Study On Hydrodynamic Field Characteristics And Waterflooding Development Of Low Permeability Fault Block Reservoir

Low permeability fault-block reservoirs have the characteristics such as incomplete injection-production well pattern, complicated boundary conditions, complex oil-water system. Besides features similar to conventional fault-block reservoirs, Low permeability fault-block reservoirs also have the traits such as non-darcy seepage, the necessary of fracturing before production, inadequate formation energy. Therefore, how to develop low permeability fault-block reservoirs effectively needs to fully demonstrate the validity of injection-production system, the adaptability and perfection of injection-production well pattern.As to different types of low permeability complex fault-block oil reservoirs, considering the impact of artificial fracture and complicated boundary on the seepage characteristics, this paper studys the seepage characteristics of low permeability complex fault block oil reservoirs and analyzes the influence of different factors on fractured well productivity by means of reservoir engineering, seepage flow mechanics, the complex function theory. On the basis of theoretical study, this paper optimizes the injection technology for different types of low permeability complex fault block oil reservoirs. The achievements received are as follows:(1) On the basis of nonlinear seepage model with two parameters, considering the influence of nonlinear seepage on oil well productivity, this paper obtains the plate of limited injection-production well spacing. Using complex function theory and transforming the fractured well on the W plane to drainage tunnel on the plane W1with the bandwidth of n this paper analyzes the seepage characteristics of vertical wells injection—fractured wells production system, and discusses the matching relations of artificial fracture direction with limited injection-production well spacing and pressure;(2) Considering complex boundary, this paper takes using of the Comsol simulation software to establish the single-phase stable seepage model. Based on the triangular fault block oil reservoir, this paper studys the seepage characteristics and analyzes the impact of different influence factors on the range of feasible development under the influence of complicated boundary and artificial fissure. On the basis of productivity formula of pseudo-stabilized well test, considering the impact of artificial fracture and complicated boundary, this paper studys the influence of fracture conductivity, fracture half-length, shape factor, skin factor on the fractured well productivity and obtained the optimal fracture parameters;(3) By the means of numerical simulation optimization research of triangular fault block oil reservoir, this paper obtains the optimal matching relations of artificial fracture with incomplete injection-production well pattern and the optimal injection way. Through the orthogonal experiment on banded fault-block reservoir, this paper obtains the optimal injection-production pattern and artificial fracture direction. The influence degree of the different influence factors on the oil recovery is:pattern form> artificial fracture direction> artificial fracture half length;(4) As to low permeability semicircle fault block oil reservoirs with different intensity of edge water, by comparing the impact of different form of well pattern, artificial fracture direction, different injection ways on development effect, this paper analyzes the influence of different factors on sweep efficiency and oil recovery, and obtain the appropriate method of water flood for semicircle fault-block oil reservoirs with different intensity of edge water.