含不连通孔隙的致密砂岩储层岩石弹性模量预测方法

致密砂岩储层与常规储层相比具有低孔、低渗、连通性差等特性。针对致密砂岩储层中不连通孔隙的影响,提出了一种适用于致密砂岩储层的岩石物理模型建立方法,重点是利用Raymer公式引入不连通孔隙度的影响来修正基质模量的方法,阐述了依照连通孔隙度Gassmann方程在干岩石骨架的孔隙空间进行流体充填,分析讨论了不连通孔隙的引入对于岩石弹性模量及流体响应特征的影响。应用该方法对实验测量数据及某实际工区井资料进行试算发现,与常规有效介质模型预测结果相比,基于含不连通孔隙致密砂岩岩石物理模型估算的纵、横波速度值与测井结果吻合更好,验证了方法的合理性。

Tight sandstone is characterized by low-porosity,low-permeability and poor-connectivity,which is different from the conventional reservoirs.This paper proposes a method to build rock physical model for tight sandstone reservoirs due to the properties of disconnected pores and its impact.The method focuses on introducing the disconnected pores using Raymer relations to modify the matrix elastic modulus,and it also aims to accomplish fluid filling work using Gassmann equation with effective porosity.Then quantitative analysis is carried out to calculate the elastic modulus in tight sandstones saturated with fluids.Moreover,it analyzes the sensitivity of the rock elastic parameters for fluid.Finally,we discuss the accuracy of the parameters estimation based on rock physical model considering disconnected pores.The estimated S-wave velocity is consistent with the experimental measurement data and the log value,which proves the rationality of the method.

国家重点基础研究发展计划(973计划)项目(2013CB228604)资助。