The Research Of Genetic And The Distribution Regulation Of Remaining Oil Of Flaggy Lacustrine Biohermal Carbonate

Almost half of the world’s oil reserves exist in the carbonate reservoirs.Lacustrine carbonate reservoir,as a momentous part of carbonate reservoirs,extensively develop in continental petroliferous basins around the world.The lacustrine carbonate rock is a kind of complicated sedimentary body,which are influenced by paleoclimate,paleotopography and paleohydrology,etc.The lacustrine carbonate reservoirs are closely associated with organic reefs.It is very helpful to not only reveal genetic mechanism but also exploration and development of the lacustrine carbonate through the research of genetic mechanism and distribution law of organic reefs.We focused on the study of carbonate genesis through comprehensive analysis of core observation,thin section and paleontology identification.The results show that the carbonate can be divided into early-stage,mid-stage and late-stage sedimentary bodies according to the formative time.The mid-stage sedimentary body,constituting the principal part of the carbonate,can be further subdivided into the algal frame reef,inter-reef,reef-front,back-reef,continental sandbar and mudflat genetic elements.The suitable environment,resulting from changes of climatic and hydrological conditions,contributes to the flourishment of the algal reef.Because of the transgression in the late depositional stage,the euryhaline snails and ostracoda thrive and widespread snail limestone develops in the late-term sedimentary body,leading to the finality of the algal reef.We divided the contemporary sedimentary bodies in the vertical and sedimentary microfacies in the horizontal through refined reservoir research.The reservoir structural framework model and attributes model were established by microfacies-controlling stochastic modeling through trend restraint of geology analysis.Quantitative studies of remaining oil saturation distribution and reserve abundance distribution were carried out through using modern reservoir engineering methods such as numerical reservoir simulation.In addition,we conclude the remaining oil distribution patterns and distribution law,which is controlled by both geological factor and development factors.The remaining oil distribution patterns include corner type,retention area type,and injection-production imperfection type.The controlling factors of remaining oil distribution include sedimentary microfacies,micro structure,reservoir heterogeneity and well-net control degree.