural fractures are numerous and interlaced and the intersection of hydraulic fractures and multiple natural fractures occurs during the fracturing process. This intersection behavior is more complex and there is a lack of research on this topic at present. In this study, a numerical simulation model of the interaction between hydraulic fractures and a series of natural fractures was established, the main factors that affect the formation scale of a fracture network during the hydraulic fracturing of a fractured reservoir were studied using the numerical simulation method, and the parameters were also studied. The results showed that the natural fracture trend, in situ stress difference, and injection flow rate have an impact on the scale of a fracture network. The larger the in situ stress difference, the smaller the scale of the fracture network, which gradually changes from multiple clusters of fractures to single fractures. The larger the injection flow rate, the larger the scale of the fracture network. In the uniform stress field, the direction of a natural fracture is closer to the direction of principal stress, so the lower the fracture extension pressure, the smaller the scale of the network. On the contrary, the farther away from the principal stress direction, the lower the fracture extension pressure and the higher the extension pressure, the larger the scale of the fracture network.
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Zhang, Peng, Yaniv Brick e Mukul M. Sharma. "Numerical study of an electrode-based resistivity tool for fracture diagnostics in steel-cased wellbores". GEOPHYSICS 83, n. 2 (1 marzo 2018): D41—D48. http://dx.doi.org/10.1190/geo2017-0355.1.
Testo completoAbstract (sommario):
The efficiency of a hydraulic fracture treatment depends primarily on the dimensions and orientation of propped fractures. We have developed a novel electrode-based resistivity tool concept for mapping proppant distribution in hydraulic fractures in steel-cased wellbores. The proposed tool configuration is shown to overcome the severe limitations of induction tools for the detection and resolution of propped fracture geometries in such wellbores. The concept makes use of an array of electrically insulating gap subsections, which are installed and cemented as permanent parts of the casing string, separating the casing sections. By imposing voltages on the insulating gaps, the conductive casing is excited directly, thus avoiding through-casing signal degradation caused by its high electrical conductivity. This allows us to detect subsurface fractures propped with conductive proppant. The envisioned measurements are performed by running a bottom-hole assembly into the fractured zone on a coiled tubing to impose a voltage across each insulating gap at a time, before and after hydraulic fracture operations. For each excited insulating gap, the voltages across all other insulating gaps are recorded by the electronics embedded in the insulating gaps. To interpret the envisioned measurements, a forward model of the tool, based on a finite volume method, is developed, and the design’s sensitivity to the fracture parameters is demonstrated via case studies. The results indicate that measurements made based on the proposed concept will be highly sensitive to a fracture’s location, size, and angle, and less sensitive to a fracture’s shape. Simulations also indicate that direct contact of the fracture with an excited casing section enables the differentiation of fractures of up to a 100 m radius. Fractures with angles greater than 30° or aspect ratios greater than two can also be distinguished from the ones orthogonal to the well or with an aspect ratio of one.
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Feng, Yueli, Yuetian Liu e Gang Lei. "Study on Stress-Dependent Permeability of Fracture Networks in Fractured Porous Media". Geofluids 2021 (24 giugno 2021): 1–19. http://dx.doi.org/10.1155/2021/7433547.
Testo completoAbstract (sommario):
In order to investigate the stress-sensitive characteristics of fracture networks under reservoir actual stress condition and its influence on the seepage in fractured porous media, we carried out permeability tests on experimental models with fracture networks under constant-volume boundary condition. In addition, a novel analytical stress-dependent permeability model of fracture networks in different directions was derived. Based on the test results and the proposed analytical model, the effects of various parameters (e.g., initial fracture aperture, fluid pressure, rock elastic modulus, effective-stress coefficient, and fracture dip) on deformation characteristics of fracture networks and the corresponding permeability tensor of fracture networks were studied. The research results show that, for a fractured porous media with a single group of fractures, the principal value of permeability is always parallel to the fracture-development direction. With increasing effective stress, the principal value of permeability decreases; however, the principal value direction remains unchanged. Moreover, for the fractured porous media with multiple sets of fractures, the principal direction of equivalent permeability will be inclined to the fractures with larger fracture aperture. Specifically, for the fractured porous media with two sets of intersecting fractures, the principal direction of equivalent permeability is parallel to the angular bisector of these two sets of intersecting fractures. Furthermore, the greater the difference of the fracture aperture change rate under effective stress, the more obvious the deviation of the permeability principal direction. The derived analytical model is of great theoretical and scientific significance to deepen the understanding of the stress-sensitive permeability of fractured reservoirs.
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Shi, Shanzhi, Renyan Zhuo, Leiming Cheng, Yuankai Xiang, Xinfang Ma e Tao Wang. "Fracture Characteristics and Distribution in Slant Core from Conglomerate Hydraulic Fracturing Test Site (CHFTS) in Junggar Basin, Northwest China". Processes 10, n. 8 (19 agosto 2022): 1646. http://dx.doi.org/10.3390/pr10081646.
Testo completoAbstract (sommario):
Hydraulic fracture networks, especially fracture geometry, height growth, and proppant transport within the networks, present a critical influence on productivity evaluation and optimization of fracturing parameters. However, information about hydraulic fracture networks in post-fractured formations is seldom available. In this study, the characteristics (density and orientation) of hydraulic fractures were obtained from field observations of cores taken from conglomerate hydraulic fracturing test site (CHFTS). A large number of fractures were observed in the cores, and systematic fracture description was carried out. The fracture analysis data obtained includes fracture density, fracture depth, fracture orientation, morphology, fracture surface features, apertures, fill, fracture mechanical origin (type), etc. Our results show that 228 hydraulic fractures were intersected in a span of 293.71 m of slant core and composed of irregularly spaced single fractures and fracture swarms. One of the potential sources of the observed fracture swarms is near-wellbore tortuosity. Moreover, for regions far away from the wellbore, reservoir heterogeneity can promote complex hydraulic fracture trajectories. The hydraulic fractures were mainly cross-gravel and high-angle fractures and align with maximum horizontal stress (SHmax) ± 15°. The fracture density, orientations, and types obtained from the core fracture description provided valuable information regarding fracture growth behavior. For the near-wellbore area with a transverse distance of less than 25 m from the hydraulically-fractured wellbore, tensile fractures were dominant. While for the area far away from the wellbore, shear fractures were dominant. Our results provide improved understanding of the spatial hydraulic fracture dimensions, proppant distribution, and mechanism of hydraulic fracture formation. The dataset acquired can also be used to calibrate numerical models and characterize hydraulic fracture geometry and proppant distribution.
