礁滩储层内部孔隙结构模型模拟与孔隙度预测

Pore structure model simulation and porosity prediction in reef-flat reservoir

地下岩石是由岩石基质和孔隙流体组成的双相介质,其有效弹性参数受岩石基质、孔隙度、孔隙结构及孔隙流体的影响,因此为了得到孔隙度与岩石有效弹性参数之间的关系,必须消除其他因素对孔隙度的影响.本文首先引进等效体的概念和Eshelby椭球包体裂缝理论,然后在合理的假设前提下,运用Gassman流体替换方程,推导并建立了生物礁滩储层孔隙度与其他弹性参数和描述岩石孔隙形状的孔隙纵横比的关系式,合理和有效地模拟了非均质性较强的生物礁滩储层的孔隙结构.经实际资料验证,利用建立的孔隙度与弹性参数的关系式可以较有效地进行生物礁滩储层的孔隙度预测.

Rock in underground composed of rock matrix and pore fluid is two-phase medium, the effective elastic parameters of which are influenced by rock matrix, pore structure and pore fluid. Therefore, in order to get the relationship between porosity and effective elastic parameters of rock, the influence of the other factors must be removed. Based on the basic theory of rock physics and test data, the paper proposes the concept of equivalent volume and utilizes the Eshelby ellipsoid xenoliths fracture theory. In the case of reasonable assumption, the Gassman equation is applied to deduce and establish the equation between porosity and related factors including the compressibility of saturated rock （no drainage）,the compressibility of rock matrix, pore aspect ratio describing pore shape and parameter m,and simulate properly pore structure in reef-flat reservoir, which has strong heterogeneity. At the last, the practical data proves that the formula between porosity and elastic parameters we build is more effective to predict porosity in reef-flat reservoir.