Polymer embedded cadmium sulfide nanoparticles/quantum dots were synthesized by a chemical route ... more Polymer embedded cadmium sulfide nanoparticles/quantum dots were synthesized by a chemical route using polyvinyl alcohol (lmw) as the desired matrix. In an attempt to measure the electrical properties of nano-CdS/Ag samples, we propose that contribution from surface traps are mainly responsible in determining the I~ V and C~ V characteristics in high frequency ranges. To be specific, beyond 1.2 MHz, the
Over the past two decades, Diagnostic Fracture Injection Tests (DFIT) or Injection-Fall-off Fract... more Over the past two decades, Diagnostic Fracture Injection Tests (DFIT) or Injection-Fall-off Fracture Calibration Tests have evolved into a commonly used and reliable technique to evaluate reservoir properties, fracturing parameters and obtain in-situ stresses. Since the introduction of DFIT analysis based on G-function and its derivative, this method has become standard practice for quantifying minimum in-situ stress and leak-off coefficient. However, the pressure decline model that underlies the G-function plot makes two distinct and important assumptions: (1) leak-off is not pressure-dependent and, (2) fracture stiffness (or compliance) is assumed to be constant during fracture closure. Fracture closure is a gradual process that starts when asperities at the fracture tip first come into contact with each other. As pressure declines due to leak-off, more and more of the fracture wall comes into contact. It is important to model this process quantitatively to obtain good estimates o...
Summary A new method is proposed to estimate the compliance and conductivity of induced unpropped... more Summary A new method is proposed to estimate the compliance and conductivity of induced unpropped fractures as a function of the effective stress acting on the fracture from diagnostic-fracture-injection-test (DFIT) data. A hydraulic-fracture resistance to displacement and closure is described by its compliance (or stiffness). Fracture compliance is closely related to the elastic, failure, and hydraulic properties of the rock. Quantifying fracture compliance and fracture conductivity under in-situ conditions is crucial in many Earth-science and engineering applications but is very difficult to achieve. Even though laboratory experiments are used often to measure fracture compliance and conductivity, the measurement results are influenced strongly by how the fracture is created, the specific rock sample obtained, and the degree to which it is preserved. As such, the results may not be representative of field-scale fractures. During the past 2 decades, the DFIT has evolved into a comm...
Journal of Petroleum Science and Engineering, 2016
Diagnostic fracture injection tests (DFITs) are performed in low permeability formations to estim... more Diagnostic fracture injection tests (DFITs) are performed in low permeability formations to estimate the minimum principal stress, formation pressure, permeability, and other parameters. G-function derivative plots are used for diagnosing fracture closure and "non-ideal" reservoir processes. In this study, we use a discrete fracture network hydraulic fracturing simulator to investigate non-ideal DFIT mechanisms. The simulator fully couples fluid flow with the stresses induced by fracture deformation. DFITs are simulated for six different scenarios: a single hydraulic fracture, multiple fracture strands, opening of transverse fractures, near-wellbore complexity, far-field complexity, and height recession. The results indicate that pressure transient behavior commonly ascribed to "fracture height recession," "closure of transverse fractures," and "fracture tip extension" are likely to be misinterpreted by conventional techniques. In previous studies, we found that a curving upward G Â dP/dG plot is caused by changing fracture stiffness after closure and that the closure pressure is best picked when G Â dP/dG begins to deviate upward. In contrast, the commonly used "tangent" method can significantly underestimate the minimum principal stress. The results of this study confirm those prior results. The results suggest that in most cases, it should be possible to use pump-in/flowback tests to confirm estimates of the minimum principal stress. However, if a flow bottleneck occurs at the wellbore due to near-wellbore complexity, the pump-in/ flowback test may be uninterpretable.
