Sedimentary system and distribution characteristics of Shawan formation in Chunguang exploration area

Through analysis of core descriptions,drill logs and seismic data,it is believed that three kinds of sedimentary facies have been developed in Chunguang exploration area,namely alluvial fan,braided river and braided river delta.In Sha-1st member,it is developed alluvial fan and braided river delta sedimentary system.In Sha-2nd member,it is developed braided river-braided river delta sedimentary system.In combination with tectonic evolution characteristics of Chepaizi uplift,the sedimentary evolution of Shawan formation has been determined.The braided river and braided river delta Plain River are favorable sedimentary facies.By studying the control of sedimentary facies on trap development,the lateral pinchout zone is believed to be favorable for lithologic trap development,and on the basis of it,it is recognized that the banded distribution pattern of lithologic reservoir is controlled by the pinchout line.