Sequence Stratigraphy And Sendimentary Microfacies Research Of The Lower3rd Member Of Shahejie Formation Of Weicheng Oilfield, Wei2Block

Wei2Block blonging to the antithetic fault blocks is a horst structure holding bythe three major secondary fault which are Wei32, Wei35and Wei2fault,constructing to the NEE narrow elongated structure form. After thirty years of waterflooding development, great changes have taken place in the original oil-waterinterface. With the complicated underground oil, gas, water relations, the difficultyof development is bigger and bigger. Oil and gas accumulation optimization andeffective sand body identification demands more. This thesis is focused on theLower3rdmembers of Shahejie Formation of Wei2Block, Weicheng Oilfield.Meantime comprehensive utilization of more than130Wells’ geological, geochemical,geophysical, analysis assay data and viarieties of correlation methods, thehigh-resolution sequence stratigraphic frameworks of Wei2Block have beenestablished; Making clear the influences tectonic evolution effects on sedimentary andthe distributions, the types and the evolutions of sedimentary microfacies is beneficialto establish distribution patterns of sedimentary system.Understanding and results about this research on the Lower3rdmembers ofShahejie Formation of Wei2Block are listed as follows：(1) On the basis of cores and logging data,6high-resolution sequence stratigraphicframeworks, applied the theories of different hierarchical base-level cycles andmethods of correlations are established. The Lower3rd members of ShahejieFormation can be divided into one long-term cycle, three middle-term base-levelcycles and a quantity of short term base-level cycles;(2)Based on the analysis of high-resolution sequence stratigraphy, through specificcore observations and descriptions, applied with logging and analysis of regionalgeological data, the identification information, the sedimentary characteristics andsedimentary facies have been gotten a comprehensively understanding. There ismainly delta depositional system in the Lower3rd members of Shahejie FormationPeriod; By a detail core description, sequence characteristics of different microfacieshave been described; the logging response characteristics of the different microfaciesin the study area have been made on the foundation of single well facies. Combinedwith the thickness of sand body figure and the contact relationships of sand body, the distribution characteristics have been clear and sedimentary evolution model isestablished.