The shape of fractures in an elastic medium under different stress distributions have been well s... more The shape of fractures in an elastic medium under different stress distributions have been well studied in the literature, however, the fracture closure process during unloading has not been investigated thoroughly. The fracture surface is normally assumed to be perfectly smooth so that only the width and stress intensity at the fracture tip are critical in the analysis. In reality, the creation of a fracture in a rock seldom produces smooth surfaces and the resulting asperities on the fracture surfaces can impact fracture closure. Correctly modeling this fracture closure behavior has numerous applications in structural engineering and earth sciences. In this article, we present an approach to model fracture closure behavior in a 2D and 3D elastic media. The fracture surface displacements under arbitrary normal load are derived using superposition method. The contact stress, deformation, and fracture volume evolution can be estimated in a computationally efficient manner for various fracture surface properties. When compared with the traditional integral transform methods used to model fracture closure, the superposition method presented in this study produces comparable results with significant less computation time. In addition, with the aid of parallel computation, large scale fracture closure and contact problems can be successfully simulated using our proposed dynamic fracture closure model (DFCM) with very modest computation times.
Journal of Petroleum Science and Engineering, 2018
This study is an attempt to investigate the mechanical behavior of proppant packs deforming under... more This study is an attempt to investigate the mechanical behavior of proppant packs deforming under compression loading. A generalized confined compression test (CCT) was simulated in the present study to investigate the deformation of walnut/ceramic proppants against compression. In this way, the CCT was simulated using ABAQUS explicit code. Unlike ordinary CCT, we obtained permeability of compressed packs through image processing of deformed packs. It was observed that a pack with small particles could markedly withstand deformation, however, at the expense of having lower permeability. Also, selecting a proper proppant pack strongly depends on the prevailing stress regime, where at low stress (<30 MPa) uniform walnut pack has the same permeability as a medley of walnut/ceramic pack. But, at greater stresses (> 40 Mpa), the pack with more ceramic is the best choice. Mixtures of walnut and ceramic proppants showed greatly strength improvement compared to similar cases with pure walnut granules. As a result, making use of such packing is highly recommended due to significant mechanical stability and also being of lower price compared to packs of pure ceramic granules.
Journal of Petroleum Science and Engineering, 2017
Natural fractures, hydraulic fractures, and acid etched fractures have some degree of fracture su... more Natural fractures, hydraulic fractures, and acid etched fractures have some degree of fracture surface roughness. These surface asperities are largely responsible for the hydraulic conductivity of these fractures. This paper presents a model to quantify the fracture closure process that is crucial to predicting the stress dependent conductivity of fracture networks in unconventional reservoirs and estimating the minimum in-situ stress using fracture injection tests. Past studies that have investigated the fracture closure process have assumed the fracture surfaces to be two parallel plates closing in uniformly on rough surfaces and asperities. In reality hydraulically induced fractures are wider in the middle and narrower near the fracture tip. As a result, asperities on the rough fracture surfaces come into contact near the fracture tip well before they do near the middle of the fracture. The evolution of the entire fracture geometry and its impact on stress redistribution and dynamic fracture closure behavior has not yet been investigated. In this paper, we present a method and general algorithms to model the dynamic closure behavior of a hydraulic fracture while accounting for the initial fracture shape, rough fracture surfaces and deformation of asperities in contact. Analytic solutions from linear elastic fracture mechanics for three fracture models (PKN, KGD and radial fracture geometry) are coupled with a general contact law to show that the fracture closure process is a gradual, non-local process, which occurs at the fracture edges initially and then moves progressively to the center of fracture, as the fluid pressure inside the fracture declines. Our study also reveals that the minimum in-situ stress should not be picked at the occurrence of mechanical closure as conventional practice suggests.
During hydraulic fracturing, natural fractures and bedding planes can intersect with growing hydr... more During hydraulic fracturing, natural fractures and bedding planes can intersect with growing hydraulic fractures and form complex fracture networks. This can result in the flow of fluid and proppant in convoluted fracture pathways with highly variable fracture width and height. Existing models of hydraulic fracturing assume a planar fracture geometry and are unable to simulate proppant placement in such complex networks. In this work, we investigate proppant transport in growing fracture networks using a fully three-dimensional, geomechanical fracture flow, network model with the ability to simulate proppant transport. A three-dimensional hydraulic fracturing simulator developed using the displacement discontinuity method is coupled with a network model for proppant transport. The simulator captures the effect of proppant concentration, fracture width, and fluid rheology on proppant transport. The equations for the fracture network geomechanics, the fluid flow, and the proppant tran...
