Shale reservoirs have abundant bedding structures,which deeply alter the mechanical properties of rocks,and thus affect the reservoir stimulation performance.Previous research mostly focuses on the effects of parallel...Shale reservoirs have abundant bedding structures,which deeply alter the mechanical properties of rocks,and thus affect the reservoir stimulation performance.Previous research mostly focuses on the effects of parallel bedding on fracture propagation,while the mechanical properties and mechanisms of fracture propagation remain unclear for rocks with complex wavy bedding(e.g.China’s continentalorigin Gulong shale).Herein,a mixed phase-field fracture model of the wavy-bedding shale was applied,based on the local tension-compression decomposition phase field method(PFM)and geometric structure generation algorithm for the bedding with controllable morphological features.The parametric analysis of fracture propagation behaviors in the case of abundant complex bedding structures showed that with wavy bedding,the vertical fracture propagation rate is far higher than the horizontal propagation rate.Moreover,the development of branch fractures is suppressed during the fracturing process of the wavy-bedding sample,and the stimulated volume is limited,which is different from the characteristic of parallel bedding that promotes horizontal fracture initiation and propagation.The results showed that larger amplitudes,higher frequencies,higher inclination angles,and larger strengths of wavy bedding all promote the formation of vertical penetrating fractures and suppress the growth of branch fractures.Under such circumstances,it is hard to create a well-connected fracture network after fracturing.This research may provide a theoretical basis for understanding fracture behaviors in rocks with such complex wavy bedding.展开更多
Carbon capture,utilization,and storage(CCUS)represents a critical technological pathway for global car-bon emission reduction.CCUS-enhanced oil recovery(EOR)technology is the most feasible CCUS technol-ogy demonstrati...Carbon capture,utilization,and storage(CCUS)represents a critical technological pathway for global car-bon emission reduction.CCUS-enhanced oil recovery(EOR)technology is the most feasible CCUS technol-ogy demonstrating dual benefits of enhanced energy production and carbon reduction.This study comprehensively described the key influencing factors governing CO_(2)-EOR and geological storage and systematically analyzed reservoir properties,fluid characteristics,and operational parameters.The mech-anisms of these parameters on EOR versus CO_(2) storage performance were investigated throughout CCUS-EOR processes.This paper proposes a coupled two-stage CCUS-EOR process:CO_(2)-EOR storage stage and long-term CO_(2) storage stage after the CO_(2) injection phase is completed.In each stage,the main control factors impacting the CO_(2)-EOR and storage stages are screened and coupled with rigorous technical anal-ysis.The key factors here are reservoir properties,fluid characteristics,and operational parameter.A novel CCUS-EOR synergistic method was proposed to optimize the lifecycle performance of dual objective of EOR and storage.Furthermore,based on multi-objective optimization,considering the lifecycle,a multi-scale techno-economic evaluation method was proposed to fully assess the CCUS-EOR project per-formance.Finally,a set of recommendations for advancing CCUS-EOR technologies by deploying multi-factor/multi-field coupling methodologies,novel green intelligent injection materials,and artificial intel-ligence/machine learning technologies were visited.展开更多
The development of shale reservoirs is important in ensuring China’s national energy security by achiev-ing energy independence.Among the key technologies for shale oil production,CO_(2) fracturing is an effec-tive m...The development of shale reservoirs is important in ensuring China’s national energy security by achiev-ing energy independence.Among the key technologies for shale oil production,CO_(2) fracturing is an effec-tive method that can not only enhance oil recovery but also promote large amounts of CO_(2) storage,thereby supporting China’s goals of achieving a carbon peak and carbon neutrality.This research paper aims to study the impacts and prospective applications of CO_(2) fracturing in shale reservoirs,using real exploitation parameters from the Gulong shale reservoir well 1(GYYP1)well in the Songliao Basin.By utilizing numerical simulation,the dynamics of CO_(2) production are analyzed.Adsorption and diffusion are identified as pivotal mechanisms for CO_(2) storage in shale reservoirs.After the analysis of the fractur-ing process,approximately 22.13%of CO_(2) is found to be