This study was undertaken to investigate the transient behavior of particulate plugging of porous media. The objective of the experiments was to study in detail a well-characterized system and check the validity of theoretical predictions.1  Kaolin and bentonite suspensions were injected into 40 to 170 mesh Ottawa sandpacks. The pore size distribution of the pack was measured. The permeability and effluent particle concentrations were monitored continuously. Experiments were conducted at different flow rates, pH values, ionic strengths, and particle concentrations with each clay mineral. The effect of each of these parameters on the permeability reduction and effluent particle concentration profile was evaluated. The particle size distribution of the influent stream was also measured at different pH and ionic strengths.

It was observed that high ionic strengths, low pH, low flow rates and high particle concentrations cause more rapid permeability reduction.

The particle and pore size distributions together with the surface charges on the particles and pores2  can be used to estimate theoretically the rates of permeability decline. A comparison of theoretical predictions with experimental observations shows a semi-quantitative agreement. All trends in the permeability reduction profile obtained by varying parameters (such as flow rate, pH, …) are consistently predicted.

The usefulness of studying well-characterized systems is demonstrated. The results provide a better insight into the mechanisms responsible for particulate plugging. The findings will be useful for estimating and minimizing damage due to drilling mud infiltration, waterflooding and fines migration in unconsolidated sands.

Electrochemical conditions under which particle deposition occurs can be qualitatively predicted. Coagulation effects due to changes in pH and ionic strength may affect interpretation of the results.

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