Research On The Reasonable Development Technology Policies Of Low Permeability Reservoir

Low permeability reservoirs are usually quite different with thouse high permeability reservoirs. The prominent performance of these reservoirs is low porosity, low permeability, low abundance, and low productivity, low recovery, which lead to that the difference in pressure between tend to much high, and which caused high water injection pressure, producing well bottom-hole flowing down, injecting water pressure spread slowly, and which even affected low degree of water flooding, production decline quickly.The problem urgently being solved of low permeable reservoirs is reasonable developing technology policy which is the key of low permeable oilfield development, and the key to effective further improvement of oil recovery late. The research of the reasonable development technology policy is important for the sustainable development of low permeability reservoirs. It can improve the economic benefits of low permeable reservoirs and improve the water drive process of low permeability reservoirs. Further more it can ensure the national energy security and provide energy security for the comprehensive construction well-off society.The research content specific application to the actual inspection based on Changqing Jiyuan Chang81 low permeability reservoir as the main research object. It is carried careful study of the oil reservoir geology by which Improved the cognition of Changqing Jiyuan Chang81 low permeability reservoir. The reasonable development technology policy of Changqing Jiyuan Chang81 low permeability reservoir was determined by the approach of establishing 3D oil reservoir geology model, carring out reservoir numerical simulation, starding reservoir engineering and analysising reservoir dynamic. The following main achievements are made by this research.1、It was analyzed the reservoir geologic features, physical property characteristics and pore structure, fluid characteristics, exploration and development present situation of the Changqing Jiyuan oilfield Chang81 low permeability reservoir. A 3D geological model was established of the reservoir based on above studing;2、After the reservoir numerical simulation, the overall index fits up to 90%, reserves 98%. Most of the production index fits up 95%, but a few wells fits poor nearly 85%. At last, it provides a reliable 3d geological model to forecast the production;3、A reasonable well nets type and reasonable well spacing and row spacing was determined by the theoretical researching and economic evaluation and reservoir numerical simulation method carried out in the Changqing Jiyuan Oilfield Chang81 low permeability reservoir. According to the studing, lozenge inverted nine spot water flooding pattern adapts this kind of low permeability reservoirs very well and 480m×130m spacing between wells and rows is the best;4、A forecast of the conventional wells network and vector wells network was carried on Separately by reservoir numerical simulation method and the development effect was compared. The simulation results show that, vector well spacing can obviously increase the areal sweepout performance, improve the injected efficiency and improve the reservoir development effect;5、A reasonable waterflooding technical policy and a reasonable timing of water injection was determined by the theoretical research and reservoir numerical simulation method. The studing results show that, 54 days ahead of injection is optimal and the rational pressure maintain level is 110% compared with the primitive formation pressure. The target reservoir oil recovery can improve by 7% through the reasonable advanced water injection.