adsorbed,which decreases to 11.06%after ten years due to pressure decline.Diffusion increases the volume of CO_(2) interacting with a greater extent of shale,thereby enhancing the adsorption mechanism.Over time,the diffusion process results in a remarkable increase of 26.02%in CO_(2) adsorption,ensuring the long-term and stable storage of CO_(2) within the shale reservoir.This investigation delves into the contribution of these two crucial mechanisms of CO_(2) storage in shale reservoirs,ultimately predicting that,by 2030,approximately two million tons of CO_(2) can be effectively stored in the Daqing Oilfield through CO_(2) fracturing in shale oil reservoirs.Such an achievement will undoubtedly contribute to the sustainable development of the energy sector and foster the transformation and upgrading of China’s energy structure.展开更多
The oil and gas industry is increasingly focusing on exploring and developing resources in deep earth layers.At high temperatures,confining pressures,and geostress differences,rock has the mechanical characteristics o...The oil and gas industry is increasingly focusing on exploring and developing resources in deep earth layers.At high temperatures,confining pressures,and geostress differences,rock has the mechanical characteristics of plastic enhancement,which leads to the unclear mechanism of hydraulic fracture expansion.The current fracturing model and construction design lack pertinence,and the fracturing reform is difficult to achieve the expected effect.This paper established a model of elastoplastic hydraulic fracture propagation in deep reservoirs.It considered the enhancement of plasticity by examining the elastoplastic deformation and nonlinear fracturing characteristics of the rock.The results confirmed that the hydraulic fractures in deep reservoirs propagated due to plastic energy dissipation after fracture tip passivation,while the stress concentration declined,which increased propagation resistance.The relationship between geology,engineering factors,degree of plasticity,and fracture propagation is discussed,while the conditions that promote fracture propagation are analyzed to provide theoretical support for deep reservoir fracturing design.展开更多
Understanding the phase behavior of hydrocarbons and their mixtures,especially under confinement,is crucial for the extraction of shale oil and gas.In this study,we employed molecular dynamics simulations to investiga...Understanding the phase behavior of hydrocarbons and their mixtures,especially under confinement,is crucial for the extraction of shale oil and gas.In this study,we employed molecular dynamics simulations to investigate the phase behaviors of three typical hydrocarbons(methane,pentane,and octane)in the bulk phase and in nanopores.We find that the confinement effect can alter the phase behavior of a single-component hydrocarbon.For the mixture of methane and octane in nanopores,a rather high proportion of methane could inhibit the capillary condensation of octane.We also studied the influence of phase behavior on the recovery dynamics of hydrocarbon mixtures from blind nanopores of different sizes at different gas-oil ratios.The capillary condensation of the heavy hydrocarbon components in the nanopore throat could hinder the transport of light.These findings increase the understanding of the occurrence states of shale oil and gas and their migration through nanopore throats,providing practical guidance for shale oil and gas development.展开更多
The core of China’s low-carbon development includes optimization of industrial structure,clean energy technologies,emission reduction technologies,and innovation of relevant systems and institutions.China National Pe...The core of China’s low-carbon development includes optimization of industrial structure,clean energy technologies,emission reduction technologies,and innovation of relevant systems and institutions.China National Petroleum Corporation(CNPC)has always been a proactive participant in developing low-carbon economy,shouldering the responsibilities of safeguarding oil and gas supply,conserving energy,and reducing emission.Therefore,CNPC fulfills those responsibilities as a substantial part of its overall strategy.Guided by low carbon and driven by innovation,petroleum corporations have taken constant innovation of low-carbon technologies,especially the development of green and low-carbon petroleum engineering technologies and equipment,as major measures for energy conservation and emission reduction.Large-scale development mode o f unconventional resource anhydrous fracturing should be innovated.And supercritical C 02 should be used to replace water for fracturing operation,in order to achieve multiple objectives of C 02 burying,conserve