Split-String Coiled Tubing Field-Validated for Extended-Reach Operations

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 231394, “Go Further: Field Validation of Split-String Coiled Tubing for Extended-Reach Operations, ” by Patrick Jeschke, SPE, and Brad Watson, SPE, STEP Energy Services. The paper has not been peer-reviewed. _ Horizontal well laterals exceeding 15, 000 ft present a fundamental mechanical limitation for coiled tubing (CT) interventions: the inability to reliably reach total depth (TD). This paper presents a novel approach to overcoming extended-reach limitations in CT interventions by using a split-string system, demonstrating measurable improvements in lateral reach and operational speed in laterals exceeding 3 miles. Beyond the technical performance gains, the study explores the operational thresholds at which this technology delivers the greatest value. Motivation for Technology A Permian Basin operator faced recurring operational challenges during horizontal drillout and cleanout interventions in ultralong laterals. Across several wells, conventional CT struggled to sustain rate of penetration (ROP) and frequently failed to reach TD without transitioning to jointed pipe. To preserve the efficiency and logistical advantages of CT, the operator sought a method to improve downhole friction reduction and increase speed in CT operations. During a cross-disciplinary design review, the team revisited a concept long used in drilling operations: deploying vibratory friction-reduction tools in the middle of the drillstring rather than exclusively in the bottomhole assembly (BHA). Though conceptually attractive, this approach had never been applied to CT because of the continuous string and the lack of a practical method for inserting a midstring assembly into a live CT string already deployed in hole. The most critical challenge in realizing this concept was establishing a safe, repeatable method to join two CT segments around a midstring assembly while maintaining well control. The system would need to be deployed under live-well conditions, withstand the vibration produced during drillouts, and remain compatible with reel transport and spooling constraints between wells. Development of the Split-String Deployment Concept To meet these requirements the team designed, over multiple iterations, a split-string CT deployment method that enables installation of a tool package at an intermediate location along the tubing string. Specialized procedures were developed to ensure safe handling, repeatable rig-up, and reliable tool function. The minimum midstring assembly configuration included CT connectors on either end of the midstring assembly, a ball-drop disconnect, and a vibratory extended-reach tool (ERT). Additional tools could be incorporated depending on job requirements. This configuration established the basis for the field trials and multibasin deployment described in the complete paper. As of November 2025, the technology had been implemented in more than 100 wells across the Permian Basin, Bakken Shale, and Montney, demonstrating a consistent ability to increase ROP and reach TD with a 99% success rate. Field Trial 1: Delaware Basin The first field trial for technology occurred in the Delaware Basin, where a two-well pad was selected. The wells were completed with 6-in. 24. 5 lb/ft crossed over at the kickoff point to 5. 5-in. 20lb/ft casing, with lateral lengths of approximately 14, 500 ft. Each well was completed with 49 bridge plugs.