Pushing the Boundaries of Extended Reach Perforation in Horizontal Gas Wells: Advancements with Downhole Tractors and Selective Firing Systems

Abstract This paper presents the next stage in the evolution of extended reach coiled tubing (CT) perforation for the world's largest non-associated gas expansion project. Building on the 2023 introduction of CT tractors for long lateral perforation, this study documents efficiency improvements that enabled up to 2,300 ft. of perforating guns to be conveyed in a single run. A key advancement is the deployment of a selective firing system that allowed multi-zone perforation in live wells, reducing operational complexity and improving campaign efficiency. As wells increased in depth and lateral length, CT tractors became essential for accessing the lower zones. To support these extended-reach perforations, the downhole assembly was optimized to balance tractor operation with hydraulic firing head functionality. The integration of a selective firing system with two independently activated intelligent firing heads allowed for the perforation of multiple intervals in a single run, eliminating the need for multiple trips and reducing operational time. Controlled pressure pulses through tubing and annulus were used to trigger the firing sequence without interfering with tractor operation. Job design focused on defining safe pressure windows, refining tool string configurations, and ensuring smooth functional decoupling of tractor and firing systems in actual well runs, supported by continuous monitoring with real-time downhole data. In 2024 and 2025, over 200 perforation runs were completed in the field, with nearly half requiring extended-reach tractor assistance and/or selective firing. Compared to traditional tubing-conveyed perforation (TCP), the CT approach consistently delivered superior operational efficiency. Selective firing eliminated additional trips per zone, delivering approximately 40 hours of efficiency gains for each interval and reducing string length by eliminating spacer gun sections. The combined use of tractors and selective firing enabled safer, faster, and more economical multi-zone completions, directly supporting the operator's vision for streamlined field development.