河道砂体内部物性分布趋势的模拟

Simulation on Petrophysical Property Trends within Channel Sandbodies

对于河道砂体而言一般具有河道中部物性好于河道边部物性的趋势,传统的建模方法难以描述这种分布趋势。介绍了两种方法实现这一目的:一是采用局部变化均值的方法,根据模拟网格位于河道内部位置的不同而设置不同的属性均值;二是利用多点地质统计学方法。传统的多点地质统计学方法主要针对离散变量的建模,如相建模,在该研究中以多点统计算法SNESIM为基础实现了对连续变量(孔隙度、渗透率等)的模拟。首先根据一系列门槛值把连续变量离散成若干类别,然后对这些离散的类进行多点统计模拟,最后再把模拟结果转换成连续的变量值。对这2种方法进行了分析对比,阐明了各自的优缺点。

There was usually a petrophysical trend within channel sandbodies,such as porosity,permeability decreasing from the centre to both sides.However,this trend was hard to be reproduced by traditional simulation methods.Two methods were introduced to solve this problem:the first one was to use locally varying mean in which different means were set based on the position of simulation cells in the channel;the second was based on multiple-point statistics simulation(MPS).Traditional MPS was a typical facies modeling method which was only for discrete variables.The MPS simulation algorithm SNESIM is modified to model the continuous properties,such as porosity and permeability.The method includes two main steps:the first step is to divide continuous properties into several categories and multiple-points statistics based on these categories.The second one is to back translate the discretional simulation results into continuous properties.The simulation results of both are compared,and the merits and demerits of the methods are discussed.