Water-based drilling fluids containing crosslinked polyacrylic acid
AssigneeNewpark Drilling Fluids LLC
InventorsDavid L. Breeden, Scott Gordon
Life of this patent
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Abstract
A water-based drilling fluid containing high molecular weight crosslinked polyacrylic acid as viscosifying agent exhibits stability at well temperatures in excess of 150° C. The drilling fluid may further contain a lubricant, weighting agent and/or a wetting agent as well as laponite clay. The aqueous based drilling fluid exhibits a coefficient of friction which is substantially close to the coefficient of friction of oil based drilling muds.
Claims29
A water-based drilling fluid comprising a a crosslinked polyacrylic acid dispersed in an aqueous phase and a density agent suspended in the aqueous phase, the aqueous phase consisting essentially of fresh water or saline water, the crosslinked polyacrylic acid having a Brookfield viscosity of greater than about 20,000 cPs in a 1% dispersion, the pH of the dispersion being greater than or equal to 7.0, and wherein the weight average molecular weight of the polyacrylic acid is from about 100,000 to 10 million, and the coefficient of friction of the water-based drilling fluid is less than or equal to 0.15.
A water-based drilling fluid comprising a lubricant, a liquid phase, a crosslinked polyacrylic acid dispersed in the liquid phase, wherein the liquid phase consists essentially of fresh water or saline water and wherein the crosslinked polyacrylic acid has Brookfield viscosity at 20 rpm at 25° C. between from about 3,500 and 13,000 at 0.5 wt. % mucilage, the amount of crosslinked polyacrylic acid in the water-based drilling fluid being between from about 0.2 to about 0.5 weight percent and further wherein the weight average molecular weight of the polyacrylic acid is between from about 100,000 to 10 million and the coefficient of friction of the water-based drilling fluid is less than or equal to 0.15.
A water-based drilling fluid having a liquid phase and a solid phase suspended in the liquid phase, wherein the liquid phase consists essentially of either fresh or saline water and the suspended solid phase comprises a crosslinked polyacrylic acid having a Brookfield viscosity at 20 rpm at 25° C. between from about 3,500 and 13,000 at 0.5 wt. % mucilage, the pH of the water-based drilling fluid being greater than or equal to 7.0 and wherein the weight average molecular weight of the crosslinked polyacrylic acid is between from about 100,000 to 10 million and the coefficient of friction of the water-based drilling fluid is less than or equal to 0.15.
Dependencies are inferred from the claim text.