Study On Sedimentary Microfacies And Reservoir Heterogeneity Of S₃～4 Member In Block Shen84-An12

This paper studies heterogeneity and remaining oil of shen84-an12 of Liaohe basin applying Sequences stratigraphy according to complicated reservoir structure of that block.During the oil field exploitation, the key of studying reservoir heterogeneity is high accuracy stratum's partition and contrast. Fine degree of petroleum deposit's partition and contrast direct decide cognition's deepness and precision of that reservoir. This research apply the method of high accuracy sequences stratigraphy, and establish high accuracy geologic stratum trellis of Shahejie formation S34 of Shen 84 -An 12, identified 3 indicate layers.Study on sedimentary microfacies is base of reservoir heterogeneity research. There are abundant core data and log data. From sedimentology symbol such as rock assembled, sediment gradus, sandstone grading analysis, protogene sedimentary structure, ichnofossile and logging facies etc and palaeoenvironment background, it is confirmed that shen84-an12block S34 segment is braid river delta system, not fan delta system (abrupt slope). Then it can be more partition as braid river delta plain sedimentary assembled, delta front sedimentary assembled and prodelta sedimentary assembled on core and log assembled. And delta plain sedimentary assembled can be identified four microfacies: braided distributary channel, crevasse splay, overbank deposits and interdistributary bay. Delta front sedimentary assembled can be identified three microfacies: underwater distributary channel, underwater overbank deposits and distributary mouth bar.Reservoir heterogeneity can divide macro heterogeneity and micro heterogeneity according to reservoir scale. Macro heterogeneity research based on sedimentology and studied on sandstone longitudinal and landscape orientation distributing mode, it's inner structure character. Research section braided distributary channel sandstone is mostly positive rhythm, and high porosity and seepage rate in its central-top section, low seepage rate kalk interbed in its bottom. Underwater distributary channel sandstone is relatively homogeneous positive rhythm, high porosity and seepage rate in its bottom, its top low. Distributary mouth bar sandstone is complex rhythm, many interbeds inside.Flowing unit's partition mostly according to sedimentary microfacies type, rock median grain diameter, porosity and seepage rate character, pore throat radius. Research section divided into 4 flowing units: E, G, PC, Pm. And E, G unit are mostly exploitation oil storage unit. The two units have distinct difference in oil remaining distributing on exploitation process. Unit E is high degree floodout in below and oil remaining relative concentrate in top. Oil remaining multiplestage enrich in Unit G.