Tesi sul tema "Fractures"
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Fatahi, Hassan. "Simulation of Hydraulic Fracture Propagation Interacted with Natural Fractures". Thesis, Curtin University, 2016. http://hdl.handle.net/20.500.11937/51882.
Testo completoAbstract (sommario):
This study developed an advance understanding of the mechanisms of hydraulic fracture initiation, propagation, and natural fractures interaction based-on thorough investigation of effects of various parameters associated with hydraulic and natural fractures through numerical modelling, simulation and laboratory experiments. Thesis progressively demonstrates different steps of the development of numerical modelling, simulation and experimental validation. Factors influencing the initiation and propagation of hydraulic fracture, and natural fractures interactions are thoroughly discussed based upon comprehensive sensitivity studies.
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Hastings, Elizabeth. "FRACTURES". Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3136.
Testo completoAbstract (sommario):
A stoplight at night. A dim bedroom. The smell of smoke and loss in summer. In winter, the crackle of snow underfoot, the city cold as a lavender planet. These are the settings within Fractures, and it is to these backdrops that the conflicts of the poems' speakers bare themselves. In the glow of these places, the truth of fractures, the gaps and slivers within us all, are illuminated. Below the visible wholeness of life lies a masked truth, the truth of a world that exists as a collection of fragments, of lives, of stories that connect, intersect, and sometimes overlap to create the tapestry of life as we know it. Each of us, in our own way, is fractured: in our minds, bodies, families, or relationships. And yet we live with these breakages, embrace them, even, because these splinters--personalities, moments, obstacles--are what make us whole. Fractures is a collection of poems that examines these pieces that characterize human life. The events and speakers in this manuscript are fictional, yet, like all fiction, they reflect some remnants of reality, some recognizable truths of ourselves stitched throughout. Each section of the collection can be viewed as a separate fracture, and each poem may also be a fracture. Some poems are broken even further: within stanzas, within lines, sometimes within the mind of the speaker. The poems do not tell a linear story, but rather tell bits of stories that often overlap. These narrative gaps too are indicative of a fracture as they mirror the disconnect, both physical and emotional, that frequently occurs in the stories of one's life. The sections of Fractures address different topics, ranging from loss to love to self destruction. The speakers are linked by a sense of searching, a self-awareness of being splintered, and, as one poem states, of recognizing a "hunger" for something more. One has lost a dear friend; another destroys her body in a quest for beauty. Some reflect on their families. Others mourn for lovers past, while one clings to a fleeting moment of love in its perfection. Just as the body suffers its broken bones that heal with time, so too these speakers suffer rifts that mend but are not forgotten. In this way, Fractures is a dissection, an X-ray of its speakers, each break a lit scar, fluorescent on the page.M.F.A.
Department of English
Arts and Humanities
Creative Writing MFA
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Loutzenheiser, Max J. "Fractures". Kent State University Honors College / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ksuhonors1463053698.
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Flinkkilä, T. (Tapio). "Intramedullary nailing of humeral shaft fractures". Doctoral thesis, University of Oulu, 2004. http://urn.fi/urn:isbn:951427296X.
Testo completoAbstract (sommario):
Abstract
Although nonoperative treatment is recognized as an effective treatment method for humeral shaft fractures, it is associated with an approximately 10% risk of nonunion and long-term impairments of the shoulder joint. There is a growing interest to treat even simple humeral shaft fractures operatively to avoid these problems. Intramedullary (IM) nailing has proven to be very effective in the treatment of femoral and tibial shaft fractures and the same method has been adopted for humeral shaft fractures. However, the results regarding union rate and shoulder joint function after antegrade insertion of an IM nail have been very controversial.
The purpose of this study was to investigate fracture union, shoulder joint function and symptoms after antegrade IM nailing of humeral shaft fractures, to assess safety and results of IM nailing in pathological fractures, to evaluate the efficacy of exchange nailing and Ilizarov's technique in the treatment of nonunion after IM nailing and to find out, by comparing shoulder joint symptoms and function after antegrade IM nailing and dynamic compression (DC) plate fixation, whether antegrade access to the medullary cavity is the main reason behind shoulder joint problems.
During the years 1987-1997, 126 humeral shaft fractures were operated upon in Oulu University Hospital using antegrade IM nailing. The nonunion rate was 22% and distraction of the fracture fragments was the most important risk factor associated with nonunion. The reoperation rate, for various reasons, was 25%. Shoulder joint pain and impairment of function was present in 37% of the patients. In the treatment of 18 pathological fractures IM nailing was a rapid and safe operation, associated with good pain relief.
Exchange nailing of 13 cases of nonunion after IM nailing resulted in a union rate of 47% and this method is not useful in the humerus in contrast to tibial and femoral fractures. Permanent nonunion leaves the patient with severe impairment of the shoulder joint and a loose nail may lead to severe osteolysis of cortical bone. In complicated nonunion with poor bone quality, Ilizarov's technique, although associated with a high rate of minor complications and reoperations, worked well.
When IM nailing was compared with DC plating it was found that there were no significant differences in shoulder pain, function scores, range-of-motion and strength. Antegrade insertion of the nail, if carried out properly, is probably not the main reason for shoulder joint impairment after IM nailing.
Antegrade IM nailing of humeral shaft fractures is associated with several problems, e.g. shoulder joint impairment and difficulties in reconstruction after nonunion, and indications for this method may be exceptional, such as comminuted and pathological fractures.
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何柏康 e Pak-hong Henry Ho. "A new implant for distal radius fracture fixation: from design to testing". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31226061.
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Jrad, Rami. "Etude rétrospective d'un an de fractures des membres chez les enfants de moins de seize ans au C. H. G. De Perpignan". Montpellier 1, 1996. http://www.theses.fr/1996MON11024.
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Aird, J. "Human Immunodeficiency Virus and open fractures : is wound or fracture healing affected in surgically stabilised open fractures? : a prospective study". Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1343913/.
