Monterey Formation and Its Equivalents

This dataset shows the estimated extent of Monterey formation and its equivalents in California. In California, most of the oil and gas originated in deep portions of the Monterey formation - the state's most prolific source rock - and yet most petroleum is not produced directly from Monterey source rocks. Rather, California's production consists of petroleum that has migrated away from source rock into conventional traps. Recent estimates of vast resources in the Monterey formation have focused attention on Monterey source rock, which underlies a much smaller area than the entirey of the Monterey formation, as an untapped oil resource. Outside of California, new technologies such as high-volume hydraulic fracturing in conjunction with long-reach horizontal wells has allowed for source-rock production of oil and gas. One major barrier to applying these technologies in the Monterey is that it is highly discontinuous (folded and faulted) and prohibits running horizontal wells for long distances. The recent California Council on Science and Technology report concluded that large-scale production from source rock (shale) in the Monterey formation is unlikely without some as-yet unforeseen technological advance.