Seismic Prediction Of Thin Sand Layer Distribution In The Fourth Member Of Shahejie Formation In The Qingnan Subsag Of Jiyang Depression

As one of the oil-generating sags in the Jiyang Depression,the Qingnan Sag found high-yield oil flow in a few exploration wells in the upper fourth member of Shahejie Formation,indicating that the Qingnan Sag has high exploration potential,so it is necessary to carry out reservoir prediction studies in the upper fourth member of Shahejie Formation to determine favorable reservoir development location,thus providing a basis for later reservoir research and exploration and development.Through previous studies,it was found that the number of exploratory wells in the east subsag of Qingnan is small,the burial depth of the upper fourth member of the Shahejie Formation is large,and the resolution of seismic data is poor.Therefore,it is difficult to predict reservoirs,the distribution characteristics of thin sand layers are unclear,and favorable reservoir developmental position is not clear,so needs further analysis and research.In response to the above problems,this paper starts with improving the resolution of seismic data,carries out seismic facies-reservoir facies-seismic attributes analysis research,and obtains the following four research results:(1)Using new seismic frequency reconstruction technology to improve the resolution of seismic data(2)Through seismic facies analysis,it is found that the Qingnan east subsag develops oblique cross forset-weak amplitude chaotic filling facies in the northeast-southwest direction,and according to its distribution characteristics,speculates that the upper fourth member of Shahejie Formation develops a fan delta provenance in the northeast direction;(3)According to the seismic attribute analysis method,the instantaneous amplitude is selected as the sensitive attribute to predict the thickness distribution characteristics of thin sandstone;(4)The favorable reservoirs are determined by combining the distribution characteristics of the reservoir facies,the thickness prediction results and the distribution characteristics of key well oil-bearing layers.The development direction is located in the northwest direction of the key well.The north deep sub-trough in the east subsag of Qingnan is a favorable reservoir development zone and can be used as a target area for later exploration and deployment.This achievement also supports the demonstration work of an evaluation well.