Study On Sedimentary Characteristics Of Cretaceous Shahezi Formation In The Northern Slope Of Lishu Fault Depression

The Lishu Fault Depression is located in the southeast uplift area of the Songliao Basin,and it was developed in the Early to Late Cretaceous.The basin is a sulcus-like faulted basin with a subsidence center in Sangshutai.Sedimentology,petrology,and well logging theory and methods were used to study the sedimentary characteristics of the Shahezi Formation.The structural features of the sequence and the division of the sedimentary facies,as well as the identification signs and petrological characteristics of the various facies belts were identified.In this paper,through the core and logging data,the characteristics of the sedimentary facies of the Shahezi Formation,the analysis of the vertical sequence of sedimentary facies and the sequence division of the sedimentary facies are studied and discussed.This paper divides the Shahezi Formation in the Lishu Fault Depression into two third-order sequences,namely the first member of the Shahezi Formation and the second member of the Shahezi Formation,the integrated core facies,and equal well logging identification signs.The Shahezi Formation is divided into fan deltas as a whole.Lake sedimentary system.Including fan delta plain,fan delta front,front fan delta,shallow lake,deep lake-semi-deep lake and other five sub-facies.The Shahezi Formation is located in the lake and the Shahezi section and the second section have different characteristics.The Shahezi section is a “narrow basin deep water” type,and the Shahezi section is the characteristic of “the wide basin deep water”.The fan-delta deposits with the long-axis source developed in the Shahezi area of the Lishu Fault Depression.The thickness of the sand body is large,and it is a good source rock and caprock together with the Yingcheng Formation of the overlying strata.It has become a quality accumulation combination.