Effect of Stochasticity in Porosity and Permeability Profiles on Matrix Acidizing

ABSTRACT: Matrix acidizing is a common stimulation technique used to improve permeability near the wellbore. Numerical modeling is used to simulate matrix acidizing behavior observed in experimental studies. Besides model limitations, imprecise model parameters can cause differences in results. This study is motivated to observe uncertainty in matrix acidizing simulations caused by porosity/permeability distributions, porosity heterogeneity magnitude, and permeability variance. Uncertainty in acidizing results is studied using sequential Gaussian simulation (SGSIM). Multiple equiprobable realizations of porosity and permeability profiles are generated using SGSIM and simulated with UTCOMP. The results of 2700 simulations are aggregated and analyzed for two case studies. The first case study compares acidizing curves for a hundred realizations each for spatially correlated and random distribution types. The second case study is a factorial experiment that considers five levels of porosity heterogeneity magnitude and three levels of permeability variance. The results indicate significant uncertainty in results based on randomness in porosity and permeability distributions. Additionally, porosity heterogeneity magnitude had negligible impact on uncertainty in results compared to permeability variance. This study shows the importance of incorporating uncertainty analysis in matrix acidizing assessments.