A Study Of Feasibility For Horizontal Well Excavating Potential Of Residual Oil In Thick Oil Formation Of LaSaXing Oil Field

This paper describes distributing character and heterogeneity character of shaly formation in different river channel sand, and established typical heterogeneity geological model of thick oil reservoir using modern deposit theory and anatomic data of field outcrop and technology production of oil field refined geology study. This paper also makes sure the character of major factors that dominating distribution of residual oil in thick oil reservoir during the later period that contain more water and gives out the distribution character of residual oil in sand that cause of formation is different through the study of effect that sandwich structure in sands and its rhythmic nature on water displacing oil. The results show that the thick oil reservoir in Lasaxing oil-field compose of five riverway sands Which are braided river sand, meandering river sand, high bending distributary bar, low bending distributary bar, and cataclinal disrtibutary bar. Thick oil reservoir may may be single sand which has single cause of formation, but most of them are superposition body which are piled up or interacted by many single sands which is the same or different styles of cause of formation; the effect factor of residual oil distribution are reservoir reservoir microstructure, reservoir macroscopic heterogeneity, fluid property and distribution rules, and injection-production pattern etc., but the contribution of the factors vary with different sedimentary microfaces; the top of the thick oil reservoir which is lateral deposited or vertical deposited contains blocks of residual oil. Horizontal well can employ remaining oil better than vertical well; horizontal well can lead into the formation of water ridge. It also shows by numerical simulation that lower rate of liquid production and lower intensity of liquid production can postpone the time of water flooded effectively, and reduce the rising rate of water cut; the productivity prediction model of horizontal well for vertical deposited sand is set up, and the results go well with that of the estimation of empirical method, and the yield of single well improves 2-4 times than that of vertical well's. It shows that horizontal well is an effective method to produce the residual oil in the top sand of positive rhythm. At last it bring forward some new ideas for improving the development effect of thick oil reservoir.