Near Wellbore Permeability and Damage Measurements: Experiments and Numerical Simulations for Interpretation of WFT Data

Abstract

Wireline Formation Test (WFT) can provide a valuable, cost effective source of near wellbore formation damage data. Interpretation of WFT data can be improved with numerical simulation and laboratory experimental data. A 3-D numerical simulator for WFT was developed and a comprehensive study of problems associated with the wireline test was made. The simulator results are interpreted with the concept of geometric factor. Case studies include sensitivity to formation damage, internal probe diameter, fluid compressibility and viscosity, formation permeability, and drawdown tank volume. The radial grid system used in finite element method is particularly amenable to handling practical problems with real WFT flow geometries and configurations. The simulated test pressures match well with actual field data. In addition to the numerical simulations, an experimental setup which models measurements on a downhole damaged formation was built and attached to a laboratory probe permeameter equipment. This experiment enabled us determine dependence of the measured permeability of the damaged formations on the severity and the depth of damage. The results of the experiments are also in good agreement with the 3-D numerical simulator results.