Study On Hydrocarbon Accumulation Process Of Paleogene Low-permeability Area In Weizhou 12-2 Target Region,Beibuwan Basin

Low permeability crude oil resources in South China Sea are huge,and there are many exploration zones.It is of great significance to carry out research on the accumulation process of Paleogene low-permeability reservoirs in Weizhou 12-2 target region,Beibuwan Basin.In this paper,the hydrocarbon accumulation process is studied from four aspects: reservoir pore structure,hydrocarbon accumulation period,hydrocarbon charging process and the sources of oil and gas.The characteristics of lowpermeability reservoirs are studied by field emission scanning electron microscopy,nitrogen adsorption,high pressure mercury injection and full pore size distribution.It is believed that the macropores in low permeability reservoirs are developed,the pore shape is mainly slit-type pores,the pore types are diverse.and the pores show great heterogeneity.The fluorescence analysis and homogenization temperature test of inclusions were used to determine the accumulation time.The study believes that there is a phase of oil and gas charging event,the overall oil and gas charging time is relatively late,and the low permeability is formed at the time of accumulation.The one-dimensional and two-dimensional physical simulation experiments are used to simulate the charging process of oil and gas.The low permeability reservoir properties affect the hydrocarbon accumulation process.The physical properties of low-permeability reservoirs affect the hydrocarbon accumulation process,and the development of faults and the formation of traps that match the accumulation period control the characteristics of hydrocarbon migration and accumulation.The hydrocarbon-generating pressurization is the main driving force,and the closed fracture plays a controlling role in oil and gas accumulation.Through the saturated hydrocarbons,nitrogenous compounds and maturity analysis,the migration path of crude oil is analyzed.The oil and gas sources of the samples are the same source rock,which is the hydrocarbon source from the sag B source rock.The migration direction of the crude oil is from the deep sag to the bulge edge and from the deep area to the shallow area.