Geological Characteristics And Logging Prediction Of Shale Gas In Dazu Block,sichuan Basin

This paper is based on the project of "design of well test in Sichuan Basin by Petro China Southwest Oil and gas Field Company",taking Dazu block of Sichuan Basin as the research object,combined with the regional geological data of this area.Taking the shale gas reservoir of well Z201 as an example,a set of well logging evaluation method of marine shale gas reservoir is established by using a large number of statistics of core test analysis data and well logging data,and is applied to well Z201 for verification.Dazu Block and surrounding shale gas resources are one of the shale gas blocks with good industrial gas flow and exploration effect in China.The reservoir thickness of Longmaxi Formation is large,and the logging shows well,and the deep and large faults in this area are not developed.Based on the analysis of regional geological data,this paper clarifies the regional geological characteristics,sedimentary characteristics and structural characteristics of the study area.With the support of core data,we can get the content characteristics of mineral components,physical properties such as porosity and saturation.And based on the analysis of response characteristics of comprehensive logging data,the "five properties"(organic matter characteristics,physical properties,gas content,mineral composition and brittleness)indexes of shale gas reservoir are processed,and the shale gas reservoir evaluation parameter model is established based on the support of theoretical model and logging data.Finally,the "five properties" evaluation parameter model is applied to Longmaxi formation of shale gas reservoir in well Z201 of Dazu block.The results show that the thickness of shale in the high gamma section at the bottom of the reservoir is more than 30 m,the electrical characteristics are quite different,the average TOC content is 3.0%,the porosity is high,the gas content is high,and the low angle fracture is relatively developed.It can be determined as the main target interval,and the result is very consistent with the actual data of exploration and development.It can be seen that it is feasible to use conventional logging data to evaluate shale gas favorable reservoir,which can be used as an effective means to identify shale gas favorable reservoir sections and potential blocks.