Study and Application of New Vegetable Lubricant Used in Drilling Fluid

A new vegetable lubricant was developed by reacting waste vegetable oils with low molecular weight alcohols to form long chain fatty acid ester being treated with surfactants and other treatments to render it high temperature stability. At room temperature, 6% bentonite slurry treated with 1% vegetable lubricant had extreme pressure friction coefficient reduced by 85.5%-88.6%, and coefficient of adhesion reduced by 80.0%-86.7%. This lubricant remained its lubricating capacity at 140℃, and tolerated contamination by 15% salt. It had fluorescence level of 3 and EC₅₀ of over 50,000 mg/L, and was well compatible with polymers and sulfonates commonly used in water base drilling fluid. In field application in the Well Zhuang23, crude oil previously used as lubricant was reduced at least by 50%. Experimental wells drilled with drilling fluid containing this vegetable lubricant, 3900m in depth, had average well construction time reduced from 33.55 d to 29.11 d. Furthermore, the use of waste oil from manufacturing this vegetable lubricant was also beneficial to environment protection.