基于多孔介质模型的储层裂缝孔隙度计算方法

A Method for Calculating Reservoir Fracture Porosity Based on the Porous Media Model

针对裂缝性储层裂缝孔隙度定量计算的难题,提出了一种基于多孔介质模型的储层裂缝孔隙度计算方法。通过定义孔隙纵横比谱函数表征岩石裂缝分布特征及对岩石宏观岩石物理特征的影响,并代入多孔介质模型中,建立含裂缝条件下多孔介质模型。理论正演表明,孔隙纵横比谱分布特征与岩石体积模量变化一一对应,通过建立岩石模量反演函数,利用现场阵列声波测井资料实现孔隙纵横比谱定量反演,进而计算裂缝孔隙度。应用结果表明,计算的裂缝孔隙度能够较好地反映储层裂缝发育情况,与电成像测井计算结果吻合较好,文中方法所计算的裂缝孔隙度符合实际生产情况,为裂缝孔隙度计算提供一种新的途径,扩展了阵列声波测井应用范围。

To address the difficulty of calculating the fracture porosity of fractured reservoirs, a calculation method based on the porous media model is proposed. The pore aspect ratio spectrum function is defined to characterize the distribution of rock fractures and its effect on the macroscopic petrophysical characteristics of rocks. This function is added to the porous media model to account for the fractures. Theoretical calculations show a correlation between the distribution of the pore aspect ratio spectrum and the change in the bulk modulus of rocks. An inverse function of the rock modulus is also defined, and the array of acoustic logging data obtained from field measurements is utilized for the inverse calculation of the pore aspect ratio spectrum. Finally, this result is used to calculate the fracture porosity. Results obtained from actual data demonstrate that the calculation fracture porosity can better reflect the fracture development of the reservoirs and is in good agreement with the calculation results of electrical imaging logs. The fracture porosity calculated by the method proposed in this paper is consistent with the actual production of the reservoirs. Therefore, the method is considered suitable for the calculation of fracture porosity and expands the applications of array acoustic logging.