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Jing Chao - One of the best experts on this subject based on the ideXlab platform.
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The effect of Clay-Swelling induced cracks on imbibition behavior of marine shale reservoirs
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Mianmo Meng, Yinghao Shen, Gao Zhiye, Tonghui Tian, Jing ChaoAbstract:Abstract Due to the low matrix porosity and permeability of gas shales, the horizontal well drilling and hydraulic fracturing technologies become a necessity to exploit the unconventional shale resources. While a large volume of fracturing fluid is injected into the shale formation to create cracks, some shale reservoirs have a low flowback rate, about which the mechanism is still unclear. In order to clarify the associated fluid retention mechanism, the spontaneous imbibition experiments were conducted, and interpreted with theoretical analyses. Shale imbibition process can be divided into three stages, including initial imbibition, transition and late imbibition stages. Longmaxi Formation shale from Sichuan Basin usually has Clay-Swelling induced cracks, while Niutitang Formation shale from Guizhou province commonly has no such cracks. Shale samples with induced cracks show both higher initial and late imbibition rates. Induced cracks increase new pathways for liquid entering into samples, which lead to a higher initial imbibition rate. Liquid in induced cracks has a large contact area with matrix and liquid moves quickly from cracks into matrix, which causes a higher late imbibition rate. As a contrast, shale samples without induced cracks have a lower initial imbibition rate and a lower late imbibition rate. In addition, the ultimate normalized imbibed volume is higher than the pore volume in shale samples with induced cracks. Furthermore, models were established to interpret the imbibed water saturation with the density of Clay-Swelling induced cracks. Theoretical analyses indicate normalized imbibed volume increases with the density of induced cracks, and the imbibed water volume can be higher than pore volume with enough density of induced cracks. As a result, Clay-Swelling induced cracks could account for the retention of a large volume of fracturing fluid in gas shales, and our research contributes to explaining the mechanism of fracturing liquid retention in shale gas reservoirs.
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The effect of Clay-Swelling induced cracks on shale permeability during liquid imbibition and diffusion
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Mianmo Meng, Yinghao Shen, Tonghui Tian, Jing ChaoAbstract:Abstract Shale gas wells with high production rates usually have large amounts of hydraulic liquid retention, which can cause aqueous phase trapping (APT). However, the APT can be auto-relieved after a well shut-in for a certain period. To clarify its mechanism, the experiments of shale permeability during liquid imbibition and diffusion were conducted. Then, theoretical analysis was interpreted. Samples include the Longmaxi Formation (LMX Fm) from Sichuan province and the Niutitang Formations (NTT Fm) from Sichuan and Guizhou provinces. Permeability during imbibition in Sichuan LMX Fm has decreasing and increasing stages. Increase in permeability is caused by new cracks induced by Clay-Swelling. Only the decreasing stage of permeability occurs during imbibition in NTT Fm, tight sand, and tight volcanic rock because imbibed liquid reduces the gas-flow channel. The relative permeability of gas recovers during liquid diffusion among all samples. The permeability recovers quickly initially, which is caused by liquid migrating from large pores and cracks into small pores. The large pores and cracks have more contribution to permeability than the small pores. Subsequently, permeability nearly keeps constant because liquid migrates among the small pores, which have less influence on permeability. Sichuan LMX Fm has induced cracks, and its gas relative permeability can exceed 1 after liquid diffusion. In theoretical analysis, four types of gas-flow channels are considered, namely, organic pores, inorganic pores, organic cracks, and inorganic cracks. Initial cracks are mainly water wet. Induced cracks include both organic cracks and inorganic cracks. The ratio between inorganic induced cracks and total induced cracks influences permeability. The lower the ratio is, the more evident the permeability increase is during imbibition. The denser the cracks are, the higher the permeability recovery is during liquid diffusion. Overall, the induced cracks can contribute to the relief of APT in shale gas reservoirs.
Mianmo Meng - One of the best experts on this subject based on the ideXlab platform.
