DETERMINATION OF RELATIVE PERMEABILITY FROM PRODUCTION DATA IN FORCED GRAVITY DRAINAGE

Viscous dominated flow regime in gravity drainage process occurs when gas advances at high flow rates from injection wells toward the production end. The gas/oil relative permeability is an essential parameter for reservoir evaluation and prediction in the forced gravity drainage processes. The contribution of this paper is an extension of Hagoort’s method for determination of relative permeability, when oil displacement occurs by injection of gas from the top. Application of this method results in Corey type oil relative permeability without need for pressure data. To examine the validity of the relative permeability curves, these were used in a numerical model to predict the pre-determined relative permeability data. To verify the applicability of the method, the experimental production data from a long core laboratory tests has been used. Numerical experimentations indicated that at high displacement velocities, the results are not only a function of relative permeability to oil, but also that to gas. In these cases, the relative permeability to gas was determined by history matching. The use of the analytically-determined relative permeability to oil along with the history-matched relative permeability to gas reduced the non-uniqueness problem associated with backward modeling of two-phase flow experiments.

Keywords:

gravity drainage , relative permeability , Hagoort method , history matching , Corey type