Description Of Chang 6 Reservoir In Southeast Wangjiawan Area,Ordos Basin

The southeastern part of Wangjiawan is located in the middle of the Yishan slope in the Ordos Basin,and is located in Ansai County,Yan’an City,Shaanxi Province,chang 6 reservoir is one of the main oil producing period,has great potential for exploration,at present,the long interval 6 exploration degree is higher,because the research area of reservoir distribution,reservoir thickness and oil saturation change is bigger,The study of reservoir description needs to be refined,so the study of fine reservoir description of chang 6 member in the study area is carried out to provide a favorable basis for realizing the sustainable development of crude oil production in the area.Based on geological logging data,scanning electron microscope data,casting thin section data,mercury injection test data,physical property data,oil-water phase permeability data and core data,this paper establishes a geological database of the study area,and carries out stratigraphic division and correlation study of Chang 6 oil formation to clarify its structural characteristics,sedimentary facies characteristics and sand body distribution,the characteristics of petrology,physical property,heterogeneity and pore structure of Chang 6reservoir are systematically studied,and the reservoir is classified and evaluated,reservoir characteristics are studied to identify reservoir types and their influencing factors,and favorable blocks are predicted.Finally,3d geological models are established using Petrel software.The research results show that the chang 6 member in the study area can be divided into four oil reservoir subgroups,namely chang 6₁,Chang 6₂,Chang 6₃and Chang 6₄,according to phase mark,isopach principle and logging curve response characteristics,Chang 6 member in the study area is a delta sedimentary system,and Chang 6₁,6₂and 6₃are delta plain subfacies,with distributary channel and interchannel as the main microfacies,and Chang 6₄is a delta front subfacies,and the microfacies are mainly underwater distributary channel and interdistributary bay;The channel sandstone is dominated by fine-grained feldspar sandstone with high structural maturity,and the pore types are mainly primary pore and secondary pore.Intergranular pore and dissolution intergranular pore are the most developed in the reservoir in the study area,the pore throat types are divided into meso-fine throat type and pore-micro throat type,and the reservoir is low porosity and ultra-low permeability reservoir,the overall heterogeneity within the reservoir layer is moderate-weak,moderate and moderate-strong,and the heterogeneity between layers is strong,based on the evaluation criteria of reservoir classification,the reservoir types in the study area can be divided into two types:ⅡandⅢ,It can be divided into four subtypesⅡa,Ⅱb,Ⅲa andⅢb,respectively,the main reservoir types in the study area areⅢa,followed byⅢb,Ⅱb andⅡa;The reservoir type in the study area is structure-lithologic reservoir,which is affected by lithology,structure and diagenesis,the reservoir is mainly developed in the area with well-developed sandstone,high structural point and good physical properties,a total of 10 favorable blocks are predicted for each subgroup of Chang 6 reservoir;Petrel software was used to establish the structure,lithofacies and attribute models of the study area.the models had a good correspondence with the geological research results,and the lithofacies model and attribute model had a high consistency in their distribution forms,which provided a reliable basis for the next development.