Aiming at the technology of hydraulic fracturing assisted oil displacement which combines hydraulic fracturing,seepage and oil displacement,an experimental system of energy storage and flowback in fracturing assisted ...Aiming at the technology of hydraulic fracturing assisted oil displacement which combines hydraulic fracturing,seepage and oil displacement,an experimental system of energy storage and flowback in fracturing assisted oil displacement process has been developed and used to simulate the mechanism of percolation,energy storage,oil displacement and flowback of chemical agents in the whole process.The research shows that in hydraulic fracturing assisted oil displacement,the chemical agent could be directly pushed to the deeper area of the low and medium permeability reservoirs,avoiding the viscosity loss and adhesion retention of chemical agents near the pay zone;in addition,this technology could effectively enlarge the swept volume,improve the oil displacement efficiency,replenish formation energy,gather and exploit the scattered residual oil.For the reservoir with higher permeability,this measure takes effect fast,so to lower cost,and the high pressure hydraulic fracturing assisted oil displacement could be adopted directly.For the reservoir with lower permeability which is difficult to absorb water,hydraulic fracturing assisted oil displacement with surfactant should be adopted to reduce flow resistance of the reservoir and improve the water absorption capacity and development effect of the reservoir.The degree of formation energy deficit was the main factor affecting the effective swept range of chemical agents.Moreover,the larger the formation energy deficit was,the further the seepage distance of chemical agents was,accordingly,the larger the effective swept volume was,and the greater the increase of oil recovery was.Formation energy enhancement was the most important contribution to enhanced oil recovery(EOR),which was the key to EOR by the technology of hydraulic fracturing assisted oil displacement.展开更多
To clarify microscopic mechanisms of residual oil displacement by hydraulic pulsation wave,microscopic visualization experiments of hydraulic pulsation wave driving residual oil were carried out by using the microscop...To clarify microscopic mechanisms of residual oil displacement by hydraulic pulsation wave,microscopic visualization experiments of hydraulic pulsation wave driving residual oil were carried out by using the microscopic visualization device of pulsating water drive.For the four types of residual oil left in the reservoir after water flooding,i.e.membrane,column,cluster,and blind end residual oils,hydraulic pulsation waves broke the micro-equilibrium of the interface by disturbing the oil-water interface,so that the injected water invaded into and contacted with the remaining oil in small pores and blind holes,and the remaining oil was pushed or stripped to the mainstream channel by deformation superposition effect and then carried out by the injected water.In the displacement,the pulsation frequency mainly affected the cluster and blind end remaining oil,and the hydraulic pulsation wave with a frequency of about 1 Hz had the best effect in improving the recovery.The pulsation amplitude value mainly affected the membrane and column residual oil,and the larger the amplitude value,the more remaining oil the hydraulic pulsation wave would displace.The presence of low intensity continuous flow pressure and holding pressure end pressure promoted the concentration of pulsating energy and greatly improve the recovery of cluster residual oil.The rise in temperature made the hydraulic pulsation wave work better in displacing remaining oil,improving the efficiency of oil flooding.展开更多
基金Supported by the National Natural Science Foundation of China(52074087,51804076)Postdoctoral Natural Science Foundation of China(2021M690528).
文摘Aiming at the technology of hydraulic fracturing assisted oil displacement which combines hydraulic fracturing,seepage and oil displacement,an experimental system of energy storage and flowback in fracturing assisted oil displacement process has been developed and used to simulate the mechanism of percolation,energy storage,oil displacement and flowback of chemical agents in the whole process.The research shows that in hydraulic fracturing assisted oil displacement,the chemical agent could be directly pushed to the deeper area of the low and medium permeability reservoirs,avoiding the viscosity loss and adhesion retention of chemical agents near the pay zone;in addition,this technology could effectively enlarge the swept volume,improve the oil displacement efficiency,replenish formation energy,gather and exploit the scattered residual oil.For the reservoir with higher permeability,this measure takes effect fast,so to lower cost,and the high pressure hydraulic fracturing assisted oil displacement could be adopted directly.For the reservoir with lower permeability which is difficult to absorb water,hydraulic fracturing assisted oil displacement with surfactant should be adopted to reduce flow resistance of the reservoir and improve the water absorption capacity and development effect of the reservoir.The degree of formation energy deficit was the main factor affecting the effective swept range of chemical agents.Moreover,the larger the formation energy deficit was,the further the seepage distance of chemical agents was,accordingly,the larger the effective swept volume was,and the greater the increase of oil recovery was.Formation energy enhancement was the most important contribution to enhanced oil recovery(EOR),which was the key to EOR by the technology of hydraulic fracturing assisted oil displacement.
基金Supported by the National Natural Science Foundation of China(5187433951904320)National Key R&D Program(2020YFA0711804).
文摘To clarify microscopic mechanisms of residual oil displacement by hydraulic pulsation wave,microscopic visualization experiments of hydraulic pulsation wave driving residual oil were carried out by using the microscopic visualization device of pulsating water drive.For the four types of residual oil left in the reservoir after water flooding,i.e.membrane,column,cluster,and blind end residual oils,hydraulic pulsation waves broke the micro-equilibrium of the interface by disturbing the oil-water interface,so that the injected water invaded into and contacted with the remaining oil in small pores and blind holes,and the remaining oil was pushed or stripped to the mainstream channel by deformation superposition effect and then carried out by the injected water.In the displacement,the pulsation frequency mainly affected the cluster and blind end remaining oil,and the hydraulic pulsation wave with a frequency of about 1 Hz had the best effect in improving the recovery.The pulsation amplitude value mainly affected the membrane and column residual oil,and the larger the amplitude value,the more remaining oil the hydraulic pulsation wave would displace.The presence of low intensity continuous flow pressure and holding pressure end pressure promoted the concentration of pulsating energy and greatly improve the recovery of cluster residual oil.The rise in temperature made the hydraulic pulsation wave work better in displacing remaining oil,improving the efficiency of oil flooding.
