煤系地层地震岩石物理建模及横波预测方法

煤系地层油气资源发育潜力较大,现有地震岩石物理建模方法欠缺对储层含煤后岩石物理性质的系统研究。为此,利用自洽(SCA)模型耦合煤的影响,将其以包含物的形式加入背景介质中,构建一种适用于含煤储层的地震岩石物理模型;通过分析煤层占比、泥质含量、含水饱和度及孔隙度等微观物性参数对岩石弹性模量的影响,优选表征储层物性特征的敏感弹性参数;推导出以纵波速度为约束的岩石物理反演目标泛函,利用模拟退火全局寻优算法实现了横波速度的预测。将该方法应用于实际测井数据,预测横波速度与实测数据吻合度较高,证明了该模型对煤系地层的适用性。

Seismic rock physics modeling and shear wave velocity prediction method of coal measure strata

The development potential of oil and gas resources in coal measure strata is great. However, existing seismic rock physics modeling methods lack systematic research on petrophysical properties of reservoirs containing coal. In response, a self-consistent approximation (SCA) model was used to couple the influence of coal and added it to the background medium in the form of inclusion. In this way, a seismic rock physics model was constructed which was suitable for coal-bearing reservoirs. The sensitive elastic parameters characterizing physical properties of reservoirs were selected according to the analysis of how the rock elastic modulus was influenced by microphysical parameters, such as the proportion of coal seam, shale content, water saturation, and porosity. The objective function of petrophysical inversion was derived with P-wave velocity as constraint, and S-wave velocity was predicted by using simulated annealing global optimization algorithm. The method was applied to actual logging data, and the predicted shear wave velocity was in good agreement with the measured data, which proved the applicability of the model to coal measure strata.