Testo completoAbstract (sommario):
Background: 33 million people worldwide are infected with HIV, a complex disease that affects many of the processes involved in wound and fracture healing. There is little evidence available to guide acute management of open fractures in these patients and fears of acute and delayed sepsis often inhibit the use of surgical fixation, which may be the most effective way of achieving union. This study addresses the hypothesis that the presence of either HIV or advanced HIV (CD4 count <=350) leads to an increased risk of complications in patients with open fractures treated with surgical stabilization. South Africa has one of the highest rates of both HIV and high energy trauma in the world, so was deemed an appropriate place for the study of this interaction. Methods: This prospective observational study compared surgical fixation of open fractures in HIV positive and negative patients. 133 patients with 135 open fractures fulfilled the inclusion criteria. 86 fractures were in HIV negative and 33 in HIV positive patients. The remaining 16 patients refused HIV tests. 12 HIV positive patients had advanced disease (CD4 <=350), 14 had early disease (CD4 >350), 7 refused CD4 count testing. This cohort was three times larger (number of HIV positive patients) than any similar previously published study. There was no randomised allocation; the treatment of these patients was based on locally developed protocols and was dependent on; fracture type, location and the grade of wound. Patients were followed up either till union had been achieved or for 6 months in tibia/femur fractures, and 3 months in other fractures. The primary outcome was acute wound infection, secondary outcomes tested were fracture union and pin site sepsis. The analysis of the binary nominal data was done using the Chi squared test. In cases where the expected value was less than 5, then the Fisher’s exact test was used. In the assessment of multiple potential risk factors, binary logistic regression was used. Results: Analysis of background characteristics showed that HIV positive and negative populations were broadly similar with regard to demographics, injury type/location and grade of wound. In the analysis of the primary outcome, the risk of wound infection was marginally higher in patients without HIV (22%) as compared to patients with HIV (15%). This difference was small and did not reach statistical significance (n=135, Risk Ratio 0.7, p value 0.40). However, as hypothesized, the infection risk was higher in patients with advanced HIV (26%), compared to patients with early HIV (5%). The numbers, however, were small and this did not reach statistical significance (n=33, Risk Ratio=4.8, P value= 0.12). Sub group analyses, conceived prior to the study, provided strong evidence that patients with Gustilo Anderson grade 1 injuries had a higher risk of wound infection in patients with advanced HIV than controls (HIV negative and early HIV) (n=46, Risk Ratio=6.3, P value =0.02). Of note, departmental guidelines meant that patients with grade 1 injury were not prioritised for theatre and had, on average, a delay of 3.5 days to surgery. The average delay was similar in both HIV positive and negative groups. Analysis of the secondary outcome, nonunion, provided strong evidence that the risk of nonunion was higher in HIV positive than HIV negative patients (n=115, Risk Ratio=4.1, P value=0.04). Interestingly, the patients with advanced HIV had a slightly lower nonunion risk (13%) than patients with early HIV (20%). However the numbers were small and the difference was not statistically significant (n=33, Risk Ratio=0.8, P value=1). The incidence of nonunion was not correlated with the presence of wound infection. The risk of mild pin site sepsis in fractures treated with external fixation was similar in both HIV positive (60%) and negative (67%) patients (n=31, Risk Ratio=0.9, P value=1). An increased risk of severe pin site sepsis was noted in patients with advanced HIV (50%), compared to controls (25%). Although the difference is large, the numbers are small and the difference was not statistically significant (n=28, Risk Ratio=2, P value= 0.31). It would require 160 patients to prove a difference of this size. Conclusions: Data from this study appears to dispute the conclusion of previous studies that suggest that all patients with HIV are at higher risk of wound infection, and therefore internal fixation should be considered with caution. In this study it was only the patients with advanced HIV that showed a small increase in the risk of wound infection. Based on this study the author suggests that early HIV should not be a contraindication to either internal or external fixation in open fractures, due to concerns of wound infection. However, advanced HIV should continue to be considered a relative contraindication to internal fixation, until further data becomes available. Since this finding applied equally to grade 1 (Gustilo Anderson) injuries, the data suggests that any theatre delays in patients with advanced HIV may be detrimental to outcomes. This is contrary to published data that suggests that grade 1 injuries do not need to be prioritised. The data provides strong evidence that HIV leads to an increased risk of non unions. Interestingly, the risk of non union is less in patients with advanced HIV. This may fit with recently published laboratory studies suggesting that the absence of lymphocytes is beneficial to bone healing. Based on this evidence the author suggests that in patients with HIV treatment strategies should be aimed at achieving union, rather than on potentially unfounded concerns of preventing infection. In patients treated with external fixation, the data provides weak evidence of an increased risk of severe pin site sepsis in advanced HIV. This observation may be due to an increased susceptibility to infection, or to problems with bone healing in these patients. Based on this evidence, and the evidence that patients with HIV may be at increased risk of non union, the author suggests that HIV positive patients being treated with external fixators, should be considered for treatment strategies that will prolong the life of the pin bone interface. These may include additional pins, wires and/or the use of hydroxyapatite coated half pins.
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Blackwelder, Reid B. "Wrist Fractures". Digital Commons @ East Tennessee State University, 2000. https://www.amzn.com/072168002X.
Testo completoAbstract (sommario):
Book Summary: The New Edition provides the latest, essential information on the symptoms, diseases, treatments, and procedures most commonly encountered in everyday practice. It features step-by-step clinical guidance for more than 320 common diseases and disorders, as well as explicit guidelines for over 60 office procedures. An organ-system organization, extensive alphabetical index, and cross references within the individual chapters make the information easy to find.
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Blackwelder, Reid B. "Wrist Fractures". Digital Commons @ East Tennessee State University, 1995. https://www.amzn.com/0721651925/.
Testo completoAbstract (sommario):
Book Summary: The 451 chapters in this introductory text are organized by organ system, and provide data on 318 specific diseases and disorders - including their aetiology, symptoms, clinical findings, laboratory tests, differential diagnosis, treatment and follow-up. Nearly 60 office procedures are described in detail, with discussions of indications, contraindications, preparation, equipment, anaesthesia, precautions, technique and follow-up. A complete list of procedures and ICD-9 codes is also included.
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Mdlalose, Lindubuhle. "Immediate versus delayed surgical management of septic mandibular fractures". Thesis, University of the Western Cape, 2015. http://hdl.handle.net/11394/4611.
