The Fine Study Of Sequence Stratigraphy And Reservoir Of The Sinian System Dengying Formation In The South-east Of Sichuan

Introduction: In this paper, comprehensive utilization of outcrop, core, logging and testing data for the study area to Sequence Stratigraphy Reseach the sequence stratigraphic framework, including the sedimentary microfacies, diagenesis and reservoir distribution. Finally, prediction and evaluation of reservoir. Through research, the main results of this paper is as follows:1.Through the outcrop, Lithology Overlay, phase sequence characteristics and logging, The first time,the south-east Sichuan Dengying formation is divided into 5 third-order sequence and 27 fourth-order sequence, and established a third-order sequences and high-frequency sequence stratigraphic framework in this area.2.The isochronal unit of sequence system tract reveals the distribution of sedimentary facies of the law, Pointed out that the study area is mainly restricted platform sedimentary subfacies, The main development of supralittoral zone,intertidal zone,subtidal zone,lagoon and beach. And established the sedimentary facies model of the south-east Sichuan.3.Based on detailed observation of core, rock thin section, casting thin section and geochemical data, elaborating the important influence of diagenesis for the reservoir forming, just like dissolution,dolomitization and fracture diagenesis, Considering that the Dolomite of dengying formation mainly esperience syngenetic,early stage of diagenesis, supergene stage, early stage of diagenesis, late stage of diagenesis and supergene stage, and discusses the main factors in the formation of reservoir,point out the dissolution is the main mechanism in the formation of reservoir, fracture diagenesis of the tectonic movement and dolomitization is also important in the formation of reservoir.4.Through the outcrop,core and thin section,point out the main reservoir space of dolomite reservoir of dengying formation is secondary pores, The types of reservoir and flow space including intracrystalline pore,intracrystalline solution pore , intragranular dissolved pore,solution pore and cracks. solution pore and cracks is the major, intracrystalline pore and intracrystalline solution pore is the minor. The types of reservoir including fracture-pore type reservoir, solution-pore reservoir, dissolution-pore reservoir and structural fracture reservoir. 5.The physical property analysis data showed that the dolomite reservoir of dengying formation is low porosity and low permeability, fine pore-throat,poor connectivity, tight lithology, the dolomite reservoir have strong heterogeneity in space, Through the typical single-well profile sequence and reservoir anatomy, found that the reservoir of dengying formation controlled by distribution of sedimentary facies on the plane. he distribution controlled by the third-order sequence and high frequency sequence in longitudinal direction,because the reservoir have the stronger septation in longitudinal direction and the worse continuity on the plane.the reservoir was isolated and separated6. Through study the sedimentary facies, factors of reservoir development controlling,reservoir characteristics,reservoir space distribution and physical property analysis, point out that the reservoir quality is differences in the study area, no matter in longitudinal direction or on the plane. On the plane, The stronger dissolution area have good reservoir;in longitudinal direction,the dolomite reservoir of deng2 seg and deng4 seg worse better than others.