Fine Reservoir Description Of Qian 5 Member Of Tight Sandstone Gas Field In Linxing Block Of Ordos Basin

The pilot test area C of the western Linxing area of the Ordos Basin is 28.2km~2.One of the main gas-bearing intervals is the Qian 5 member of the Shiqianfeng Formation in the Upper Permian.The faults in this area are not developed,but due to the complex reservoir distribution and low awareness,the development effect of the gas field is affected,which restricts the gas field plan deployment.In this paper,fine division and comparison of sedimentary units,interpretation of reservoir logging,quantitative evaluation of reservoir heterogeneity and other techniques and methods are used to carry out fine reservoir description.The following main results have been achieved.1.Comprehensive use of log interpretation data,core data,and comparison methods such as lithological thickness differentiation,sedimentary cycle contrast,and river channel undercut were used to divide the Qian 5 member into 3 small layers,and gradually build a fine stratigraphic framework.2.Based on comprehensive analysis of the characteristics of logging facies and cores,it is considered that the Qian 5 member in the study area is a subfacies of braided river delta plain,and the distributary channel and the interdistributary bay are the main types of the microfacies.The shunt channel is subdivided into three types of microfacies:block thick layer channel,medium-thick interlayer channel,and thin layer interlayer channel.Among them,block thick layer channel is most developed in the Qian5-3,and its physical properties are better.It is the main reservoir in pilot test area C.In the study area,three channels with overlapping sand belts developed,which are distributed in a north-south direction,and the overall trend is thinner in the north and thicker in the south.The areas with high thickness are mainly located at the intersection of the southern rivers.3.Reservoir heterogeneity research was carried out by comprehensively using log curve data,core data,mercury pressure curve and other data,and the results showed that the heterogeneity of the Qian 5 member of the pilot test area C was moderate to strong.4.According to the capillary pressure saturation curve made by the sandstone samples in the study area,and closely related to the geophysical and logging results,the reservoirs of the Qian 5 main gas-bearing interval in the gas field of the Linxing West Area are divided into four types,of which the type I reservoir is the best reservoir.Type II is the better reservoir,type III is the medium reservoir,and type IV is the poor reservoir.Finally,the contour maps of the physical properties of the reservoirs and the classification criteria of the reservoirs were used to draw favorable areas in each small layer,Qian5-3small layer has the best quality and is suitable as the main target layer for development.