Comprehensive studies on CO_(2)breakthrough times and flooding effects are crucial for optimizing CO_(2)flooding strategies.This study utilized numerical simulations to investigate the effects of hydraulic fractures,p...Comprehensive studies on CO_(2)breakthrough times and flooding effects are crucial for optimizing CO_(2)flooding strategies.This study utilized numerical simulations to investigate the effects of hydraulic fractures,permeability,and CO_(2)injection rates on CO_(2)breakthrough times and cumulative oil production.Nonlinear relationships among the respective variables were established,with Sobol method analysis delineating the dominant control factors.The key findings indicate that although hydraulic fracturing shortens CO_(2)breakthrough time,it concurrently enhances cumulative oil production.The orientation of hydraulic fractures emerged as a pivotal factor influencing flooding effectiveness.Furthermore,lower permeability corresponds to lower initial oil production,while higher permeability corresponds to higher initial daily oil production.When reservoir permeability is 1 mD,oil production declines at 1000 days,and at 2 mD,it declines at 700 days.At a surface CO_(2)injection rate of 10,000 m^(3)/d,the daily oil production of a single well is approximately 7.5 m^(3),and this value remains relatively stable over time.The hierarchical order of influence on CO_(2)breakthrough and rapid rise times,from highest to lowest,is permeability,well spacing,CO_(2)injection rate,porosity,and hydraulic fracture conductivity.Similarly,the order of influence on cumulative oil production,from highest to lowest,is well spacing,porosity,permeability,CO_(2)injection rate,and hydraulic fracture conductivity.This paper analyzed the impact of geological and engineering parameters on CO_(2)flooding and oil production and provided insights to optimize CO_(2)injection strategies for enhanced oil recovery.展开更多
Dimensional analysis and numerical simulations were carried out to research prediction method of breakthrough time of horizontal wells in bottom water reservoir. Four dimensionless independent variables and dimensionl...Dimensional analysis and numerical simulations were carried out to research prediction method of breakthrough time of horizontal wells in bottom water reservoir. Four dimensionless independent variables and dimensionless time were derived from 10 influencing factors of the problem by using dimensional analysis. Simulations of horizontal well in reservoir with bottom water were run to find the prediction correlation. A general and concise functional relationship for predicting breakthrough time was established based on simulation results and theoretical analysis. The breakthrough time of one conceptual model predicted by the correlation is very close to the result by Eclipse with less than 2% error. The practical breakthrough time of one well in Helder oilfield is 10 d, and the predicted results by the method is 11.2 d, which is more accurate than the analytical result. Case study indicates that the method could predict breakthrough time of horizontal well under different reservoir conditions accurately. For its university and ease of use, the method is suitable for quick prediction of breakthrough time.展开更多
The existing models for calculating the water breakthrough time of gas wells in gas reservoirs with edge water ignore the effects of reservoir's interlayer heterogeneity,so their calculation results are more devia...The existing models for calculating the water breakthrough time of gas wells in gas reservoirs with edge water ignore the effects of reservoir's interlayer heterogeneity,so their calculation results are more deviated from the actual water breakthrough time of gas wells.As a result,they cannot accurately and effectively guide the adjustment of gas well production system and the formulation of technical water control measures.In this paper,a water-flooding seepage experiment of parallel core was conducted by taking the gas reservoir with edge water of Lower Triassic Feixianguan Formation in the Puguang Gas Field of the Sichuan Basin as an example.Then,the effects of edge water inrush caused by the interlayer heterogeneity of reservoir on water breakthrough time of gas wells was analyzed by means of reservoir numerical simulation.Based on this,the inrush coefficient was introduced to characterize the interlayer heterogeneity of reservoir,and a model for calculating the water breakthrough time of gas wells in the commingled gas reservoir with edge water considering the influence of interlayer heterogeneity was established.Finally,five wells in the gas reservoir of Feixianguan Formation in the Puguang Gas Field were selected for case