利用局部变差函数描述储层非均质性

Characterization of Reservoir Heterogeneity by Using Locally Varying Variogram

在地质统计学的实际应用中,一般是在整个研究区采用相同的变差函数,这样不能很好的描述地质变量变化的复杂性。特别是河流相储层,由于河道方向经常发生改变,在相控的基础上模拟储层物性参数分布特征的时候,只采用一个全局的变差函数,无法精细地描述物性参数沿着河道方向具有最好连续性的分布特点。因此,需要根据变量局部的最大连续性方向建立局部的变差函数,然后在此基础上进行模拟。以河流相储层为例,在确定局部变差函数的基础上,对P油田沙三中亚段油组进行了模拟计算。并且与传统的采用全局变差函数的模拟结果进行了对比。研究表明,在地质变量存在明显局部变化特征时,采用局部变化的变差函数进行模拟计算,能够更真实地描述地质变量的空间分布特征。

In the application of geostatistics,a single stationary variogram was often set for the whole research area. The geologic complexities could not well described,especially for channel reservoirs,because the local direction of a channel was often changed,the continuity of reservoir petrophysical parameters was also changed along the flow direction of channels. In this situation,the anisotropy was varied locally. Locally varying variogram parameters based on their location should be established before simulation. According to the differences of positions in the research area,the variogram had different azimuths,ranges,nuggets and sill. When the local conditional distribution function was calculated,the local variogram was considered instead of global one. An example of Es3 reservoir in Pucheng Oilfield was presented. The result shows the ability of this method results in complex features that would be difficult to characterize a single global variogram.