Field Trial Achieves Post-Frac-Plug Drillout Using 27/8-in. Coiled Tubing

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 231322, “World’s First Post-Frac Plug Drillout Using 2⅞-in. Coiled Tubing: Results, Lessons, and a Path Forward, ” by Jason Burke, SPE, and Kyle J. Baros, ConocoPhillips, and Christopher Schneider, SPE, Cudd Pressure Control. The paper has not been peer-reviewed. _ As unconventional basins continue to evolve, operators are drilling longer laterals and increasing both the number of stages during stimulation and the volume of material pumped. Coiled tubing (CT) must also evolve to reach extended depths and manage the growing volume of solids placed in the wellbore. The largest land unit ever built for North America, combined with one of the largest 2⅞-in. CT strings ever milled, has resulted in a transportable CT unit capable of holding 30, 000 ft of high-strength 2⅞-in. CT. In June 2025, the first post-fracturing-plug drillouts were completed on a 13-well trial. Background The ultimate length of the wellbores being drilled and completed in unconventional basins has increased from 2020 to 2024 by 18%. CT has often been used for its operational speed and ability to control pressure. The tradeoff has always been ultimate horizontal-reach capability and hole-cleaning efficiency. Jointed pipe generally is larger in size than the traditional CT pipe sizes that are utilized currently in the US unconventional shale plays. One way for CT to close the gap with jointed pipe in these metrics is to increase the size of the CT. That has, until recently, been difficult because the next size up in readily manufacturable CT is 2⅞-in. outer diameter, which, when milled to useable lengths, can weigh between 160, 000 and 190, 000 pounds. However, the newest-generation CT units have been engineered to transport these massive CT strings and remain compliant with regulations in Texas, New Mexico, and Oklahoma. These units travel at 16 ft in height and 14½ ft in width. With such reel capabilities, the pipe options range from 30, 250 ft of 2⅞ to 34, 972 ft of 2⅝-in. CT. This overall unit gross weight is 430, 000 lbs; innovation in the design has allowed this one-piece unit to drive to the location with pipe stabbed, eliminating the risk of handling the larger pipe on location. The demand for longer and larger pipe size requires the unit to be fit with an injector capable of 180, 000 lbs of pulling and snubbing capacity (Fig. 1). This advancement allows for the testing of 2⅞-in. CT in post-stimulation cleanouts to determine added advantages. Initial Engineering Work To obtain the additional efficiencies desired from the larger pipe size, two criteria were measured and improved upon. The first is ultimate horizontal reach and, consequently, run in hole (RIH) speeds near the toe of the wellbore. In wells deeper than 19, 000 ft measured depth (MD), the proportionality of time spent past 19, 000 ft is on average 15% longer, in extreme cases up to 73%. Even a moderate increase in RIH speeds can yield a major gain in efficiency and reduction in overall cost. Using the critical buckling force equation, holding all variables constant between the pipe sizes except those that are unique to the pipe and using a base of 5½-in. 23# casing yields a ratio that can be used to estimate the benefit of the larger pipe size.