Sequence Stratigraphy And Geological Properties Of The Reservoir In Member 3 At ShaHeJie Formation In Dongying Depression

Dongying depression, a oil-rich faulted lacustrine basin, after 40 years of oil and gas exploration, has now become a mature basin with high degree of exploration. In this paper, based on the theory of sedimentology, sequence stratigraphy and reservoir sedimentology, the sequence stratigraphic and high resolution sequence stratigraphic correlation, sedimentary characteristics and geological properties of the delta in Es₃ member in Dongying depression is studied systematically.Based on the study of the target area, four large scale unconformity surfaces (including the roof and floor of Es₃) are identified, each corresponding to the standard reflecting layer T6' ,T2' , and standard layer T6, T4 on seismic sections. According to the characteristics of these sequence boundaries, Es₃ is classified into three sequences, including the lower sequence, the middle sequence and the upper sequence. And each sequence is subdivided into three system tracts, LST, EST and HST. Based on the study of single well sequence stratigraphy combining with cross-section analysis, sequence stratigraphy framework is established for Es₃ member in Dongying Depression. And according it, we select the upper part of the Es₃, which is related to delta, and focus on the typical areas. High resolution sequence stratigraphic correlation is made in such areas. According to which, the upper sequence is devided into six parasequence sets, among which the fifth parasequence set is subdivided into nine parasequences, and the sixth into three.For the study of sequence stratigraphic framework, we make clear the macro distribution characteristics of delta sandbody based on third-order sequence, and make clear sedimentary characteristics of delta plain facies and delta front facies based on fourth-order sequence, and we established the sedimentary model of the fifth and the sixth parasequence set accordingly.The study of reservoir petrology shows that rock types of Es₃ member in Dongying depression is mostly packsand and siltstone, and most of interstitial material is carbonate, shale and secondary quartz. Study of diagenesis, physical Property and characteristics of pore structure in this area shows that the physical properties of reservoir of the delta sand-body is mainly affected by sedimentary facies, cementation and diagenesis.