考虑应力敏感性的低渗透油藏注水井试井分析

Analysis of Water Injection Wells Test in Low Permeability Oil Reservoirs Considering Stress Sensitivity

低渗透油藏由于渗透率低及存在启动压力梯度,油在地层中传播压力速度很慢,难以获得足够资料对储层做出合理的解释,油井试井效果不佳,而低渗透油藏注水井试井可以很好地解决这个难题。综合考虑启动压力梯度、应力敏感性、流度比等的影响,建立了低渗透油藏注水井低速非达西渗流有效井径试井的数学模型。鉴于该模型的强非线性,采用稳定的有限差分格式利用Newton-Raphson迭代法求得数值解,进一步研究了压力动态特征及影响因素,绘制了用于实际资料拟合分析的典型试井曲线。

Low-permeability reservoirs have low permeability and threshold pressure gradient,oil in formation pressure spreads slowly.It is difficult to obtain sufficient information to make a reasonable interpretation.Water-injection wells test is a good way to solve this problem.Based on analysis of the effects of stress sensibility,threshold pressure gradient and mobility ratio,one water-injection wells test mathematical model for low-permeability reservoirs was established.Since this model has strong-nonlinearity,stable finite-difference scheme and Newton-Raphson iteration method was adopted to obtain the arithmetic solution.The pressure performance and influencing factors were evaluated; the typical well testing curves for analysis of real data are plotted.