Novel Application of Winchless Fiber Optic DTS/DAS Technology for Sustained Casing Pressure Diagnosis in Offshore Malaysia

Summary The paper describes the first application of winchless fiber optic technology in offshore Malaysia to diagnose Sustained Casing Pressure (SCP) in Well “A.” This innovative method involved gravity-deploying bare fiber optic through tubing to gather Distributed Acoustic Sensing (DAS) data without conventional wireline operations. The deployment consisted of three phases: establishing baseline acoustic signatures, inducing flow paths through programmed bleed-offs, and analyzing data to determine source locations. Uniquely, the fiber was left in the well post-survey to degrade naturally, eliminating retrieval risks. Compared to conventional Spectral Noise logs, the DAS technology provided significantly denser and more continuous data, revealing subtle flow patterns that traditional methods might miss. The survey successfully identified that the SCP source in the C annulus originated from below 1443ft, while also detecting downward flow behind production casing at 3,030–3,630ft. The technology demonstrated operational advantages including reduced footprint, fewer personnel requirements, and shorter survey duration. This approach enables operators to make more informed decisions regarding wells with sustained casing pressure, ultimately improving safety and efficiency in offshore environments.