Conveying Extended Reach Solutions: First Coiled Tubing Perforation in Horizontal Live Gas Wells with Downhole Tractors

Abstract

A comprehensive study was conducted on the strategic utilization of coiled tubing (CT) to convey over 1,200 ft of perforating guns in single runs in extended reach wells, effectively overcoming the lockup effect in 7-in. monobore completion using downhole tractor and real-time monitoring tools. This solution serves as the key enabler for the project, reducing risks and maximizing operational efficiency. CT reach simulations exposed the limitations in conveying long 2 7/8-in. perforating guns using 2 3/8-in. outside diameter (OD) CT strings to the lowermost intervals. The assessment highlighted the need for additional forces, achievable through hydraulic hammers or downhole tractors, or the options to convey the perforating guns with CT in multiple runs to perforate the lowermost intervals or to rely on conventional tubing-conveyed perforations (TCP) for the most challenging combination of interval length and well trajectory. After a comprehensive risk analysis, downhole tractors emerged as the preferred choice, being less intrusive and more reliable. The main challenge was to design the bottomhole assembly to allow appropriate circulating parameters for the tractor activation without disrupting the hydraulic firing head activation. Fiber-optics-enabled CT strings facilitated real-time downhole data collection to meet all parameters. Collaborative efforts, meticulous planning, yard tests, and strategic arrangements demonstrated the operational feasibility, inspiring confidence in this technique. The successful implementation of the CT downhole tractor proved transformative for the project by achieving the ability to perforate deeper and longer intervals without relying on conventional TCP. This resulted in significant cost savings by reducing rig time by at least 3 days per run and minimizing operational complexities. It also eliminated the need for an electromechanical plug setting between the TCP perforation and the completion stages and the removal of the plug prior to the CT stimulation of the perforated intervals. Compared to TCP, the CT approach exhibited superior efficacy. The strategic implementation of downhole tractors serves as a prime example of innovation, enhancing operational efficiency while staying aligned with the project's vision.