Testo completoAbstract (sommario):
Magister Scientiae Dentium - MSc(Dent)Aim: The aim of the study was to compare immediate and delayed surgical management of septic mandibular fractures. Introduction: Infected mandible fractures can be treated via diverse protocols. Two recognized protocols are the so-called delayed approached and the immediate approach. In the delayed approach, sepsis is resolved first, followed by surgery. With the immediate approach, the sepsis is first drained, followed by open reduction and internal fixation of the jaw fracture in one continuous surgical procedure. Material and methods: 20 clinical cases where included in the study. Patients were randomly selected and assigned to the two treatment protocol groups. Pain, vital signs, fracture union, fracture stability, surgical time, hospital time, follow-up visits and patients’ demographics were recorded. Results: No statistically significant findings were made in the analysis of the demographic data and clinical parameters relating to the sepsis. The only significant data were related to the surgical time and hospital time. It was found that the advantages of the immediate approach versus the delayed approach related only to shorter surgical time and less days spent in hospital for the immediate approach. Conclusion: Septic mandibular fractures can be managed either by an immediate or a delayed approach. The immediate surgical approach seems to have an advantage over the delayed approach regarding the surgical time and hospital admission days.
Libri sul tema "Fractures"
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Apley, A. Graham. Concise system of orthopaedics and fractures. London: Butterworth Heinemann, 1988.
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Adler, Pierre M., e Jean-François Thovert. Fractures and Fracture Networks. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-017-1599-7.
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Adler, Pierre M. Fractures and Fracture Networks. Dordrecht: Springer Netherlands, 1999.
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Adler, Pierre M. Fractures and fracture networks. Boston: Kluwer, 1999.
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5
A, Wiss Donald, a cura di. Fractures. Philadelphia: Lippincott-Raven, 1998.
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Louis, Solomon, e Apley A. Graham, a cura di. Concise system of orthopaedics and fractures. 2a ed. Oxford: Butterworth-Heinemann, 1994.
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Louis, Solomon, e Apley A. Graham, a cura di. Concise system of orthopaedics and fractures. London: Butterworths, 1988.
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A, Wiss Donald, a cura di. Fractures. 2a ed. Philadelphia: Lippincott Williams & Wilkins, 2006.
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Naudé, Michelle. Fractures. Grahamstown: Aerial Publishing, 2013.
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Charnley, John. The Closed treatment of common fractures. 4a ed. Cambridge: Colt Books in association with The John Charnley Trust, 1999.
Cerca il testo completoCapitoli di libri sul tema "Fractures"
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Zhao, Yu, Yongfa Zhang e Pengfei He. "Formation of Complex Networks". In Hydraulic Fracturing and Rock Mechanics, 231–65. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-2540-7_9.
Testo completoAbstract (sommario):
AbstractWhen a hydraulic fracture interacts with multiple natural fractures (such as bedding planes, faults, weak interlayers, and formation interfaces) in the formation, arrests, bifurcations, crossings, and openings may occur, contributing to forming a complex fracture network (referred as CFN). Shale differs from other types of rocks due to its apparent bedding anisotropy, making it easier to form complex fracture networks during hydraulic fracturing. A mass of field hydraulic fracturing data and laboratory studies have confirmed that the hydraulic fractures generated in shale reservoirs are not bi-wing planar fractures in homogeneous media, but multi-dimensional, asymmetric, and non-planar complex hydraulic fractures (as shown in Fig. 9.1) (Liu et al. in Guti Lixue Xuebao/Acta Mech Solida Sin 37:34–49, 2016; Xiao in Research of hydraulic fracturing dynamic propagation in fractured reservoirs, 2014; Guo and Wang in J Eng Geol 26:118–128, 2016).
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Panneerselvam, Elavenil, Poornima Ravi e B. Sasikala. "Fractures of the Zygomaticomaxillary Complex". In Oral and Maxillofacial Surgery for the Clinician, 1151–99. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-1346-6_56.
Testo completoAbstract (sommario):
AbstractFractures of the Zygomatico Maxillary complex result in cosmetic deformity as well as functional deficits such as altered vision, restricted mouth opening and paresthesia. Accurate restitution of the form and function of the ZMC is challenging because of its multipoint- articulation within the cranio facial skeleton and the difficulty involved in intra-operative assessment of reduction at all articulations. Management of ZMC fractures is unique; (1) The approaches used for reduction may be different from those for fixation (2) Lack of complete visualization of fracture predisposes to over or under reduction resulting in sub optimal outcomes (3) Philosophies of fixation and stabilization are numerous and debatable.With advancements in the imaging technology, armamentarium and refinement of approaches to fracture, there is an emerging trend towards achieving utmost precision in reduction and fixation with minimally invasive surgical principles. This chapter aims at elaborating the biodynamics of ZMC fractures, the evolution of various techniques for reduction & fixation along with their rationale and finally the cutting-edge technology in management of fractured ZMC.
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Jacob, Oommen Aju, e Akhilesh Prathap. "Maxillary Fractures". In Oral and Maxillofacial Surgery for the Clinician, 1125–49. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-1346-6_55.
Testo completoAbstract (sommario):
AbstractFacial trauma is often associated with severe morbidity with respect to loss of function and disfigurement. The maxilla is arguably the most anatomically intricate structure of the face and blunt trauma due to interpersonal violence, motor vehicle accidents, gunshot wounds, industrial accidents and falls contribute to etiology of maxillary fractures. Fractures of the midface are often challenging to the maxillofacial surgeon, due to wide variety of patterns of the fracture, diagnostic challenges and treatment dilemmas. The basic tenet in the management of these fractures is to reconstitute the vertical and horizontal buttresses of the midface, thus reestablishing structure and function. This chapter gives a comprehensive overview on the diagnosis, management and treatment of fractures of the Maxilla.
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van der Pol, Bram, Geert-Jan Rutten, Peter J. J. Gooris e J. Eelco Bergsma. "Orbital Roof Fractures". In Surgery in and around the Orbit, 237–44. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-40697-3_11.
Testo completoAbstract (sommario):
AbstractOrbital roof fractures contribute only to a very limited extent to the number of facial fractures. Apart from a skeletal-orbital fracture, concomitant neurologic and/or ophthalmological injury can be present. Surgical intervention is indicated when specific findings are present. One should be aware of the potential development of late complications. Three illustrative patient cases will be discussed.
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Schwartz, Brandon S., Raymond Pensy, W. Andrew Eglseder e Joshua M. Abzug. "Clavicle Fractures Clavicle fracture". In The Pediatric Upper Extremity, 1259–76. New York, NY: Springer New York, 2015. http://dx.doi.org/10.1007/978-1-4614-8515-5_57.
