Geological Detail Description And Residual Oil Distribution Study On The East Sanan Transition Zone 300 Meter Region

The oil formation which is located 300 meters away from the east of Sanan area belongs to the combination of hydrocarbon bearing in the middle of Cretaceous formation at Songliao basin. In order to tap its potential at the later stage of high water-cut, we analyze its detail geology, study the remaining oil distribution, thus lay foundation for dynamic analysis and adjustment.Firstly, we make use of the natural divisibility of logging curves to find relatively stable cyclic boundary dividing unit, identify four major categories and ten kinds of micro-facies and models, and a detail geological description was given.1. Distributary plain facies sands body: 1).Meandering sands micro-facies, which represents large low sinuosity meandering disposition, and the channel sands is very large. 2).High sinuosity distributary sands micro-facies, whose sands body is relatively large, and the distributary channel sands body is the product of laterally aggradational deposit. 3).Low sinuosity distributary sands micro-facies , whose sands body is relatively small, and on a gross sense the continuity of sands is good and there exists abandoned channel.2. Inner front facies sands: 1).dendritic deltaic sands micro-facies, which formed by natural extent from land distributary channel to marine front facies at the shallow water stage. 2).Transitional type deltaic sands micro-facies, which formed at the stage when fluvial action weakens and wave action strengthens, have apparent reverse directionality. 3). Cuspate deltaic sands micro-facies, which formed at the time of powerful wave action, the continuity of marine distributary channel is bad, and distributes in cuspate shape.3. Outer front facies sands: 1).Stable sands micro-facies developed by main belt, which mainly consists of main shelf blanket sands with stable distribution, and almost no pinchout area. 2).Sands micro-facies with transitional distribution, which sands area is large, and have certain belt directionality. 3).Sands micro-facies with unstable distribution, whose sands mainly distribute at the outer boundary of outer front facies, is not stable, and pinchout area accounts for more than 40%. 4. Front deltaic pinchout area, which mainly consists of large pinchout area, and disperses sporadic surface reservoir.Secondly, based on the above detail geologic analysis and former remaining oil research results, combining with dynamic and static information, understand water out behavior by each formation and each, we evaluated and summarized five kinds of remaining oil microscopic types. The first one is uncontrollable well pattern type, which is resulted from the original well pattern being drilled but not perforated, or the original well pattern not being drilled but infill well pattern drilled. the second one is injection-production imperfection type, which is resulted from the original well pattern not being perforated and led to imperfection injection-production on the plane. The third one is interlayer plane interference type, which exists in the oil formation with relatively bad petrophysical property at the longitudinal and planar directions, and resulted from non water absorption and oil production led by interlayer and plane interference. The fourth one is inner layer non-water-flooded type, which exists in thick oil formation. Inner formation heterogeneity leads to serious water out at the bottom. If there is stable petrophysical interbed in the formation, it will form remaining oil at the top. The fifth one is bad oil formation with sheet distribution, which is formed by bad production or non-production because of thin oil formation.Finally, we get a better production effect by using accurate geologic analysis results.