Gas production from multiple coal seams has become common practice in many coal basins around the world. Although gas production rates are typically enhanced, the economic viability of such practice is not well studie...Gas production from multiple coal seams has become common practice in many coal basins around the world. Although gas production rates are typically enhanced, the economic viability of such practice is not well studied. In order to investigate the technical and economic feasibility of multiple coal seams production, reservoir simulation integrated with economics modelling was performed to study the effect of important reservoir properties of the secondary coal seam on production and economic performance using both vertical and horizontal wells. The results demonstrated that multiple seam gas production of using both vertical and horizontal wells have competitive advantage over single layer production under most scenarios. Gas content and permeability of the secondary coal seam are the most important reservoir properties that have impact on the economic feasibility of multiple seam gas production. The comparison of vertical well and horizontal well performance showed that horizontal well is more economically attractive for both single well and gas field. Moreover, wellhead price is the most sensitive to the economic performance, followed by operating costs and government subsidy. Although the results of reservoir simulation combined with economic analysis are subject to assumptions, multiple seam gas production is more likely to maintain profitability compared with single layer production.展开更多
CO_(2)geological storage and utilization(CGSU)is considered a far-reaching technique to meet the demand of increasing energy supply and decreasing CO_(2)emissions.For CGSUs related to shale gas reservoirs,experimental...CO_(2)geological storage and utilization(CGSU)is considered a far-reaching technique to meet the demand of increasing energy supply and decreasing CO_(2)emissions.For CGSUs related to shale gas reservoirs,experimental investigations have attracted variable methodologies,among which low-field NMR(LF-NMR)is a promising method and is playing an increasingly key role in reservoir characterization.Herein,the application of this nondestructive,sensitive,and quick LF-NMR technique in characterizing CGSU behavior in shale gas reservoirs is reviewed.First,the basic principle of LF-NMR for 1H-fluid detection is introduced,which is the theoretical foundation of the reviewed achievements in this paper.Then,the reviewed works are related to the LF-NMR-based measurements of CH_(4)adsorption capacity and the CO_(2)-CH_(4)interaction in shale,as well as the performance on CO_(2)sequestration and simultaneous enhanced gas recovery from shale.Basically,the reviewed achievements have exhibited a large potential for LF-NMR application in CGSUs related to shale gas reservoirs,although some limitations and deficiencies still need to be improved.Accordingly,some suggestions are proposed for a more responsible development of the LF-NMR technique.Hopefully,this review is helpful in promoting the expanding application of the LF-NMR technique in CGSU implementation in shale gas reservoirs.展开更多
1 Introduction All over the world,with the intense longing for carbon emission reduction and the demand for clean energy(Feng et al.,2020;Iddphonce et al.,2020;Zhao et al.,2022),a promising and far-reaching technology...1 Introduction All over the world,with the intense longing for carbon emission reduction and the demand for clean energy(Feng et al.,2020;Iddphonce et al.,2020;Zhao et al.,2022),a promising and far-reaching technology called CO_(2) geological storage and utilization(CGSU)has attracted increasing attention(Iddphonce et al.,2020;Ma et al.,2020).This CGSU technique enjoys huge potential and broad prospect,because it usually enables dual rewarding consequences–to sequester CO_(2) and to acquire energy from geological formations,such as geothermal rock,oil and gas reservoirs(Iddphonce et al.,2020;Klewiah et al.,2020;Liu et al.,2020).In fact,the CGSU has been followed by interest of scientists all around world since geological storage was first proposed in the 1970s as a way to dispose of the CO_(2).Meanwhile,the CGSU technique is not mature enough and usually involves a complicated THMC coupled process,making it necessary to deploy more insightful investigations to boost the development of CGUS technique in a robust,safe and cost-effective manner(Liu et al.,2021b;Zhao et al.,2021;Liu et al.,2023).Basically,this theme is expected to enhance the knowledge about the crucial role of CGSU in achieving the carbon emission reduction–an issue concerned to the world(Liu et al.,2021a;Xie et al.,2021;Zhao et al.,2021;Zhao et al.,2022).Therefore,this special issue is organized and tends to present newest achievements regarding the CGSU,such as the theory expansion,economic analysis,experimental investigation and numerical simulation.展开更多
