鄂尔多斯盆地延长组地震前积反射与页岩油储层展布规律研究OA

[Objective]During the Late Triassic depositional period of the Chang 7 member of the Yanchang Forma-tion in the Ordos Basin,a set of continuously traceable shales was deposited,and the shale is currently the main stratigraphic strata for unconventional oil exploration and development.The laminated-type shale oil reservoir at the Chang 73 sub-member features fast lateral changing,which introduces problems such as unclear reservoir distribu-tion,high exploration difficulty,and low drilling rate.Therefore,it is urgent to study and clarify the distribution pat-tern of laminated-type shale oil reservoirs.[Methods]First,through the latest three-dimensional(3D)seismic data,the stratigraphic dip flipping method was used to recover sedimentary paleogeomorphology.Then,we marked the seismic reflection of lacustrine mudstones,identified seismic stratigraphic comparison and division,and proposed four-stage progradational clinoforms and distribution patterns of shale oil reservoirs based on sedimentary pa-leogeomorphology.[Results and Conclusions]Combining seismic progradational sequences with palaeotopography of the lake basin,the distribution pattern of the Chang 73 sub-member shale oil reservoir and the genesis of shale oil gravity flow sedimentation have been clarified.The laminated-type shale oil reservoir in the Chang 73 sub-member is a gravity flow deposit developed on the lake paleo-uplift,located at the end of the progradational clinoforms,with poor connectivity and complex stacking relationships.In actual production,it should be explored as a"box body".The above perspective has assisted in the deployment of risky well locations and exploration discoveries for laminated-type shale oil reservoirs.It provides technical support for the scale and efficiency development of interbedded-type shale oil reservoirs.