Case Study: Innovative World's Slimmest Coiled Tubing Tractor for Stimulation of Extended Reach Wells

摘要

In extended Reach wells, existing coiled tubing (CT) technologies were unable to pass narrow downhole restrictions and reach target depth (TD) for stimulation operations. Overcoming current limitations in extended reach downhole tools resulted in the development and field use of a slim, compact, and record-setting high pull- force tractor that enables rig-less stimulation, thereby maximizing production and cost effectiveness. A development project evaluated multiple tractor design concepts, yielding a new generation of an ultra-slim (2- 1/8 inch OD) and high pulling force tractor. Exhaustive shop, yard, and flow loop testing verified the tractor’s ability to reliably pull in both cased and open hole, employ multiple layers of failsafe technologies, and facilitate rigging up with simpler and less expensive operations. A series of wells with increasing depth and difficulty were used to demonstrate the technology for field use. The design process verified that the new generation tractor efficiently moves in an accordion-like motion, grips the roof of the hole with an eccentric gripper assembly, and is powered by differential pressure created by pumping fluid down the CT centerline. Shop and Flow Loop testing verified that the eccentric gripper automatically orients itself to engage the high side of the hole, thereby providing an excellent and debris-free surface for traction. Flow Loop testing verified that tractor’s ability to circumnavigate high dog leg severity well bores. In one field demonstration, the tractor successfully passed a 2.44 inch restriction, conveyed coiled tubing 2400 feet past lockup reaching well TD of almost 21,400 ft, and averaged 15 feet per minute while running in hole. The benefits of this technology come in the successful operation of a tractor that produces up to 3500 lbs. pulling force, collapses to 2-1/8 inch outside diameter, and operates in 6-1/8 to 7-1/2” inch diameter open hole. The paper summarizes the research and development of this innovative world's slimmest coiled tubing tractor for stimulation of extended reach wells. It discusses a recent field trial operation including the yard and function surface tests to prepare for this field trial. The paper also explains in details how this technology was successfully deployed, in addition to the broad implications resulting from production engineers having this technology in their tool box, which will permit them to ensure cost efficient operations, maximize production, and will enable rig-less intervention of restricted extended reach wells all over the world.