Tribological Performance of Manganese Tetraoxide-Weighted Potassium Formate Brine as Reservoir Drilling Fluid

Abstract The depletion of conventional fossil fuel reserves has compelled the oil and gas industry to adopt unconventional drilling techniques, such as deepwater, multilateral, and horizontal drilling. To access previously unreachable reserves, advanced technologies like extended-reach drilling (ERD) are employed. However, these methods often present operational challenges, particularly under high-pressure, high-temperature (HPHT) conditions. A critical factor in addressing these challenges is the selection of appropriate drilling fluids that ensure environmental safety while maintaining operational efficiency. Non-aqueous drilling fluids (NADFs) are often preferred for their superior thermal stability and high rate of penetration; however, they present significant environmental concerns and incur high disposal costs. As a result, there is an interest in high-performance, environmentally friendly alternatives such as potassium formate (KFo) brine-based aqueous fluids, which offer a balance between operational efficiency and environmental compliance. However, its limited maximum saturation density (1.57 SG) restricts its application in deep wells. This limitation can be addressed by adding solid weighting agents. Manganese tetraoxide (Mn3O4) offers high density (4.8 SG), and ultra-fine particle size, making it compatible with KFo brines. A challenge with aqueous fluids, especially high-density brines, is their higher friction factor during drilling compared to NADFs, which can hinder operations in deviated wells. Existing lubricants often underperform in saturated brines, prompting the need for tailored solutions. This study evaluates the frictional and wear behavior of cesium and potassium formate brines, as well as Mn3O4/ KFo system, in the presence of three lubricant additives aimed at reducing friction. The best-performing additive was further analyzed using Quartz Crystal Microbalance (QCM) techniques to simulate downhole conditions. Final tests with high-density fluids confirmed improved frictional performance, supporting the viability of KFo-based systems as an NADF alternatives.