Uncertainties associated with laboratory-based predictions of well index and formation damage

Abstract

The filtration and the formation damage coefficients are the parameters in the mathematical models determining the degree of permeability decline during flow of colloidal suspensions in porous media. Measuring pressure in 3 points along the core allows simultaneous calculation of the filtration and the formation damage coefficients. We have calculated the combined standard uncertainties of the filtration and the formation damage coefficients. Application of the law of propagation of uncertainty to Darcy’s equation and the weighted least squares method to impedance index curves for the half- and the overall core resulted in the values of their slopes and intercepts, and the respective combined standard uncertainties. Combination of the values of these slopes into a transcendental equation and solving it analytically fully determined the filtration and formation damage coefficients with their relative combined standard uncertainties being significantly lower than those reported in the literature.