Flocculation of drilling fluids occurs when clay, polymer additives and charged particles attach together to form a visible clump. When mechanical agitation is stopped, the dispersed clay particles form flocs because of the forces of attraction between negative and positive particle edges.
Drilling fluids consist of bentonite clay and added polymers to give it the desired viscosity and gel strength. Adequate circulating pressure has to be maintained for the drilling fluid to function effectively.
Trenchlesspedia Explains Flocculation
The main constituent of drilling fluid is water and bentonite clay. In the dry state, the plates are arranged face to face. When this clay is inserted in water, adsorption, hydration and swelling of the packets occurs. When the water is agitated, these packets disperse into smaller packets of plates, and remain in a state of dispersion till agitation is continued. When agitation is stopped, the plates and other suspended particles are mutually attracted and form clusters known as flocs.
Flocculation can be used to remove suspended solids and additives from water-based fluids after which the fluid can be recycled and reused.