water resource,improve single well production and ultimate recovery,realizing reduced emission and efficient utilization o f C 02 resources.Artificial lifting energy-saving and efficiencyincreasing technologies and injection-production technology in the same well should also be innovated.Energy consumption of high water-cut wells is reduced to support the new low-carbon operation mode of high water-cut oilfields and realize energy saving and efficiency improvement during oil production by developing the operation efficiency of the lifting system and reducing the ineffective lifting of formation water.These technologies have been widely recognized by local and international experts and have greatly enhanced CNPC's international influence.This study expounds the key technologies and equipment with regard to the development of green and low-carbon petroleum engineering and provide relevant suggestions.展开更多
The development of shale oil is of considerable strategic importance,particularly concerning national security implications.Effective management is vital to maximize both efficiency and socio-economic benefits.This pr...The development of shale oil is of considerable strategic importance,particularly concerning national security implications.Effective management is vital to maximize both efficiency and socio-economic benefits.This process necessitates addressing four critical relationships:balancing local and global factors,reconciling universality with particularity,integrating inheritance with innovation,and resolving primary and secondary contradictions.These relationships pose several management challenges that must be overcome to develop a robust management model for shale oil extraction.This paper uses the Gulong shale oil in the Daqing oilfield as a case study to examine the implications and specific manifestations of these relationships.To address the limitations of traditional management models,which often overly emphasize local factors,particularity,innovation,and secondary contradictions,we have developed the“Integrated Dialectical Four-Domain Coupling Management Model.”This model incorporates systems engineering theory into management strategies.Key strategies include the global deployment of experimental zone construction,systematic geological and engineering integration,combining historical practices with innovative approaches,phase analysis,and contradiction coordination.These strategies have significantly advanced the development of Gulong shale oil,demonstrating positive on-site results.The innovative management processes detailed in this paper provide valuable insights applicable to similar reservoirs and other large-scale engineering management projects.展开更多
基金supported by the Technology Project of CNPC(Grant No.2023ZZ08)the National Natural Science Foundation of China(Grant No.52274058)the USTC Research Funds of the Double First-Class Initiative(Grant No.YD2090002025).
文摘Shale reservoirs have abundant bedding structures,which deeply alter the mechanical properties of rocks,and thus affect the reservoir stimulation performance.Previous research mostly focuses on the effects of parallel bedding on fracture propagation,while the mechanical properties and mechanisms of fracture propagation remain unclear for rocks with complex wavy bedding(e.g.China’s continentalorigin Gulong shale).Herein,a mixed phase-field fracture model of the wavy-bedding shale was applied,based on the local tension-compression decomposition phase field method(PFM)and geometric structure generation algorithm for the bedding with controllable morphological features.The parametric analysis of fracture propagation behaviors in the case of abundant complex bedding structures showed that with wavy bedding,the vertical fracture propagation rate is far higher than the horizontal propagation rate.Moreover,the development of branch fractures is suppressed during the fracturing process of the wavy-bedding sample,and the stimulated volume is limited,which is different from the characteristic of parallel bedding that promotes horizontal fracture initiation and propagation.The results showed that larger amplitudes,higher frequencies,higher inclination angles,and larger strengths of wavy bedding all promote the formation of vertical penetrating fractures and suppress the growth of branch fractures.Under such circumstances,it is hard to create a well-connected fracture network after fracturing.This research may provide a theoretical basis for understanding fracture behaviors in rocks with such complex wavy bedding.
基金the financial support from the National Key Research and Development Program of China(2022YFE0206700)the Science Foundation of China University of Petroleum,Beijing(2462021YJRC012).
