The adsorption of various polysaccharides on peptized montmorillonite is examined and their influence on the fluid loss properties of polymer-modified bentonite drilling mud (14 lb/bbl) formulations is studied as a function of increasing solution salinity and temperature. The studies indicate that adsorption per se does not facilitate fluid loss control, but adsorption is necessary in saline solutions. The ability of an anionic polymer to effect fluid loss control is related to the nature and amount of anionic substituent in the polymer (i.e., the total ionization of the macromolecule).

Mechanistically the data can be interpreted in terms of minimization of the electrical repulsive forces of the anionically charged water-soluble polymer and montmorillonite surface, with adsorption of the polyelectrolytes on the clay's surface positive edges.

Keywords:
drilling fluids and materials, drilling fluid formulation, adsorption, dependence, viscosity, polysaccharide, drilling fluid selection and formulation, drilling fluid property, upstream oil & gas, substrate
Subjects:
Drilling Fluids and Materials, Drilling fluid selection and formulation (chemistry, properties), Drilling fluid management & disposal
Copyright 1985, Society of Petroleum Engineers
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