Stranded gas emission from the field production because of the limitations in the pipeline infras... more Stranded gas emission from the field production because of the limitations in the pipeline infrastructure has become one of the major contributors to the greenhouse effects. How to handle the stranded gas is a troublesome problem under the background of global “net-zero” emission efforts. On the other hand, the cost of water for hydraulic fracturing is high and water is not accessible in some areas. The idea of using stranded gas in replace of the water-based fracturing fluid can reduce the gas emission and the cost. This paper presents some novel numerical studies on the feasibility of using stranded natural gas as fracturing fluids. Differences in the fracture creating, proppant placement, and oil/gas/water flowback are compared between natural gas fracturing fluids and water-based fracturing fluids. A fully integrated equation of state compositional hydraulic fracturing and reservoir simulator is used in this paper. Public datasets for the Permian Basin rock and fluid properties ...
This paper demonstrates how simulation of wellbore pressures during different blowout scenarios; ... more This paper demonstrates how simulation of wellbore pressures during different blowout scenarios; borehole stability analysis and solids transport can be applied to the problem of blowout risk assessment. This is a technology area that previously has been overlooked by petroleum geomechanics practitioners. The proposed analysis methodology emphasizes the importance of understanding the transient evolution of the kick within the borehole, as this is a key factor in assessing whether bridging is likely to occur during the events leading up to a blowout. Three representative situations are analyzed and conditions leading to self-killing are reviewed. Analyses of a shallow-gas kick and blowout reproduce the numerous field observations that self-killing is likely from the combination several possible mechanisms – borehole collapse of soft shales, sand erosion leading to cavity collapse in the initially-overpressured aquifer zone, gas depressurization and brine influx. For deeper water sce...
The members of the Hydraulic Fracturing and Sand Control consortium financially supported this re... more The members of the Hydraulic Fracturing and Sand Control consortium financially supported this research. I am very grateful to the participating companies. I would like to offer my sincere thanks to Dr. Jon E. Olson for his constant support and encouragement during this research. I am deeply indebted to Dr. Jon Holder for his help with the experiments and his expert comments on my simulation models. I would also like to express my deep gratitude to Dr. Mukul M. Sharma, head of the abovementioned consortium, for keeping me on track and helping me understand the scope and limitations of this research. I highly appreciate the help, time and support provided by Dr. Maša Prodanović while dealing with the fluid flow aspect of the project. Additionally, I would like to thank my colleagues Farrukh Hamza and Javad Behsresht who helped in conducting the experiments and shared their codes with me respectively. I owe a debt of gratitude to my parents Gurinder and T.S. Manchanda for their persistent support, encouragement and love throughout my life. I also owe a lot to my brother Ramit and wish to thank him for his unconditional love.
his continuous support towards my research, for his patience, motivation, and immense knowledge. ... more his continuous support towards my research, for his patience, motivation, and immense knowledge. I could not have imagined having a better advisor and mentor for my graduate study. My sincere thanks also goes to Mr. Rod Russell, who has helped me all along, to build my experimental setup. Without his efforts and guidance, it would not have been possible to complete this work. Finally, I thank my friends, Robin Singh, Donna Vakharia,
Proppant mapping is critical for optimizing fracture treatment design and improving wells’ produc... more Proppant mapping is critical for optimizing fracture treatment design and improving wells’ productivity. An electrode-based resistivity tool concept was developed earlier for proppant mapping in cased-hole wells. An array of insulating gaps is installed and cemented in place as a permanent part of the casing string. The electrical measurements are performed by imposing a voltage across each insulating gap, one at a time, before and after hydraulic fracture operations. The voltages across other insulating gaps near the transmitter gap are recorded. The method relies on direct excitation of the casing, which is expected to overcome the severe limitations of induction tools in cased-hole wells. A forward model based on a finite volume method has been developed to simulate the tool’s response to one or multiple fractures. To enable the implementation of such a practical system in multistage fractured horizontal wells, a fast and robust inversion approach is required. To that end, we hav...
