Gravity assistance is a critical factor influencing CO_(2)-Oil mixing and miscible flow during EOR and CO_(2)geological storage.Based on the Navier-Stokes equation,component mass conservation equation,and fluid proper...Gravity assistance is a critical factor influencing CO_(2)-Oil mixing and miscible flow during EOR and CO_(2)geological storage.Based on the Navier-Stokes equation,component mass conservation equation,and fluid property-composition relationship,a mathematical model for pore-scale CO_(2) injection in oilsaturated porous media was developed in this study.The model can reflect the effects of gravity assistance,component diffusion,fluid density variation,and velocity change on EOR and CO_(2) storage.For nonhomogeneous porous media,the gravity influence and large density difference help to minimize the velocity difference between the main flow path and the surrounding area,thus improving the oil recovery and CO_(2) storage.Large CO_(2) injection angles and oil-CO_(2) density differences can increase the oil recovery by 22.6% and 4.2%,respectively,and increase CO_(2) storage by 37.9% and 4.7%,respectively.Component diffusion facilitates the transportation of the oil components from the low-velocity region to the main flow path,thereby reducing the oil/CO_(2) concentration difference within the porous media.Component diffusion can increase oil recovery and CO_(2) storage by 5.7% and 6.9%,respectively.In addition,combined with the component diffusion,a low CO_(2) injection rate creates a more uniform spatial distribution of the oil/CO_(2) component,resulting in increases of 9.5% oil recovery and 15.7% CO_(2) storage,respectively.This study provides theoretical support for improving the geological CO_(2) storage and EOR processes.展开更多
Stabilizing global climate change to within 1.5℃requires a reduction in greenhouse gas emissions,with a primary focus on carbon dioxide(CO_(2))emissions.CO_(2)flooding in oilfields has recently been recognized as an ...Stabilizing global climate change to within 1.5℃requires a reduction in greenhouse gas emissions,with a primary focus on carbon dioxide(CO_(2))emissions.CO_(2)flooding in oilfields has recently been recognized as an important way to reduce CO_(2)emissions by storing CO_(2)in oil reservoirs.This work proposes an advanced CO_(2)enhanced oil recovery(EOR)method-namely,storage-driven CO_(2)EOR-whose main target is to realize net-zero or even negative CO_(2)emissions by sequestrating the maximum possible amount of CO_(2)in oil reservoirs while accomplishing the maximum possible oil recovery.Here,dimethyl ether(DME)is employed as an efficient agent in assisting conventional CO_(2)EOR for oil recovery while enhancing CO_(2)sequestration in reservoirs.The results show that DME improves the solubility of CO_(2)in in situ oil,which is beneficial for the solubility trapping of CO_(2)storage;furthermore,the presence of DME inhibits the"escape"of lighter hydrocarbons from crude oil due to the CO_(2)extraction effect,which is critical for sustainable oil recovery.Sto rage-driven CO_(2)EOR is superior to conventional CO_(2)EOR in improving sweeping efficiency,especially during the late oil production period.This work demonstrates that storage-driven CO_(2)EOR exhibits higher oil-in-place(OIP)recovery than conventional CO_(2)EOR.Moreover,the amount of sequestrated CO_(2)in storage-driven CO_(2)EOR exceeds the amount of emissions from burning the produced oil;that is,the sequestrated CO_(2)offsets not only current emissions but also past CO_(2)emissions.By altering developing scenarios,such as water alternating storage-driven CO_(2)EOR,more CO_(2)sequestration and higher oil recovery can be achieved.This work demonstrates the potential utilization of DME as an efficient additive to CO_(2)for enhancing oil recovery while improving CO_(2)storage in oil reservoirs.展开更多
Injecting CO2into hydrocarbon reservoirs can enhance the recovery of hydrocarbon resources,and simultaneously,CO2can be stored in the rese rvoirs,reducing considerable amount of carbon emissions in the atmosphere.Howe...Injecting CO2into hydrocarbon reservoirs can enhance the recovery of hydrocarbon resources,and simultaneously,CO2can be stored in the rese rvoirs,reducing considerable amount of carbon emissions in the atmosphere.However,injected CO_(2)tends to go through fractures,high-permeability channels and streaks present in reservoirs,resulting in inefficient hydrocarbon recovery coupled with low CO_(2)storage performance.Conformance treatments with CO_(2)-resistant crosslinked polymer gels were performed in this study to mitigate the CO_(2)channeling issue and promote the synergy between enhanced oil recovery(EOR) and subsurface sequestration of CO_(2).Based on a typical low-permeability CO_(2)-flooding reservoir in China,studies were performed to investigate the EOR and CO_(2)storage performance with and without conformance treatment.The effect of permeability contrast between the channels and rese rvoir matrices,treatment size,and plugging strength on the efficiency of oil recovery and CO_(2)storage was systematically investigated.The results indicated that after conformance treatments,the CO_(2)channeling problem was mitigated during CO_(2)flooding and storage.The injected CO_(2)was more effectively utilized to recover the hydrocarbons,and entered wider spectrum of pore spaces.Consequently,more CO_(2)was trapped underground.Pronounced factors on the synergy of EOR and CO_(2)storage were figured out.Compared with the treatment size,the CO_(2)storage efficiency was more sensitive to the plugging strength of the conformance treatment materials.This observation was important for conformance treatment design in CCUS-EOR projects.According to this study,the materials should reduce the channel permeability to make the channel/matrix permeability ratio below 30.The results demonstrate the importance of conformance treatment in maximizing the performance of CCUS-EOR process to achieve both oil recovery improvement and efficient carbon storage.This study provides guidelines for successful field applications of CO_(2)transport control in CO_(2)geo-utilization and storage.展开更多
基金The project supported by National Natural Science Foundation of China(No.51991364,51974347)the Major Scientific and Technological Projects of CNPC under Grant ZD2019-184-002。
文摘Gravity assistance is a critical factor influencing CO_(2)-Oil mixing and miscible flow during EOR and CO_(2)geological storage.Based on the Navier-Stokes equation,component mass conservation equation,and fluid property-composition relationship,a mathematical model for pore-scale CO_(2) injection in oilsaturated porous media was developed in this study.The model can reflect the effects of gravity assistance,component diffusion,fluid density variation,and velocity change on EOR and CO_(2) storage.For nonhomogeneous porous media,the gravity influence and large density difference help to minimize the velocity difference between the main flow path and the surrounding area,thus improving the oil recovery and CO_(2) storage.Large CO_(2) injection angles and oil-CO_(2) density differences can increase the oil recovery by 22.6% and 4.2%,respectively,and increase CO_(2) storage by 37.9% and 4.7%,respectively.Component diffusion facilitates the transportation of the oil components from the low-velocity region to the main flow path,thereby reducing the oil/CO_(2) concentration difference within the porous media.Component diffusion can increase oil recovery and CO_(2) storage by 5.7% and 6.9%,respectively.In addition,combined with the component diffusion,a low CO_(2) injection rate creates a more uniform spatial distribution of the oil/CO_(2) component,resulting in increases of 9.5% oil recovery and 15.7% CO_(2) storage,respectively.This study provides theoretical support for improving the geological CO_(2) storage and EOR processes.
