Study On Heterogeneous Reservoir Characteristics Of The Xu6 Section Of Xujiahe Formation In The Quangan Gasfield Of The Central Sichuan Basin

The Xu6 Gas Reservior of Guangan Gasfield is the key gas reservoirs with the largest reserves found in XuJiaHe Formation of Central Sichuan Basin in recent years,and also is the key replaced gas reservoirs in the Outline of the Eleventh Five-Year Plan of The Southwest Oil and Gas Field Company. However, the complexity of its geological features, the fuzzy of its gas-water interface, and the unclear main controlling factor of the Reservoir distribution have brought enormous difficulties to the gas reservoir development. based on the Information of core, logging,analysis,production test,etc,This paper Analysis the distributed characteristics and controling factors of reservoir from the perspective of the sedimentary facies and sedimentary microfacies, diagenetic facies, characteristics and heterogeneity of reservoir ,etc,Aim at dividing reservoir range of profitability,to provide technical support to exploration and development.Based on the former study,and according to the analysis of rock type,sedimentary structures,fossils,logging, the sedimentary facies of The Xu6 Section is determined to be Braided river delta plain,and microfacies types are recognized including channel, channel bar, Single channel and limnetic facies,etc, and then this paper analysis sedimentary microfacies characteristics of the single well, profiles and flat.the main sedimentary microfacies are channel and channel bar in middle and down subsection of The Xu6 Section,only in some of which are Single channel and limnetic facies,and limnetic facies in The Upper Subsection of The Xu6 Section.To sum up the study above,The channel and channel bar are the higt quality sedimentary microfacies which the favorable reservoirs are distributed in The Xu6 Section.According to observing and analyzing the thin, four Synthesize types of Diagenetic facies are determined in the study area, pore grasket-solutional Diagenetic facies, pore grasket-weak solutional diagenetic facies, strong compacted diagenetic facies, Calcite cemented diagenetic facies.and then this paper analysis This diagenetic facies of the single well, establish the Criteria for the classification of diagenetic phase and discuss the distributed features of diagenetic facies in plane. it is known that by analysising above: pore grasket- solutional Diagenetic facies and pore grasket-weak solutional diagenetic facies are The main constructive diagenetic facies.the criteria of reservoir zonation has been established Based on analysis of physical property, pore structure, and reservoir predication has been finished by the use of neural network technology, and then this paper analysis longitudinal, horizontal and planar characteristics of The Xu6'reservoir.Summarized the study as follow:reservoir,superimposed Different types, is implicative with good continuity in middle subsection of The Xu6 Section,while lenticular with poor continuity in down subsection of The Xu6 Section. Study shows that channel and channel-bar which superimposed pore grasket- solutional Diagenetic facies or pore grasket-weak solutional diagenetic facies, are excellent facies with developed reservoir in the area.For the purpose of solving the problem of reservoir heterogeneity in development phase,the evaluation criterion of the reservoir heterogeneity is established,this paper analyzed intrabed,in-layer and areal heterogeneity, and find that the reservoir heterogeneity is controlled by sedimentary diagenetic facies in macroscopy,restricted by superimposing different types of reservoir On the microscopic. And then proposed that exploit solutions should consider about the perspective of the type of reservoir.Finally, according to geological analysis above,combined logging with oil-gas production test results, this paper established the evaluation criterion of reservoir range of profitability,and offer some optimum area including XH1 well field, GA108 well field North of the Guangan Gasfield and GA115~ GA21~38 Well Triangle in middle subsection of The Xu6,South of the Guangan Gasfield; GA111 well field in down subsection of The Xu6,North of the Guangan Gasfield.