Application Research Of New Reservoir Engineering Method In The Late Stage Of Ultra High Water Cut In Xingbei Development Area

After more than 50 years of water flooding development,Xingbei Development Zone has entered the ultra-high water cut stage.The change of reservoir pore structure leads to the change of permeability saturation curve.The traditional oil rate and water cut prediction methods based on permeability saturation curve have large errors.The existing methods need to be improved to adapt to the production planning in the later development stage of ultra-high water cut.Based on the permeability saturation curve of Xingbei Development Zone and the data of micro-pore structure parameters provided by the site,this paper makes clear the relationship between the influence of injection multiple on average pore radius and permeability and the characteristic parameters of relative permeability curve and permeability,and then establishes the dynamic relative permeability curve of the whole process of water injection development.On the basis of that the applicability of the traditional calculation models of oil rate such as Hubbert predictive model and Arps decline curve and the traditional calculation models of water cut such as Logistic cycle,displacement series and water drive curve are analyzed and studied.The results show that because the traditional model takes the static relative permeability curve as the theoretical basis and does not consider the change of the relative permeability curve in the later stage of ultra-high water cut,the deviation between the theoretical value and the actual value calculated by the traditional model in the later stage of ultra-high water cut is increasing.Therefore,based on the whole process dynamic relative permeability curve,an improved Arps decline curve is proposed by establishing the relationship between oil index and Arps decline index.Through the relationship between oil-water relative permeability ratio and water saturation,an improved water drive curve is proposed,which can accurately describe the phenomenon that the water flooding curve deflects in the later stage of ultra-high water cut.As a supplement to the above methods,this paper also proposes a growth curve method to apply to specific infill well networks.The oil rate and water content of 25 sets of well networks in 7blocks of Xingbei development area were calculated by using the new method of reservoir engineering.In the late development stage of ultra-high water cut,the calculation error of oil rate is reduced by 2.56 percentage points compared with the traditional method,and the calculation error of water content is reduced by 0.2164 percentage points.The new method is used to predict the ten-year development index of each block in Xingbei Development Zone,and the economic evaluation of the development plan is carried out in combination with the economic index,which provides a reference for the economic and effective development of the oilfield.