The productivity of a hydraulically fractured well depends on the fracture geometry and fracture–... more The productivity of a hydraulically fractured well depends on the fracture geometry and fracture–wellbore connectivity. Unlike other fracture diagnostics techniques, flowback tracer response will be dominated only by the fractures, which are open and connected to the wellbore. Single well chemical tracer field tests have been used for hydraulic fracture diagnostics to estimate the stagewise production contribution. In this study, a chemical tracer flowback analysis is presented to estimate the fraction of the created fracture area, which is open and connected to the wellbore. A geomechanics coupled fluid flow and tracer transport model is developed to analyze the impact of (a) fracture geometry, (b) fracture propagation and closure effects, and (c) fracture complexity on the tracer response curves. Tracer injection and flowback in a complex fracture network is modeled with the help of an effective model. Multiple peaks in the tracer response curves can be explained by the closure of...
The productivity of a hydraulically fractured well depends on the fracture geometry and fracture–... more The productivity of a hydraulically fractured well depends on the fracture geometry and fracture–wellbore connectivity. Unlike other fracture diagnostics techniques, flowback tracer response will be dominated only by the fractures, which are open and connected to the wellbore. Single well chemical tracer field tests have been used for hydraulic fracture diagnostics to estimate the stagewise production contribution. In this study, a chemical tracer flowback analysis is presented to estimate the fraction of the created fracture area, which is open and connected to the wellbore. A geomechanics coupled fluid flow and tracer transport model is developed to analyze the impact of (a) fracture geometry, (b) fracture propagation and closure effects, and (c) fracture complexity on the tracer response curves. Tracer injection and flowback in a complex fracture network is modeled with the help of an effective model. Multiple peaks in the tracer response curves can be explained by the closure of...
The objective of this work is to develop an engineering framework for the exploitation of microor... more The objective of this work is to develop an engineering framework for the exploitation of microorganisms to enhance oil recovery. Specific goals include: (i) the production, isolation, chemical characterization and study of the physical properties of microbially produced surfactants, (ii) development of simuh, tors for MEOR and i", ' (..._. (iii) model studies in sandstone cores for the characterization of the interactions!..
... A review of fracture-diagnostic data col-lected from various wells in different areas (for co... more ... A review of fracture-diagnostic data col-lected from various wells in different areas (for conventional gel fracs and waterfracs) suggested that ... B. Gadde, U. of Texas at Austin; Richard Sullivan, SPE, Richard Sigal, SPE, Robin Fielder, SPE, and David Copeland, SPE, Anadarko ...
Cationic ion-exchange resins, particularly the macroporous variety, are versatile catalysts which... more Cationic ion-exchange resins, particularly the macroporous variety, are versatile catalysts which offer several advantages over the homogeneous acid catalysts with respect to corrosion, product recovery, selectivity, etc. In some cases, such as etherification of phenols/naphthols with isobutylene/isoamylene, resin catalysts allow the reaction to occur, but the homogeneous catalysts fail. A noteworthy development has been the use of distillation column reactors (DCR) where the exothermicity of the reaction is usefully employed and the resin inventory, for a specified level of conversion and productivity, can be significantly reduced. The availability of methyl-tert-butyl ether and tert-amyl methyl ether allows tert-butyl and tert-amyl derivatives of phenolic substances to be produced with the attendant advantages. The removal of low concentrations of substances like formaldehyde in aqueous medium offers new opportunities for resin catalysts and methylal formation with methanol in DCR has been realized in bringing down formaldehyde concentration from 1 to 2% (wt) to as low as 0.02%. Resin catalysts are useful for oligomerization of olefins like isobutylene, isoamylene, a-methyl styrene, etc.; cross-dimerization of olefins for making precursors for synthetic musks, can also be advantageously carried out. The alkylation of dissolved polyvinyl phenol with isobutylene, with resin catalysts is interesting in several ways. Many close-boiling substances, such as isomeric and non-isomeric phenolic substances, can be separated through selective reactions based on resin catalysts.
