Metal-to-metal lubricants used within the Coiled Tubing(CT)industry have become an essential resource for the successful completion of a variety of operations,most notably extended reach practices.A vast selection of metal-to-metal lubricants exist within the industry,which provides an abundance of options for CT applications.However,the effectiveness of these lubricants based on different well parameters is not well understood. The objective of this study is to provide a quantitative analysis comparing the friction reducing characteristics of various CT metal-to-metal lubricants used in optimized extended reach practices. Fourteen different lubricants commonly used in the Eagle Ford and the Bakken resource plays were tested using an OFITE EP(extreme pressure)and lubricity tester to determine their respective lubricity coefficient and film strength.The lubricity coefficient test used a torque arm which applied 150 in-pounds of force(the equivalent of 5,000 to 10,000 psi on the intermediate fluid)between two hardened steel surfaces(a block and a ring)rotating at 60 RPM.The EP test produced an indication of the film lubricant strength by applying a measured force to a torque-sensitive bearing cup with the torque arm. The EP test was performed at a high shear rate of 1,000 RPM with fluid pressures ranging from 5,000 to 100,000 psi between the steel surfaces. Tests with multiple solutions and various conditions were conducted to provide a better understanding of how the lubricant reacts in field applications.Each lubricant was mixed with fresh water,brine fluid,friction reducer,and 15%HCl fluid at different temperatures. The effectiveness of the top-performing metal-to-metal lubricants was validated by comparing the laboratory results with field data and computer modeling.The outcome of this analysis was used in conjunction with previously completed extended reach studies to further understand and improve the effects of metal-to-metal lubricants in CT operations. This paper provides a comprehensive analysis of the performance of the different metal-to-metal lubricants based on the applications and well conditions.A more in-depth understanding of the lubricants will help to improve accuracy when modeling and designing extended reach CT operations,which will result in improved overall efficiency.
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