裂缝性油藏射孔完井产能的有限元分析

PRODUCTIVITY EVALUATION AND MODELING OF PERFORATED WELL IN NATURALLY FRACTURED RESERVOIR USING FINITE ELEMENT METHOD

负压射孔已成为一种工业标准 ,成熟的砂岩油藏射孔优化设计理论只适用于无裂缝油藏的情形。裂缝的存在使得射孔完井油井的产能评价变得十分复杂 ,本文通过裂缝孔隙性油藏特征的三维物理模型描述及流体渗流的连续性方程建立 ,推导出了描述该问题的有限元数学模型。通过网格剖分、有限元数值求解和二次回归正交设计分析 ,首次获得了不同的射孔参数和地层参数与裂缝孔隙性油藏油井产能的定量关系 ,并进行了单因素及多因素结果分析 ,获得了一些重要结论。它可用于指导裂缝性及裂缝孔隙性油藏的射孔参数优化 。

Underbalance perforating has been widely adopted as a standard for perforating to obtain the optimum perforating performance.However,almost all studies about perforating optimization did not take into account the presence of natural fracture reservoir.The productivity evaluation of perforated producing well becomes very complicated in the presence of natural fracture in reservoirs.The mathematical model has been established in this paper based upon the given three dimensional physical model describing the characteristics of seepage flow in the naturally fractured reservoir and continuity equation.The equation of variation for the finite element derivation has been deduced for obtaining the solution of the elliptical boundary value problem.The study has acquired the quantitative analysis results about the influence of different perforation and formation parameters towards the productivity of oil well in the naturally fractured reservoir through mesh subdivision,finite element numerical modeling and quadratic regression analysis in orthogonal designing.The important points obtained are very valuable to direct the operation of perforating completion in natural fracture reservoirs.