The requirement for intervention operations in long-reach lateral wells continues to grow. In the US, it is not uncommon to be asked to run coiled tubing (CT) in 10,000-ft laterals. In general terms, a 2-in. CT typically has enough weight reserves to perform work to approximately half such a lateral. Even though increasing the CT diameter remains a theoretical option to improve reach, practically, it creates logistical challenges with both road transport and offshore crane-lifting/deck-loading limitations. Although fluid-hammer tools and downhole tractors have extended the reasonable operational range of CT significantly, they also increase circulating pressures and operational complexity. To reach a 10,000-ft lateral, the use of metal-on-metal lubricants will be required to work in conjunction with the other systems.Obviously, the use of lubricants is not new. Typical real-life results of current systems are approximately a 15 to 20% reduction in the coefficient of friction (CoF) from a generic 0.24 to 0.19. Occasionally, one could obtain smaller CoF values in the field. However, these actual results compare poorly to laboratory testing with a high-pressure rotational friction test.An extensive set of laboratory measurements was carried out with a linear-friction measuring device to understand and quantify the mechanical, chemical, and thermal metal-on-metal wet frictional effects. Particular attention was paid to the synergy between lubricants and the other commonly circulated brines and fluid friction reducers. Other tests, such as regained-permeability and aging tests were also performed.Arising from the trials is a new lubricant that reduced the linear CoF by approximately 40 to 60% (0.10 to 0.12) under downhole conditions. Friction reduction of this magnitude is expected to make it feasible to run CT in 10,000-ft laterals without the use of fluid-hammer tools or tractors.