Low and high temperature drilling fluids based on sulfonated terpolymer ionomers

Abstract

The present invention relates to sulfonated thermoplastic terpolymers which are terpolymers of t-butyl styrene, styrene and sodium styrene sulfonate wherein these sulfonated terpolymers function as viscosification agents when added to oil-based drilling muds which are the fluids used to maintain pressure, cool drill bits and lift cuttings from the holes in the drilling operation for oil and gas wells. The sulfonated thermoplastic terpolymer of the latex have about 5 to 100 meg. of sulfonate groups per 100 grams of the sulfonated thermoplastic terpolymer, wherein the sulfonated groups are neutralized with a metallic cation or an amine or ammonium counterion. A polar cosolvent can optionally be added to the mixture of oil drilling mud and sulfonated thermoplastic polymer, wherein the polar cosolvent increases the solubility of the sulfonated thermoplastic terpolymer in the oil drilling mud by decreasing the strong ionic interactions between the sulfonate groups of the sulfonated polymer. The drilling muds formed from these latices of the sulfonated thermoplastic terpolymers exhibits markedly improved low and high temperature rheological properties as compared to drilling muds formed from sulfonated thermoplasitc copolymers.

Dependencies are inferred from the claim text.