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The effect of Clay-Swelling induced cracks on imbibition behavior of marine shale reservoirs
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Mianmo Meng, Yinghao Shen, Gao Zhiye, Tonghui Tian, Jing ChaoAbstract:Abstract Due to the low matrix porosity and permeability of gas shales, the horizontal well drilling and hydraulic fracturing technologies become a necessity to exploit the unconventional shale resources. While a large volume of fracturing fluid is injected into the shale formation to create cracks, some shale reservoirs have a low flowback rate, about which the mechanism is still unclear. In order to clarify the associated fluid retention mechanism, the spontaneous imbibition experiments were conducted, and interpreted with theoretical analyses. Shale imbibition process can be divided into three stages, including initial imbibition, transition and late imbibition stages. Longmaxi Formation shale from Sichuan Basin usually has Clay-Swelling induced cracks, while Niutitang Formation shale from Guizhou province commonly has no such cracks. Shale samples with induced cracks show both higher initial and late imbibition rates. Induced cracks increase new pathways for liquid entering into samples, which lead to a higher initial imbibition rate. Liquid in induced cracks has a large contact area with matrix and liquid moves quickly from cracks into matrix, which causes a higher late imbibition rate. As a contrast, shale samples without induced cracks have a lower initial imbibition rate and a lower late imbibition rate. In addition, the ultimate normalized imbibed volume is higher than the pore volume in shale samples with induced cracks. Furthermore, models were established to interpret the imbibed water saturation with the density of Clay-Swelling induced cracks. Theoretical analyses indicate normalized imbibed volume increases with the density of induced cracks, and the imbibed water volume can be higher than pore volume with enough density of induced cracks. As a result, Clay-Swelling induced cracks could account for the retention of a large volume of fracturing fluid in gas shales, and our research contributes to explaining the mechanism of fracturing liquid retention in shale gas reservoirs.
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The effect of Clay-Swelling induced cracks on shale permeability during liquid imbibition and diffusion
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Mianmo Meng, Yinghao Shen, Tonghui Tian, Jing ChaoAbstract:Abstract Shale gas wells with high production rates usually have large amounts of hydraulic liquid retention, which can cause aqueous phase trapping (APT). However, the APT can be auto-relieved after a well shut-in for a certain period. To clarify its mechanism, the experiments of shale permeability during liquid imbibition and diffusion were conducted. Then, theoretical analysis was interpreted. Samples include the Longmaxi Formation (LMX Fm) from Sichuan province and the Niutitang Formations (NTT Fm) from Sichuan and Guizhou provinces. Permeability during imbibition in Sichuan LMX Fm has decreasing and increasing stages. Increase in permeability is caused by new cracks induced by Clay-Swelling. Only the decreasing stage of permeability occurs during imbibition in NTT Fm, tight sand, and tight volcanic rock because imbibed liquid reduces the gas-flow channel. The relative permeability of gas recovers during liquid diffusion among all samples. The permeability recovers quickly initially, which is caused by liquid migrating from large pores and cracks into small pores. The large pores and cracks have more contribution to permeability than the small pores. Subsequently, permeability nearly keeps constant because liquid migrates among the small pores, which have less influence on permeability. Sichuan LMX Fm has induced cracks, and its gas relative permeability can exceed 1 after liquid diffusion. In theoretical analysis, four types of gas-flow channels are considered, namely, organic pores, inorganic pores, organic cracks, and inorganic cracks. Initial cracks are mainly water wet. Induced cracks include both organic cracks and inorganic cracks. The ratio between inorganic induced cracks and total induced cracks influences permeability. The lower the ratio is, the more evident the permeability increase is during imbibition. The denser the cracks are, the higher the permeability recovery is during liquid diffusion. Overall, the induced cracks can contribute to the relief of APT in shale gas reservoirs.
Jianxi Zhu - One of the best experts on this subject based on the ideXlab platform.
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coupling between Clay Swelling collapse and cationic partition
Geochimica et Cosmochimica Acta, 2020Co-Authors: Huijun Zhou, Meng Chen, Runliang Zhu, Jianxi ZhuAbstract:Abstract The semipermeability of Clay aggregates in mudstones, shales, and marine sediments gives rise to geological ultrafiltration of ions and water. This behavior has been numerically analyzed based on the theory of the electric double layer (EDL). The model of EDL is suited for describing ionic partitions in Clay pore with a width of a few nanometers. However, the interlayer space of smectite might be hardly described by the EDL model. An explicit atomic-scale description is more appropriate for the interlayer space. Besides, Clay Swelling or collapse corresponding to a variation of environmental conditions, and its impact on partitions of water and ions between interlayers and environment, have not been taken into account numerically. With atomic-scale molecular dynamics simulations and thermodynamic integrations based on them, the coupling between montmorillonite Swelling/collapse and partitions of water and cations under different aqueous activity conditions is systematically disclosed here. With the combination of the Horinek’s force field to describe cations and ClayFF force field for atoms in solid layers, consistent Swelling/collapse of Na- and K-montmorillonite with experimental observations as a function of water activity is shown. The Swelling/collapse is connected to the transition between monolayer and bilayer hydration states. Decomposition of the Swelling/collapse free energy shows both energy and entropy contributions are important in determining the thermodynamically stable hydration state. Taking environmental water activity and Na+/K+ ionic activity ratio as variables, a picture of cationic partition in response to those variables is established. It shows, under all circumstances, K+ ions are enriched in montmorillonite, which might explain K+ depletion in pore fluids of sediments. A low water activity improves K+ enrichment in montmorillonite. In addition, cationic partition accompanies variations of hydration states and alters the ionic concentration of the aqueous environment. These results can be applied to explain water and ionic partitions during subsurface water flow and the diagenesis processes of sediments.