Proppant is a key material in the hydraulic fracturing process,which has been widely used in unconventional oil exploitation.Normal proppants are easy to sedimentate and accumulate at the entrance of shale fracture,wh...Proppant is a key material in the hydraulic fracturing process,which has been widely used in unconventional oil exploitation.Normal proppants are easy to sedimentate and accumulate at the entrance of shale fracture,which will block the diversion of water,oil and gas.Coated proppants(CPs) are fabricated by coating resin on normal ceramic proppants through a simple method,which is dramatically enhanced the supporting properties in shale fracture and easy to scale up.Compared with uncoated ceramic proppants,the self-suspension ability of CPs is ~11 times higher,which are able to migrate and distribute farther and deeper inside the fracture.At the same time,Coating enhanced the 23.7% of adhesive force in maximum,which makes the CPs easier to adhere on the fracture surface to supportthe shale fracture.Besides,the liquid conductivity of CPs is 60% higher than uncoated ceramic proppants at13.6 MPa pressure.This method is expected to fabricated varieties of proppantsfor shale fracture supporting to improve the exploration of unconventional oil and gas resources.展开更多
Regarding CO_(2)enhanced shale gas recovery,this work focuses on changes in the multiphase(free/adsorbed)CH_(4)in the process of CO_(2)enhanced shale gas recovery,by utilizing a rigorous numerical model with real geol...Regarding CO_(2)enhanced shale gas recovery,this work focuses on changes in the multiphase(free/adsorbed)CH_(4)in the process of CO_(2)enhanced shale gas recovery,by utilizing a rigorous numerical model with real geological parameters.This work studies nine injection well(IW)and CH_(4)production well(PW)combinations of CO_(2)to determine the influence of IW and PW locations on the dynamic interaction of multiphase CH_(4)during 10000 d of CO_(2)injection.The results indicate that the content of both the adsorbed CH_(4)and free CH_(4)is strongly variable before(and during)the CO_(2)-CH_(4)displacement.In addition,during the simulation process,the proportion of the adsorbed CH_(4)among all extracted CH_(4)phases dynamically increases first and then tends to stabilize at 70%-80%.Moreover,the IW-PWs combinations signifi-cantly affect the outcomes of CO_(2)enhanced shale gas recovery-for both the proportion of adsorbed/free CH_(4)and the recovery efficiency.A longer IW-PW distance enables more adsorbed CH_(4)to be recovered but results in a lower efficiency of shale gas recovery.Basically,a shorter IW-PWs distance helps recover CH_(4)via CO_(2)injection if the IW targets the bottom layer of the Wufeng-Longmaxi shale formation.This numerical work expands the knowl-edge of CO_(2)enhanced gas recovery from depleted shale reservoirs.展开更多
文摘Gas production from multiple coal seams has become common practice in many coal basins around the world. Although gas production rates are typically enhanced, the economic viability of such practice is not well studied. In order to investigate the technical and economic feasibility of multiple coal seams production, reservoir simulation integrated with economics modelling was performed to study the effect of important reservoir properties of the secondary coal seam on production and economic performance using both vertical and horizontal wells. The results demonstrated that multiple seam gas production of using both vertical and horizontal wells have competitive advantage over single layer production under most scenarios. Gas content and permeability of the secondary coal seam are the most important reservoir properties that have impact on the economic feasibility of multiple seam gas production. The comparison of vertical well and horizontal well performance showed that horizontal well is more economically attractive for both single well and gas field. Moreover, wellhead price is the most sensitive to the economic performance, followed by operating costs and government subsidy. Although the results of reservoir simulation combined with economic analysis are subject to assumptions, multiple seam gas production is more likely to maintain profitability compared with single layer production.
基金the Science and Technology Department of Sichuan Province(Nos.2021YFH0048 and 2021YFH0118)the Fundamental Research Funds for the Central Universities(No.20826041E4199)+3 种基金the National Natural Science Foundation of China(Grant No.20740099)the Natural Science Foundation of Chongqing,China(No.CSTB2022NSCQ-BHX0721)the Chongqing Natural Science Foundation for Distinguished Young Scientists(No.cstc2021jcyj-jqX0007)the Key Laboratory of Shale Gas Exploration,Ministry of Natural Resources(No.KLSGE-202103).
文摘CO_(2)geological storage and utilization(CGSU)is considered a far-reaching technique to meet the demand of increasing energy supply and decreasing CO_(2)emissions.For CGSUs related to shale gas reservoirs,experimental investigations have attracted variable methodologies,among which low-field NMR(LF-NMR)is a promising method and is playing an increasingly key role in reservoir characterization.Herein,the application of this nondestructive,sensitive,and quick LF-NMR technique in characterizing CGSU behavior in shale gas reservoirs is reviewed.First,the basic principle of LF-NMR for 1H-fluid detection is introduced,which is the theoretical foundation of the reviewed achievements in this paper.Then,the reviewed works are related to the LF-NMR-based measurements of CH_(4)adsorption capacity and the CO_(2)-CH_(4)interaction in shale,as well as the performance on CO_(2)sequestration and simultaneous enhanced gas recovery from shale.Basically,the reviewed achievements have exhibited a large potential for LF-NMR application in CGSUs related to shale gas reservoirs,although some limitations and deficiencies still need to be improved.Accordingly,some suggestions are proposed for a more responsible development of the LF-NMR technique.Hopefully,this review is helpful in promoting the expanding application of the LF-NMR technique in CGSU implementation in shale gas reservoirs.
