Performance evaluation of a novel environmentally friendly lubricants for water-based drilling fluids

The continuous depletion of shallow oil and gas reserves, the exploration focus has shifted to deeper geological formations. This transition has led to significantly higher demands on the lubricity of drilling fluids. Traditional lubricants, which often contain harmful elements, are increasingly facing regulatory restrictions due to environmental and safety concerns. Consequently, the development of new, environmentally friendly lubricants has emerged as a prominent area of research in the oil and gas industry. In this study, choline chloride and 1,3-butanediol were selected as raw materials to synthesize a deep eutectic solvent, designated as HTG-1, which serves as a novel environmentally friendly drilling fluid lubricant. A series of experimental tests were carried out to comprehensively evaluate the performance of HTG-1. At temperatures below 180 °C, HTG-1 demonstrated a remarkable enhancement in the lubricating properties of both drilling fluids and filter cakes. The adhesion coefficient was effectively maintained within the range of 0.1, resulting in a reduction rate exceeding 50%. As the concentration of HTG-1 increased, the filter cakes consistently maintained a low adhesion coefficient, ranging from 0.0761 to 0.1157 at 160 °C and from 0.0642 to 0.1053 at 180 °C. Moreover, it exhibited higher reduction rate values, indicating its superior performance in reducing friction and enhancing overall drilling efficiency. HTG-1 exhibited remarkable salt resistance. The lubricating mechanism of HTG-1 involves the adsorption of choline chloride and the formation of numerous hydrogen bonds. This mechanism contributes to its excellent lubricating properties and ability to reduce friction in drilling operations.