RECONNAISSANCE SURVEY OF PETROLEUM RESERVOIRS FOR ENERGY-RELATED STORAGE: THE CASE OF WESTERN EUROPE

Energy producers and utilities use oil and gas reservoirs for storage to meet peak seasonal demand or to supplement intermittent energy production. Governments use depleted oil and gas reservoirs for strategic storage in the event of national emergencies. Petroleum structures may also be suitable for the long-term storage of carbon dioxide (CO₂), a greenhouse gas. This study reports on a reconnaissance analysis of the potential magnitude of storage capacity in 9424 known oil and gas reservoirs from 24 countries within highly industrialized western Europe. To standardize the storage capacity of the oil and gas reservoirs, their capacity is expressed in terms of the tonnes (mass) of CO₂. Estimates of recoverable barrels of oil and cubic feet of gas at the surface are converted to their relative subsurface volumes and then converted to the equivalent mass (in tonnes) of CO₂ at reservoir conditions. The results indicate 25.9 billion tonnes of CO₂ could be stored, oil reservoirs accounting for 31 percent of that total with natural gas reservoirs comprising the remaining 69 percent. About four-fifths of the reservoir storage capacity is offshore, with about three-fourths of that offshore capacity at water depths of 200 meters or less. Countries in the northern part of western Europe account for about 80 percent of total storage capacity, the countries of the southern and eastern parts divide the remainder almost evenly. Moreover, four-fifths of the estimated total capacity is in reservoirs discovered before 1991, suggesting most of the capacity is in reservoirs near the end of their productive life. Maps have been prepared that show accessibility of potential storage sites to potential points of storage demand represented by high CO₂-emission industries and potential users of natural gas storage. Although the largest reservoirs by volume are offshore, the facilities maps suggest opportunities to meet storage demand by users located in close physical proximity. Most countries do not have the national capacity to store 15 years of CO₂ emissions at 2017 levels. With a few exceptions the storage is offshore for the countries that do have the capacity for at least 15 years of storage.