用交替条件期望变换确定岩石物性参数

DETERMINING PETROPHYSICAL PARAME- TERS BY ALTERNATING CONDITIONAL EX- PECTATION TRANSFORM

影响油气储层声学性质的参数众多,包括孔隙度、饱和度、孔隙压力、温度、孔隙流体性质、泥质含量以及波的频率等,而各种参数间往往并非相互独立,又相互作用和依赖,共同产生效应。因此,在确定岩石声学物性参数时,一般应用多元回归。但传统的回归技术需要先假定一个函数关系,由于受到函数关系的限制,常常导致参数回归失败。交替条件期望变换提供了一个随机因变量和多个随机自变量之间具有最大相关系数的最优变换, 可对实验数据进行有效处理,提高回归曲线的相关系数。文章通过对含气岩样实验数据的分析,证明了交替条件期望变换的优越性。对白云岩而言,变换前,其单参数的相关系数均在0.72以下,变换后相关系数提高到0.9894。

The parameters affecting the acoustic property of reservoir are numerous, including porosity, saturation, pore pressure, temperature, fluid nature, shale content and wave frequency, etc. These parameters are not independent of each other, but have the characteristics of double interaction and dependence as well as common effect, so that the multivariate regression method was often used for determining the parameters. It was necessary, however, for the conventional regression method to suppose a function relation firstly and the regression result of parameter was often defeated because of the limitation of the function relation. The alternating conditional expectation transform may provide the optimal transform which can make a maximum correlation coefficient occurring between a random dependent variable and many random independent variables, and can effectively process the experimental data, thus raising the correlativity of regression curve. Through analyzing the experimental data of gas-bearing rock samples, it was proved that this method is excellent. In regard to dolostone, the correlation coefficient of each parameter is less than 0.72 befor transform but up to 0.9894 after transform.