Seminars Archive

Residual oil distribution in a range of selected sandstones observed via synchrotron computed tomography

Abstract
We analyze the residual oil (Sor) distribution in six selected sandstones. Sor was established by waterflooding in a flow displacement process representative of reservoir flow in small cylindrical cores (5 mm diameter) and fluid and rock topology were observed via synchroton micro-computed tomography (µ-CT) with a radiographic modality of 9 microns. Porosity values extracted from the µ-CT images matched porosity numbers measured by independent methods (Helium pycnometry and mass balance) provided that the pore space was sufficiently resolved. For sandstones with small pores, porosity was under predicted because of limited resolution. We computed average residual oil saturations which were consistent with literature data for the sandstone cores for which the pore morphology could be sufficiently resolved. We recorded residual oil cluster volume frequency distributions which followed a power law with an exponent 2.1, which validates the invasion percolation theory with trapping (IP) experimentally. These data also demonstrate that a few large residual oil clusters were present in the cores where µ-CT resolution was sufficient. These large residual clusters contributed significantly to the total Sor, again consistent with IP.