文摘Carbon capture,utilization,and storage(CCUS)represents a critical technological pathway for global car-bon emission reduction.CCUS-enhanced oil recovery(EOR)technology is the most feasible CCUS technol-ogy demonstrating dual benefits of enhanced energy production and carbon reduction.This study comprehensively described the key influencing factors governing CO_(2)-EOR and geological storage and systematically analyzed reservoir properties,fluid characteristics,and operational parameters.The mech-anisms of these parameters on EOR versus CO_(2) storage performance were investigated throughout CCUS-EOR processes.This paper proposes a coupled two-stage CCUS-EOR process:CO_(2)-EOR storage stage and long-term CO_(2) storage stage after the CO_(2) injection phase is completed.In each stage,the main control factors impacting the CO_(2)-EOR and storage stages are screened and coupled with rigorous technical anal-ysis.The key factors here are reservoir properties,fluid characteristics,and operational parameter.A novel CCUS-EOR synergistic method was proposed to optimize the lifecycle performance of dual objective of EOR and storage.Furthermore,based on multi-objective optimization,considering the lifecycle,a multi-scale techno-economic evaluation method was proposed to fully assess the CCUS-EOR project per-formance.Finally,a set of recommendations for advancing CCUS-EOR technologies by deploying multi-factor/multi-field coupling methodologies,novel green intelligent injection materials,and artificial intel-ligence/machine learning technologies were visited.
基金funded by the General Program of the National Natural Science Foundation of China(52274058,52174052,52474058)the Central Program of Basic Science of the National Natural Science Foundation of China(72088101)the"Enlisting and Leading"Science and Technology Project of Heilongjiang Province(RIPED-2022-JS-1740 and RIPED-2022-JS-1853).
文摘The development of shale reservoirs is important in ensuring China’s national energy security by achiev-ing energy independence.Among the key technologies for shale oil production,CO_(2) fracturing is an effec-tive method that can not only enhance oil recovery but also promote large amounts of CO_(2) storage,thereby supporting China’s goals of achieving a carbon peak and carbon neutrality.This research paper aims to study the impacts and prospective applications of CO_(2) fracturing in shale reservoirs,using real exploitation parameters from the Gulong shale reservoir well 1(GYYP1)well in the Songliao Basin.By utilizing numerical simulation,the dynamics of CO_(2) production are analyzed.Adsorption and diffusion are identified as pivotal mechanisms for CO_(2) storage in shale reservoirs.After the analysis of the fractur-ing process,approximately 22.13%of CO_(2) is found to be adsorbed,which decreases to 11.06%after ten years due to pressure decline.Diffusion increases the volume of CO_(2) interacting with a greater extent of shale,thereby enhancing the adsorption mechanism.Over time,the diffusion process results in a remarkable increase of 26.02%in CO_(2) adsorption,ensuring the long-term and stable storage of CO_(2) within the shale reservoir.This investigation delves into the contribution of these two crucial mechanisms of CO_(2) storage in shale reservoirs,ultimately predicting that,by 2030,approximately two million tons of CO_(2) can be effectively stored in the Daqing Oilfield through CO_(2) fracturing in shale oil reservoirs.Such an achievement will undoubtedly contribute to the sustainable development of the energy sector and foster the transformation and upgrading of China’s energy structure.
基金The Youth Science Fund Project of National Natural Science Foundation of China,52404027,Jinbo Lithe General Program of the National Natural Science Foundation of China,52274036,Suling Wang。
文摘The oil and gas industry is increasingly focusing on exploring and developing resources in deep earth layers.At high temperatures,confining pressures,and geostress differences,rock has the mechanical characteristics of plastic enhancement,which leads to the unclear mechanism of hydraulic fracture expansion.The current fracturing model and construction design lack pertinence,and the fracturing reform is difficult to achieve the expected effect.This paper established a model of elastoplastic hydraulic fracture propagation in deep reservoirs.It considered the enhancement of plasticity by examining the elastoplastic deformation and nonlinear fracturing characteristics of the rock.The results confirmed that the hydraulic fractures in deep reservoirs propagated due to plastic energy dissipation after fracture tip passivation,while the stress concentration declined,which increased propagation resistance.The relationship between geology,engineering factors,degree of plasticity,and fracture propagation is discussed,while the conditions that promote fracture propagation are analyzed to provide theoretical support for deep reservoir fracturing design.
