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.
