复杂分支水平井产能研究

分支水平井是一项新型的油气开采技术，它能够数倍增加储集层泄油体积，但所引起的渗流问题十分复杂。用积分变换等方法首先求解封闭地层水平井的三维不定常渗流问题，通过渐近分析得到水平井的均匀流量拟稳态当量井径模型，再利用压降叠加原理建立复杂分支水平井产能计算方法。计算分析结果表明，如果水平井的分支数适当增加，则各分支的特殊采油指数下降、总特殊采油指数不断增加；若分支数过分增加，总特殊采油指数的增加幅度将不断减小，因此在钻井设计中存在合理的分支数；各分支的长度和夹角均影响分支水平井特殊采油指数的分布；若以各分支特殊采油指数均等为原则，需要设计合适的分支长度和分支间夹角，以便获得均衡的分支井特殊采油指数。此结果可用于复杂分支水平井的产能分析和优化设计。图6参11

Productivity of horizontal wells with complex branches

Using a horizontal well with multiple branches to enlarge the drainage volume is a newly developed recovery technology. It brings up complex problems in flow of fluid in porous media. After solving the mathematical model of fluid unsteady flow for a horizontal well in 3D circular-boxed media, a novel equivalent radius model was presented by asymptotic analyses to the solutiorL A productivity-evaluating procedure was presented based on the model and the principle of superposition. There is a reasonable branch number in local drilling design because, as the number properly increases, the productivity index of each branch declines while the total productivity index ascends, and when the number increases excessively, the growth of the total productivity index continuously declines. Both the branch length and the intersection angle between branches influence the distribution of the branch productivity index. If the index has to be taken as a balance, each branch length and intersection angle should be designed.