基金supported by the National Natural Science Foundation of China(Grant Nos.U22B2075 and 12241203)。
文摘Understanding the phase behavior of hydrocarbons and their mixtures,especially under confinement,is crucial for the extraction of shale oil and gas.In this study,we employed molecular dynamics simulations to investigate the phase behaviors of three typical hydrocarbons(methane,pentane,and octane)in the bulk phase and in nanopores.We find that the confinement effect can alter the phase behavior of a single-component hydrocarbon.For the mixture of methane and octane in nanopores,a rather high proportion of methane could inhibit the capillary condensation of octane.We also studied the influence of phase behavior on the recovery dynamics of hydrocarbon mixtures from blind nanopores of different sizes at different gas-oil ratios.The capillary condensation of the heavy hydrocarbon components in the nanopore throat could hinder the transport of light.These findings increase the understanding of the occurrence states of shale oil and gas and their migration through nanopore throats,providing practical guidance for shale oil and gas development.
文摘The core of China’s low-carbon development includes optimization of industrial structure,clean energy technologies,emission reduction technologies,and innovation of relevant systems and institutions.China National Petroleum Corporation(CNPC)has always been a proactive participant in developing low-carbon economy,shouldering the responsibilities of safeguarding oil and gas supply,conserving energy,and reducing emission.Therefore,CNPC fulfills those responsibilities as a substantial part of its overall strategy.Guided by low carbon and driven by innovation,petroleum corporations have taken constant innovation of low-carbon technologies,especially the development of green and low-carbon petroleum engineering technologies and equipment,as major measures for energy conservation and emission reduction.Large-scale development mode o f unconventional resource anhydrous fracturing should be innovated.And supercritical C 02 should be used to replace water for fracturing operation,in order to achieve multiple objectives of C 02 burying,conserve water resource,improve single well production and ultimate recovery,realizing reduced emission and efficient utilization o f C 02 resources.Artificial lifting energy-saving and efficiencyincreasing technologies and injection-production technology in the same well should also be innovated.Energy consumption of high water-cut wells is reduced to support the new low-carbon operation mode of high water-cut oilfields and realize energy saving and efficiency improvement during oil production by developing the operation efficiency of the lifting system and reducing the ineffective lifting of formation water.These technologies have been widely recognized by local and international experts and have greatly enhanced CNPC's international influence.This study expounds the key technologies and equipment with regard to the development of green and low-carbon petroleum engineering and provide relevant suggestions.
基金supported by the National Natural Science Foundation of China(Grant No.U22B2075).
文摘The development of shale oil is of considerable strategic importance,particularly concerning national security implications.Effective management is vital to maximize both efficiency and socio-economic benefits.This process necessitates addressing four critical relationships:balancing local and global factors,reconciling universality with particularity,integrating inheritance with innovation,and resolving primary and secondary contradictions.These relationships pose several management challenges that must be overcome to develop a robust management model for shale oil extraction.This paper uses the Gulong shale oil in the Daqing oilfield as a case study to examine the implications and specific manifestations of these relationships.To address the limitations of traditional management models,which often overly emphasize local factors,particularity,innovation,and secondary contradictions,we have developed the“Integrated Dialectical Four-Domain Coupling Management Model.”This model incorporates systems engineering theory into management strategies.Key strategies include the global deployment of experimental zone construction,systematic geological and engineering integration,combining historical practices with innovative approaches,phase analysis,and contradiction coordination.These strategies have significantly advanced the development of Gulong shale oil,demonstrating positive on-site results.The innovative management processes detailed in this paper provide valuable insights applicable to similar reservoirs and other large-scale engineering management projects.