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Coupling between Clay Swelling/collapse and cationic partition
Geochimica et Cosmochimica Acta, 2020Co-Authors: Huijun Zhou, Meng Chen, Runliang Zhu, Jianxi ZhuAbstract:Abstract The semipermeability of Clay aggregates in mudstones, shales, and marine sediments gives rise to geological ultrafiltration of ions and water. This behavior has been numerically analyzed based on the theory of the electric double layer (EDL). The model of EDL is suited for describing ionic partitions in Clay pore with a width of a few nanometers. However, the interlayer space of smectite might be hardly described by the EDL model. An explicit atomic-scale description is more appropriate for the interlayer space. Besides, Clay Swelling or collapse corresponding to a variation of environmental conditions, and its impact on partitions of water and ions between interlayers and environment, have not been taken into account numerically. With atomic-scale molecular dynamics simulations and thermodynamic integrations based on them, the coupling between montmorillonite Swelling/collapse and partitions of water and cations under different aqueous activity conditions is systematically disclosed here. With the combination of the Horinek’s force field to describe cations and ClayFF force field for atoms in solid layers, consistent Swelling/collapse of Na- and K-montmorillonite with experimental observations as a function of water activity is shown. The Swelling/collapse is connected to the transition between monolayer and bilayer hydration states. Decomposition of the Swelling/collapse free energy shows both energy and entropy contributions are important in determining the thermodynamically stable hydration state. Taking environmental water activity and Na+/K+ ionic activity ratio as variables, a picture of cationic partition in response to those variables is established. It shows, under all circumstances, K+ ions are enriched in montmorillonite, which might explain K+ depletion in pore fluids of sediments. A low water activity improves K+ enrichment in montmorillonite. In addition, cationic partition accompanies variations of hydration states and alters the ionic concentration of the aqueous environment. These results can be applied to explain water and ionic partitions during subsurface water flow and the diagenesis processes of sediments.
Peter V. Coveney - One of the best experts on this subject based on the ideXlab platform.
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Rule based design of Clay-Swelling inhibitors
Energy and Environmental Science, 2011Co-Authors: James L. Suter, Richard L. Anderson, H. C. Greenwell, Peter V. Coveney, S. CliffeAbstract:In oil and gas drilling operations, drilling fluids perform essential tasks such as lubricating the drill bit, providing hydrostatic pressure and removing drill cuttings. One important function of the drilling fluid is to stop compacted Clay minerals, commonly encountered in drilling operations, from taking up water from the drilling fluids and consequently Swelling. Such a scenario can have an adverse impact on drilling operations and may lead to significantly increased oil well construction costs. With increasingly stringent environmental guidelines determining which Swelling inhibitors are available for use in the oilfield as drilling fluid additives, there is a need to fully understand the mechanisms of Clay hydration in order to design new Swelling inhibitors which conform to evolving regulations. Using a range of computational techniques and analysis, combined with known experimental results, we have devised a set of “rule-based” design criteria for Clay-Swelling inhibitors. To achieve this, we have formulated a hydration energy parameter, which assesses the changes in energy during the step-wise progression from mono- to bi- to trilayers of water in the Clay sheet galleries. This parameter can be used to rationalise and predict the Swelling profiles for Clays containing both cationic and neutral Clay Swelling inhibitors. The rules we have devised are as follows: (i) Cationic inhibitors should be able to replace sodium ions in the interlayer. (ii) Cationic inhibitors should possess a water soluble, hydrophobic backbone. (iii) Cationic inhibitors should have primary di-amine or mono-quaternary amine functionality. (iv) Cationic inhibitors should have little alcohol functionality. (v) The hydrophobic backbone of the cationic inhibitor should be long enough to form a dense monolayer in the interlayer. (vi) For neutral inhibitors, the inhibitor should be a water soluble organic molecule of low molecular weight with well defined domains of relatively high hydrophobicity and small domains of hydrophobicity. Our “rule-based” criteria will facilitate the rational design of improved—and more environmentally acceptable—Clay Swelling inhibitors for oilfield drilling operations.
