Research On The Reservoir Geological Characteristic Of Upper 3rd Member Of Shahe-jie Formation In The East Of Che 40 Block In Dongfenggang Oilfield

Che40 block,Dong Fenggang oilfield is in middle to late period of development of the oil field, the significant prospecting target is subtle reservoirs which include lithological reservoirs and structure-lithology reservoirs. This paper investigates the geological reservoir characteristics of upper 3rd Member of Shahejie, through study of detailed stratigraphic division and sedimentary microfacies heterogeneity as well as the research of reservoir characterization and comprehensive evaluation. This all lay foundation for the further establishment of the reservoir geological model and the adjustment of development plan design.Through correlation of strata of upper 3rd Member of Shahejie, There are 3 sands groups and 19 thin layer are classified.The first sand group evolves best, while the second and third sand group relatively poorly develop. On the basis of stratigraphic classification and correlation, we analyze the sedimentary microfacies. The sedimentary system is deep-semideep lacustrine facies mixed with turbidity current deposit,the staple microfacies styles are the primary channel and the main water channel edge of the fan root subfacie, the braided channel, the inter channel and the fan front microfacies of the middle fan subfacies, fan distal subfacies and the lobes body microfacies. Different types of sedimentary microfacies control sand body development characteristics differently, the main water channel sedimentary and the braided channel sedimentary develop best, in the plane, the sand body develop regional obviously,mainly in the west;in profile, multi-stage fan bodies scatters randomly with poor lateral continuity, braided channel microfacies have most extensive development in the region.The main lithologies of upper 3rd Member of Shahejie Formation of the region are power and fine sandstone, fragmentary material chiefly are quartz, feldspar and debris, secondary pore is comparative development that includes dissolved interparticle and intraparticle pores and fissures. Through statistical analysis of the reservoir permeability, porosity is mainly distributed in the range of 14%~18% and permeability is mainly distributed in 12~100×10-3um2 range which belong to medium porosity and medium permeability or medium porosity and low permeability reservoirs. Reservoir is divided into four categories.classⅡand classⅢ are mainly developed which accounted for 96.1%. Reservoir developed poorly and sedimentary microfacies are the greatest influence on reservoir quality factor in the region, through comprehensive evaluation using porosity, permeability, sand ligancy, variation coefficient and sedimentary microfacies, which of five parameters can reflex reservoir heterogeneity and the connectedness of sand bodies.A lot of small scale structure-lithology reservoirs developed in the region, a small amount of lithologic reservoirs also developed. The main control factors for oil and gas distribution are reservoir property, microfacies and faults analysising of enrichment characteristics of oil and gas, structural conditions,comprehensive study of the reservoir and sedimentary system.