Polymer embedded cadmium sulfide nanoparticles/quantum dots were synthesized by a chemical route ... more Polymer embedded cadmium sulfide nanoparticles/quantum dots were synthesized by a chemical route using polyvinyl alcohol (lmw) as the desired matrix. In an attempt to measure the electrical properties of nano-CdS/Ag samples, we propose that contribution from surface traps are mainly responsible in determining the I~ V and C~ V characteristics in high frequency ranges. To be specific, beyond 1.2 MHz, the
Over the past two decades, Diagnostic Fracture Injection Tests (DFIT) or Injection-Fall-off Fract... more Over the past two decades, Diagnostic Fracture Injection Tests (DFIT) or Injection-Fall-off Fracture Calibration Tests have evolved into a commonly used and reliable technique to evaluate reservoir properties, fracturing parameters and obtain in-situ stresses. Since the introduction of DFIT analysis based on G-function and its derivative, this method has become standard practice for quantifying minimum in-situ stress and leak-off coefficient. However, the pressure decline model that underlies the G-function plot makes two distinct and important assumptions: (1) leak-off is not pressure-dependent and, (2) fracture stiffness (or compliance) is assumed to be constant during fracture closure. Fracture closure is a gradual process that starts when asperities at the fracture tip first come into contact with each other. As pressure declines due to leak-off, more and more of the fracture wall comes into contact. It is important to model this process quantitatively to obtain good estimates o...
Summary A new method is proposed to estimate the compliance and conductivity of induced unpropped... more Summary A new method is proposed to estimate the compliance and conductivity of induced unpropped fractures as a function of the effective stress acting on the fracture from diagnostic-fracture-injection-test (DFIT) data. A hydraulic-fracture resistance to displacement and closure is described by its compliance (or stiffness). Fracture compliance is closely related to the elastic, failure, and hydraulic properties of the rock. Quantifying fracture compliance and fracture conductivity under in-situ conditions is crucial in many Earth-science and engineering applications but is very difficult to achieve. Even though laboratory experiments are used often to measure fracture compliance and conductivity, the measurement results are influenced strongly by how the fracture is created, the specific rock sample obtained, and the degree to which it is preserved. As such, the results may not be representative of field-scale fractures. During the past 2 decades, the DFIT has evolved into a comm...
Journal of Petroleum Science and Engineering, 2016
Diagnostic fracture injection tests (DFITs) are performed in low permeability formations to estim... more Diagnostic fracture injection tests (DFITs) are performed in low permeability formations to estimate the minimum principal stress, formation pressure, permeability, and other parameters. G-function derivative plots are used for diagnosing fracture closure and "non-ideal" reservoir processes. In this study, we use a discrete fracture network hydraulic fracturing simulator to investigate non-ideal DFIT mechanisms. The simulator fully couples fluid flow with the stresses induced by fracture deformation. DFITs are simulated for six different scenarios: a single hydraulic fracture, multiple fracture strands, opening of transverse fractures, near-wellbore complexity, far-field complexity, and height recession. The results indicate that pressure transient behavior commonly ascribed to "fracture height recession," "closure of transverse fractures," and "fracture tip extension" are likely to be misinterpreted by conventional techniques. In previous studies, we found that a curving upward G Â dP/dG plot is caused by changing fracture stiffness after closure and that the closure pressure is best picked when G Â dP/dG begins to deviate upward. In contrast, the commonly used "tangent" method can significantly underestimate the minimum principal stress. The results of this study confirm those prior results. The results suggest that in most cases, it should be possible to use pump-in/flowback tests to confirm estimates of the minimum principal stress. However, if a flow bottleneck occurs at the wellbore due to near-wellbore complexity, the pump-in/ flowback test may be uninterpretable.
