he cement sheath is the heart of any oil or gas well for providing zonal isolation and well integrity during the life of a well.Loads induced by well construction operations and borehole pressure and temperature chang...he cement sheath is the heart of any oil or gas well for providing zonal isolation and well integrity during the life of a well.Loads induced by well construction operations and borehole pressure and temperature changes may lead to the ultimate failure of cement sheath.This paper quantifies the potential of cement failure under mechanically and thermally induced stress during the life-of-well using a coupled thermalehydrologicalemechanical(THM)modeling approach.A staged finite-element procedure is presented considering sequential stress and displacement development during each stage of the well life,including drilling,casing,cementing,completion,production,and injection.The staged model quantifies the stress states and state variables,e.g.,plastic strain,damage,and debonding at cement/rock or cement/casing interface,in each well stage from simultaneous action of in-situ stress,pore pressure,temperature,casing pressure,and cement hardening/shrinkage.Thus,it eliminates the need to guess the initial stress and strain state before modeling a specific stage.Moreover,coupled THM capabilities of the model ensure the full consideration of the interaction between these influential factors.展开更多
Hot dry rock,as a renewable and sustainable energy source,can alleviate resource shortages and environmental pollution.Based on data from the Qiabuqia geothermal field and an established thermal-hydrological-mechanica...Hot dry rock,as a renewable and sustainable energy source,can alleviate resource shortages and environmental pollution.Based on data from the Qiabuqia geothermal field and an established thermal-hydrological-mechanical coupled mathematical model,a novel horizontally layered enhanced geothermal system(EGS)is proposed and compared with the conventional double vertical well EGS.Under the simulated conditions in this paper,the comprehensive heat recovery performance of the horizontally layered EGS is significantly better than that of the double vertical well EGS.Specifically,although the average production temperature of the double vertical well EGS is higher than that of the horizontally layered EGS in the attenuation stage,the heat power output of the horizontally layered EGS ranges from 6.10 MW to 12.25 MW,which is 1.36 to 1.67 times that of the double vertical well EGS.Additionally,the heat recovery rate of the horizontally layered EGS is 6.63%higher than that of the double vertical well EGS and is thus more economical.Finally,parametric analysis was performed to investigate the influence of the controllable parameters on heat recovery for the horizontally layered EGS.The heat power output and heat extraction ratio are proportional to the pressure difference and well spacing and inversely proportional to the injection fluid temperature.The thermal power output is most greatly influenced by the pressure difference,followed by the well spacing and injection fluid temperature.The effects of the pressure difference and well spacing on the heat recovery rate are almost the same,and the injection fluid temperature has no effect.展开更多
基金This work was financially supported by Science Foundation of China University of Petroleum,Beijing(No.2462019BJRC011 and No.2462020YXZZ051)National Natural Science Foundation of China(No.52004298).
文摘he cement sheath is the heart of any oil or gas well for providing zonal isolation and well integrity during the life of a well.Loads induced by well construction operations and borehole pressure and temperature changes may lead to the ultimate failure of cement sheath.This paper quantifies the potential of cement failure under mechanically and thermally induced stress during the life-of-well using a coupled thermalehydrologicalemechanical(THM)modeling approach.A staged finite-element procedure is presented considering sequential stress and displacement development during each stage of the well life,including drilling,casing,cementing,completion,production,and injection.The staged model quantifies the stress states and state variables,e.g.,plastic strain,damage,and debonding at cement/rock or cement/casing interface,in each well stage from simultaneous action of in-situ stress,pore pressure,temperature,casing pressure,and cement hardening/shrinkage.Thus,it eliminates the need to guess the initial stress and strain state before modeling a specific stage.Moreover,coupled THM capabilities of the model ensure the full consideration of the interaction between these influential factors.
基金supported by the Fundamental Research Funds for the Central Universities(No.2020ZDPY0222)。
文摘Hot dry rock,as a renewable and sustainable energy source,can alleviate resource shortages and environmental pollution.Based on data from the Qiabuqia geothermal field and an established thermal-hydrological-mechanical coupled mathematical model,a novel horizontally layered enhanced geothermal system(EGS)is proposed and compared with the conventional double vertical well EGS.Under the simulated conditions in this paper,the comprehensive heat recovery performance of the horizontally layered EGS is significantly better than that of the double vertical well EGS.Specifically,although the average production temperature of the double vertical well EGS is higher than that of the horizontally layered EGS in the attenuation stage,the heat power output of the horizontally layered EGS ranges from 6.10 MW to 12.25 MW,which is 1.36 to 1.67 times that of the double vertical well EGS.Additionally,the heat recovery rate of the horizontally layered EGS is 6.63%higher than that of the double vertical well EGS and is thus more economical.Finally,parametric analysis was performed to investigate the influence of the controllable parameters on heat recovery for the horizontally layered EGS.The heat power output and heat extraction ratio are proportional to the pressure difference and well spacing and inversely proportional to the injection fluid temperature.The thermal power output is most greatly influenced by the pressure difference,followed by the well spacing and injection fluid temperature.The effects of the pressure difference and well spacing on the heat recovery rate are almost the same,and the injection fluid temperature has no effect.
