Geothermal energy from deep underground (or geological) formations,with or without its combination with carbon capture and storage (CCS),can be a key technology to mitigate anthropogenic greenhouse gas emissions and m...Geothermal energy from deep underground (or geological) formations,with or without its combination with carbon capture and storage (CCS),can be a key technology to mitigate anthropogenic greenhouse gas emissions and meet the 2050 net‐zero carbon emission target.Geothermal resources in low‐permeability and medium‐and high‐temperature reservoirs in sedimentary sequence require hydraulic stimulation for enhanced geothermal systems (EGS).However,fluid migration for geothermal energy in EGS or with potential CO_(2) storage in a CO_(2)‐EGS are both dependent on the in situ flow pathway network created by induced fluid injection.These thermo‐mechanical interactions can be complex and induce varying alterations in the mechanical response when the working fluid is water (in EGS) or supercritical CO_(2)(in CO_(2)‐EGS),which could impact the geothermal energy recovery from geological formations.Therefore,there is a need for a deeper understanding of the heat extraction process in EGS and CO_(2)‐EGS.This study presents a systematic review of the effects of changes in mechanical properties and behavior of deep underground rocks on the induced flow pathway and heat recovery in EGS reservoirs with or without CO_(2) storage in CO_(2) ‐EGS.Further,we proposed waterless‐stimulated EGS as an alternative approach to improve heat energy extraction in EGS.Lastly,based on the results of our literature review and proposed ideas,we recommend promising areas of investigation that may provide more insights into understanding geothermo‐mechanics to further stimulate new research studies and accelerate the development of geothermal energy as a viable clean energy technology.展开更多
Organic-rich shales have gained significant attention in recent years due to their pivotal role in unconventional hydrocarbon production.These shale rocks undergo thermal maturation processes that alter their mechanic...Organic-rich shales have gained significant attention in recent years due to their pivotal role in unconventional hydrocarbon production.These shale rocks undergo thermal maturation processes that alter their mechanical properties,making their study essential for subsurface operations.However,characterizing the mechanical properties of organic-rich shale is often challenging due to its multiscale nature and complex composition.This work aims to bridge that knowledge gap to fully understand the nanomechanical properties of Shale organic matter at various thermal maturation stages.This study employs PeakForce Quantitative Nanomechanical Map-ping(PF-QNM)using Atomic Force Microscopy(AFM)to investigate how changes at the immature,early mature,and peak mature stages impact the mechanical properties of the Bakken Shale organic matter.PF-QNM provides reliable mechanical measurements,allowing for the quantification and qualification of shale constituents'elastic modulus(E).We also accounted for the effect of probe type and further analyzed the impact of probe wear on the nanomechanical properties of shale organic matter.In immature shale,the average elastic modulus of organic matter is approximately 6 GPa,whereas in early mature and peak mature shale,it decreases to 5.5 GPa and 3.8 GPa,respectively.Results reveal a mechanical degradation with increasing thermal maturation,as evidenced by a reduction in Young's modulus(E).Specifically,the immature shale exhibits an 8%reduction in E,while the early mature and peak mature shales experience more substantial reductions of 31%and 37%,respectively.This phenomenon could be attributed to the surface probing of low-modulus materials like bitumen generated during heating.The findings underscore the potential of AFM PF-QNM for assessing the nanomechanical characteristics of complex and heterogeneous rocks like shales.However,it also highlights the need for standardized mea-surement practices,considering the diverse components in these rocks and their different elastic moduli.展开更多
文摘Geothermal energy from deep underground (or geological) formations,with or without its combination with carbon capture and storage (CCS),can be a key technology to mitigate anthropogenic greenhouse gas emissions and meet the 2050 net‐zero carbon emission target.Geothermal resources in low‐permeability and medium‐and high‐temperature reservoirs in sedimentary sequence require hydraulic stimulation for enhanced geothermal systems (EGS).However,fluid migration for geothermal energy in EGS or with potential CO_(2) storage in a CO_(2)‐EGS are both dependent on the in situ flow pathway network created by induced fluid injection.These thermo‐mechanical interactions can be complex and induce varying alterations in the mechanical response when the working fluid is water (in EGS) or supercritical CO_(2)(in CO_(2)‐EGS),which could impact the geothermal energy recovery from geological formations.Therefore,there is a need for a deeper understanding of the heat extraction process in EGS and CO_(2)‐EGS.This study presents a systematic review of the effects of changes in mechanical properties and behavior of deep underground rocks on the induced flow pathway and heat recovery in EGS reservoirs with or without CO_(2) storage in CO_(2) ‐EGS.Further,we proposed waterless‐stimulated EGS as an alternative approach to improve heat energy extraction in EGS.Lastly,based on the results of our literature review and proposed ideas,we recommend promising areas of investigation that may provide more insights into understanding geothermo‐mechanics to further stimulate new research studies and accelerate the development of geothermal energy as a viable clean energy technology.
文摘Organic-rich shales have gained significant attention in recent years due to their pivotal role in unconventional hydrocarbon production.These shale rocks undergo thermal maturation processes that alter their mechanical properties,making their study essential for subsurface operations.However,characterizing the mechanical properties of organic-rich shale is often challenging due to its multiscale nature and complex composition.This work aims to bridge that knowledge gap to fully understand the nanomechanical properties of Shale organic matter at various thermal maturation stages.This study employs PeakForce Quantitative Nanomechanical Map-ping(PF-QNM)using Atomic Force Microscopy(AFM)to investigate how changes at the immature,early mature,and peak mature stages impact the mechanical properties of the Bakken Shale organic matter.PF-QNM provides reliable mechanical measurements,allowing for the quantification and qualification of shale constituents'elastic modulus(E).We also accounted for the effect of probe type and further analyzed the impact of probe wear on the nanomechanical properties of shale organic matter.In immature shale,the average elastic modulus of organic matter is approximately 6 GPa,whereas in early mature and peak mature shale,it decreases to 5.5 GPa and 3.8 GPa,respectively.Results reveal a mechanical degradation with increasing thermal maturation,as evidenced by a reduction in Young's modulus(E).Specifically,the immature shale exhibits an 8%reduction in E,while the early mature and peak mature shales experience more substantial reductions of 31%and 37%,respectively.This phenomenon could be attributed to the surface probing of low-modulus materials like bitumen generated during heating.The findings underscore the potential of AFM PF-QNM for assessing the nanomechanical characteristics of complex and heterogeneous rocks like shales.However,it also highlights the need for standardized mea-surement practices,considering the diverse components in these rocks and their different elastic moduli.
