Post-Stimulation Plug Removal in Unconventional Wells with Extended Reach Horizontal Lateral, Leveraging Dissolvable Plugs and Hourglass Coiled Tubing String Design

• DOI: 10.2118/224093-ms
• Publication Date: 2025-03-18T04:23:13Z
• Authors: Abdulrahman M. Al...; Karim Mechkak; Hassan A. Khan; Rafiq H. Zahaezuani; Mohammed A. Kneina

Abstract Post-fracturing plug removal is an ever-evolving challenge in unconventional fields, with an upward trend in average lateral lengths necessitating the deployment of additional fracturing plugs. Within the subject area, high wellhead pressure (WHP) coupled with the presence of Hydrogen Sulfide (H2S) both pose coiled tubing (CT) reach and compatibility limitations, demanding the need for innovative fit-for-purpose applications. Dissolvable plugs were selected during plug and perforation operations, with one variant identified to be the most consistent and suitable for the field. Hourglass CT string was engineered to strategically position the heaviest wall thickness at the heel section, with minimum thickness along the lateral. Extended-reach tool (ERT) was also added to the tool string to improve reachability, with the generated vibrations aiding in dispersing any plug debris remnants downhole. Complete dissolution of fracturing plugs enabled the shift from a typical milling bottom-hole assembly (BHA) with a motor and mill to a simplified cleanout BHA with a wash nozzle and ERT. Removing the motor eliminated all issues related to stalls and potential elastomer failure during lengthy operations, which previously contributed to more than 50% of BHA failures. It also resulted in lower circulating pressures, reducing fatigue on the pipe and prolonging its usable life. As a result, plug removal operations were consistently completed in a single run, even in wells with extended horizontal laterals. An efficient single-run operation saved up to 3 operating days per well, reduced overall operating cost, water and chemicals consumption, as well as overall carbon emissions from the operation. Moving from a milling to a cleanout BHA also reduces the cost of downhole tools by up to 70%. Additionally, complete dissolution of the dissolvable plugs led to a cleaner wellbore with less debris and lower risks of getting stuck. Combined with the effective use of ERT, and the strategic placement of metal-to-metal friction reducer, a 37% reduction in friction coefficient was achieved, enhancing CT's ability to overcome challenging bottom-hole conditions and travel deeper into the wellbore. The success of the proprietary dissolvable plugs to achieve 100% drift rate during post-stimulation CT intervention at a subject PAD-A was a game-changer for wells stimulated with multi-stage plug and perforate hydraulic fracturing. The simplified cleanout BHA and the engineered hourglass CT string were proven capable of cleaning and drifting long horizontal laterals efficiently through a single run, instead of complicated milling runs related to conventional mill and motor BHAs.