| 摘要 |
Methods and compositions for use in such methods are provided for drilling, running casing in, and/or cementing a borehole in a subterranean formation using aqueous based drilling fluids. The drilling fluids are thinned or dispersed with a blend of non chrome, ferro lignosulfonate and acrylate copolymer with one or more acrylo amido propane sulfonate functional groups, at a pH in the range of about 8.0 to about 10.5. The drilling fluids do not contain heavy metals and are rheologically tolerant to contaminants such as cement, anhydrite and sodium and temperatures as high as about 350° F.
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