Study On Well - Type Well Pattern For Effective Waterflooding In Marine Low - Permeability Z Oilfield

With the exploration of offshore oil and gas,more and more high-quality reserves have been developed,so it is urgent to enlarge the low-grade reserves and improve the development effect.It already has a mature development theory and technology of the low permeability oil fields onshore which can provide important reference for the offshore oil and gas fields in low permeability and effective research and development.However,developing the offshore oil and gas fields of low permeability reservoirs,it is not only to face buried deep reservoir,poor reservoir properties,high heterogeneity,pressure gradient,stress sensitivity and fast decline of production,but also the challenges of the offshore environment,the limited space and bearing,and many other adverse conditions brought about by high development costs. So the cost of offshore oil and gas field is much higher than the onshore fields,which makes the offshore oil and gas development meet the minimum initial single well production, the lowest daily output per well and the minimum requirements of individual well production.Therefore,when researching the effective water development well network and well type of offshore low permeability oilfield,it is necessary to learn from the experience of low permeability reservoir onshore development,and combine the characteristics of offshore oilfield development with it.This paper,based on the basic geological characteristics and development features of Z oilfield,as well as accomplishing the pressure gradient and stress sensitivity experiments,preferred the type of injection and production wells to meet the efficient development of Z oilfield,conducted the injection and production net and optimized the development indicators with the methods of combining the reservoir engineering with numerical simulation. This paper had made the following achievements:(1)Summarized the geological characteristics and development features of Z oilfield.Obtained the nonlinear flow characteristics of each block.It obtains the relationship between pressure gradient and mobility equation and the relationship between permeability changes and effective stress equation.(2)Different types of wells for oil capacity and direct injection wells capacity are studied and determined the Z oilfield with fractured vertical wells as water injection well and horizontal wells fractured oil development model for development with reservoir engineering theory and methods.(3)The seepage theory of direct injection well-horizontal oil well are studied with conformal mapping principle.It determines the limit injector spacing as well as the effective utilization of the area of direct injection well-horizontal oil well.(4)A geological model and numerical simulation model are established of Sand3-5Wellblock in Z oilfield with numerical simulation methods.It determines the optimum horizontal well fracturing parameters, optimum injection well network parameters and the optimal injection well network indicators.