确定低渗透储层启动压力梯度的新方法

A New Method of Determining the Starting Pressure Gradient in Low Permeability Reservoir

低渗透储层中流体渗流与中高渗储层相比最主要的特征是存在启动压力梯度。启动压力梯度目前大多采用岩心实验来测定,另外也可通过理论模型计算、数值模拟、试井分析等方法加以确定,但这些方法都是单纯地从静态角度予以考虑,离开了实际生产资料的矫正与检验,因此,得到的结果与实际启动压力梯度往往有较大出入。根据渗流理论和启动压力梯度规律,利用稳态逐次替换法,推导出了低渗透储层注水见效时间的预测公式。在此基础上,得到了根据低渗透储层注水见效时间计算启动压力梯度的表达式。实例计算表明,该方法得到的启动压力梯度是可信的,准确的,这为低渗透储层启动压力梯度的求取提供了一种新的方法。

Determination of starting pressure gradient is signifi- cant for economic and effective exploitation in low permea- bility reservoir.However,it's usually obtained by water drives cores experiments,theoretical model calculation, numerical simulation,well test analysis and so on.In con- clusion,these methods are simply considered from static aspects,without the consideration of adjustment and rec- tification by dynamic data of oilfield.Based on the theory of fluid flow mechanics and regularity of starting pressure gradient,the correlation between the pressure influence radius and time of the low permeability reservoir is de- rived by using the steady replacement method.In addi- tion,an expression by which the starting pressure gradi- ent can be determined was provided.The case study shows that this method is a more reliable and accurate ba- sis to be used for determination of starting pressure gradi- ent in low permeability reservoir.