Correlation Between Pore Structure of Sandstones and Tertiary Oil Recovery

Abstract

An excellent correlation has been attained between pore structure and additional recoveries obtained in tertiary surfactant floods for 15 different sandstones. A reasonably good correlation exists between the reciprocal of mean neck diameter (as obtained from mercury porosimetry) and the additional recoveries obtained in tertiary surfactant floods. THEORY AND EXPERIMENT When conducting laboratory tertiary surfactant floods on a variety of different sands, sometimes great differences are found in the tertiary oil recoveries - the reasons for which are often not well understood. In the present study it has been demonstrated that, for the set of conditions used, the observed differences in tertiary oil recoveries could be correlated with the pore structure of the samples. The problem of how pore structure might influence tertiary oil recovery has been discussed by Dullien et al. In the present study, 15 outcrop sandstones have been successfully ranked on the basis of their pore structure in the order of increasing amounts of tertiary recoveries expected under identical conditions of flooding.