Study On The Construction Structure Of Point Bar Sandbody And Its Control Action On The Residual Oil Distribution

Fluvial facies reservoir is the most common oil and gas reservoir types in continental oilfield, accounting for half of the current development of reservoir the types of existing development oilfield reservoir, and over half of fluvial facies reservoir is occupied by meandering fluvial facies, so as the most important reservoir, the research significance of point bar into late high water stage in Beierdong re-test area of DaQing Chang Yuan is very significant. Rich logging curves, sandstone interpretation, water flooded condition and so on in dense well network area provides a true and reliable supporting data for accurately identifying point bar underground and provide technical support and assurance for the study of improving the water flooding recovery ratio.8 oil layers and 110 sedimentary unit were corrected and adjusted in the use of River Sedimentology, Oil and Gas Field Development Geology, Oil and Gas Reservoir Evaluation Technology and other methods and theories, reached a single cause sand body division and contrast, realizing the unity of sedimentary unit closed at various levels. sedimentary facies of 35 small layer are divided on this basis, on the emphasis of the sand body distribution patterns of PI2 and the development of abandoned channel in the meandering river subfacies and delta distributary's plain subfacies conducted a study, building a set of comprehensive method which can identify point bar lateral accretion by using microfacies, abandoned channel identification and combining with single well vertical sedimentary rhythm, identified a total of 10 point bar in 4 small layers.For the interior building structure of point bar sand body, mainly research and forecast the development condition, type and characteristics of the lateral accretion layer, By analyzing the causes and influencing factors of lateral accretion, determined that shale lateral accretion and a small amount of calcium lateral accretion are mainly developed in the experimental area,and use the empirical formula of Leeder river bankfull depth and bankfull width and the fitting formula of the river breadth and depth ratio and lateral accretion dip angle to determine the tendency, dip angle, spacing of lateral accretion, and carried on a detailed anatomy for the typical point bar's interior building structures in the test area, analyzed the space structure form of lateral accretion, cleared the distribution characteristics of lateral accretion in the plane. The residual oil distribution in point bar formed different types of higher level of oil use, poor use of thin and poor layer due to the sedimentary facies type, reservoir heterogeneity and its internal lateral accretion and distribution of abandoned channels, the top of the river sand, poor reservoir properties, low permeability zone block, layer interference and imperfect injection and five types of remaining oil distribution are determined by analyzing the inner permeability changes of sedimentary unit in characteristics and the influence mechanism of point bar internal fluid by lateral accretion, and through the analysis and inspection of flood data of core wells and relatively new wells, study the vertical distribution characteristics of remaining oil in the major reservoirs, point that the favorable zones of remaining oil's distribution is formed by the lateral shelter affection of lateral accretion and abandoned channel, this should be the important goal of tapping and an effective measure to improve the ultimate recovery.