基金financial support from the Science Foundation of China University of Petroleum,Beijing(2462021QNXZ012 and 2462021YJRC012)supported by the Fundamental Research Funds for the Central Universities。
文摘Stabilizing global climate change to within 1.5℃requires a reduction in greenhouse gas emissions,with a primary focus on carbon dioxide(CO_(2))emissions.CO_(2)flooding in oilfields has recently been recognized as an important way to reduce CO_(2)emissions by storing CO_(2)in oil reservoirs.This work proposes an advanced CO_(2)enhanced oil recovery(EOR)method-namely,storage-driven CO_(2)EOR-whose main target is to realize net-zero or even negative CO_(2)emissions by sequestrating the maximum possible amount of CO_(2)in oil reservoirs while accomplishing the maximum possible oil recovery.Here,dimethyl ether(DME)is employed as an efficient agent in assisting conventional CO_(2)EOR for oil recovery while enhancing CO_(2)sequestration in reservoirs.The results show that DME improves the solubility of CO_(2)in in situ oil,which is beneficial for the solubility trapping of CO_(2)storage;furthermore,the presence of DME inhibits the"escape"of lighter hydrocarbons from crude oil due to the CO_(2)extraction effect,which is critical for sustainable oil recovery.Sto rage-driven CO_(2)EOR is superior to conventional CO_(2)EOR in improving sweeping efficiency,especially during the late oil production period.This work demonstrates that storage-driven CO_(2)EOR exhibits higher oil-in-place(OIP)recovery than conventional CO_(2)EOR.Moreover,the amount of sequestrated CO_(2)in storage-driven CO_(2)EOR exceeds the amount of emissions from burning the produced oil;that is,the sequestrated CO_(2)offsets not only current emissions but also past CO_(2)emissions.By altering developing scenarios,such as water alternating storage-driven CO_(2)EOR,more CO_(2)sequestration and higher oil recovery can be achieved.This work demonstrates the potential utilization of DME as an efficient additive to CO_(2)for enhancing oil recovery while improving CO_(2)storage in oil reservoirs.
基金supported by Science Foundation of China University of Petroleum,Beijing(No.2462022BJRC001,2462021YJRC012)the funding from State Key Laboratory of Petroleum Resources and Prospecting(No.PRP/indep-1-2103)
文摘Injecting CO2into hydrocarbon reservoirs can enhance the recovery of hydrocarbon resources,and simultaneously,CO2can be stored in the rese rvoirs,reducing considerable amount of carbon emissions in the atmosphere.However,injected CO_(2)tends to go through fractures,high-permeability channels and streaks present in reservoirs,resulting in inefficient hydrocarbon recovery coupled with low CO_(2)storage performance.Conformance treatments with CO_(2)-resistant crosslinked polymer gels were performed in this study to mitigate the CO_(2)channeling issue and promote the synergy between enhanced oil recovery(EOR) and subsurface sequestration of CO_(2).Based on a typical low-permeability CO_(2)-flooding reservoir in China,studies were performed to investigate the EOR and CO_(2)storage performance with and without conformance treatment.The effect of permeability contrast between the channels and rese rvoir matrices,treatment size,and plugging strength on the efficiency of oil recovery and CO_(2)storage was systematically investigated.The results indicated that after conformance treatments,the CO_(2)channeling problem was mitigated during CO_(2)flooding and storage.The injected CO_(2)was more effectively utilized to recover the hydrocarbons,and entered wider spectrum of pore spaces.Consequently,more CO_(2)was trapped underground.Pronounced factors on the synergy of EOR and CO_(2)storage were figured out.Compared with the treatment size,the CO_(2)storage efficiency was more sensitive to the plugging strength of the conformance treatment materials.This observation was important for conformance treatment design in CCUS-EOR projects.According to this study,the materials should reduce the channel permeability to make the channel/matrix permeability ratio below 30.The results demonstrate the importance of conformance treatment in maximizing the performance of CCUS-EOR process to achieve both oil recovery improvement and efficient carbon storage.This study provides guidelines for successful field applications of CO_(2)transport control in CO_(2)geo-utilization and storage.
