Abstract The completion of a total of 17 oil, gas and water injection zones from 7 dry tree wells on the TOTAL Matterhorn TLP, offered the perfect arena for the consolidation of technique and teamwork as the pillars of success. The challenge for economical production from the Matterhorn Field relied not only on what the reservoir could give but also on how the completion could deliver it. The challenging scenario was set with an extremely short time for delivery, combined with the low temperature of the completion set at a water depth of around 3,000', low reservoir pressure and temperature, highly deviated wells and a challenging reservoir management plan. The completion system integrates multiple tools and techniques such as Vacuum Isolation Tubing, Specially Designed Thermal Protectors, Gas Lift System with Gas injected from the Short String of the Dual Pack Off Tubing Hanger, Reservoir Monitoring Systems, Stacked frac-pack Sand Control, Optimized Fracturing Treatments, Pressureoperated fluid-loss/well control devices, Mechanical "Smart" Flow Control System, one trip isolating locating device. Utility of Wireline Tractor Services as a reliable contingency tool to address the high deviation; above all the knowledge and desire of an outstanding team made in part by traditional competitors that clearly understood the meaning of service and synergy using a quality system concept which is an industry first. The following lines describe the main events, acknowledge those who contributed to them and we hope, will also inspire others to undertake similar challenging projects. Introduction The Matterhorn Field is located in the Gulf of Mexico, Block Mississippi Canyon 243 (MC 243) in 2,811' of water. MC 243 is located 30 miles SE of the mouth of the Mississippi river and 100 miles SE of New Orleans (Louisiana) Fig. 1. The field will be developed utilizing a 9 slot dry tree floating structure, a mini TLP (Tension Leg Platform) 1–2-3-4-5 in place. The development plan called for a total of 8 wells, 7 dry tree wells off the TLP and 1 sub sea well. The design of gas, oil producers, and water injectors combined with different tubing sizes, different metallurgy and reservoir management lead to a new and innovative approach for completions. Completion work is ongoing (this paper was written while finishing the 3rd well) and is performed utilizing a work-over rig (1,000 HP) installed on the Matterhorn TLP structure. The risk associated with a sidetrack or performing a workover on these wells was one of the main key drivers for the chosen completion design. Significant challenges were faced and overcome. Numerous "firsts" for TOTAL and the industry were implemented. This paper is an overview of the completion program a focus on downhole equipment and installation. Many operations went well or better than planned with room for improvement on others. A good and unique example is that two competing companies were assigned pumping of Frac Pack (FP) treatments. The team spirit and the leadership of the operator contributed to this achievement. Every effort is made to implement the identified improvements on the subsequent wells in the completionprogram. These lessons will be incorporated in future projects.