Study On The Reservoir Characteristics Of Upper Youshashan Formation In Nanyishan Oilfiled

Nanyishan oilfield is located in the west depression of Qaidam Basin. With thedevelopment of mining time and increased investment, oil production has increasedsignificantly. However, in the study area the injection efficiency is low, each well productionslows down fastly and is not easy to stable just because of poor lithology and property.Therefore, it is necessary to carry out the detailed study of reservoir characteristics and thecomprehensive evaluation.Upper Youshashan reservoir Characteristics have been researched in this paper. Thesewere results and understandings:①this paper researches on the reservoir rock and find thesand reservoirs and carbonate reservoirs, according to coring, logging data, logging data.Sandstone and siltstone reservoirs is anti-cycle in the longitudinal direction; rock texturalmaturity is medium-good; reservoir cement composition mainly calcite cement type base;the types of rock is sandstone and lithic-sandstone. Carbonate rock reservoirs are five maincategories: granular limestone, micritic limestone, granular dolomite, micritic yunyan, algaebonded rock. The cementation main types are pores and base. These features indicate that thelake the deposition of Youshashan late with back sedimentary characteristics.②it is foundthat Nanyishan oilfield reservoir is in the late diagenetic stage. Compaction, cementation,dissolution, metasomatism are the main diagenesis. Compaction is low-moderate cementationis developed, the dissolution medium to strong, moderate to strong metasomatism in this area.③reservoir properties of the reservoir groups were analyzed and found I Oil Group is a highporosity and low permeability-ultra-low permeability reservoir; II reservoir group are-highporosity and low permeability-ultra-low permeability reservoir; III oil group are hole,ultra-low permeability reservoir; IV oil group genus-low porosity and ultra-low permeabilityreservoir.④the paper finds I reservoir group the medium heterogeneous reservoirs, II, IVreservoir group is strongly heterogeneous reservoirs; the layer heterogeneity closely related to lithology; grain bank heterogeneity strongest, cloud floor, gray floor, sand flat are in turnweakened; there are Connectivity differences between the reservoir group on the plane,permeability plane distribution is different, the plane heterogeneity is strong. Reservoirheterogeneity of the study area is mainly controlled by sedimentary facies.⑤combined withprevious researches of the reservoir evaluation criteria, the district target layer reservoir isdivided into good, normal and poor. Distribution of reservoir plane are certain rules, Ireservoir is less than class II reservoir in the study area. The paper provides a reliabletheoretical basis and support for the next stage of oilfield development of rationaldevelopment programs.