Effect of Nitric Acid on the Low Fluorescing Performance of Drilling Fluid Lubricant Based Animal and Vegetable Oils

Abstract

After synthesis of mixed fatty acid triethanolamine ester surfactant based on animal and vegetable mixed oils, the reaction solution was added into 4% (wt/wt) liquid nitric acid or 9% (wt/wt) solid nitric acid as eliminating fluorescent agent continuing to react from 1 to 2 hours. The low fluorescence lubricant named E167 for drilling fluid was prepared, in which maximum fluorescence intensity (Fmax) was less than 10 in three-dimensional fluorescence spectra of excitation wavelength range. When the E167 was added into fresh water based drilling fluid at the dosage of 0.5% (wt/wt), the sticking coefficient reduced rate (ΔKf) is 78% and the extreme pressure (E-P) friction coefficient reduced rate (Δf) is 79%. In the case of 4% brine mud with 0.5% (wt/wt) E167 in it, the ΔKf and Δf are 75% and 62%, respectively. After the hot rolling ageing test 180°C × 16 h with the E167 was added into fresh water based drilling fluid at the dosage of 1% (wt/wt), the ΔKf and Δf are greater than 70%, which shows a much better lubrication properties of strong resistance to high temperature. The fresh water based drilling fluid which contains 1% (wt/wt) E167 is almost nonfoaming even after hot rolling ageing 120°C × 16 h.