Reservoir Characteristics And Evaluation Of The 4^th Member Of The Leikoupo Formation In Pengzhou Area,sichuan Basin

The 4^thmember of the Leikoupo Formation of the middle Triassic in Sichuan basin is one of the main oil and gas bearing strata.In particular,the central and western Sichuan gas field and the Wolong River gas field in eastern Sichuan have been discovered.After the analysis of the basic geological conditions of the area,a batch of exploratory well drilling is carried out on the Jinma structure,the Xiaoquan-Xinchang structure and the Zitong structure.The test results are very considerable.This reveals that the marine strata in the Leikoupo Formation have good oil and gas exploration potential.On the basis of previous studies,this paper combines the theoretical research of sedimentary facies,sequence,logging,geology and other disciplines,using core observation,rock thin film observation,mercury pressure analysis and various logging techniques to analyze the reservoir characteristics of the4^th member of the Leikoupo Formation in the Western Sichuan area and evaluate the reservoir.By analyzing the sedimentary facies of the drilling section and the sedimentary facies of the core,combining the geographical background and geological structure of the Leikoupo,the main reservoir of the 4^th member of the Leikoupo Formation is the depositional model of the platform facies to the platform and the lagoon.The petrological characteristics,physical characteristics,pore throat characteristics,diagenesis and fracture characteristics of the 4^th member of the Leikoupo Formation are studied.The 4^th member of the Leikoupo Formation is mainly dolomite,mainly including intergranular dissolving hole and intragranular hole dissolving hole.The sedimentary environment,diagenesis and structural rupture have a great influence on the reservoir of the 4^th member of the Leikoupo Formation.The dissolution and fracture effect have constructive effect on the reservoir,which can greatly improve the reservoir performance,and the cementation,filling and pressure-solution and coMPaction are very destructive,causing the porosity of the reservoir to be reduced.Using the conventional parameters of logging data to identify the reservoir lithology,the porosity and permeability of the reservoir are explained by the method of single parameter rendezvous,multiple stepwise regression and BP neural network.According to the interpretation results,the most accurate model of pore permeability interpretation in the research area is established by using multiple stepwise regression method.According to the previous research,we divide the reservoirs into the upper and lower reservoirs.The upper reservoir is mainly composed of limestone and dolomite,and is a porous reservoir.The lower reservoir is mainly dolomite,which is a fractured-porous reservoir.The relationship between regional structure,sedimentary facies,cracks,porosity,dolomite thickness and single well test yield is studied,and whether they affect the test yield is analyzed.Porosity and fracture have the strongest influence on the yield of single well test,and the sedimentary facies are the second,and the thickness of dolomite is relatively weak.Finally,the influence factors are synthetically analyzed.The physical properties,sedimentary facies and dolomite thickness of the upper reservoir are all lower than those of the lower reservoir.Combined with single well test results,it is known that reservoir of 4^th member of the Leikoupo Formation has high exploration and development value,and the lower reservoir section is more conducive to production and development than the upper reservoir section.