关键词: 断溶体油藏, 井间连通性, 高速非达西渗流, 敏感性分析, 预测

Abstract: To address the problems caused by the complex geological characteristics of fault-karst reservoir and difficult to be solved by accurate and fast simulation, the complex fault-karst structure was discretized into a one-dimensional connected unitamong well, fracture and vugbased on the static physical parameters of reservoirs and the dynamic injection and extraction data. Two characteristic parameters, i.e., conductivity and control volume, were proposed to characterize the inter-well connectivity properties and material basis. Meanwhile, this paper introduces the high-speed non-Darcy flow term to describe the characteristics of real flow in the fracture body, sets up the material balance equation of the well-fracture-vug interconnection unit in fault-karst reservoirs, and realizes the simulation of oil-water dynamics in fault-karst reservoirs. The results research show that under the constant fluid regime, when the non-Darcy flow coefficient β=0, the conductivity value remains unchanged; when β>0, with the increasing of β value, the conductivity decline in the connected unit increases, and the water phase is more obviously affected by the non-Darcy effect, which leads to the lag time of water occurrence in the well, the decrease of formation pressure and bottom flow pressure, and the increase of the required production pressure difference. For the Z fracture zone, it is difficult toperform the fitting between the calculation indexes and the actual values under the Darcy flow conditions; when β is set to be 10³-10⁴, the single well flow pressure is well fitted with the block oil production, and are more in line with the actual flow. The connectivity is even better in the unit with obvious high-speed non-Darcy effect, providing a guidance for accurate prediction of inter-well connectivity.

Key words: fault-karst reservoir, inter-well connectivity, high-speed non-Darcy flow, sensitivity analysis, prediction