基于相似流动替换法预测水平井产量

随着水平井技术在油气田开发中运用得日益广泛，准确预测水平井产量变得至关重要。以水平井周围椭球体等压面为基础，将水平井的渗流划分为近井地带若干个椭圆形供给边界中一点汇的渗流问题以及远井地带的线性渗流问题，基于相似流动替换法以及等值渗流阻力法求得水平井产量计算的新公式。通过实例分析以及与Borisov 等较为经典的产量公式计算结果相比较，新公式计算结果大，但与实际生产数据的相对误差最小，约为10.09%。分析表明，这是因为新公式推导过程中考虑内部渗流场为一个个椭圆形组成的椭球体，内阻较小，而Borisov等产量公式中将内部渗流场简化为拟圆形组成的圆柱体，内阻较大，使得计算结果与实际生产数据相对误差较大。因此新公式不仅能够准确预测水平井产量，而且符合水平井客观渗流模式。

Deduction of productivity formula for horizontal well with displacement method between two similar flow

As the technology of horizontal well had been widely used in the gas and oil fields, the productivity forecast of horizontal wells will be of great importance. Based on the ellipse constant pressure surfaces near the wellbore, the author divides the seepage prob?lem of horizontal well into two parts, one is the problem in several ellipsoidal supply boundary near the wellbore, the other is the linear flow far from the well bore, based on the displacement between two similar flow mode and the law of equivalence percolation resistance,then eventually proposing a new productivity formula of horizontal well. Through case study, the results calculated by new formula has been compared with that calculated by the formulas of Borisov et al, it shows that the new result is more than the results calculated by conventional formulas, meanwhile, the new result has a small relative error compared to the practical oil production by only 10.09%.Analysis shows that this is because the resistance in ellipse drainage area is less than that in pseudo-circular drainage area, and the assumption of pseudo-circular will bring a great relative error. So, we can conclude that the new formula will not only predict the productivity accurately, but also accord with the practical flow mode of horizontal well.