The shape of fractures in an elastic medium under different stress distributions have been well s... more The shape of fractures in an elastic medium under different stress distributions have been well studied in the literature, however, the fracture closure process during unloading has not been investigated thoroughly. The fracture surface is normally assumed to be perfectly smooth so that only the width and stress intensity at the fracture tip are critical in the analysis. In reality, the creation of a fracture in a rock seldom produces smooth surfaces and the resulting asperities on the fracture surfaces can impact fracture closure. Correctly modeling this fracture closure behavior has numerous applications in structural engineering and earth sciences. In this article, we present an approach to model fracture closure behavior in a 2D and 3D elastic media. The fracture surface displacements under arbitrary normal load are derived using superposition method. The contact stress, deformation, and fracture volume evolution can be estimated in a computationally efficient manner for various fracture surface properties. When compared with the traditional integral transform methods used to model fracture closure, the superposition method presented in this study produces comparable results with significant less computation time. In addition, with the aid of parallel computation, large scale fracture closure and contact problems can be successfully simulated using our proposed dynamic fracture closure model (DFCM) with very modest computation times.
Journal of Petroleum Science and Engineering, 2018
This study is an attempt to investigate the mechanical behavior of proppant packs deforming under... more This study is an attempt to investigate the mechanical behavior of proppant packs deforming under compression loading. A generalized confined compression test (CCT) was simulated in the present study to investigate the deformation of walnut/ceramic proppants against compression. In this way, the CCT was simulated using ABAQUS explicit code. Unlike ordinary CCT, we obtained permeability of compressed packs through image processing of deformed packs. It was observed that a pack with small particles could markedly withstand deformation, however, at the expense of having lower permeability. Also, selecting a proper proppant pack strongly depends on the prevailing stress regime, where at low stress (<30 MPa) uniform walnut pack has the same permeability as a medley of walnut/ceramic pack. But, at greater stresses (> 40 Mpa), the pack with more ceramic is the best choice. Mixtures of walnut and ceramic proppants showed greatly strength improvement compared to similar cases with pure walnut granules. As a result, making use of such packing is highly recommended due to significant mechanical stability and also being of lower price compared to packs of pure ceramic granules.
Journal of Petroleum Science and Engineering, 2017
Natural fractures, hydraulic fractures, and acid etched fractures have some degree of fracture su... more Natural fractures, hydraulic fractures, and acid etched fractures have some degree of fracture surface roughness. These surface asperities are largely responsible for the hydraulic conductivity of these fractures. This paper presents a model to quantify the fracture closure process that is crucial to predicting the stress dependent conductivity of fracture networks in unconventional reservoirs and estimating the minimum in-situ stress using fracture injection tests. Past studies that have investigated the fracture closure process have assumed the fracture surfaces to be two parallel plates closing in uniformly on rough surfaces and asperities. In reality hydraulically induced fractures are wider in the middle and narrower near the fracture tip. As a result, asperities on the rough fracture surfaces come into contact near the fracture tip well before they do near the middle of the fracture. The evolution of the entire fracture geometry and its impact on stress redistribution and dynamic fracture closure behavior has not yet been investigated. In this paper, we present a method and general algorithms to model the dynamic closure behavior of a hydraulic fracture while accounting for the initial fracture shape, rough fracture surfaces and deformation of asperities in contact. Analytic solutions from linear elastic fracture mechanics for three fracture models (PKN, KGD and radial fracture geometry) are coupled with a general contact law to show that the fracture closure process is a gradual, non-local process, which occurs at the fracture edges initially and then moves progressively to the center of fracture, as the fluid pressure inside the fracture declines. Our study also reveals that the minimum in-situ stress should not be picked at the occurrence of mechanical closure as conventional practice suggests.
During hydraulic fracturing, natural fractures and bedding planes can intersect with growing hydr... more During hydraulic fracturing, natural fractures and bedding planes can intersect with growing hydraulic fractures and form complex fracture networks. This can result in the flow of fluid and proppant in convoluted fracture pathways with highly variable fracture width and height. Existing models of hydraulic fracturing assume a planar fracture geometry and are unable to simulate proppant placement in such complex networks. In this work, we investigate proppant transport in growing fracture networks using a fully three-dimensional, geomechanical fracture flow, network model with the ability to simulate proppant transport. A three-dimensional hydraulic fracturing simulator developed using the displacement discontinuity method is coupled with a network model for proppant transport. The simulator captures the effect of proppant concentration, fracture width, and fluid rheology on proppant transport. The equations for the fracture network geomechanics, the fluid flow, and the proppant tran...