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Mears, Dana C., e Harry E. Rubash. "Fractures and Fracture Dislocations". In Surgery of the Hip Joint, 85–132. New York, NY: Springer New York, 1987. http://dx.doi.org/10.1007/978-1-4613-8628-5_5.
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Speerin, Robyn, Andréa Marques e Marsha van Oostwaard. "Secondary Fracture Prevention". In Perspectives in Nursing Management and Care for Older Adults, 75–94. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-33484-9_5.
Testo completoAbstract (sommario):
AbstractFragility fractures signal that osteoporosis or osteopenia may be present. These are fractures often sustained through minimal trauma and commonly happen because of a fall from standing height or less. Low bone density due to osteoporosis or osteopenia means that such falls easily result in fractures. Fragility fractures are common, and the incidence is increasing despite global efforts to improve access to secondary prevention. Fragility fractures can lead to hospitalisation, increased risk of death due to complications, worsening chronic health conditions, and frailty. Hip and vertebral fractures are associated with the worst morbidity, mortality, and loss of functional ability. Pain and disability contribute to impaired quality of life.All people aged 50 years and over who sustain fragility fractures should, therefore, undergo investigation for osteoporosis and, if confirmed, be commenced on osteoporosis medication and be supported to participate in behaviours that are known to improve bone health. Organised and coordinated secondary fragility fracture prevention is the best option to prevent further fractures. This approach requires a multidisciplinary team working across care sectors in collaboration with the patient and family to ensure that care is consistent and person-centred and addresses individual need.Many communities across the globe who sustain fragility fractures, however, do not have access to diagnosis and evidence-informed treatment to prevent the next fracture despite strong evidence that access to treatment and supportive follow-up prevent many subsequent fractures. This chapter aims to explore how secondary fractures can be prevented through evidence-based interventions and services.
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Santy-Tomlinson, Julie, Karen Hertz, Anita J. Meehan, Ami Hommel, Andréa Marques, Lingli Peng e Robyn Speerin. "Orthogeriatric and Fragility Fracture Nursing: An Introduction". In Perspectives in Nursing Management and Care for Older Adults, 1–16. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-33484-9_1.
Testo completoAbstract (sommario):
AbstractCaring for people following a fragility fracture is often a complex, medium- to long-term undertaking with several phases from acute care through to rehabilitation and secondary fracture prevention. Fragility fractures can have a substantial impact on older peoples’ longer term function, place of residence and quality of life, sometimes leading to long-term residential or end-of-life care.Health professionals caring for patients following fragility fracture are required to provide evidence-based care and coordinate interdisciplinary care. Not all ‘care’ is provided by those professionals who are identified as nurses, and in the future the boundaries of care-giving roles are likely to be more flexible. For these reasons, this book, although focused on nursing (because a significant amount of fragility facture/orthogeriatric care is provided by them), aims to broaden its relevance to all healthcare professionals who provide care in any part of the world.Avoiding the devastating impacts of fragility fractures drives the need to prevent fractures through secondary fracture prevention. This prevention care is lifelong and usually delivered and monitored by a primary care team including general practitioners, nurses, physiotherapists and other specialist practitioners. The pathway of care is, therefore, dynamic and involves the collaboration of many individuals and agencies.Fragility fractures are important indicators that there may be undiagnosed osteoporosis that requires treatment to prevent further fractures. If left untreated, osteoporosis and associated bone fragility can, ultimately, lead to significant injuries such as hip or femoral fractures, which will require hospital admission and surgery, and severely threaten an individual’s health and well-being. This presents significant challenges for clinical teams in every care setting.The aim of this chapter is to introduce the reader to orthogeriatric and fragility fracture care and to both familiarise them with the multiple topics covered in this book and support the interdisciplinary care team in achieving optimal recovery of independent function and quality of life, with no further fractures for all people with fragility fractures.
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Szendrői, M. "Stress Fractures (Fatigue Fractures, Marsh-Fractures)". In Color Atlas of Clinical Orthopedics, 111–14. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-85561-3_5.
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Li, Yuneng, Liangpeng Lai e Xinbao Wu. "Talar Fractures and Fracture Dislocations". In Fracture Reduction and Fixation Techniques, 403–16. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-24608-2_30.
Testo completoAtti di convegni sul tema "Fractures"
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Wang, Rujun, Wei Zhou, Shiti Cui, Yiming Wu, Hanbing Xu, Hui Ma, Liming Lian et al. "Fully Coupled 3D Geomechanical and Natural Fracture Modeling for Fracture Propagation Simulation in Unconventional Resources". In International Petroleum Technology Conference. IPTC, 2022. http://dx.doi.org/10.2523/iptc-22345-ms.
Testo completoAbstract (sommario):
Abstract Hydraulic fracturing is one of the major production enhancement measures for low permeability fractured reservoirs, where a large amount of oil and gas is stored worldwide. In recent years, during the development and research of these reservoirs, it has been found that the hydraulic fractures formed are no longer the single planar fractures produced by fracturing in homogeneous reservoirs, but complex, non-planar, multiple hydraulic fractures are formed, and the post-fracturing production often shows a positive correlation with the fracture complexity. A large amount of hydraulic fracturing diagnostic data indicates that the interaction between pre-existing natural fractures and induced hydraulic fractures is the key condition leading to the formation of complex hydraulic fractures. Simulation of hydraulic fracture extension in fractured reservoirs requires simulation of fluid pressure changes after the intersection of hydraulic fractures and natural fractures, as well as hydraulic fracture steering and other complex conditions. The traditional hydraulic fracture extension simulation models and theories are no longer suitable for such inhomogeneous reservoir conditions, but the relevant theoretical research is still immature and the interaction between hydraulic fractures and natural fractures during hydraulic fracture extension in fractured reservoirs is still not well understood. It is necessary to further develop theoretical research on hydraulic fracture expansion in fractured reservoirs to understand the mechanism and influencing factors of complex fracture formation, in order to promote the development of field development and theoretical research system of similar reservoirs. In this paper, we simulate and analyze the factors influencing hydraulic fracture expansion in fractured reservoirs. Through a series of numerical simulations, we found that horizontal bedding may open up during hydraulic fracturing to form horizontal fractures, and horizontal and vertical fractures intersect each other to form a complex volumetric fracture network; The distribution length of volumetric fractures increases and the distribution width decreases when the horizontal principal stress difference increases, and the aspect ratio of volumetric fractures increases; the distribution length of volumetric fractures decreases and the width increases when the fracturing construction displacement increases, and the aspect ratio of fractures increases. The residual tensile strength of natural fractures increases, the distribution width of volumetric fractures decreases, the distribution length increases, and the aspect ratio of volumetric fractures increases. The research results can provide some reference and reference for the fracture design and construction of fractured reservoirs.
