摘要 |
Biodegradable organophilic clays for use in drilling fluids may, in some instances, include clay treated with a surfactant system that includes biodegradable quaternary ammonium surfactants and nonbiodegradable quaternary ammonium surfactants. The biodegradable quaternary ammonium surfactant may be capable of degrading by more than about 90% over 28 days as determined by Method 306 of the OECD Guidelines for the Testing of Chemical. |