Fluid Flow Law And Optimization Of Injection-production Imitated-horizontal Pattern In Low Permeability Reservoirs

Low permeability reservoirs are low abundance, poor physical property. The regular developments have low production and low efficiency. The imitated horizontal well are vertical wells that have long fractures, they can improve the flow characteristics of the reservoir in a wide range and get a good stimulation effect, but there is little study on the fluid flow law of imitated horizontal well and its optimal design in low permeability reservoirs. In this article, through the reservoir numerical simulation and the theory of the fluid flow low, use the streamline model of imitated horizontal well in low permeability reservoirs, compare the flow characteristic, the water flooding characteristic, and the injection-production characteristic. Get the fluid flow low and the mechanism of increasing oil well production. Based on the true reservoir characteristics, established a fine reservoir geology model, formed an optimization system of the well pattern parameters, the fracture parameters, and the injection and production parameters. It is showed that imitated horizontal well water flooding can be broadly divided into three phases: linear flow in the early stage, pseudo radial flow and linear flow in the layers. The stage of linear flow in the layers is the main contribution to the development of imitated horizontal well. The main mechanism of imitated horizontal well in low permeability reservoirs are that linear displacement increases the sweep efficiency, high fracture conductivity reduces the injection production pressure difference, and the fracture seepage flow zone widen the well spacing. With the increasing of the producing pressure drop, the liquid production index increased, the oil production index decreased, the water-cut increased, and the recovery degree decreased. The recovery degree of staggered line drive is much higher than vertical wells. Under the same recovery degree, the moisture content of staggered line drive is lower than direct line drive. The recovery degree of staggered line drive is higher than direct line drive in equal times, and the residual oil is distributed evenly. While the staggered line drive is the best, the most optimal well spacing is about 540 m, and the row spacing is about 200 m. The oil well fracture penetration ratio is about 0.35 and the water well is about 0.20. The best conductivity of hydraulic fracture is about 240mD·m. The reasonable production pressure is 12 MPa, the reasonable injection pressure is 46 MPa. The optimal injection-production ratio is about 1~1.1, and the optimal rate of oil production is 1.8%.