基金the National Key Research and Development Program of China(No.2022YFE0129800)the National Natural Science Foundation of China(Grant No.42202204).
文摘1 Introduction All over the world,with the intense longing for carbon emission reduction and the demand for clean energy(Feng et al.,2020;Iddphonce et al.,2020;Zhao et al.,2022),a promising and far-reaching technology called CO_(2) geological storage and utilization(CGSU)has attracted increasing attention(Iddphonce et al.,2020;Ma et al.,2020).This CGSU technique enjoys huge potential and broad prospect,because it usually enables dual rewarding consequences–to sequester CO_(2) and to acquire energy from geological formations,such as geothermal rock,oil and gas reservoirs(Iddphonce et al.,2020;Klewiah et al.,2020;Liu et al.,2020).In fact,the CGSU has been followed by interest of scientists all around world since geological storage was first proposed in the 1970s as a way to dispose of the CO_(2).Meanwhile,the CGSU technique is not mature enough and usually involves a complicated THMC coupled process,making it necessary to deploy more insightful investigations to boost the development of CGUS technique in a robust,safe and cost-effective manner(Liu et al.,2021b;Zhao et al.,2021;Liu et al.,2023).Basically,this theme is expected to enhance the knowledge about the crucial role of CGSU in achieving the carbon emission reduction–an issue concerned to the world(Liu et al.,2021a;Xie et al.,2021;Zhao et al.,2021;Zhao et al.,2022).Therefore,this special issue is organized and tends to present newest achievements regarding the CGSU,such as the theory expansion,economic analysis,experimental investigation and numerical simulation.
基金supported by National Natural Science Foundation of China(Nos.51875577,51604050)Science Foundationof China University of Petroleum,Beijing(Nos.2462019QNXZ02,2462019BJRC007)Chongqing Science and Technology Innovation Talent Support Program(No.CSTCCXLJRC201712)。
文摘Proppant is a key material in the hydraulic fracturing process,which has been widely used in unconventional oil exploitation.Normal proppants are easy to sedimentate and accumulate at the entrance of shale fracture,which will block the diversion of water,oil and gas.Coated proppants(CPs) are fabricated by coating resin on normal ceramic proppants through a simple method,which is dramatically enhanced the supporting properties in shale fracture and easy to scale up.Compared with uncoated ceramic proppants,the self-suspension ability of CPs is ~11 times higher,which are able to migrate and distribute farther and deeper inside the fracture.At the same time,Coating enhanced the 23.7% of adhesive force in maximum,which makes the CPs easier to adhere on the fracture surface to supportthe shale fracture.Besides,the liquid conductivity of CPs is 60% higher than uncoated ceramic proppants at13.6 MPa pressure.This method is expected to fabricated varieties of proppantsfor shale fracture supporting to improve the exploration of unconventional oil and gas resources.
基金supported by the Project funded by China Postdoctoral Science Foundation(No.2020M683253)the Key Laboratory of Shale Gas Exploration,Ministry of Natural Resources(No.KLSGE-MLR-202003)the National Natural Science Foundation of China(Grant No.51704197).
文摘Regarding CO_(2)enhanced shale gas recovery,this work focuses on changes in the multiphase(free/adsorbed)CH_(4)in the process of CO_(2)enhanced shale gas recovery,by utilizing a rigorous numerical model with real geological parameters.This work studies nine injection well(IW)and CH_(4)production well(PW)combinations of CO_(2)to determine the influence of IW and PW locations on the dynamic interaction of multiphase CH_(4)during 10000 d of CO_(2)injection.The results indicate that the content of both the adsorbed CH_(4)and free CH_(4)is strongly variable before(and during)the CO_(2)-CH_(4)displacement.In addition,during the simulation process,the proportion of the adsorbed CH_(4)among all extracted CH_(4)phases dynamically increases first and then tends to stabilize at 70%-80%.Moreover,the IW-PWs combinations signifi-cantly affect the outcomes of CO_(2)enhanced shale gas recovery-for both the proportion of adsorbed/free CH_(4)and the recovery efficiency.A longer IW-PW distance enables more adsorbed CH_(4)to be recovered but results in a lower efficiency of shale gas recovery.Basically,a shorter IW-PWs distance helps recover CH_(4)via CO_(2)injection if the IW targets the bottom layer of the Wufeng-Longmaxi shale formation.This numerical work expands the knowl-edge of CO_(2)enhanced gas recovery from depleted shale reservoirs.