From Pre-Screening to Monitoring of Plugged and Abandoned Marine Exploration Wells - Enabling Reuse of Reservoirs for Co2 Storage through Geophysical Monitoring
Chapter, Peer reviewed, Conference object
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Decommissioning of platforms and permanent plugging and abandonment (P&A) of oil and gas wells is a major future financial challenge for oil producing countries. This is especially true for offshore wells in deep water, where heavyduty drilling rigs with high day rates need to be applied for well closure. Even if well monitoring is typically not done after abandonment, this is an emerging topic – which is crucial to enable reuse of reservoirs for e.g., CO2 or hydrogen storage. With this respect, it is important to find new cost-efficient ways of monitoring plugged offshore wells, where in-situ gas measurements, satellite- and/or air- based monitoring techniques are difficult to implement or not possible. In the present paper, we propose the first steps for a data-based, geophysical monitoring strategy for permanently plugged wells. The foundation is a detailed analysis of documents provided by operators towards the Norwegian authorities. Based on these open-access data, we construct numerical wells and simulate/evaluate the geophysical response of the different well barrier materials. The data can be used for future field reuse/monitoring campaigns to detect missing or damaged cement barriers in abandoned oil and gas wells. This will broaden the available sites for future large-scale CO2 storage.