Many interpretation methods have been proposed to convert experimental data from a centrifuge into capillary pressure curves. Of all these, Bentsen's parameter estimation technique appears superior to others. However, Bentsen's capillary pressure model (Model I and Model II) may not have the flexibility to describe the downward bending section of the capillary pressure curves when Sw approaches unit, which is sometimes a typical feature of such curves. We propose in this paper two new capillary pressure models which can be used in the parametric estimation method to consider the downward bending feature of capillary pressure curves. The new models take the following forms:

where Sn is the normalized wetting phase saturation, a.b.c are the estimation parameters. When c=l, the Model 1 as presented will be reduced to Bentsen's Model I, which is the common form used previously. Comparisons are made between the results of the new models and Bentsen's models and those obtained from Skuse et al's method for various core sample data. Our results show the great flexibility of new capillary pressure models.

You can access this article if you purchase or spend a download.