Research And Evaluation Of Shale Gas Reservoirs Of Qiongzhusi And Longmaxi Formation In Changning-weiyuan Area

In recent years,our country has devoted itself to the development of unconventional oil and gas,among which relatively clean unconventional resources such as shale gas and coalbed methane have become increasingly important.In the actual development process,there are problems such as imperfect reservoir effectiveness evaluation system and the inability of the reservoir evaluation system to meet the needs of efficient shale gas development,which restricts the growth rate of shale gas development scale.This article takes the southern part of the Sichuan Basin as the research target.Based on a large number of domestic and foreign related studies,the basic theories are stratigraphy,paleontology,sedimentary petrology,organic geochemistry,unconventional oil and gas geology,and petroleum geology.The basis is to make full use of the original data of drilling,logging,logging,and shale geochemical analysis and testing,and on this basis,combined with regional background data,it is carried out from three aspects of shale gas generation capacity,storage capacity and mining difficulty.Shale gas reservoir evaluation.Combined with foreign data and post-production parameters in the study area,a parameter selection model with higher value for reservoir static evaluation was determined,and based on this,the importance of each parameter in the development and utilization of shale gas reservoirs was evaluated,and evaluation weights were assigned respectively.In order to formulate a static evaluation method for shale gas reservoirs based on the results of shale gas reservoir analysis and research,and improve the content and standards of reservoir evaluation.Two sets of shale gas reservoirs developed in Changning and Weiyuan,the main producing areas of southern Sichuan in the study area,are the Lower Cambrian Qiongzhusi Formation and the Lower Silurian Longmaxi Formation.The main muddy shallow sea shelf facies in the Qiongzhusi Formation and Longmaxi Formation.The thickness of the shale meets the effective standards for accumulation,and the thickness distribution is uniform.It can be seen that the proportion of organic carbon is large,and the geothermal evolution is overmature,and the content of type I kerogen is dominant.The shale in the reservoir has a large proportion of siliceous content.The Longmaxi Formation shale in the two sets of formations has a higher gas content,but the Zhuzhusi Formation shale has a different gas content.The Changning area has a higher gas content but Weiyuan The area is poor.The formation and distribution of shale gas reservoirs have the more important control capabilities of organic carbon content in shale and gas storage capacity of shale,as well as migration channels such as micro-fractures formed by tectonic movement in shale.Several parameters such as shale thickness,burial depth,organic matter types,organic matter abundance,organic matter maturity,shale porosity,and siliceous mineral content are selected as the basis for establishing the reservoir evaluation system,and weight values are assigned according to the degree of influence.Form a reservoir static evaluation system suitable for the study area,and try to evaluate the reservoir in the study area.In the study,it was found that the reservoir static evaluation system could not fully explain the contradiction between the actual reservoir evaluation and gas well production.An attempt was made to analyze the dynamic parameters after fracturing to study the superposition of the micro-fracture fracturing fluid’s ability to "water lock and self-solve" Comprehensive reservoir evaluation system for dynamic evaluation of shale pressure.