Numerical simulation of miscible flooding with natural gas injection in ultra-deep fault-karst reservoir
At present,ultra-deep fault-karst reservoirs in Shunbei No.1 fault zone has entered the stage of natural gas injection for oil displacement,and the average formation pressures of most reservoirs meets the miscible conditions of natural gas.However,the gas injection mechanism is still unclear in ultra-deep fault-karst reservoirs during natural gas injection.In order to optimize the gas injection parameters of Shunbei No.1 fault zone in the stage of natural gas injection and oil displacement,a gas injection mechanism model was established for the well group S unit of Shunbei No.1 strip.The sweep efficiency,oil change efficiency,differentiation speed,and the movement characteristics of miscible zone under natural gas injection wer studied through high-precision numerical simulation.The simulation results showed that:1)The miscible zone in the ultra-deep fault-karst reservoir first moves along the fracture to the top to form a gas cap flooding and then moves laterally to both sides of the fracture;2)The high injection and low production mode will form gas cap flooding and miscible flooding,which will delay the breakthrough time of injected gas by comparing with low injection and high production;3)The swept volume of natural gas in well group S increases with the increase of gas injection PV,and the oil change efficiency increases first and then decreases with the increase of gas injection PV.The optimal total gas injection volume is 0.08 PV.
fault-karst reservoirnatural gas injectionmiscible floodinggas injection mechanismnumerical simulationparameter optimization
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维普
