Evolution of platform margin reef beach reservoir of Permian Changxing Formation in Liangping area:petrological and geochemical evidence from Well Tiandong 110
Well Tiandong 110 is one of the high and stable production wells obtained in Changxing Formation in eastern Sichuan area in recent years.The study on the genesis and model establishment of different types of reservoir in this well is of great significance to the exploration of Changxing Formation in Liangping area.Based on the rich coring data of Well Tiandong 110 in Changxing Formation,the paper carried out petrological and geochemical analysis,established the evolution model of different reservoir space,and put forward the reservoir distribution model of high production wells.The results show that:(1)Isolated caverns,karst caverns,pores(including needle-shaped pores and intercrystalline pores)and high-angle structural corrosion fractures are developed in Changxing Formation of Well Tiandong 110.(2)The needle-shaped pores of Changxing Formation in Well Tiandong 110 are distributed in the granular dolomite of reef-shoal bodies,and the atmospheric fresh water dissolved into pores in the penecontemporaneous,and the seepage reflux dolomitization played a key role in preserving pores.(3)The formation of fractures and caverns was controlled by formation water and hydrothermal corrosion in the Late Triassic Norian and Ruetic,and the former was fully filled with bitumen and macrocrystalline calcite,with poor reservoir performance.The latter was partially filled with calcite,dolomite,fluorite,etc.,the filling rate was low,with good porosity and permeability.The next exploration should pay attention to the microgeomorphic high point of the dolomite reef-shoal bodies at the platform edge and the hydrothermal solution superposition development area of the Ruetic faults and fractures in the late Triassic,which is expected to get a bigger breakthrough.
reservoir genesisreservoir evolutionreef-shoal bodiesplatform marginWell Tiandong 110Changxing FormationUpper PermianLiangping area
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