Hydraulic Oscillation Based Friction Reduction for Enhanced CT Reach in Extended Horizontal Wells; A Case Study from UAE

Abstract Extended reach open-hole sections in water injector wells present significant challenges for coiled tubing (CT) operations, especially during acid stimulation treatments where tool reach and precise fluid placement are critical. Excessive friction and drag often limit CT accessibility, resulting in incomplete stimulation and reduced injectivity. This case study highlights the successful deployment of a Hydraulic Activated Friction Reduction Tool (HOFRT) in two UAE water injector wells—Well B and Well C—to overcome these limitations and improve treatment effectiveness. Both wells had a history of unsuccessful CT interventions due to high frictional forces and limited reach. The recent operation involved three approaches: Conventional bottom hole assembly (BHA)Conventional BHA with acid spottingBHA with HOFRT deployment HOFRT was introduced to generate axial oscillations along the CT string, reducing contact with the wellbore and converting static friction into dynamic friction. This mechanism extended CT reach beyond previous lock-up points. Once improved accessibility was achieved, targeted acid stimulation was performed to treat the full open-hole interval. The use of HOFRT significantly reduced friction and extended CT reach beyond prior limits. In Well X, the intervention achieved 100% coverage of the open-hole section, with a 92% improvement in accessibility and an 80% increase in injectivity index (II). In Well Y, although CT reach improved by 117% compared to previous attempts, full coverage was not possible due to CT size constraints. Nevertheless, the injectivity index improved fivefold, demonstrating the tool's effectiveness even under limited access conditions. The operation confirmed that HOFRT could delay lock-up and prevent buckling, enabling smoother and deeper tool conveyance. This study demonstrates the practical value of HOFRT in extended reach wells where conventional CT BHAs fail to provide adequate access. By enabling deeper reach and more effective acid placement, HOFRT opens new possibilities for stimulation in complex well geometries. The lessons learned—particularly regarding CT sizing and tool activation timing—offer valuable guidance for future interventions in similarly challenging environments. This case study sets a precedent for adopting friction reduction technologies to enhance well performance and intervention success in extended reach applications.