多孔可变临界孔隙度模型及储层孔隙结构表征

碳酸盐岩、致密砂岩和页岩等储层具有孔隙类型多样、孔隙结构复杂和非均质性强等特征,属于典型的多重孔隙储层,孔隙结构表征是多重孔隙储层预测和流体识别的关键.现有的孔隙结构表征方法大多利用孔隙纵横比或者构建一种新参数来描述孔隙结构.岩石临界孔隙度模型是一种常用的岩石物理模型,具有一定的物理意义和地质含义.本文推导了岩石临界孔隙度与岩石孔隙结构(孔隙纵横比)之间的关系,进而利用极化(形状)因子建立临界孔隙度与弹性参数之间的关系,构建了能够包含多种孔隙类型的多孔可变临界孔隙度模型.利用多孔可变临界孔隙度模型由储层的弹性参数反演不同孔隙类型的体积含量.实验室测量数据和实际测井数据表明,多孔可变临界孔隙度模型能够适用于多重孔隙储层岩石物理建模和孔隙结构表征.

Multiple-porosity variable critical porosity model and pore structure characterization

Carbonate,tight sandstone and shale reservoirs are characterized by variety of pore types,complicated pore structures and strong heterogeneity,which belong to the multiple-porosity reservoirs.Their pore structure characterization is the key to reservoir prediction and fluid identification.The existing pore structure characterization methods mostly use the pore aspect ratio or construct a new parameter to describe the pore structure.The critical porosity model is a commonly used rock physics model,which has certain physical and geological meanings.This paper derives the relationship between the critical porosity of rocks and the pore structure(i.e.the pore aspect ratio)of rocks,uses the polarization(shape)factor to establish the relationship between critical porosity and elastic parameters,and proposes a new model named the multiple-porosity variable critical porosity model.Based on this novel model,the volume content of different pore types can be inverted by elastic properties.Tests on experimental data and well logging data show this multiple-porosity variable critical porosity model can be used for modeling complex reservoirs and characterizing pore structures.