Changqing old oilfield Jurassic reservoir's average calibration recovery is 24.7%,with geological reserves recovery of 16.6%,water cut of 65.2%.And most of Jurassic reservoirs are in the middle and later field lif...Changqing old oilfield Jurassic reservoir's average calibration recovery is 24.7%,with geological reserves recovery of 16.6%,water cut of 65.2%.And most of Jurassic reservoirs are in the middle and later field life,part of them has entered the high water cut and high recovery stage.Traditional water flooding way for improving oil recovery becomes more difficult,and new method has to be considered.Maling oilfield BS district is a typical representative,with high water cut of 90.8%,high recovery percent of 26.1%and low oil recovery rate of 0.25%.To explore the new way to improve oil recovery,the polymer and surfactant(SP for short)important pilot test has been developed.The low permeability reservoir indoor core data in high water cut stage and inspection well results indicate that the reservoir permeability,pore combination characteristics and pore type changed greatly after long-term water flooding development.These changes bring more difficulties to the continue development,especially the high injection pressure,which can cause other problems for well pattern infilling and EOR.This paper takes the high injection pressure problem of Maling BS district Jurassic reservoir for example,analyzes the physical property change law on the following aspects:the development mode in the past,core analysis,formation sensitivity,interstitial matter,well test interpretation results,in order to help to further effective development and provide important parameters for tertiary oil recovery technique for similar reservoirs and others.展开更多
The paper presents the results of comprehensive studies of filtration and capacitance properties of highly porous reservoir rocks of the aquifer of an underground gas storage facility.The geomechanical part of the res...The paper presents the results of comprehensive studies of filtration and capacitance properties of highly porous reservoir rocks of the aquifer of an underground gas storage facility.The geomechanical part of the research included studying the dependence of rock permeability on the stress-strain state in the vicinity of the wells,and physical modeling of the implementation of the method of increasing the permeability of the wellbore zone-the method of directional unloading of the reservoir.The digital part of the research included computed tomography(CT)-based computer analysis of the internal structure,pore space characteristics,and filtration properties before and after the tests.According to the results of physical modeling of deformation and filtration processes,it is found that the permeability of rocks before fracture depends on the stress-strain state insignificantly,and this influence is reversible.However,when downhole pressure reaches 7-8 MPa,macrocracks in the rock begin to grow,accompanied by irreversible permeability increase.Porosity,geodesic tortuosity and permeability values were obtained based on digital studies and numerical modeling.A weak degree of transversal anisotropy of the filtration properties of rocks was detected.Based on the analysis of pore size distribution,pressure field and flow velocities,high homogeneity and connectivity of the rock pore space is shown.The absence of pronounced changes in pore space characteristics and pore permeability after non-uniform triaxial loading rocks was shown.On the basis of geometrical analysis of pore space,the reasons for weak permeability anisotropy were identified.The filtration-capacitance properties obtained from the digital analysis showed very good agreement with the results of field and laboratory measurements.The physical modeling has confirmed the efficiency of application of the directional unloading method for the reservoir under study.The necessary parameters of its application were calculated:bottomhole geometry,stage of operation,stresses and pressure drawdown value.展开更多
文摘Changqing old oilfield Jurassic reservoir's average calibration recovery is 24.7%,with geological reserves recovery of 16.6%,water cut of 65.2%.And most of Jurassic reservoirs are in the middle and later field life,part of them has entered the high water cut and high recovery stage.Traditional water flooding way for improving oil recovery becomes more difficult,and new method has to be considered.Maling oilfield BS district is a typical representative,with high water cut of 90.8%,high recovery percent of 26.1%and low oil recovery rate of 0.25%.To explore the new way to improve oil recovery,the polymer and surfactant(SP for short)important pilot test has been developed.The low permeability reservoir indoor core data in high water cut stage and inspection well results indicate that the reservoir permeability,pore combination characteristics and pore type changed greatly after long-term water flooding development.These changes bring more difficulties to the continue development,especially the high injection pressure,which can cause other problems for well pattern infilling and EOR.This paper takes the high injection pressure problem of Maling BS district Jurassic reservoir for example,analyzes the physical property change law on the following aspects:the development mode in the past,core analysis,formation sensitivity,interstitial matter,well test interpretation results,in order to help to further effective development and provide important parameters for tertiary oil recovery technique for similar reservoirs and others.
基金supported by the Russian Science Foundation(Grant No.22-11-00273).
文摘The paper presents the results of comprehensive studies of filtration and capacitance properties of highly porous reservoir rocks of the aquifer of an underground gas storage facility.The geomechanical part of the research included studying the dependence of rock permeability on the stress-strain state in the vicinity of the wells,and physical modeling of the implementation of the method of increasing the permeability of the wellbore zone-the method of directional unloading of the reservoir.The digital part of the research included computed tomography(CT)-based computer analysis of the internal structure,pore space characteristics,and filtration properties before and after the tests.According to the results of physical modeling of deformation and filtration processes,it is found that the permeability of rocks before fracture depends on the stress-strain state insignificantly,and this influence is reversible.However,when downhole pressure reaches 7-8 MPa,macrocracks in the rock begin to grow,accompanied by irreversible permeability increase.Porosity,geodesic tortuosity and permeability values were obtained based on digital studies and numerical modeling.A weak degree of transversal anisotropy of the filtration properties of rocks was detected.Based on the analysis of pore size distribution,pressure field and flow velocities,high homogeneity and connectivity of the rock pore space is shown.The absence of pronounced changes in pore space characteristics and pore permeability after non-uniform triaxial loading rocks was shown.On the basis of geometrical analysis of pore space,the reasons for weak permeability anisotropy were identified.The filtration-capacitance properties obtained from the digital analysis showed very good agreement with the results of field and laboratory measurements.The physical modeling has confirmed the efficiency of application of the directional unloading method for the reservoir under study.The necessary parameters of its application were calculated:bottomhole geometry,stage of operation,stresses and pressure drawdown value.
