The objective of this study was to develop a reservoir-assessment tool based on novel and robust borehole seismic technology that can generate ultra-high resolution P and S wave images for detailed characterization and precise monitoring of CO2 storage sites. Paulsson investigators built and tested a prototype downhole seismic system capable of deploying a thousand 3C downhole receivers using fiber optic sensor technology deployed on drill pipe. The system was tested at a CO2 storage site. There are three primary components of a downhole seismic system: (1) the seismic sensor, (2) the deployment system, and (3) the surface electronics and recording system. The planned approach for the sensor involved designing a high-temperature fiber optic receiver. For a deployment system, a small diameter, high strength drill pipe using offshore drill pipe manufacturing technology was used. The drill pipe was used as the backbone for the high-temperature deployment system and power is supplied through the tubing to clamp the receiver pods to the borehole wall. The strain on the fiber was recorded, analyzed, and transformed into a seismic record using an interferometric technique with all electronics and instruments placed at the surface.
This project focused on characterization of storage sites and the tracking of CO2 in the subsurface by designing, building, and testing a next-generation downhole seismic system. Improved site characterization CO2 tracking enables an operator to more confidently demonstrate that the storage formation is being efficiently utilized and that the CO2 is permanently stored. Specifically, the project employed a fiber-optic seismic sensor technology deployed on drill pipe to provide enhanced, high-resolution, seismic imaging technology. Improved site characterization contributes to better storage techniques thus reducing CO2 emissions to the atmosphere.
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