calculation.And the following research results were obtained.First,the interlayer heterogeneity of gas reservoir results in edge water burst.And the stronger the interlayer heterogeneity,the more severe the edge water coning and the sooner the water breakthrough.The water breakthrough time of gas wells depends on the water breakthrough time in the reservoir with the highest permeability.Second,a model for calculating the water breakthrough time of gas wells in the gas reservoirs with edge water considering the influence of reservoir interlayer heterogeneity is established based on the seepage theory.And the relative errors of its calculation results are in the range of 3.43e4.70%,which can satisfy the accuracy requirement of engineering errors.In conclusion,this newly established model can provide an effective method for accurately calculating the water break-through time of the gas well in the commingled gas reservoir with edge water.Furthermore,it is conducive to the adjustment of the production system of gas wells in the gas reservoir with edge water and the formulation of technical water control measures.展开更多
Sand-bentonite(SB)cutoff walls are commonly used as barriers in polluted areas.The embedded part of an SB wall in an aquitard is crucial for its performance.In this study,a centrifuge modeling test was carried out to ...Sand-bentonite(SB)cutoff walls are commonly used as barriers in polluted areas.The embedded part of an SB wall in an aquitard is crucial for its performance.In this study,a centrifuge modeling test was carried out to investigate the effect of contact between the key and the aquitard on the migration behavior of contaminants within an SB cutoff wall.The centrifuge was accelerated to 100g(gravitational acceleration)and maintained in-flight for 36 h,equivalent to 41 years of transport time in the prototype.Results showed that the contaminant concentration within the SB wall was higher downstream than in the middle in the thickness direction,and deeper regions exhibited a greater concentration than shallower ones.This concentration distribution indicated that contaminants were transported along the interface between the SB wall and the aquitard,bypassing the base of the SB wall to reach the downstream aquifer rapidly.An improved numerical simulation considering preferential interface migration was performed,which agreed with the centrifuge test results.The simulation results indicated that preferential interface migration,as a defect,significantly accelerated the speed of contaminant migration,reducing the breakthrough time of the SB wall to 1/9 of that without preferential interface migration.展开更多
基金supported by the China Postdoctoral Science Foundation(No.2024M752803)the National Natural Science Foundation of China(No.52179112)+1 种基金the Open Fund of National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,China(No.PLN2023-02)the Open Fund of Key Laboratory of Deep Geothermal Resources,Ministry of Natural Resources of the People's Republic of China(No.KLDGR2024B01).
文摘Comprehensive studies on CO_(2)breakthrough times and flooding effects are crucial for optimizing CO_(2)flooding strategies.This study utilized numerical simulations to investigate the effects of hydraulic fractures,permeability,and CO_(2)injection rates on CO_(2)breakthrough times and cumulative oil production.Nonlinear relationships among the respective variables were established,with Sobol method analysis delineating the dominant control factors.The key findings indicate that although hydraulic fracturing shortens CO_(2)breakthrough time,it concurrently enhances cumulative oil production.The orientation of hydraulic fractures emerged as a pivotal factor influencing flooding effectiveness.Furthermore,lower permeability corresponds to lower initial oil production,while higher permeability corresponds to higher initial daily oil production.When reservoir permeability is 1 mD,oil production declines at 1000 days,and at 2 mD,it declines at 700 days.At a surface CO_(2)injection rate of 10,000 m^(3)/d,the daily oil production of a single well is approximately 7.5 m^(3),and this value remains relatively stable over time.The hierarchical order of influence on CO_(2)breakthrough and rapid rise times,from highest to lowest,is permeability,well spacing,CO_(2)injection rate,porosity,and hydraulic fracture conductivity.Similarly,the order of influence on cumulative oil production,from highest to lowest,is well spacing,porosity,permeability,CO_(2)injection rate,and hydraulic fracture conductivity.This paper analyzed the impact of geological and engineering parameters on CO_(2)flooding and oil production and provided insights to optimize CO_(2)injection strategies for enhanced oil recovery.
