低渗透底水油藏长水平井产能公式

低渗透底水油藏长水平井产能对长水平井开发可行性论证及优化有重要指导意义。依据渗流力学与油藏工程相关理论方法,在考虑低渗透底水油藏的各向异性、启动压力梯度、定压边界特征及长水平井流场特征的基础上,运用流场劈分、镜像反映原理、等值渗流阻力法及复势理论推导了低渗透底水油藏长水平井稳态产能公式,并通过实例计算研究了避水高度与启动压力梯度对产量的影响。发现产量随无因次避水高度增加而降低,并综合确定最佳无因次避水高度为0.5；启动压力梯度增加,产油量降低；启动压力梯度越大,油藏各向异性对底水油藏长水平井开发的产能影响越小。

Productivity of Long Horizontal Well in Low-Permeability Bottom-Water Reservoirs

The productivity of long horizontal wells in low-permeability bottom-water reservoirs has an important significance for the feasibility demonstration and optimization of the development of long horizontal wells. Based on the theory of fluid mechanics and reservoir engineering, considering the reservoir anisotropy, threshold pressure gradient, constant pressure boundary characteristics and long horizontal well flow field characteristics, the steady-state productivity of low-permeability bottom-water reservoirs is deduced with the methods of flow field splitting, mirror image projection, equivalent flow resistance and complex potential theory. With case study, the effects of water-avoidance height and starting pressure gradient on production are studied. It is found that the production is decreased with the increase of dimensionless water-avoidance height. The optimal dimensionless water avoidance height is 0.5. The increase of the starting pressure gradient, the decrease of oil production, and the larger the starting pressure gradient, the smaller the effect of reservoir anisotropy on the productivity of long horizontal wells in bottom water reservoirs is.