Water Invasion Characteristics Of Fractured Edge And Bottom Water Gas Reservoirs And Cooperative Development Policy Of Gas Reservoir Groups

Fractured gas reservoirs with edge and bottom water are widely distributed,the structure of fracture system is complex,the formation pressure drops in the development process,and the edge and bottom water quickly invades the gas reservoir through fractures,resulting in complex gas reservoir seepage law.For fractured gas reservoirs connected with edge and bottom water,because the characteristics of each gas reservoir are different,the conventional gas reservoir seepage theory is difficult to predict its production performance.It is particularly important to carry out the "water invasion characteristics of fractured edge and bottom water gas reservoirs and the cooperative development policy of gas reservoir groups" to correctly understand this kind of gas reservoirs and formulate a reasonable development plan.Firstly,based on the full study of the geological and water characteristics of fractured edge and bottom water gas reservoirs,this paper simulates the development process of real gas reservoirs,carries out conventional stress sensitivity experiments,and creatively puts forward in-situ stress sensitivity experiments that can reflect the permeability changes in the process of real reservoir exploitation,including in-situ stress sensitivity experiments considering ceiling effect and in-situ stress sensitivity experiments considering ceiling effect and pillar effect,The characteristics and errors of different stress sensitivity experiments are compared and analyzed;Then,according to the variation characteristics of water body,the multiple of water body is selected as 5,and two full diameter cores in parallel are selected to carry out the physical simulation experiment of collaborative development of water body connected gas reservoir group;Then,according to the geological characteristics and seepage law of gas reservoir,the mechanism model of dual medium gas reservoir group considering fracture characteristics is established by using CMG numerical simulation software;Finally,based on the optimal daily gas production ratio under different influencing factors simulated by the dual medium water invasion mechanism model,a rapid prediction model of gas reservoir group collaborative development system based on BP neural network theory is established,and the best production system of each geological characteristic gas reservoir in the gas reservoir group is summarized.The results show that the energy of water body in block a and block B of deep gas reservoir is higher in the West than in the East,and the multiple of water body increases linearly with time.It is predicted that the water invasion degree of deep gas reservoir will be further deepened in the future;By comparing and analyzing the conventional reservoir stress sensitivity experiment and the reservoir in-situ stress sensitivity experiment reflecting the original formation pressure change of the reservoir,it is known that the sequence of reservoir stress sensitivity from strong to weak is:conventional stress sensitivity experiment,in-situ stress sensitivity experiment,in-situ stress sensitivity experiment of 1mm stress layer,in-situ stress sensitivity experiment of1 mm stress layer considering pillar effect and in-situ stress sensitivity experiment of2 mm stress layer.The analysis of the experimental results shows that the in-situ stress sensitivity experiment can better reflect the change of reservoir permeability when the reservoir stress changes;Permeability and fracture development are important factors affecting water invasion of gas reservoir and cooperative development of gas reservoir group.The higher the permeability,the more developed the fractures,the earlier the water breakthrough and the more water production of the gas reservoir,and the more serious the water invasion of the gas reservoir.The greater the permeability difference of gas reservoir,the more obvious the difference of fracture development,and the worse the cooperative development effect of gas reservoir group;According to the mechanism model,the optimal daily gas production ratio of the two gas reservoirs is obtained under the conditions of different fracture permeability,different matrix permeability,different water avoidance height,different stress sensitivity coefficient and different reserves;A rapid prediction model of reservoir stress sensitivity based on BP neural network theory is established,and the prediction error is less than 5%.