New Life for Old Offshore Platforms – Where is Geothermal an Option?

Abstract

Abstract Many offshore wells and platforms are nearing abandonment, in the Gulf of Mexico, the North Sea, Offshore West Africa, and other areas. The current decommissioning process, however, is expensive. Instead of decommissioning, do these assets create an opportunity to decrease cost of decarbonization efforts using this existing infrastructure? Some platform repurposing options include geothermal energy generation (heat or electricity) using modular power generation units or pipelines back to the beach, carbon dioxide storage, hydrogen generation, and potentially others. Each option has both a technical probability of success and a financial outcome. In this study, we begin to answer the question "Where is geothermal energy an option for repurposing offshore wells and platforms?" Here, we examine the Corpus Christi Bay and the Galveston Bay for geothermal power potential as shallow water offshore platforms that will have the highest likelihood to sell power if a geothermal resource exists. Geothermal power potential is calculated and several end use scenarios for the geothermal energy, including cost of energy and project financials, are examined. Using these two regions as test cases, estimations on the potential shallow water offshore geothermal market is discussed. To perform this assessment, we examine published geothermal gradient maps and produce an industry standard geothermal resource assessment based on existing well production from the offshore platform. Using the thermal energy production, we estimate electrical power potential and total potential revenue, and then calculate high level financial metrics. Technical gaps and data gaps are assessed. CAPEX, OPEX, discounted cash flows, internal rates of return, and project lifetimes are part of the financial analysis. Indicative results are presented from the sample case studies in Corpus Christi Bay and Galveston Bay. There is no offshore geothermal energy production to date, although this is a topic of interest with significant publicity from Gulf of Mexico and North Sea operators. While there is interest, there are no public studies showing potential economics. This paper, to our knowledge, summarizes and publicly presents technical and financial parameters for shallow water offshore geothermal energy production with the specific goal to extend the life of offshore platforms and re-use existing wellbores.