BASIN WIDE PRESSURE CHANGES DUE TO CO2 STORAGE: CALIFORNIA PRODUCTION AS A REVERSE ANALOG

Storage of point source generated CO2 (such as from fossil‑fueled electricity plants) within geologic strata is proposed as an alternative to emitting this greenhouse gas to the atmosphere. Large quantities (billions of tonnes) will have to be stored for this technology to provide significant climate change mitigation. Storage of such quantities raises concern about basin‑wide pressure increases and the consequences for hydrocarbon and water resources as well as land surface configuration. The history of hydrocarbon production in California offers a reverse analog for studying basin‑scale pressure perturbations due to industrial‑scale CO2 storage. Cumulative oil production in the State, with most from the San Joaquin Basin, was 4.4 billion cubic meters (27.8 billion barrels) by the end of 2006 (California Division of Oil, Gas and Geothermal Resources, 2007). This is a volume equivalent to 3.1 billion tonnes of carbon dioxide (assuming a specific density of 0.7 tonnes/m3). This volume is approximately 40 times the average annual CO2 emissions from electricity generation within California from 2000 to 2006 (California Environmental Protection Agency Air Resources Board, 2009). "Virgin" oil and gas field pressures from almost a century of discovery in the San Joaquin Basin were analyzed for time and spatial trends in the first part of a multi‑year study. With a few possible exceptions, significant pressure declines were not observed in this data set. This suggests significant interfield compartmentalization of the San Joaquin reservoirs. Such compartmentalization would limit the impact of CO2 storage‑induced pressure increases beyond the target storage volume. This would come at the cost of less storage capacity, however "refilling" the pore spaces from which oil has been removed would provide California with decades of capacity, although pore collapse has also reduced this capacity in some areas.