Difference In Characteristics And Control Factors Of Sandstone Reservoir In The 1st Member And 2nd Member Of Shanxi Formation,daning Area

The Daning area in Shanxi is located in the Jinxi tortuous belt in the southern part of the eastern margin of the Ordos Basin,and it has a monoclinic structure.The resource evaluation results show that the area has great potential for oil and gas exploration.However,with the continuous deepening of the exploration and development in the Ordos Basin,the understanding of the Shanxi Formation in the study area has gradually increased,and the sandstone reservoirs of the Shanxi 1st and 2nd Member of the Shanxi Formation have shown obvious Difference.It is necessary to study the factors that cause this difference in Shanxi Formation,and provide a theoretical basis for oil and gas development of Shanxi Formation in Daning area.Based on the references in relevant literature,this paper mainly studies the petrological characteristics,pore types and controlling factors of sandstone reservoirs in the first and second members of the Shan 1st and 2nd Member of Shanshan through casting thin slices and drilling histograms.Reservoir lithology of the second member of Shan is mainly composed of quartz sandstone and detrital quartz sandstone,of which the content of quartz sandstone of member 23 of Shan is about 90%,the total debris content of member 2 of Shan 2 is on average 13%,and it is mainly sedimentary rock debris and metamorphic rock Less shavings.Compared with the second member of Shanshan,the debris composition is obviously different.The rock types are mainly detrital sandstone and detrital quartz sandstone.Among the sandstone reservoirs in the Shanxi Formation,the sandstone reservoirs of the first member of the Shan Formation are generally dense in character,while the sandstone reservoirs of the second member of the Shan Formation exhibit good reservoir physical properties.In the sandstone reservoirs of Shanxi Formation,the primary pores have almost disappeared due to the large buried depth and complex geological conditions.The secondary pores in the first member of Shanshan are not developed,and mainly consist of intragranular dissolved pores.A large number of secondary pores are developed in the second member of the Shan,specifically: intergranular dissolution pores and intragranular dissolution pores are the main,mold pores,intergranular pores,cracks are also developed,intergranular dissolution pores and intragranular dissolution pores and so on Compound pores composed of pores are generally developed in the second member of the mountain.The controlling factors for the difference in sandstone reservoir characteristics between Shan 1 and Shan 2 include sedimentary facies,provenance and diagenesis.The sedimentary facies in the target layer in the study area mainly developed meander river delta plain facies.The sedimentary microfacies of the sandstone reservoirs in the first member of the Shan are mainly flanking microfacies and inter-distributary bay facies,and the sedimentary microfacies of the sandstone reservoirs in the second member of the Shan are mainly distributary channel facies.The provenance of the first member is the northern provenance area of Alxa-Yinshan ancient land,and the provenance of the first member is the unified southern provenance area formed by Qilian and Qinling Mountains;during diagenesis,the dissolution is caused Fundamental factors for pore development in a section of sandstone reservoir.Based on the reservoir petrological characteristics,pore development and reservoir physical properties,it is speculated that the sandstone reservoir of the second member of Shanxi Formation has certain exploration potential.