Huff-n-puff by water has been conducted to enhance oil recovery after hydraulic fracturing in tight/shale oil reservoirs.However,the mechanisms and capacity are still unclear,which significantly limits the application...Huff-n-puff by water has been conducted to enhance oil recovery after hydraulic fracturing in tight/shale oil reservoirs.However,the mechanisms and capacity are still unclear,which significantly limits the application of this technique.In order to figure out the mechanisms,the whole process of pressurizing,high-pressure soaking,and depressurizing was firstly discussed,and a mechanistic model was established.Subsequently,the simulation model was verified and employed to investigate the significances of high-pressure soaking,the contributions of different mechanisms,and the sensitivity analysis in different scenarios.The results show that high-pressure soaking plays an essential role in oil production by both imbibition and elasticity after hydraulic fracturing.The contribution of imbibition increases as the increase in bottom hole pressure(BHP),interfacial tension,and specific surface area,but slightly decreases as the oil viscosity increases.In addition,it first decreases and then slightly increases with the increase in matrix permeability.The optimal soaking time is linear with the increases of both oil viscosity and BHP and logarithmically declines with the increase in matrix permeability and specific surface area.Moreover,it shows a rising tendency as the interficial tension(IFT)increases.Overall,a general model was achieved to calculate the optimal soaking time.展开更多
There are various issues for CO_(2)flooding and storage in Shengli Oilfield,which are characterized by low light hydrocarbon content of oil and high miscible pressure,strong reservoir heterogeneity and low sweep effic...There are various issues for CO_(2)flooding and storage in Shengli Oilfield,which are characterized by low light hydrocarbon content of oil and high miscible pressure,strong reservoir heterogeneity and low sweep efficiency,gas channeling and difficult whole-process control.Through laboratory experiments,technical research and field practice,the theory and technology of CO_(2)high pressure miscible flooding and storage are established.By increasing the formation pressure to 1.2 times the minimum miscible pressure,the miscibility of the medium-heavy components can be improved,the production percentage of oil in small pores can be increased,the displacing front developed evenly,and the swept volume expanded.Rapid high-pressure miscibility is realized through advanced pressure flooding and energy replenishment,and technologies of cascade water-alternating-gas(WAG),injection and production coupling and multistage chemical plugging are used for dynamic control of flow resistance,so as to obtain the optimum of oil recovery and CO_(2)storage factor.The research results have been applied to the Gao89-Fan142 in carbon capture,utilization and storage(CCUS)demonstration site,where the daily oil production of the block has increased from 254.6 t to 358.2 t,and the recovery degree is expected to increase by 11.6 percentage points in 15 years,providing theoretical and technical support for the large-scale development of CCUS.展开更多
基金This work was supported by the National Natural Science Foundation of China(No.52074316)Science Foundation of China University of Petroleum,Beijing(No.2462018QNXZ01)+2 种基金Open Fund(No.SXCU-201905)of Shaanxi Cooperative Innovation Center of Unconventional Oil and Gas Exploration and Development(Xi'an Shiyou University)National Basic Research Program(No.2015CB250906)National S&T Major Project(No.2017ZX05009004)。
文摘Huff-n-puff by water has been conducted to enhance oil recovery after hydraulic fracturing in tight/shale oil reservoirs.However,the mechanisms and capacity are still unclear,which significantly limits the application of this technique.In order to figure out the mechanisms,the whole process of pressurizing,high-pressure soaking,and depressurizing was firstly discussed,and a mechanistic model was established.Subsequently,the simulation model was verified and employed to investigate the significances of high-pressure soaking,the contributions of different mechanisms,and the sensitivity analysis in different scenarios.The results show that high-pressure soaking plays an essential role in oil production by both imbibition and elasticity after hydraulic fracturing.The contribution of imbibition increases as the increase in bottom hole pressure(BHP),interfacial tension,and specific surface area,but slightly decreases as the oil viscosity increases.In addition,it first decreases and then slightly increases with the increase in matrix permeability.The optimal soaking time is linear with the increases of both oil viscosity and BHP and logarithmically declines with the increase in matrix permeability and specific surface area.Moreover,it shows a rising tendency as the interficial tension(IFT)increases.Overall,a general model was achieved to calculate the optimal soaking time.
基金Supported by the Sinopec"Ten Dragon"Major ProjectKey Research Projects of Sinopec(P22180)。
文摘There are various issues for CO_(2)flooding and storage in Shengli Oilfield,which are characterized by low light hydrocarbon content of oil and high miscible pressure,strong reservoir heterogeneity and low sweep efficiency,gas channeling and difficult whole-process control.Through laboratory experiments,technical research and field practice,the theory and technology of CO_(2)high pressure miscible flooding and storage are established.By increasing the formation pressure to 1.2 times the minimum miscible pressure,the miscibility of the medium-heavy components can be improved,the production percentage of oil in small pores can be increased,the displacing front developed evenly,and the swept volume expanded.Rapid high-pressure miscibility is realized through advanced pressure flooding and energy replenishment,and technologies of cascade water-alternating-gas(WAG),injection and production coupling and multistage chemical plugging are used for dynamic control of flow resistance,so as to obtain the optimum of oil recovery and CO_(2)storage factor.The research results have been applied to the Gao89-Fan142 in carbon capture,utilization and storage(CCUS)demonstration site,where the daily oil production of the block has increased from 254.6 t to 358.2 t,and the recovery degree is expected to increase by 11.6 percentage points in 15 years,providing theoretical and technical support for the large-scale development of CCUS.
