A High Performance Lubricant for Complex Shale Oil Drilling Conditions

Shale oil drilling is faced with challenges such as high friction, poor stability of drilling fluid additives in high-temperature high-salinity environment and increasingly stringent environment protection requirement. To address these problems, a novel ester-based lubricant LUBM-1 was developed through one-pot synthesis with raw materials such as ricinoleic acid, oleic acid, n-octanol and iso-octanol. Laboratory experiments were conducted to systematically evaluate LUBM-1 for its molecular structure characteristics and its performance in water-based drilling fluids. FT-IR characterization shows that the synthetic product has high degree of esterification and stable molecular structure. Laboratory drilling fluid experimental results show that a treatment of 1% LUBM-1 can remarkably reduce the friction coefficient of the base drilling fluid to 0.069 and the wear scar diameter, demonstrating an excellent friction reducing and wear resistant ability. The membrane formed by LUBM-1 remains stable in high-temperature and high-salinity environment; after aging at 200 ℃, it still reduces the friction of the drilling fluid by at least 80%, and in a drilling fluid containing 30% NaCl, LUBM-1 still retains high lubrication performance, showing excellent performance in high-temperature high-salinity environment. Water-based drilling fluids treated with LUBM-1 show good rheology, very low filtration rate, strong inhibitive capacity and low bio-toxicity which is required by "green-drilling". The results of the research show that LUBM-1 can significantly enhance the lubricity and borehole wall stabilizing performance of water-based drilling fluids, providing a reliable technical solution for complex shale oil drilling with high safety, high performance and environmental friendliness.