Stranded gas emission from the field production because of the limitations in the pipeline infras... more Stranded gas emission from the field production because of the limitations in the pipeline infrastructure has become one of the major contributors to the greenhouse effects. How to handle the stranded gas is a troublesome problem under the background of global “net-zero” emission efforts. On the other hand, the cost of water for hydraulic fracturing is high and water is not accessible in some areas. The idea of using stranded gas in replace of the water-based fracturing fluid can reduce the gas emission and the cost. This paper presents some novel numerical studies on the feasibility of using stranded natural gas as fracturing fluids. Differences in the fracture creating, proppant placement, and oil/gas/water flowback are compared between natural gas fracturing fluids and water-based fracturing fluids. A fully integrated equation of state compositional hydraulic fracturing and reservoir simulator is used in this paper. Public datasets for the Permian Basin rock and fluid properties ...
This paper demonstrates how simulation of wellbore pressures during different blowout scenarios; ... more This paper demonstrates how simulation of wellbore pressures during different blowout scenarios; borehole stability analysis and solids transport can be applied to the problem of blowout risk assessment. This is a technology area that previously has been overlooked by petroleum geomechanics practitioners. The proposed analysis methodology emphasizes the importance of understanding the transient evolution of the kick within the borehole, as this is a key factor in assessing whether bridging is likely to occur during the events leading up to a blowout. Three representative situations are analyzed and conditions leading to self-killing are reviewed. Analyses of a shallow-gas kick and blowout reproduce the numerous field observations that self-killing is likely from the combination several possible mechanisms – borehole collapse of soft shales, sand erosion leading to cavity collapse in the initially-overpressured aquifer zone, gas depressurization and brine influx. For deeper water sce...
The members of the Hydraulic Fracturing and Sand Control consortium financially supported this re... more The members of the Hydraulic Fracturing and Sand Control consortium financially supported this research. I am very grateful to the participating companies. I would like to offer my sincere thanks to Dr. Jon E. Olson for his constant support and encouragement during this research. I am deeply indebted to Dr. Jon Holder for his help with the experiments and his expert comments on my simulation models. I would also like to express my deep gratitude to Dr. Mukul M. Sharma, head of the abovementioned consortium, for keeping me on track and helping me understand the scope and limitations of this research. I highly appreciate the help, time and support provided by Dr. Maša Prodanović while dealing with the fluid flow aspect of the project. Additionally, I would like to thank my colleagues Farrukh Hamza and Javad Behsresht who helped in conducting the experiments and shared their codes with me respectively. I owe a debt of gratitude to my parents Gurinder and T.S. Manchanda for their persistent support, encouragement and love throughout my life. I also owe a lot to my brother Ramit and wish to thank him for his unconditional love.
his continuous support towards my research, for his patience, motivation, and immense knowledge. ... more his continuous support towards my research, for his patience, motivation, and immense knowledge. I could not have imagined having a better advisor and mentor for my graduate study. My sincere thanks also goes to Mr. Rod Russell, who has helped me all along, to build my experimental setup. Without his efforts and guidance, it would not have been possible to complete this work. Finally, I thank my friends, Robin Singh, Donna Vakharia,
Proppant mapping is critical for optimizing fracture treatment design and improving wells’ produc... more Proppant mapping is critical for optimizing fracture treatment design and improving wells’ productivity. An electrode-based resistivity tool concept was developed earlier for proppant mapping in cased-hole wells. An array of insulating gaps is installed and cemented in place as a permanent part of the casing string. The electrical measurements are performed by imposing a voltage across each insulating gap, one at a time, before and after hydraulic fracture operations. The voltages across other insulating gaps near the transmitter gap are recorded. The method relies on direct excitation of the casing, which is expected to overcome the severe limitations of induction tools in cased-hole wells. A forward model based on a finite volume method has been developed to simulate the tool’s response to one or multiple fractures. To enable the implementation of such a practical system in multistage fractured horizontal wells, a fast and robust inversion approach is required. To that end, we hav...
