Grouping minimum REV of porosity and tortuosity based on descriptors of sand grains

Abstract

In sandy reservoirs, selecting a representative elementary volume (REV) for the pore scale, is essential for predictive upscaling toward the reservoir scale. The porosity and tortuosity of a sand media are used for REV selection. The profile and size of sand grains, forms the voids morphology; as a result, hypothetically the grains size distribution can provide an indication to whether a volume size is representative of the media. Linking voids based characteristics such as tortuosity and porosity, to their solids counterparts like grains distribution; can help in standardizing REVs for rocks and sands. The aim of the study is to use grains size, uniformity coefficient and conformity coefficient; for categorizing the REV of porosity and tortuosity. Synchrotron X-ray micro-computed tomography of 15 unconsolidated sand system was studied. In order to determine the minimum REV of porosity and tortuosity, 20 sub-volumes for each system was generated. Micro tomography was shown to be an effective tool in measuring sand grains and voids space characteristics. REV analysis showed that a bigger size for porosity was always required compared to that of tortuosity. Categorizing sand systems based on the uniformity and conformity indices, was shown to be ineffective for the purpose of REV selection. EAGE 2019.