裂缝性砂岩污染储层井底压力响应特征

Response characteristics of bottomhole pressure on reservoir contamination in fractured sandstone

通过双孔介质裂缝性砂岩污染储层的研究,建立了以污染区储层渗透率呈指数变化的数学模型。采用不均匀网格的差分方法,由高斯消元法对模型求解,绘制出双孔裂缝性砂岩污染储层井底压力响应特征曲线,并分析了影响井底压力的主要因素。结果表明:井底压力响应特征曲线各阶段特征明显;污染半径越大,污染区内窜流现象越明显,外区响应越晚,压力导数曲线下凹越深;窜流系数越小,压力导数曲线下凹越深。

Through the study of reservoir contamination of dual-porosity medium fractured sandstone, a mathematical model, in which reserw）ir permeability presents index change in （tamaged zone, is estahlished. The bottomhole pressure response eharaelerislics curve of reservoir cnntaminati（m on dual-porosity fractured sandstone is drawn out through the using of differenee method with asymmetry grid and resolving of lhe nmdel with Garssian elimination. The main influencing factors of holtomhole pressure are analyzed. The resuh indicated that the response characteristics of bottomhole pressure response characteristics curve at different stages are clear, thai the greater contaminated radius is, the more obvious channeling is in the area and the later the response is in extenlal region, the deeper the derivative crate concaves, and thai the smaller channeling factor is, the deeper the derivative curve concaves.