The Accuracy of Pore Size Distribution Index Using Capillary Pressure Data: Effect of Physiochemical Factors

Abstract

The traditional plot of the logarithm of drainage capillary pressure versus the logarithm of effective water saturation provides a means of determining the pore size distribution index of sediments. However, due to certain factors such as the occurrence of pore lining clays that can be detached at high pressure gradients of flooding, this method can have a limitation. Also, possible deformation of core sample subjected to high centrifugal frequencies is another factor that can set a limitation to the applicability of this method. In this paper, we have reviewed literature to test the above two hypotheses. The results show that the accuracy of the log-log plot used by the petroleum industry for pore size distribution index determination is limited to clean sand systems where colloidal detachment from pore walls at high hydraulic gradients are no problem. This limitation requires screening of data to exclude affected portions.