A predictive model for formation damage resulting from particulate processes involving two-phase flow of oil and water in sandstone formations is presented. The invasion and retention of externally introduced particles, the release and capture of formation in-situ fines and the resulting formation damage in terms of permeability reduction are modeled mathematically. The release of in-situ fines, retention of external particles and in-situ fines, and interphase transfer of particles are represented by empirical rate expressions. Permeability reduction is evaluated by taking into account the effects of pore plugging and porosity variation. The effects of relative permeabilities, capillary pressure and wettability of fine particles and pore surfaces on two-phase flow formation damage are considered.

The model is first tested with laboratory data of single phase flow of water through water-sensitive sandstone cores with and without presence of residual oil, and then with two-phase flow data involving the displacement of an oil-saturated, water-sensitive sandstone core by water. It is shown that there is a reasonable agreement between model predictions and experimental data. Typical simulation results illustrating the effects of wettability of externally introduced particles on permeability impairment in two-phase flow are also presented. However, the later results could not be verified due to the lack of experimental data. The model presented in this study can be used to estimate formation damage, identify governing damage mechanisms, and provide a guide for controlling formation damage for a given rock-fluid system.

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