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Wang, Hui, Wei Zhou, Rangbin Wu, Yamin Shang, Zheng Li, Guohao Li, Xuerui Huangfu et al. "Study on the Influence of DFN on Hydraulic Fracture Propagation for Horizontal Wells in Unconventional Resource - A Case Study from China". In International Petroleum Technology Conference. IPTC, 2024. http://dx.doi.org/10.2523/iptc-23703-ms.
Testo completoAbstract (sommario):
Abstract Fractured reservoirs are distributed with natural fractures of various shapes and sizes, which are the main reservoirs. Due to the uneven distribution of natural fractures, the current main method of fracture reforming is to communicate the natural fractures through hydraulic fractures and to establish a flow channel between the fractures and the wellbore. Clarifying the expansion law of hydraulic fractures in fractured reservoirs is conducive to enhancing the effect of reservoir modification. In this paper, a numerical model of hydraulic fracture extension in a reservoir based on a discontinuous discrete fracture model is established. Firstly, a reservoir fluid-solid coupling stress model is established, and then the discrete fracture model is used to construct the hydraulic fracture, which allows the hydraulic fracture to expand along the initially delineated mesh, and the minimum strain energy density criterion is used to determine the expansion path. According to the different distribution patterns of the seam holes, three reservoir types with fracture characteristics are established in this paper. The simulation results of reservoirs with different natural fracture characteristics show that natural fractures perturb the local stress field and deflect the extension path of hydraulic fractures. The more developed the natural fractures are, the more pronounced the perturbation effect is. According to the different relative positions of hydraulic fractures and natural fractures, they can be divided into frontal repulsion and lateral attraction, which are not conducive to the communication between hydraulic fractures and natural; increasing the net pressure inside the hydraulic fractures can enhance the dominant role of the hydraulic fractures when they intersect with natural fractures, and reduce the degree of deflection, which is conducive to the breakthrough of the natural fractures’ repulsion, and communicate with natural fractures in the direction of the dominant stress. The pressure at the injection point when the hydraulic fracture penetrates the natural fracture is mainly controlled by the flow energy loss in the hydraulic fracture and the leakage rate of the natural fracture. The optimization of the fracturing fluid performance can reduce the penetration pressure and enhance the extension range of the hydraulic fracture. The results of this paper provide references for the fracturing modification evaluation of fractured reservoirs.
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Zhou, Jian, e Chengjin Xue. "Experimental Investigation of Fracture Interaction between Natural Fractures and Hydraulic Fracture in Naturally Fractured Reservoirs". In SPE EUROPEC/EAGE Annual Conference and Exhibition. Society of Petroleum Engineers, 2011. http://dx.doi.org/10.2118/142890-ms.
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Wang, Xiang, Changyu Yao, Xinchun Zhu, Tao Yang, Chang Chang, Yueli Li, Jiaoping Lu, Longjiao Li, Hanbing Xu e Xingning Huang. "Integrated Workflow With Hydraulic Fracture Propagation and Production Simulation Technology for Multi-Stage Length Optimization in Horizontal Wells". In SPE Reservoir Characterisation and Simulation Conference and Exhibition. SPE, 2023. http://dx.doi.org/10.2118/212694-ms.
Testo completoAbstract (sommario):
Abstract Low-permeability gas reservoirs generally have the lowproduction, production rapid productivity decline, and low-ultimate recovery. Staged fracturing is usually conducted for horizontal wells. Hydraulic fracturing technology isgenerally used to improve fracture conductivity and well productivity. How to accurately characterize and simulate the distribution characteristics of hydraulic fracture network in 3D space is particularly important. The stress interference between hydraulic fractures as the objective mechanical behavior in the process of staged fracturing affects the geometry fracture network and the productivity of the reservoir post-fracturing. The hydraulic fractures simulation in natural fractured reservoirs is complex shapes, mainly because natural fractures affect the propagation path of hydraulic fractures. The theoretical model used to describe the hydraulic fracturing in homogeneous reservoirs cannot accurately show the complexity of the spatial morphology of hydraulic fractures in naturally fractured formations. The operatorurgently needs a mechanical model that can show the stress interference behavior between multiple fractures and the direction of hydraulic fracture propagation, and be used to simulate the spatial form of multiple hydraulic fractures in staged fracturing of horizontal wells and their propagation behavior in naturally fractured formations. Aiming at the impact of natural fractures in the reservoir on the propagation path of hydraulic fractures, this paper established a mechanical model for distinguishing interference behavior of natural fractures and hydraulic fractures. And analyzed the stress field at the tip of the hydraulic fracture and the stress field acting on the natural fracture surface based on the theories related to rock mechanics and fracture mechanics. On the basis of coupling the 3D geomechanical model and the 3D Discrete Fracture Network (DFN) model, this paper established the discriminant model for hydraulic fractures penetrating natural fractures in 3D space to conduct hydraulic fracture propagation simulation for the horizontal well. The research results can be used to optimize the hydraulic fracturing treatment design,and provide technical support for the effective production and profitable development of low-permeability reservoir resources.
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Li, Jie, Hanbing Xu, Qiyong Xiong, Yonggang Yi, Wei Zhou, Liwei Zhang, Shengen Chen et al. "Study on the Influence of Natural Fracture Modeling on Hydraulic Fracture Propagation for Horizontal Wells in Unconventional Resource - A Case Study from China". In ADIPEC. SPE, 2022. http://dx.doi.org/10.2118/211690-ms.
