Mechanistic Study and Chemical Design of a New Lubricant for High Salinity Drilling Fluids

Abstract

Abstract The drive to reduce freshwater consumption has led to a significant increase in the use of waste streams, such as high salinity produced water brines, as base fluids in drilling fluid systems. However, the performance of conventional lubricants is typically reduced in such brines. This paper describes the design and development of a new class of lubricant specifically designed for use in high salinity water-based drilling fluids. A comprehensive literature review and a detailed laboratory testing program were undertaken to investigate the mechanism of drilling fluid lubricants under downhole conditions. The knowledge gained from this study was used to design a new class of lubricant that undergoes a chemical reaction with high salinity brines in order to activate the lubricant species and maximize performance. A series of field trials were conducted on wells targeting the Montney formation in Western Canada. The drilling fluids consisted of solids-free sodium chloride, calcium chloride, and produced water brines with densities ranging from 1080 – 1330 kg/m3. The wells had lateral lengths ranging from 1580 – 4000 meters. The new lubricant significantly out-performed conventional lubricants on 100% of the field trials and was able to achieve friction factors close to those of oil-based drilling fluids. A series of in-depth case studies are provided which highlight the unique performance characteristics of this novel drilling fluid lubricant.