基金Project(2011ZX05009-004)supported by the National Science and Technology Major Projects of China
文摘Dimensional analysis and numerical simulations were carried out to research prediction method of breakthrough time of horizontal wells in bottom water reservoir. Four dimensionless independent variables and dimensionless time were derived from 10 influencing factors of the problem by using dimensional analysis. Simulations of horizontal well in reservoir with bottom water were run to find the prediction correlation. A general and concise functional relationship for predicting breakthrough time was established based on simulation results and theoretical analysis. The breakthrough time of one conceptual model predicted by the correlation is very close to the result by Eclipse with less than 2% error. The practical breakthrough time of one well in Helder oilfield is 10 d, and the predicted results by the method is 11.2 d, which is more accurate than the analytical result. Case study indicates that the method could predict breakthrough time of horizontal well under different reservoir conditions accurately. For its university and ease of use, the method is suitable for quick prediction of breakthrough time.
基金Project supported by the National Science and Technology Major Project“Research on Gas-Water Two-Phase Flow Characteristics of Deep Reef-Shoal Reservoirs”(No.2016ZX05017-001-HZ02)Chongqing Graduate Research and Innovation Project“Water Invasion Mechanism and Prediction Model of Water Breakthrough Time of Ultra-Deep Carbonate Gas Reservoirs”(No.CYS19351)。
文摘The existing models for calculating the water breakthrough time of gas wells in gas reservoirs with edge water ignore the effects of reservoir's interlayer heterogeneity,so their calculation results are more deviated from the actual water breakthrough time of gas wells.As a result,they cannot accurately and effectively guide the adjustment of gas well production system and the formulation of technical water control measures.In this paper,a water-flooding seepage experiment of parallel core was conducted by taking the gas reservoir with edge water of Lower Triassic Feixianguan Formation in the Puguang Gas Field of the Sichuan Basin as an example.Then,the effects of edge water inrush caused by the interlayer heterogeneity of reservoir on water breakthrough time of gas wells was analyzed by means of reservoir numerical simulation.Based on this,the inrush coefficient was introduced to characterize the interlayer heterogeneity of reservoir,and a model for calculating the water breakthrough time of gas wells in the commingled gas reservoir with edge water considering the influence of interlayer heterogeneity was established.Finally,five wells in the gas reservoir of Feixianguan Formation in the Puguang Gas Field were selected for case calculation.And the following research results were obtained.First,the interlayer heterogeneity of gas reservoir results in edge water burst.And the stronger the interlayer heterogeneity,the more severe the edge water coning and the sooner the water breakthrough.The water breakthrough time of gas wells depends on the water breakthrough time in the reservoir with the highest permeability.Second,a model for calculating the water breakthrough time of gas wells in the gas reservoirs with edge water considering the influence of reservoir interlayer heterogeneity is established based on the seepage theory.And the relative errors of its calculation results are in the range of 3.43e4.70%,which can satisfy the accuracy requirement of engineering errors.In conclusion,this newly established model can provide an effective method for accurately calculating the water break-through time of the gas well in the commingled gas reservoir with edge water.Furthermore,it is conducive to the adjustment of the production system of gas wells in the gas reservoir with edge water and the formulation of technical water control measures.
基金supported by the National Key Research and Development Program of China(No.2018YFC1802304)the National Natural Science Foundation of China(Nos.51988101 and 42077241)the Natural Science Foundation of Zhejiang Province(No.LCZ19E080002),China.
文摘Sand-bentonite(SB)cutoff walls are commonly used as barriers in polluted areas.The embedded part of an SB wall in an aquitard is crucial for its performance.In this study,a centrifuge modeling test was carried out to investigate the effect of contact between the key and the aquitard on the migration behavior of contaminants within an SB cutoff wall.The centrifuge was accelerated to 100g(gravitational acceleration)and maintained in-flight for 36 h,equivalent to 41 years of transport time in the prototype.Results showed that the contaminant concentration within the SB wall was higher downstream than in the middle in the thickness direction,and deeper regions exhibited a greater concentration than shallower ones.This concentration distribution indicated that contaminants were transported along the interface between the SB wall and the aquitard,bypassing the base of the SB wall to reach the downstream aquifer rapidly.An improved numerical simulation considering preferential interface migration was performed,which agreed with the centrifuge test results.The simulation results indicated that preferential interface migration,as a defect,significantly accelerated the speed of contaminant migration,reducing the breakthrough time of the SB wall to 1/9 of that without preferential interface migration.
