Sedimentary System And Favorable Reservoir Prediction Of Wutonggou Formation In The North Slope Of Dongdaohaizi Sag

Dongdaohaizi Sag is one of the most prospective exploration area,which located in the northeast of central of hinterland of Jugar Basin.To fast paces of exploration and development,it is relatively low degree of exploration,clearing the distribution of sedimentary facies and favorable reservoir becomes more and more essential.The core research method of this thesis uses geological concept which mainly combined with earthquake prediction to predict the advantaged development zone in the reservoir of research area.(1)Through combination of well and seismic to complete geologic layer of area earthquake,vertically it divides into two stage of Permian Wutonggou group.The stratigraphic distribution presents with thick depression,thin bulge characteristics.From the west to east,it shows rising slope background.This zone develops as multiple stage fracture,forming mass fault block traps.(2)Through the sequence stratigraphical comparision and division in the research area,the entire of Wutonggou group mainly with water back,entering water together on the bottom and the multi-stage water back upward.The second stage of Wu is massive stage of mudstone.Thus,it set the first stage of Wutonggou group as the targeted layer section.(3)Wutonggou group mainly is the Fan delta depositional system.Dinan provenance and Wucaiwan provenance are two large provenance systems.Based on fully uses the material of rock core,well logging and earthquake,the sedimentary facies is futher divides into plain and leading edge two subfacieses.In which,plain subfacies futher divides into distributary channel,back swamp microfacies;the leading edge subfacies divides into underwater diversion channel and tributary bay micro facies.The first stage within Wu of depression area mainly develops Fan delta leading edge subfacies that rich in sandstone.The first stage within Wu entirely grows Fan delta plain subfacies that rich in sandstone.The vertical of reservoir mainly distributed in the first stage of Wu within sand body of leading edge subfacies.(4)The reservoir in the study area is affected by digenesis,physical property characterized by low porosity and low permeability.Reservoir space can be divided into three categories:primary porosity,secondary porosity and crack,and the cracks produced by the tectonic movement can effectively improve the seepage energy of reservoir.Thus formed the fracture pore type reservoir.According to the characteristics of this reservoir,we using broadband inversion method for the reservoir wave impedance inversion and predict the distribution of dominant sand body.Highly quality sand body in the first formation of Wu more development and the total area was about 420km2.After using method to post stack attribute of coherent energy gradient for predicting of plane cracks and determined relatively favorable area of 280km2.(5)The type of oil and gas reservoir in research area mainly is the fault-block reservoir,which features "control and accumulated in nose swell,fault-block reservoir control,reservoir control of crack and premium sand body".Under the restriction of old construction,it mainly takes seismic attribute prediction technology to establish favorable sedimentary facies belt.With comprehensive prediction method,it controls the advantaged sand body of below reservoir and the distribution of crack.In addition,it takes the result of geological comprehensive evaluation to establish reservoir evaluation standard,then divides the advantaged exploration area with grade level of three.