Evaluation and application of poly(ethylene glycol) as lubricant in water-based drilling fluid for horizontal well in Sulige Gas Field

With the increasing amount of drilling of directional wells and large-displacement wells, high torque and high resistance have become critical problems. Therefore, high-performance and environment-friendly lubricants for water-based drilling fluid are urgently needed. In this paper, poly(ethylene glycol) 2000 (PEG) was used as a lubricant, and the lubricity, inhibition, compatibility and temperature resistance of the PEG lubricant were investigated. The results show that 0.1% (mass ratio) PEG in water-based drilling fluid can reduce the friction coefficient of mud cake by 44.5%. This PEG also has certain inhibition and temperature resistance. As PEG is used with other drilling fluid additives, the compatibility was good and the lubricity of drilling fluid can be improved effectively. The lubricating mechanism of PEG was explored and the results showed that the hydrophobic alkane chains in the PEG molecules were adsorbed on the surface of bentonite, forming a hydrophobic film on the friction surface, thereby forming a lubricating layer. Field application in Sulige Gas Field showed that the PEG lubricant has good lubricity and can meet the technical requirements of corresponding horizontal wells. (c) 2020 Society of Industrial Chemistry