Experimental Evaluation Of Nitrogen Recovery In X Area Of TH Oilfield

The oil of TH is a typical low permeability oil reservoir.The average porosity of X block is 12.4%;the permeability is 7.87 mD;and the viscosity of crude oil is 1.3367 mPa·s.The oilfild has entered the late stage of water flooding development after 20 years of development,facing the problems of high water cut,fast production decline,high water injection pressure and low efficiency.In order to improve the recovery rate of oil,it is urgent to study the feasibility of gas injectionThis article analysis the feasibility of gas injection in oilfield and reasonable gas injection development based on the investigation of the geological characteristics and the recovery percent through a series of indoor physical simulation experiments.(1)Gas injection expansion experiment and solid deposition experiment results show that the N2 and hydrocarbon gas can expand the crude oil,reduce the viscosity of crude oil,improve the physical properties of crude oil and increase its fluidity.Compared with N2,the viscosity reducing effect and the ability of dissolving crude oil are better.The light fraction of crude oil is extracted by injecting gas,which results in the increase of crude oil density.Two kinds of gas will not allow the solid phase deposition of crude oil.(2)Tube experiments show that N2 can't reach the miscible state even under the condition of formation fracture pressure.and hydrocarbon miscible pressure is 41.13MPa.Under the condition of 29MPa,the efficiency of two kinds of injected gas is 36.9%and 66.86%respectively.The x block can only realize the gas injection method of immiscible flooding(3)Different injection of gas long core experiment showed that gas flooding after water flooding can increase oil recovery.The maximum increase of CO2 was 23.36%.The increase of flue gas was about 13.16%.The increase of hydrocarbon gas was.The increase of N2 was about 6.74%.(4)Under different injected gas water alternative drive long core experiments show that 0.05HCPV injection is the best for N2 and hydrocarbon gas injection.N2 and hydrocarbon gas injection 0.1 HCPV enhanced recovery rate of second,0.15HCPV the worst.When the gas water ratio was 1:2,the maximum recovery rate was 16.71%,the gas water ratio of 1:1 increased by,and the gas water ratio of 2:1 increased by 8.96%.