Study On Tight Sandstone Reservoir Characteristics Of Shanxi Formation In Shenfu Area

The Shenfu area is located on the northeastern margin of the Ordos Basin.The exploration area has found good potential for the development of tight sandstone gas through preliminary exploration.Guided by the theories of tectonic geology,sedimentology and logging geology,this paper takes the compact mechanism of tight sandstone gas reservoir as the core,uses core,drilling,logging data and field outcrop to study the fine stratigraphic division and correlation and sedimentary characteristics of the two target intervals of Shanxi Formation in the study area,and uses common thin sections,casting thin sections,mercury injection data,Scanning electron microscopy(SEM)and other results have been used to study the reservoir characteristics of the two target intervals of Shanxi Formation in the study area.Finally,on the basis of studying the two intervals,the distribution of favorable reservoirs in Shanxi Formation in the study area has been predicted.According to the principle of equal thickness and sedimentary cycle,the Shanxi Formation in the study area is divided into six sand formations by identifying the markers of the study area.On the basis of fine stratigraphic division and correlation,the top structure maps of six sand formations are obtained.By observing a large number of cores in the study area,the sedimentary facies in the study area are divided by using sedimentary facies and logging facies markers.It is considered that the Shanxi Formation in the study area belongs to meandering river sediments.The distribution characteristics of sand bodies in the study area are controlled by sedimentary microfacies.The connectivity of sand bodies in the East-West direction,i.e.vertical source direction,is poor,and that in the South-North direction,the connectivity of sand bodies along source direction is good.On the basis of core observation and thin-section data statistics,it is considered that the rock types of Shan 1 and Shan 2 in the study area are lithic sandstone followed by feldspar lithic sandstone.Through the statistics of physical properties of samples and logging curves in the study area,the physical properties distribution maps of the two target intervals of Shanxi Formation in the study area are drawn,and it is considered that the physical properties of Shan 2 are better than those of Shan 1 on the whole.Based on mercury injection curves,thin section identification and scanning electron microscopy,it is considered that the pore types of Shanxi Formation in the study area are mainly intergranular and intragranular dissolution pore,and pore structure is mainly pore throat.The tight sandstone reservoirs in the study area are divided into four categories.The favorable reservoir distribution of Shanxi Formation can be predicted by comprehensive analysis of sedimentary and reservoir characteristics in the study area.