油水两相渗流压降数值试井模型的建立

数值试井问题不同于常规油藏数值模拟问题。介绍了数值试井模型中采用的非结构网格技术 ,给出了在非结构网格下油水两相流动控制方程的离散形式 ,而后耦合了井筒存储和表皮系数公式 ,得到了压力降落数值试井问题的产量模型。将压力法与数值试井模型进行了对比校验 ,发现随油井的生产 ,压力导数曲线呈上翘趋势。通过计算结果对比 ,对原压力法提出的无量纲方法进行了修正。修正后的双对数曲线均可与同参数的单相流双对数曲线重合 ,边界反应也可以从两相流的压降试井曲线中获得。

CONSTRUCTION OF NUMERICAL PRESSURE DROP MODELS FOR OIL WATER FLOW

The concept of multi phase numerical welltest(MPNW) is proposed. The difference between MPNW and conventional reservior simulation is analyzed. The unstructured gridding techniques used in MPNW is introduced. The discretization formula of governig equations for oil and water flow is given. The production rate model is derived with the coupling of wellbore storage and skin factor. The result of MPNW is checked with the pressure method for multiphase welltest analysis. It is found that the pressure derivation curve goes up with the emergence and increase of saturation gradient. The normalization method of pressure method is modified to deal with the increase. Modified log log curves overlap with the log log curves for single phased flow under the condition of the same parameters. The boundary effectiveness can be detected from the two phase pressure drop curve.