The productivity of a hydraulically fractured well depends on the fracture geometry and fracture–... more The productivity of a hydraulically fractured well depends on the fracture geometry and fracture–wellbore connectivity. Unlike other fracture diagnostics techniques, flowback tracer response will be dominated only by the fractures, which are open and connected to the wellbore. Single well chemical tracer field tests have been used for hydraulic fracture diagnostics to estimate the stagewise production contribution. In this study, a chemical tracer flowback analysis is presented to estimate the fraction of the created fracture area, which is open and connected to the wellbore. A geomechanics coupled fluid flow and tracer transport model is developed to analyze the impact of (a) fracture geometry, (b) fracture propagation and closure effects, and (c) fracture complexity on the tracer response curves. Tracer injection and flowback in a complex fracture network is modeled with the help of an effective model. Multiple peaks in the tracer response curves can be explained by the closure of...
The productivity of a hydraulically fractured well depends on the fracture geometry and fracture–... more The productivity of a hydraulically fractured well depends on the fracture geometry and fracture–wellbore connectivity. Unlike other fracture diagnostics techniques, flowback tracer response will be dominated only by the fractures, which are open and connected to the wellbore. Single well chemical tracer field tests have been used for hydraulic fracture diagnostics to estimate the stagewise production contribution. In this study, a chemical tracer flowback analysis is presented to estimate the fraction of the created fracture area, which is open and connected to the wellbore. A geomechanics coupled fluid flow and tracer transport model is developed to analyze the impact of (a) fracture geometry, (b) fracture propagation and closure effects, and (c) fracture complexity on the tracer response curves. Tracer injection and flowback in a complex fracture network is modeled with the help of an effective model. Multiple peaks in the tracer response curves can be explained by the closure of...
The objective of this work is to develop an engineering framework for the exploitation of microor... more The objective of this work is to develop an engineering framework for the exploitation of microorganisms to enhance oil recovery. Specific goals include: (i) the production, isolation, chemical characterization and study of the physical properties of microbially produced surfactants, (ii) development of simuh, tors for MEOR and i", ' (..._. (iii) model studies in sandstone cores for the characterization of the interactions!..
... A review of fracture-diagnostic data col-lected from various wells in different areas (for co... more ... A review of fracture-diagnostic data col-lected from various wells in different areas (for conventional gel fracs and waterfracs) suggested that ... B. Gadde, U. of Texas at Austin; Richard Sullivan, SPE, Richard Sigal, SPE, Robin Fielder, SPE, and David Copeland, SPE, Anadarko ...
Cationic ion-exchange resins, particularly the macroporous variety, are versatile catalysts which... more Cationic ion-exchange resins, particularly the macroporous variety, are versatile catalysts which offer several advantages over the homogeneous acid catalysts with respect to corrosion, product recovery, selectivity, etc. In some cases, such as etherification of phenols/naphthols with isobutylene/isoamylene, resin catalysts allow the reaction to occur, but the homogeneous catalysts fail. A noteworthy development has been the use of distillation column reactors (DCR) where the exothermicity of the reaction is usefully employed and the resin inventory, for a specified level of conversion and productivity, can be significantly reduced. The availability of methyl-tert-butyl ether and tert-amyl methyl ether allows tert-butyl and tert-amyl derivatives of phenolic substances to be produced with the attendant advantages. The removal of low concentrations of substances like formaldehyde in aqueous medium offers new opportunities for resin catalysts and methylal formation with methanol in DCR has been realized in bringing down formaldehyde concentration from 1 to 2% (wt) to as low as 0.02%. Resin catalysts are useful for oligomerization of olefins like isobutylene, isoamylene, a-methyl styrene, etc.; cross-dimerization of olefins for making precursors for synthetic musks, can also be advantageously carried out. The alkylation of dissolved polyvinyl phenol with isobutylene, with resin catalysts is interesting in several ways. Many close-boiling substances, such as isomeric and non-isomeric phenolic substances, can be separated through selective reactions based on resin catalysts.
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