In this paper we present a study on the feasibility of utilizing the mature Monterey oilfields of offshore California for sequestering carbon dioxide while potentially enhancing crude oil recovery from the tight matrix.
An important characteristic of these fields is that, because of natural fractures, well productivities have been high and as a result, a significant amount of reservoir voidage has been generated in each field by production of more than 780 million barrels of oil and more than a TCF of natural gas during the last three decades. These productions translate into a computed voidage of about a billion barrels allowing storage of more than 90 Million tons of CO2. This is roughly equivalent to storing 50 years of CO2 from a 400 MW Power plant. Another important observation discussed in the paper is the cap rock sealing nature of these fields allowing preservation of the oil and initial pressure as evidenced from the analyses of the initial GOR data. Furthermore many of these fields will be at the verge of abandonment during the next two decades unless steps are taken to enhance recovery by extracting oil from the tight matrix. CO2 extraction from tight rocks is a technically feasible process and our analysis indicate that CO2 storage can indeed prolong the life of many of these fields and enhance matrix oil recovery. An important infrastructure requirement for CO2 transportation into these offshore fields is the cost of building offshore pipelines. Availability of existing multiple pipelines connecting the fields to their corresponding onshore treatment facilities solves this transportation of CO2 to the offshore fields. Finally, these fields are under active water influx, where aquifers may provide additional CO2 storage possibilities.