Oil Fields of the Santa Maria Basin and Adjacent Offshore Areas,
California Santa Barbara County has two major oil-producing
areas; the Santa Maria Basin and the Santa Barbara Channel.
Although the Santa Barbara Channel is the offshore extension of
the Ventura Basin, the two basins merge offshore Point Arguello
and the oil fields in the western Santa Barbara Channel are more
similar to the Santa Maria Basin fields than to the fields in
the onshore Ventura Basin. The Monterey Shale of Miocene age is
the source of nearly all of California's oil, but in the Santa
Maria Basin and the Santa Barbara Channel it is also the
dominant reservoir. Oil is produced from fractured cherts and,
more importantly, dolomite beds within the Monterey Formation.
Most of the Monterey Formation was originally diatomite, but it
has been altered to chert or an intermediate phase rich in opal
and cristobalite. 2003 Oil Production The onshore Santa Maria
Basin produced 1.84 million barrels of oil in 2003. Orcutt was
the most productive o