1963 Paper (H)

PREDICTION OF RELATIVE PERMEABILITY CHARACTERISTICS OF INTERGRANULAR RESERVOIR ROCKS FROM ELECTRICAL RESISTIVITY MEASUREMENTS

S. J. Pirson, Professor of Petroleum Engineering, The University of Texas; E. M. Boatman, Petroleum Engineer, The Texas Company, Monahans, Texas; R. L. Nettle, Petroleum Engineer, Gulf Oil Corporation, Placenta, California

ABSTRACT

The senior author proposed more than a decade ago some theoretically derived relationships that permitted the prediction of the relative ability of reservoir fluids (oil, gas, water) to flow simultaneously within the porous structure of such rocks. While many successful predictions of fluid flow ratios from wells have been made from electric logs, the theoretical deductions have not been subjected to laboratory verifications. The junior authors' contributions consisted in such verification as subject matter of Master of Science theses.

For the relative permeability to liquid and gas, simultaneous flow of water and air was used employing the familiar external gas drive technique. While in the process of water desaturation, the test cores' (Woodbine sand) resistivities were measured. Their permeabilities varied from 10 to 280 md. The laboratory results indicated the need for changing the values of exponents in the theoretically derived formulas whereas the form of the functions of resistivities and saturations remained as derived by theory.

For the relative permeability to oil and water,, the three-core dynamic technique was used on six cores. In this case it was found that the formulas were valid, with but slight modification, as derived by theory and to a sufficient degree of accuracy for engineering use and for well productivity prediction from electric logs.