In shale gas reservoir stimulation,proppants are essential for sustaining fracture conductivity.However,increasing closing stress causes proppants to embed into the rock matrix,leading to a progressive decline in frac...In shale gas reservoir stimulation,proppants are essential for sustaining fracture conductivity.However,increasing closing stress causes proppants to embed into the rock matrix,leading to a progressive decline in fracture permeability and conductivity.Furthermore,rock creep contributes to long-term reductions in fracture performance.To elucidate the combined effects of proppant embedding and rock creep on sustained conductivity,this study conducted controlled experiments examining conductivity decay in propped fractures under varying closing stresses,explicitly accounting for both mechanisms.An embedded discrete fracture model was developed to simulate reservoir production under different conductivity decay scenarios,while evaluating the influence of proppant parameters on fracture performance.The results demonstrate that fracture conductivity diminishes rapidly with increasing stress,yet at 50 MPa,the decline becomes less pronounced.Simulated production profiles show strong agreement with actual gas well data,confirming the model’s accuracy and predictive capability.These findings suggest that employing a high proppant concentration with smaller particle size(5 kg/m^(2),70/140 mesh)is effective for maintaining long-term fracture conductivity and enhancing shale gas recovery.This study provides a rigorous framework for optimizing proppant selection and designing stimulation strategies that maximize reservoir performance over time.展开更多
Casing deformation and frac-hit pose significant challenges to the development of deep shale gas in southern Sichuan Basin.By analyzing the mechanism and main control factors of casing deformation and frac-hit,two kin...Casing deformation and frac-hit pose significant challenges to the development of deep shale gas in southern Sichuan Basin.By analyzing the mechanism and main control factors of casing deformation and frac-hit,two kinds of risk assessment methods were defined,and the overall prevention and control concept and practice were formulated.The results show that initial stress,pore pressure,fault development and large scale fracturing in local block are the main factors leading to the deformation.The development of fracture through well group and uncontrolled fracturing fluid volume are the main factors leading to pressure channeling.Based on this,the risk classification technology of casing deformation and frac-hit is established,and the dual-optimal,dual-control concept and technology are formed.In terms of the prevention and control of casing deformation,the formation of small-diameter bridge plug fracturing,large section combined fracturing,glass beads cementing,singlewell staggered and platform straddle fracturing mode,dual-dimension controlled and lift fracturing,hyperbolic diagnosis,etc.Frac-hit prevention and control formed pump sequence optimization mode,physical and chemical temporary plugging and other methods.The above technology achieved casing deformation rate decreased from 50.4%to 25.4%,frac-hit rate decreased from 58.6%to 33.9%,and the average well kilometer EUR reached 0.52e0.7 million square meters,an increase of 7.7%compared with the previous research,with remarkable results.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52204051,52304046).
文摘In shale gas reservoir stimulation,proppants are essential for sustaining fracture conductivity.However,increasing closing stress causes proppants to embed into the rock matrix,leading to a progressive decline in fracture permeability and conductivity.Furthermore,rock creep contributes to long-term reductions in fracture performance.To elucidate the combined effects of proppant embedding and rock creep on sustained conductivity,this study conducted controlled experiments examining conductivity decay in propped fractures under varying closing stresses,explicitly accounting for both mechanisms.An embedded discrete fracture model was developed to simulate reservoir production under different conductivity decay scenarios,while evaluating the influence of proppant parameters on fracture performance.The results demonstrate that fracture conductivity diminishes rapidly with increasing stress,yet at 50 MPa,the decline becomes less pronounced.Simulated production profiles show strong agreement with actual gas well data,confirming the model’s accuracy and predictive capability.These findings suggest that employing a high proppant concentration with smaller particle size(5 kg/m^(2),70/140 mesh)is effective for maintaining long-term fracture conductivity and enhancing shale gas recovery.This study provides a rigorous framework for optimizing proppant selection and designing stimulation strategies that maximize reservoir performance over time.
文摘Casing deformation and frac-hit pose significant challenges to the development of deep shale gas in southern Sichuan Basin.By analyzing the mechanism and main control factors of casing deformation and frac-hit,two kinds of risk assessment methods were defined,and the overall prevention and control concept and practice were formulated.The results show that initial stress,pore pressure,fault development and large scale fracturing in local block are the main factors leading to the deformation.The development of fracture through well group and uncontrolled fracturing fluid volume are the main factors leading to pressure channeling.Based on this,the risk classification technology of casing deformation and frac-hit is established,and the dual-optimal,dual-control concept and technology are formed.In terms of the prevention and control of casing deformation,the formation of small-diameter bridge plug fracturing,large section combined fracturing,glass beads cementing,singlewell staggered and platform straddle fracturing mode,dual-dimension controlled and lift fracturing,hyperbolic diagnosis,etc.Frac-hit prevention and control formed pump sequence optimization mode,physical and chemical temporary plugging and other methods.The above technology achieved casing deformation rate decreased from 50.4%to 25.4%,frac-hit rate decreased from 58.6%to 33.9%,and the average well kilometer EUR reached 0.52e0.7 million square meters,an increase of 7.7%compared with the previous research,with remarkable results.
