The revision of stratigraphic division of X well in Juyanhai depression, Yingen-Ejin Banner basin, Inner Mongolia, and its geological significance

Based on a comprehensive analysis of characteristics of biological assemblies, petrologic features, clastic rock colors, the relationship between the vitrinite reflectance and the depth of Bayingebi Formation, and the main layer for development of source rocks of hydrocarbon shows, this paper puts forward the existent problems concerning the previous stratigraphic division. Therefore, in combination with stratigraphic correlation between Lujing depression and Lubeing convex belt as well as analysis of seismic reflection characteristics through X well, the authors significantly revised the division of some primary lithostratigraphic units. As a result, Permian strata are regarded as the major horizon of source rocks, as evidenced by the hydrocarbon shows in Permian intersected by revised X well, which is consistent with the drilling data of Lujing depression and Lubeing convex belt. The Permian strata are hence considered to be the major target strata for oil exploration in Juyanhai depression.