Overcoming Frictional Limitation in Open Hole Acid Stimulation: Successful Deployment of Hydraulic Activated Friction Reduction Tool (HAFRT) in Highly Deviated Extended Reach Water Injector Wells in UAE
Mayank Varshney, Mohamed Abdulla Al Blooshi, Maad Subaihi, Mohammed Ibrahim Al Janahi, Mahra Alblooshi, Sultan Taheri, Abdulla Al Hashmi, Yugal Kishore Maheshwari, Amir Nadeem, Bilal Ahmad, Ali Adnan, Waheeb Javed, Muhammad Ahsan, E Butcher
Abstract
Abstract Highly deviated extended reach open-hole sections in water injector wells present significant challenges for coiled tubing (CT) operations, particularly during acid stimulation treatments, where tool reach and effective fluid placement are critical. Excessive drag and friction often limit CT reach, resulting in incomplete treatment coverage and suboptimal stimulation results. This paper presents a successful case study of Hydraulic Activated Friction Reduction Tool (HAFRT) to overcome these limitations in a challenging open hole acid stimulation application in two water injector wells in the UAE: Well X and Well Y. The subject wells had a history of multiple unsuccessful CT intervention attempts due to high frictional forces and insufficient CT reach resulting in less effective stimulation treatments. In the latest operation, multiple runs were conducted – a) with conventional bottom hole assembly (BHA), b) with conventional BHA and acid spotting, and c) with HAFRT. HAFRT was deployed to introduce axial oscillations along the CT string, reducing contact between CT and wellbore while improving tool conveyance in the challenging open hole section. HAFRT transforms hydraulic energy into gentle oscillations that convert static friction into dynamic friction, extending CT reach beyond lock up point. Improved accessibility using HAFRT was followed by pin-point acid stimulation to improve injection which was not possible earlier due to limited accessibility. These interventions resulted in significant reduction in friction, extending CT reach beyond previous lock up limits while enabling effective acid placement across the entire targeted open hole interval. HAFRT was activated from the beginning of the open hole section to delay lock up and overcome challenging hole condition without inducing buckling throughout the run, resulting in substantial CT weight improvement. Eventually, the acid stimulation operation was successfully completed with 100% coverage of open hole section in Well X as compared to previous operations. In Well Y, even though accessibility was improved compared to previous CT interventions, due to CT size limitations, 100% of the open hole could not be accessed. This is one of the lessons learned from this case study. Accessibility improvement in Well X using HAFRT compared to without HAFRT was 92% with improvement in injectivity index (II) of 80%. On the other hand, in Well Y, accessibility improvement with and without HAFRT was 117% with II improvement of 5 folds. This paper explores the use of HAFRT in extended reach wells to improve accessibility which could not be accessed with conventional CT BHAs, thereby providing access to the extended section of the open hole for any treatment. Lessons learned from these case studies are also discussed in this paper, which can form the basis of future well intervention in similar extended reach wells.