Testo completoAbstract (sommario):
Abstract Low-permeability oil reservoirs generally have the low production, production rapid productivity decline, and low-ultimate recovery. Staged fracturing is usually conducted for horizontal wells. Hydraulic fracturing technology is generally used to improve fracture conductivity and well productivity, which is one of the key technologies for Enhance Oil Recovery (EOR). How to accurately characterize and simulate the distribution characteristics of hydraulic fracture network in 3D space is particularly important. The stress interference between hydraulic fractures as the objective mechanical behavior in the process of staged fracturing affects the geometry fracture network and the productivity of the reservoir post-fracturing. The hydraulic fractures simulation in natural fractured reservoirs is complex shapes, mainly because natural fractures affect the propagation path of hydraulic fractures. The theoretical model used to describe the hydraulic fracturing in homogeneous reservoirs cannot accurately show the complexity of the spatial morphology of hydraulic fractures in naturally fractured formations. CNCP (the operator) urgently need a mechanical model that can show the stress interference behavior between multiple fractures and the direction of hydraulic fracture propagation, and be used to simulate the spatial form of multiple hydraulic fractures in staged fracturing of horizontal wells and their propagation behavior in naturally fractured formations. Aiming at the impact of natural fractures in the reservoir on the propagation path of hydraulic fractures, this paper established a mechanical model for distinguishing interference behavior of natural fractures and hydraulic fractures. And analyzed the stress field at the tip of the hydraulic fracture and the stress field acting on the natural fracture surface based on the theories related to rock mechanics and fracture mechanics. On the basis of coupling the 3D geomechanical model and the 3D Discrete Fracture Network (DFN) model, this paper established the discriminant model for hydraulic fractures penetrating natural fractures in 3D space to conduct hydraulic fracture propagation simulation for the horizontal well. The research results can be used to optimize the hydraulic fracturing treatment design, and provide technical support for the effective production and profitable development of low-permeability reservoir resources.
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Wu, Dawei, Yuan Di, Zhijiang Kang e Yu-Shu Wu. "Coupled Geomechanics and Fluid Flow Modeling for Petroleum Reservoirs Accounting for Multi-Scale Fractures". In SPE Reservoir Simulation Conference. SPE, 2023. http://dx.doi.org/10.2118/212247-ms.
Testo completoAbstract (sommario):
Abstract Accurate modeling of fractured reservoirs is very challenging due to the various scales of fractures. The fracture networks may be too complex to be represented using the equivalent continuum model (ECM) or dual porosity-dual permeability (DPDK) model, yet too computational costly to be modeled using the discrete fracture (DFM) or embedded discrete fracture (EDFM) models. This paper proposes a hybrid model that integrates ECM, DPDK, and an integrally embedded discrete fracture model (IEDFM) to account for multi-scale fractures. The hybrid model is applied to investigate the coupled geomechanics-fluid flow process in fractured reservoirs. In the hybrid model, small-scale fractures are upscaled into effective matrix permeability tensor using ECM, medium-scale fractures are considered as an individual continuum using DPDK, and large-scale fractures are explicitly represented using IEDFM. The multiphase flow in effective matrix and fracture continua is modeled using the multi-point flux approximation (MPFA), and fluid exchanges between the anisotropic continua and the large-scale fracture control volumes are precisely calculated using the IEDFM. Empirical models are used to calculate the displacement of natural fractures, and analytical models are used to calculate the aperture changes of hydraulic fractures. The overall deformation of a fractured rock is described using an equivalent method. The coupled geomechanics-fluid flow system is discretized by the finite element-finite volume method (FV-FEM) and solved using the fixed-stress split iterative coupling approach. Several examples are presented to demonstrate the applicability of the proposed method. The hybrid model is first employed to simulate water flooding process in a naturally fractured reservoir with multi-scale fractures. Effects of different scales of fractures, geomechanics coupling and capillary pressure are investigated. A case of producing from horizontal well in a hydraulic fractured tight oil reservoir is then studied, where the hydraulic fractures are modeled explicitly using IEDFM and the stimulation areas around hydraulic fractures are modeled using DPDK. Effects of stimulation area size on the pressure depletion and on the stress evolution process in the reservoir are investigated.
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Wu, Dawei, Yuan Di e Yu-Shu Wu. "Coupled Simulation of Flow and Geomechanics in Fractured Reservoirs Using an Integrally Embedded Discrete Fracture Model". In SPE Reservoir Simulation Conference. SPE, 2021. http://dx.doi.org/10.2118/203967-ms.
Testo completoAbstract (sommario):
Abstract Fluid flow in fractured reservoirs is significantly affected by the effect of geomechanics since fractures can be more stress-sensitive than rock matrix. In this work, we present a flow and geomechanics coupled model for the simulation of fractured reservoirs. The flow model uses the integrally embedded discrete fracture model (IEDFM). This model considers a more improved pressure distribution assumption in the vicinity of fractures compared to traditional EDFM and calculates the matrix-fracture transmissibility semi-analytically. Another advantage of the IEDFM is the capability of modeling flow between matrix and fractures in anisotropic reservoirs. The geomechanical model uses the equivalent continuum approach, which introduces an equivalent material to capture the deformation of both rock matrix and fractures. Constitutive models are established for both natural fractures and hydraulic fractures to capture the stress-dependent fracture stiffness. The force balance equation is discretized by the finite element method (FEM) and coupled with IEDFM to form an iterative coupling simulation approach. A water flooding example in a naturally fractured reservoir and a depletion example from a horizontal well with hydraulic fractures in a tight oil reservoir are investigated to demonstrate the feasibility of the proposed model in coupled flow and geomechanics simulation of fractured reservoirs.
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Hwang, Yunsuk, Jiajing Lin, David Schechter e Ding Zhu. "Predicting Well Performance in Naturally Fractured Reservoir". In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-11604.
Testo completoAbstract (sommario):
Multiple hydraulic fracture treatments in reservoirs with natural fractures create complex fracture networks. Predicting well performance in such a complex fracture network system is an extreme challenge. The statistical nature of natural fracture networks changes the flow characteristics from that of a single linear fracture. Simply using single linear fracture models for individual fractures, and then summing the flow from each fracture as the total flow rate for the network could introduce significant error. In this paper we present a semi-analytical model by a source method to estimate well performance in a complex fracture network system. The method simulates complex fracture systems in a more reasonable approach. The natural fracture system we used is fractal discrete fracture network model. We then added multiple dominating hydraulic fractures to the natural fracture system. Each of the hydraulic fractures is connected to the horizontal wellbore, and some of the natural fractures are connected to the hydraulic fractures through the network description. Each fracture, natural or hydraulically induced, is treated as a series of slab sources. The analytical solution of superposed slab sources provides the base of the approach, and the overall flow from each fracture and the effect between the fractures are modeled by applying the superposition principle to all of the fractures. The fluid inside the natural fractures flows into the hydraulic fractures, and the fluid of the hydraulic fracture from both the reservoir and the natural fractures flows to the wellbore. This paper also shows that non-Darcy flow effects have an impact on the performance of fractured horizontal wells. In hydraulic fracture calculation, non-Darcy flow can be treated as the reduction of permeability in the fracture to a considerably smaller effective permeability. The reduction is about 2% to 20%, due to non-Darcy flow that can result in a low rate. The semi-analytical solution presented can be used to efficiently calculate the flow rate of multistage-fractured wells. Examples are used to illustrate the application of the model to evaluate well performance in reservoirs that contain complex fracture networks.
