Sedimentation And Diagenesis Of The Ma 5 And 1-2 Subsections In The Southwestern Part Of The Yulin Gas Field

Yulin gas field is located in the northeast of Ordos Basin,is one of the most intrict of Changqing oil field.The research object is Yu37 district M5_1-2 subsection,the paper is guided by the principle and method of sedimentology and diagenesis,drilling and logging data,rock core description,thin section observation,scanning electron microscope,cathode luminescence and other analytical test methods,the M5_1-2 reservoir sedimentary characteristics,diagenesis of Yulin gasfield southwest region are studied.In turn,the distribution of reservoir in the corresponding region is evaluated and optimized.The research region is divided into three subphases?Supratidal facies,Intertidal facies and Subtidal facies?and some microfacies.The most favorable reservoir is the Supratidal facies,which is develpoped gypsum tuberculosis microfacies.The relatively favorable reservoir is located in the Midwest of the research region rather than the east,which is rich of gypsum tuberculosis microfacies in M513 period.Sedimentary facies not only vertically control the distribution characteristics of the reservoir,but also in the plane as well.Based on the analysis of sedimentary facies in the study area,the sedimentary microfacies also control the distribution of the reservoir.The research region M5_1-2 subsection carbonate mainly experienced nine diagenesis,such us,dolomitization and gypsum lay the material foundation for the reservoir,and supergene karstification provides a contour for the reservoir.Buried dissolution and various mineral filling roles determine the preservation of early pores and the ultimate conditions of the reservoir.The introduction of the concept of "negative cementation porosity" more intuitively reflects the controlling effect of sedimentation on reservoir development.Based on the study of sedimentary and diagenesis at research district.The favorable reservoir is divided into ?,?,? three categories,the favorable areas for horizontal well are four partitions of relatively sparse well network in M513.