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Clay Swelling a challenge in the oilfield
Earth-Science Reviews, 2010Co-Authors: Richard L. Anderson, Ian Ratcliffe, H. C. Greenwell, Peter A. Williams, S. Cliffe, Peter V. CoveneyAbstract:Water-based drilling fluids are increasingly being used for oil and gas exploration, and are generally considered to be more environmentally acceptable than oil-based or synthetic-based fluids. Unfortunately, their use facilitates Clay hydration and Swelling. Clay Swelling, which occurs in exposed sedimentary rock formations, can have an adverse impact on drilling operations and may lead to significantly increased oil well construction costs. Minimizing Clay Swelling is therefore an important area attracting a large amount of interest from both academia and industry. To effectively reduce the extent of Clay Swelling the mechanism by which Clay minerals swell needs to be understood so that efficient Swelling inhibitors may be developed. Acceptable Clay Swelling inhibitors must not only significantly reduce Clay hydration, but must also meet increasingly stringent environmental guidelines while remaining cost effective. The development of these inhibitors, which are generally based upon water soluble polymers, therefore represents a challenge to oilfield geochemistry. This review aims to provide a comprehensive understanding of the mechanism by which Clay minerals swell and what steps have been taken in the development of effective and environmentally friendly Clay Swelling inhibitors. (C) 2009 Elsevier B.V. All rights reserved.
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Towards the design of new and improved drilling fluid additives using molecular dynamics simulations
Anais da Academia Brasileira de Ciencias, 2010Co-Authors: Richard L. Anderson, James L. Suter, H. Christopher Greenwel, Rebecca M. Jarvis, Peter V. CoveneyAbstract:During exploration for oil and gas, a technical drilling fluid is used to lubricate the drill bit, maintain hydrostatic pressure, transmit sensor readings, remove rock cuttings and inhibit Swelling of unstable Clay based reactive shale formations. Increasing environmental awareness and resulting legislation has led to the search for new, improved biodegradable drilling fluid components. In the case of additives for Clay Swelling inhibition, an understanding of how existing effective additives interact with Clays must be gained to allow the design of improved molecules. Owing to the disordered nature and nanoscopic dimension of the interlayer pores of Clay minerals, computer simulations have become an increasingly useful tool for studying Clay-Swelling inhibitor interactions. In this work we briefly review the history of the development of technical drilling fluids, the environmental impact of drilling fluids and the use of computer simulations to study the interactions between Clay minerals and Swelling inhibitors. We report on results from some recent large-scale molecular dynamics simulation studies on low molecular weight water-soluble macromolecular inhibitor molecules. The structure and interactions of poly(propylene oxide)-diamine, poly(ethylene glycol) and poly(ethylene oxide)-diacrylate inhibitor molecules with montmorillonite Clay are studied.
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Clay Swelling — A challenge in the oilfield
Earth-Science Reviews, 2009Co-Authors: Richard L. Anderson, Ian Ratcliffe, H. C. Greenwell, Peter A. Williams, S. Cliffe, Peter V. CoveneyAbstract:Water-based drilling fluids are increasingly being used for oil and gas exploration, and are generally considered to be more environmentally acceptable than oil-based or synthetic-based fluids. Unfortunately, their use facilitates Clay hydration and Swelling. Clay Swelling, which occurs in exposed sedimentary rock formations, can have an adverse impact on drilling operations and may lead to significantly increased oil well construction costs. Minimizing Clay Swelling is therefore an important area attracting a large amount of interest from both academia and industry. To effectively reduce the extent of Clay Swelling the mechanism by which Clay minerals swell needs to be understood so that efficient Swelling inhibitors may be developed. Acceptable Clay Swelling inhibitors must not only significantly reduce Clay hydration, but must also meet increasingly stringent environmental guidelines while remaining cost effective. The development of these inhibitors, which are generally based upon water soluble polymers, therefore represents a challenge to oilfield geochemistry. This review aims to provide a comprehensive understanding of the mechanism by which Clay minerals swell and what steps have been taken in the development of effective and environmentally friendly Clay Swelling inhibitors. (C) 2009 Elsevier B.V. All rights reserved.
