底水气藏水平井见水时间研究

 底水脊进是底水气藏水平井气藏工程研究中遇到的最大问题。利用镜像反映和势的叠加原理得到底水气藏水平井势分布，导出考虑地层各向异性的水平井产能公式、水平井见水时间公式、底水脊进时任意时刻水脊高度的公式。计算结果表明，底水水平井产能受水平井位置和地层各向异性影响，减小水平井与底水的距离能增加水平井产量；垂向渗透率越大的地层更利于底水驱气藏水平井产能的提高。水平井见水时间主要受水平井位置的影响，水平井离底水距离越近，见水时间越长。投产后底水先以较缓慢的速度上升，到后期上升迅速。实例分析表明，该方法对底水气藏水平井气藏工程设计和理论研究具有一定的指导意义。

Prediction of Water Breakthrough Time of Horizontal Wells in Gas Reservoirs with Bottom Water

Development of the horizontal well technology offers a new approach to exploitation of gas reservoirs with bottom water. The most important problem for a horizontal well in gas reservoir is water cresting which restricts the horizontal well to be developed effectively. Based on the imaging theory and potential energy superposition principle, a study on prediction of water breakthrough time of horizontal wells in gas reservoir with bottom water is presented. This paper derives the water breakthrough time formula and productivity of horizontal well in a reservoir with bottom water. In the process of derivation, factors, such as impermeable boundary on the top of the reservoir, equal pressure interface, anisotropy, height of water avoidance, all have influences on the potential distribution in the gas reservoirs with bottom water. The case study indicates that for a horizontal gas well with a constant production rate, the water breakthrough time is proportional to the height of water avoidance, and that the productivity of a horizontal well in gas reservoir with bottom water is affected by horizontal well location and formation anisotropy. The productivity of the horizontal well increases with the height of water avoidance but decreases with the vertical permeability. The results and the method are useful for gas reservoir engineering design and the theoretical study of horizontal well.