边水推进对水平井产量的影响

边水油藏开发过程中,即使水平井井底未见水,但边水推进仍会影响水平井产量.基于水平井三维渗流场模型,将三维渗流场分为内部和外部2个径向渗流场,考虑外部渗流场边水推进的影响,分别运用坐标变换与保角变换方法求得内部与外部渗流场的产能公式,根据等效渗流阻力原理最终获得了考虑边水推进的水平井产能计算新公式.实例计算发现,新公式计算结果与实际产量绝对误差及相对误差均较小,表明新公式准确性较高,实用性较好.敏感性分析结果表明,考虑边水推进条件的水平并产量小于未考虑边水推进条件的水平井产量,且随着边水推进距离增大,水平段长度越小,产量减小的幅度越大;水平段长度越大,产量减小的幅度越小.该研究成果为边水推进过程中水平井产能预测提供了新思路.

Effect of edge water incursion on productivity of horizontal well

During the development of reservoir with edge water, even if the water didn＇ t break through at the bottom of the horizontal well, the edge water incursion still influences the productivity of horizontal well. Based on the three- dimensional seepage field model of horizontal well, this paper divided the three-dimensional seepage field into two two-dimensional seepage field which are called internal seepage field and external seepage field respectively, used the methods of transformation of coordinates and conformal mapping to obtain the productivity formulas of the two two-dimensional seepage field, eventually got the new productivity formula of horizontal well considering the edge water incursion according to the principle of equivalent filtration resistance. Practical example shows that result calculated by new formula has small absolute and relative error with actual output, which indicates that the new formula is of high accuracy and good practicability. Sensitivity analysis demonstrates that productivity of horizontal well in consideration of edge water incursion is lower than that with no consideration of edge water incursion. Meanwhile, as the increasing of edge water incursion distance, the productivity of horizontal well decreased to a great extent with short horizontal section, while if the horizontal well length is long enough, the effect can be neglected. This study can provide a new solution to predict the productivity of horizontal wells during edge water incursion.