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Molecular Modelling of The Mechanism of Action of Organic Clay-Swelling Inhibitors
Molecular Simulation, 2001Co-Authors: A. S. Bains, Peter V. Coveney, Edo S. Boek, Samuel J. Williams, M. V. AkbarAbstract:Abstract It is well known that the sodium smectite class of Clays swells macroscopically in contact with water, whereas under normal conditions the potassium form does not. In recent work using molecular simulation methods, we have provided a quantitative explanation both for the Swelling behaviour of sodium smectite Clays and the lack of Swelling of potassium smectites [1]. In the present paper, we apply similar modelling methods to study the mechanism of inhibition of Clay-Swelling by a range of organic molecules. Experimentally, it is known that polyalkylene glycols (polyethers) of intermediate to high relative molecular mass are effective inhibitors of smectite Clay Swelling. We use a range of atomistic simulation techniques, including Monte Carlo and molecular dynamics, to investigate the interactions between a selection of these compounds, water, and a model smectite Clay mineral. These interactions occur by means of organised intercalation of water and organic molecules within the galleries between...
Yinghao Shen - One of the best experts on this subject based on the ideXlab platform.
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The effect of Clay-Swelling induced cracks on imbibition behavior of marine shale reservoirs
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Mianmo Meng, Yinghao Shen, Gao Zhiye, Tonghui Tian, Jing ChaoAbstract:Abstract Due to the low matrix porosity and permeability of gas shales, the horizontal well drilling and hydraulic fracturing technologies become a necessity to exploit the unconventional shale resources. While a large volume of fracturing fluid is injected into the shale formation to create cracks, some shale reservoirs have a low flowback rate, about which the mechanism is still unclear. In order to clarify the associated fluid retention mechanism, the spontaneous imbibition experiments were conducted, and interpreted with theoretical analyses. Shale imbibition process can be divided into three stages, including initial imbibition, transition and late imbibition stages. Longmaxi Formation shale from Sichuan Basin usually has Clay-Swelling induced cracks, while Niutitang Formation shale from Guizhou province commonly has no such cracks. Shale samples with induced cracks show both higher initial and late imbibition rates. Induced cracks increase new pathways for liquid entering into samples, which lead to a higher initial imbibition rate. Liquid in induced cracks has a large contact area with matrix and liquid moves quickly from cracks into matrix, which causes a higher late imbibition rate. As a contrast, shale samples without induced cracks have a lower initial imbibition rate and a lower late imbibition rate. In addition, the ultimate normalized imbibed volume is higher than the pore volume in shale samples with induced cracks. Furthermore, models were established to interpret the imbibed water saturation with the density of Clay-Swelling induced cracks. Theoretical analyses indicate normalized imbibed volume increases with the density of induced cracks, and the imbibed water volume can be higher than pore volume with enough density of induced cracks. As a result, Clay-Swelling induced cracks could account for the retention of a large volume of fracturing fluid in gas shales, and our research contributes to explaining the mechanism of fracturing liquid retention in shale gas reservoirs.
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The effect of Clay-Swelling induced cracks on shale permeability during liquid imbibition and diffusion
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Mianmo Meng, Yinghao Shen, Tonghui Tian, Jing ChaoAbstract:Abstract Shale gas wells with high production rates usually have large amounts of hydraulic liquid retention, which can cause aqueous phase trapping (APT). However, the APT can be auto-relieved after a well shut-in for a certain period. To clarify its mechanism, the experiments of shale permeability during liquid imbibition and diffusion were conducted. Then, theoretical analysis was interpreted. Samples include the Longmaxi Formation (LMX Fm) from Sichuan province and the Niutitang Formations (NTT Fm) from Sichuan and Guizhou provinces. Permeability during imbibition in Sichuan LMX Fm has decreasing and increasing stages. Increase in permeability is caused by new cracks induced by Clay-Swelling. Only the decreasing stage of permeability occurs during imbibition in NTT Fm, tight sand, and tight volcanic rock because imbibed liquid reduces the gas-flow channel. The relative permeability of gas recovers during liquid diffusion among all samples. The permeability recovers quickly initially, which is caused by liquid migrating from large pores and cracks into small pores. The large pores and cracks have more contribution to permeability than the small pores. Subsequently, permeability nearly keeps constant because liquid migrates among the small pores, which have less influence on permeability. Sichuan LMX Fm has induced cracks, and its gas relative permeability can exceed 1 after liquid diffusion. In theoretical analysis, four types of gas-flow channels are considered, namely, organic pores, inorganic pores, organic cracks, and inorganic cracks. Initial cracks are mainly water wet. Induced cracks include both organic cracks and inorganic cracks. The ratio between inorganic induced cracks and total induced cracks influences permeability. The lower the ratio is, the more evident the permeability increase is during imbibition. The denser the cracks are, the higher the permeability recovery is during liquid diffusion. Overall, the induced cracks can contribute to the relief of APT in shale gas reservoirs.