关键词: 天然裂缝性油藏, 离散裂缝网络模型, 有限元法, 数值模拟, 注采参数, 敏感性分析

Abstract:

The storage and seepage spaces of naturally fractured reservoirs consist of big fractures, micro-fractures and pores. The big fractures controlling the fluid flow were taken as one-dimensional entities to compose the discrete fracture network and expressed explicitly. The pores and the micro-fractures were treated as matrix. Based on the above assumptions, the 2D and two-phase mathematical model for the numerical simulation of naturally fractured reservoirs was established. The weighted residual method was used to establish the finite element equations. The effects of fracture exsisting state in reservoir, fracture azimuth, fracture length and fracture distribution on the oil saturation were discussed. The existence of the fracture can change the direction and velocity of the waterfront. The smaller angle between the fracture orientation and the injection-production line and the longer of the fracture would result in more serious water breakthrough and higher water cut. The multi-fracture system can cause the heterogeneity of remaining oil distribution and accumulation of remaining oil.

Key words: naturally fractured reservoirs, discrete fracture network, finite element method, numerical simulation, injection-production parameter, sensitivity analysis