The Relationship of Ultra-Low Permeability Sandstone Aspect Ratio With Porosity, Permeability

摘要

The ultra-low permeability sandstone reservoir has large aspect ratio which significantly influences the multi-phase percolation characteristic. The ratio could be accurately measured by rate-controlled mercury porosimetry, but the testing technology is expensive, time-consuming and core-contaminating. There is not a simple effective method to describe the aspect ratio. The pores of the ultra-low permeability sandstone are mainly connected by the very long narrow throats, which could be advantageously simulated by the compound capillary bundles model. The analytical expressions of porosity and permeability about major pore structure parameters are established based on the model for the tight porous media. After solving the two expressions, the relationship between aspect ratio and parameter combination of porosity, permeability is obtained for the ultra-low permeable sandstone. Then the relation is fitted in this article using many previous published rate-controlled mercury data on compact sandstone and the relevance is strong, which proves that aspect ratio of tight rock is able to be calculated with its porosity and permeability.