Oil-gas Distribution And Control Factors Of Chang 6 Reservoir In The West Of Shuanghe Area

This paper aims at the Chang 6 oil layer group in the west of Shuanghe area.Using the data of drilling,logging,well logging,core,experimental analysis,oil test and production in the study area,combining with the theoretical methods of sedimentary petrology,petroleum geology and reservoir forming geology.The theoretical method is used to study the characteristics of strata,structure,sedimentary facies,reservoirs and reservoirs of the Chang 6oil layer group in the west of Shuanghe area.Through the combination of characteristic changes of the oil layer group in the longitudinal direction and the plane and the spatial distribution of oil and gas,the enrichment rules and main controlling factors of oil and gas are studied.The results show that the Chang 6 formation as a whole is a monoclinal structure with a high degree in the east and a low degree in the west,with low amplitude bulge and depression in the area constitute a nasal fold in the east of the study area.Delta front subfacies deposits are developed in this area,and the deltaic progradation features are obvious in the longitudinal direction.The sand bodies are mainly distributary channel sand bodies and estuary bar sand bodies under water.The lithology of the reservoir is mainly fine arkose sandstone with porosity of 10%~14%and permeability of 0.1~0.4mD,belonging to the low porosity and ultra-low permeability reservoir.Calcium content has a great influence on reservoir physical properties and reservoir heterogeneity is strong.Crude oil is a conventional continental black oil under low temperature and low pressure environment.It has the characteristics of low density,low viscosity,low sulfur content and high freezing point.Oil and gas are mainly distributed in the chang 6~1 and chang 6~2 sandstone reservoirs,with oil saturation ranging from42%to 68.7%.The profile shows that most of the reservoirs,except some reservoirs,have no oil-water interface and are mainly lithologic reservoirs.The sedimentary microfacies controls the distribution of oil and gas in the study area,the structure controls the differential distribution of oil saturation in the reservoir,and the reservoir physical properties have a weak control on the oil and gas distribution.Comprehensive thinking,It is concluded that the main controlling factors of oil and gas distribution are sedimentary microfacies,and the reservoir types are mainly tectonic-lithologic reservoirs.The hydrocarbon accumulation model is mainly the near-source upper reservoir.