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Jo, Hyunil. "Optimizing Fracture Spacing to Induce Complex Fractures in a Hydraulically Fractured Horizontal Wellbore". In SPE Americas Unconventional Resources Conference. Society of Petroleum Engineers, 2012. http://dx.doi.org/10.2118/154930-ms.
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Laubach, S. E., e E. R. Monson. "Coring-Induced Fractures: Indicators of Hydraulic Fracture Propagation in a Naturally Fractured Reservoir". In SPE Annual Technical Conference and Exhibition. Society of Petroleum Engineers, 1988. http://dx.doi.org/10.2118/18164-ms.
Testo completoRapporti di organizzazioni sul tema "Fractures"
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Hahn, Kim. Vitreous Fractures. Ames: Iowa State University, Digital Repository, novembre 2015. http://dx.doi.org/10.31274/itaa_proceedings-180814-1260.
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Goel, Dr Divanshu, e Dr Manjeet Singh. HYBRID EXTERNAL FIXATION FOR PROXIMAL TIBIAL FRACTURES. World Wide Journals, febbraio 2023. http://dx.doi.org/10.36106/ijar/1505336.
Testo completoAbstract (sommario):
Introduction: Intraarticular fractures of the tibial plateau and periarticular fractures of the proximal tibia, caused by high energy trauma pose a therapeutic dilemma. Such fractures are associated with extensive soft tissue damage with or without compound injury. The management of such high velocity injuries become a challenge to the trauma surgeons. The goals of these periarticular fractures management are 1. Restoration of joint congruity by anatomic reduction 2. Stable xation of fractures thus allowing early movements 3. Proper care of injured soft tissues. In earlier days uniplanar external xation were used with various complications like pin track infections and decreased stability. In this study we present the use of hybrid external xation system which includes Ilizarov ring xator and AO rod external xator connected with indigenously manufactured connecting clamps and short shafts augmented with or without minimal internal xation. The purpose of this study is to assess the utility of this hybrid external xation system and to analyse the functional outcome, soft tissue healing and fracture union. To assess the performance of the Hybrid External Fixator Aim and Objective: in the treatment of different types of proximal tibial fractures, to evaluate the functional outcome, soft tissue healing and fracture union and radiological outcome, to evaluate the biomechanical and biological advantage of hybrid external xator, to assess the utility of the indigenously made connecting clamps. Material and Method: The study included 21 cases of periarticular fractures of the proximal tibia which were treated by use of 5/8th Ilizarov ring, AO tubular external xator and with indigenously manufactured connecting clamps & short shaft in a hybrid mode. All cases were prospectively followed up and studied. Almost all the cases (99%) had sustained Road trafc Accidents (high velocity injuries) except one case which had sustained injury by fall of cement wall over her leg. Minimum follow up – 1.5 months, maximum follow up – 12 months, mean follow up – 6.42 months. All fractures were followed according to a protocol. All fractures were treated with either CLOSED REDUCTION AND HYBRID EXTERNAL FIXATION OR WITH MINIMAL OPEN REDUCTION AND A HYBRID SYSTEM. The study group was consisted of 16 males (76%) and 5 females (24%) with an average age for males of 43.06 years (range 25 to 65) and for females of 53.4 years (range 41 to 59). All the patients were in the age group of 26 to 65 years, mean age is 43.09. In the present s Result: tudy of 21 cases, the use of Hybrid external xation, as a denite treatment, for high – energy proximal tibia bicondylar fractures proved to be benecial.
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Johns, R. A. Injection through fractures. Office of Scientific and Technical Information (OSTI), maggio 1987. http://dx.doi.org/10.2172/7228925.
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Seol, Yongkoo, Hui Hai Liu e Gudmundur S. Bodvarsson. Effects of dry fractures on matrix diffusion in unsaturated fractured rocks. Office of Scientific and Technical Information (OSTI), gennaio 2002. http://dx.doi.org/10.2172/793765.
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Diomampo, Gracel, P. Relative permeability through fractures. US: Stanford University, Stanford, CA, agosto 2001. http://dx.doi.org/10.2172/896520.
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Buchbinder, Daniel. AO Nasooribitoethmoid (NOE) Fractures. Touch Surgery Publications, marzo 2018. http://dx.doi.org/10.18556/touchsurgery/2018.s0132.
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Duckworth, Mark. Trust fractures run deep. A cura di Charis Palmer. Monash University, aprile 2022. http://dx.doi.org/10.54377/afd5-52d4.
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Maurer, William, e Gregory Deskins. GRl-91-0204 Gas Reservoir Wellbore Orientation - Sensitivity Analysis of Parameters Affecting Production. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), giugno 1991. http://dx.doi.org/10.55274/r0011162.
Testo completoAbstract (sommario):
A parametric study was performed to investigate the effects of numerous well and reservoir parameters on gas well productivity. GMODl, an analytical model for gas production in homogeneous reservoirs, was used to calculate production data for more than 250 sets of reservoir/wellbore parameters. Vertical, horizontal, slant and fractured wells were investigated. Several conclusions were reached as a result of parametric sensitivity analyses. In the right applications, horizontal gas wells produce 3 to 6 times more than vertical wells. At angles above about 60�, slant wells have significantly increased production rates over vertical wells due to increased wellbore exposure. Additionally, horizontal wells intersecting multiple natural fractures can produce significantly more gas than vertical wells intersecting a single fracture.
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Zimmerman, R. W., e G. S. Bodvarsson. Hydraulic conductivity of rock fractures. Office of Scientific and Technical Information (OSTI), ottobre 1994. http://dx.doi.org/10.2172/60784.
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Ahn, J., P. L. Chambre e T. H. Pigford. Radionuclide migration through fractured rock: Effects of multiple fractures and two-member decay chains. Office of Scientific and Technical Information (OSTI), settembre 1985. http://dx.doi.org/10.2172/5752198.
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