油水两相流不稳定试井压力分析

The transient pressure analysis of well test with water-oil two-phase fluid flow

基于油水两相渗流原理,建立了油水两相流试井模型,采用数值方法获得了井底压力的数值解,研制了均质地层和压裂油井在不同含水率条件下的试井典型曲线图版,分析了压力导数曲线变化的原因:对于水驱过程,即使油井未见水,后期压力导数曲线表现出向下掉然后上翘的特征,这是因为压力波传到油水边界时,最初起恒压作用,然后水体向油井推进,出现两相流动。用导数曲线先下降后上升这种变化模式,对于未见水油井,可以早期监视水体的移动。而对于压裂油井,高含水时,即使压力导数曲线出现水平段,压裂裂缝仍然存在。压裂井试井两相流模型和常规单相流模型试井曲线有较大差别。

Based on the principle of water-oil phase flow, an integral model is developed for well test with water-oil phase flow. Numerical result of bottom hole pressure is derived from numerical methods. New typical curve on well test analysis of homogeneous reservoirs and fracturing well is developed under water cut influence. The reasons why the pressure derivative curves chang are analyzed. Late pressure derivative curves go down then go up, even though no water is produced from the oil wells when water displaces oil, because the pressure wave reaches the boundary with constant pressure effect initially, then water-oil two-phase flow for the oil reservoir appears when the aquifer moves forward to the oil well. For the well test of oilfield displaced by water, changing pattern of pressure derivative curves determines the movement of aquifer at early stage. When water cut of the fracturing wells is high, even though the pressure derivative curve shows horizontal line, the feature of fracturing crack still exists. There are great difference between two-phase flow model and conventional single-phase flow model for well test curves of the fracturing well in reservoirs.