AN IMPROVED MODEL FOR RELATIVE PERMEABILITY AND CAPILLARY PRESSURE INCORPORATING WETTABILITY

Pore sizes, pore structures, relative permeability, capillary pressure, and wettability are measured as part of special core analysis. Inconsistency among measurements sometimes occurs because, for example, residual fluid saturations are different in different experiments, and preferential wettability changes during laboratory handling, experimentation, and core restoration. Furthermore, it is expensive to conduct different experiments that duplicate information on the same porous media. This memorandum presents a model that integrates relative permeabilities, capillary pre ssure, wettability indices, and pore size di stribution in a consistent manner. The model has the potential to be used in reservoir simulations to populate unmeasured rock-fluid properties based on limited measurements. It can be used for relative permeability and capillary pressure scaling up. In near future, we will fine-tune the model with measurements and published data. We will then extend the model to incorporate lithological data and core-level parameters such as absolute permeability, porosity, residual saturations, and end-point permeabilities. I. Summary of Results An integrated model that interrelates relative permeabilities, capillary pressures, wettability indices (USBM and Amott-Harvey), and pore size distribution is presented. The model can be further extended to include water and oil residual saturations. The model is being developed for eventual use to populate and predict unmeasured core pro perties for numerical simulations of reservoir performance, and thus reduce cost for unnece ssary measurements. It could also be further developed for predicting effective relative perm eability of complex geological systems.