| The Xiasiwan area of the Ordos Basin is a low-porosity and low-permeability tight sandstone gas reservoir.The paper mainly studies the micro-heterogeneity of the Shanxi Formation reservoir in the Xiasiwan area.Basic data,through the analysis of the four aspects of reservoir petrology,sedimentary microfacies,reservoir physical property heterogeneity,and pore structure heterogeneity from the microscopic view,and further study the reservoir heterogeneity on this basis The impact of nature on gas-bearing properties provides a basis for later exploration and development of gas reservoirs in the study area.Through the analysis of the petrological characteristics of the sandstone reservoirs in the Shanxi Formation in the study area,it can be concluded that the rock types of the Shan 1 Member in the study area are most developed with quartz sandstone.The reservoir porosity distribution ranges from 0.15%to 9.84%and the permeability distribution ranges from 0.0126×10-3?m2?0.9326×10-3?m2.The rock types of the Shan 2 Member are most developed in lithic sandstone,with rapid lithological changes and strong heterogeneity.Its porosity distribution ranges from 1.09%to 2.75%,and the permeability distribution ranges from 0.0160×10-3?m2?0.0361×10-3?m2.The distribution of porosity indicates that the reservoirs of Shanxi Formation in the study area belong to low porosity-ultra-low porosity reservoirs,and the distribution of permeability indicates that the reservoirs in the study area belong to the category of tight sandstone.The sandstone maturity of Shan 1 Member is relatively higher than that of Shan 2,which generally reflects the trend of gradually higher composition maturity from bottom to top.Based on the comprehensive analysis of lithofacies,logging facies and grain size characteristics,it is concluded that the main body of the Shanxi Formation in the study area is developed with delta front subfacies,which is the main sedimentary facies of this area and the main gas reservoir.Diverging channels,underwater diversion bays and sheet sand.The quartz content and feldspar content of Shan 1 and Shan 2 reservoirs in the study area are quite different,and they are not significantly related to the burial depth.The quartz clay content of Shan 1 reservoir is higher than that of Shan 2 reservoir.The content of debris particles is heterogeneous between layers.The content of clay minerals as interstitials in the Shan 1Member and Shan 2 Member are different,and the relative content has obvious difference at each burial depth,but the correlation with the burial depth is weak,showing a certain heterogeneity.The size and arrangement of clastic particles in the same rock sample in the Shanxi Formation tight sandstone reservoirs in different directions are different,and the arrangement of particles has a greater impact on the permeability anisotropy of tight sandstone reservoirs.The reservoirs of Shan 1 Member are relatively more concentrated in physical properties than Shan 2 reservoirs,and the heterogeneity of Shan 2 is stronger than Shan 1.Research on reservoir heterogeneity and gas distribution law shows that the influence of reservoir heterogeneity on gas content is mainly manifested in:the lithology,mineral composition,pore structure and physical property heterogeneity parameters of the reservoir are in the micro The influence of the above on the aeration.The higher the percentage of quartz in the mineral composition of the reservoir,the larger the radius of the mainstream throat,the smaller the displacement pressure,the smaller the permeability range,the higher the gas saturation,and the better the gas content of the reservoir. |
PDF Full Text Request