Evaluation of formation and completion (gravel pack and screen only) flow capacity damage in unconsolidated formation material has proven difficult in the laboratory because typical core flood equipment does not adequately confine the formation material to allow drilling and cleanup fluids to be circulated at representative shear rates and pressures over the formation face.

A testing protocol and equipment have been developed which allows dynamic flow and fluid loss across unconsolidated formation material at shear rates, temperatures, differential pressures, and times representative of mud circulation rates in the wellbore.

The dynamically prepared filtercakes grow to an equilibrium thickness depending on the shear rate, differential pressure, and temperature and are more representative in composition and mass to wellbore filtercakes so that their damage to formation, gravel packs and / or screens can be better evaluated. The effectiveness of cleanup systems can also be determined by circulating the fluids across the mud filtercakes at typical shear rates, differential pressures and temperatures before allowing static soak conditions.

At the end of the test, the screen and formation material or screen, gravel pack and formation material are stressed together simulating a wellbore collapse. The permeability of the formation plus gravel pack and screen or formation and screen only are then measured and compared to the initial values to determine flow capacity impairment.

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