Oily lubricants have been used in water-based drilling fluids (WBDFs) for many years, particularly in deviant, extended reach or horizontal wells where relatively high toque and drag often be a vital issue. As environmental regulations are becoming more restrictive, traditional lubricants for WBDFs encounter severe challenges. Hence, high-performance, environmentally friendly lubricants for WBDFs are urgently needed.
In this paper, a novel lubricant based on biodiesel was introduced. On the basis of a detailed comparison of the properties of biodiesel and some other oils, the huge potential of biodiesel as a lubricant was demonstrated. The development process of the novel lubricant was described briefly and then comprehensive laboratory evaluation results were presented. The results suggested that the lubricant has great performances in different WBDFs. It was also found to have low eco-toxicity and good biodegradability, meaning a great environmental acceptability. Its performance became even better after hot-rolling at 150 °C for 16 h. In addition, the performances of the lubricant mixed with some other lubricants including zinc dialkyl dithiophosphate (ZDDP) and modified graphite (MG) in WBDFs were investigated. The results showed that the lubricity can be further enhanced by some synergetic effects between different lubricants. The action mechanisms of these synergetic effects in the friction process were proposed.
Using biodiesel-based lubricant for WBDF drilling is a promising way to compromise the legal pressure and technological demands. In view of the booming of biodiesel production and the increasing of environmental awareness, this lubricant offers a hopeful solution.