| 摘要 |
The invention relates to the inclusion of lubricants which afford lubrication in drilling fluids in which lubricant compatibility and/or performance may be adversely affected by other components of the drilling fluid, particularly divalent cations such as calcium, formate salts or highly alkaline components such as alkali silicate. In this respect the invention is to a drilling fluid having an aqueous brine phase which includes at least one of: a) dissolved calcium, usually as Ca2+ ions, particularly at a concentration of at least 0.1 molar, b) dissolved formate, usually as a potassium or, and particularly, caesium salt, (caesium formate), and particularly at a concentration of at least 0.5 molar; c) dissolved silicate, usually provided as alkali metal, especially sodium, silicate, particularly at a concentration of at least 0.4 molar; or d) brine salts at a concentration of at least 90% by weight of the concentration at saturation; aid further including at least one polyalkylene glycol and a lubricating agent which comprises at least one hydrocarbyl polyether phosphate.
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