Enhancing Well Seismic Acquisition in Deepwater with DAS and Hybrid Wireline Cable: Balancing Efficiency, Data Quality, and Environmental Stewardship

Distributed Acoustic Sensing (DAS) employs fiber optics to gather data across various applications, transforming the entire fiber length into a sensing element (Hartog, 2017). In oil wells, this data can monitor fluid levels behind casing, production, stimulation, well integrity, and seismic surveys. Different conveyance systems, each with their own advantages and disadvantages, can be used for data acquisition. This work focuses on hybrid wireline cable systems with embedded fiber optics for data acquisition in deepwater wells (Martinez et al 2021). Traditional zero-offset well seismic surveys in deepwater offshore wells are time-consuming, significantly impacting total costs due to drilling rig expenses and potentially leading to a large carbon footprint. The advantage of conventional multi-component sensors with coupling arms in the tool body is that they typically offer a high signal-to-noise ratio. However, using DAS with hybrid wireline systems can reduce the time required for a well seismic run from over 24 hours to less than one hour (Rossi, et al 2023), thereby minimizing both carbon footprint and sound exposure level (SEL) of the logging operation. Utilizing DAS in a hybrid wireline system provided a time-efficient solution for well seismic surveys. Data quality was maintained, and the deliverables—including time/depth/velocity tables, full waveform traces, VSP traces, and Q factor estimation—were comparable to traditional geophone acquisitions. The significant time savings also resulted in a reduced carbon footprint for the wireline operation. Cable coupling was improved through wireline slacking, and the depth correction applied successfully mitigated any depth mismatch, ensuring seismic-to-well tie and sonic velocity drift correction. The use of an inversion process to stabilize the first breaks resulted in a smooth velocity function.