底水凝析气藏见水时间预测新方法

A New Method to Predict Water Breakthrough Time in Condense Gas Reservoir with Bottom-Aquifer

底水锥进在凝析气藏开采过程中广泛存在,目前常用的底水凝析气藏见水时间预测模型主要是基于常规气藏提出,现场应用困难。针对该问题,对凝析气藏水侵动态进行理论研究,基于气相水平径向流和半球形向心流相结合的底水锥进物理模型,以渗流理论为基础,综合考虑表皮效应、气相非达西效应和反凝析作用的影响,建立了水锥顶点的运动方程,结合相应的产能公式推导出底水凝析气藏见水时间预测模型。实例分析表明,凝析气藏开发过程较常规气藏更为复杂;利用模型预测的见水时间更接近实际;表皮效应、气相非达西效应和反凝析作用均会导致见水时间缩短;随着气层厚度增加,气井见水越晚,随着产气量增加,见水时间呈现出先快后慢的递减趋势。研究成果对深入分析表皮效应、气相非达西效应和反凝析作用对凝析气藏底水锥进的影响,预测底水凝析气藏的见水时间有一定的指导意义。

Bottom-aquifer coning is very frequent during the development of condense gas reservoir. The water breakthrough time prediction model for bottom-aquifer coning mainly based on conventional gas reservoir theories are less applicable for field prediction. The water intrusion performance is theoretically researched based on the physical bottom-aquifer Coning model combining with horizontal radial flow and the hemispherical centripetal flow of gas. Based on the seepage theoryy the moving equation of bottom-aquifer coning apex is established by considering the effects of skin effect, gas non-Darcy flow and reverse condense effects. A water breakthrough time prediction model for the condense gas reservoir with bottom-aquifer is derived by combining with the corresponding productivi- ty equations. Case study shows that the development process of condense gas reservoir is far more complicated than that of conventional gas reservoir. The water breakthrough time predicted by this new model is closer to reality. Skin effect~ gas non-Darcy flow and reverse condense all can shorten water breakthrough time. The water breakthrough time increases with the increase of gas reservoir thickness. With the increase of gas production, the water break- through time shows a trend of decreasing in the early stage and slowing down later. This research could provider cer- tain guidance for the further analysis of skin effect, gas non-Darcy flow and reverse condense on the bottom-aquifer coning and prediction of water breakthrough time in condense gas reservoir.