Drilling fluids containing biodegradable organophilic clay

Abstract

Drilling fluids are provided that comprise an organophilic clay treated with a quaternary ammonium surfactant having an amide linkage. The quaternary ammonium surfactant may comprise a compound generally represented by the following formula: where M− is an anion such as a chloride, methyl sulfate, bromide, acetate, or iodide ion; R1 is an alkyl group such as a saturated hydrocarbon with 10 or more carbons; R2, R3, and R4 are the same or different alkyl groups such as a methyl, ethyl, or benzyl group, and x is greater than or equal to 1. The organophilic clay treated in this manner is substantially biodegradable. In embodiments, the drilling fluids comprise the foregoing organophilic clay, an oil-based fluid and a weighting agent. In still more embodiments, the drilling fluids comprise the foregoing organophilic clay, an invert emulsion, an emulsifier, and a weighting agent.

Dependencies are inferred from the claim text.