Mesa Oil Field

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RegionSanta Barbara south coast
Offshore/onshoreonshore
Mesa Oil Field
The Mesa Oil Field in Santa Barbara County, California. Other oil fields are shown in light gray.
CountryUnited States
RegionSanta Barbara south coast
LocationSanta Barbara County, California
Offshore/onshoreonshore
OperatorsTown-lot field; numerous small operators
Field history
Discovery1929
Start of development1929
Start of production1929
Peak year1935
Abandonment1976
Production
Estimated oil in place3.7 million barrels (~5.0×10^5 t)
Producing formationsVaqueros Sandstone (Lower Miocene)

The Mesa Oil Field is an abandoned oil field entirely within the city limits of Santa Barbara, California, in the United States. Discovered in 1929, it was quickly developed and quickly declined, as it proved to be but a relatively small accumulation of oil in a single geological formation. While the field was active in the 1930s, residential development in most of the Mesa neighborhood of Santa Barbara came to a halt. The field included two major productive areas with a total surface extent of only 210 acres (0.85 km2), and produced 3,700,000 barrels (590,000 m3) of oil during its brief lifetime.[1][2]

The Mesa neighborhood of Santa Barbara, showing the approximate center of the field's main area of production. In the 1930s there were no houses here, but dozens of oil derricks.

The field occupied a small area on a mesa to the west of the Santa Barbara Harbor, within the limits of the City of Santa Barbara, now the location of the neighborhood known as "The Mesa". The mesa from which the neighborhood takes its name is about two miles (3.2 km) long from west to east and about 3,000 feet (910 m) across from north to south. The northern boundary is Lavigia Hill, which rises north of Cliff Drive; some of the oil wells were drilled on the southern slopes. The southern boundary of the mesa is the abrupt drop-off at the cliff overlooking the ocean. The cliffs rise 120 feet (37 m) above the beach at the western end of the mesa, gradually diminishing in height to only 40 feet (12 m) at the eastern end, near Santa Barbara City College.[3] Prior to the oil field being developed, the flat top of the mesa was farmland, with one imposing former residence, the abandoned and earthquake-damaged "Dibblee Castle" built at the eastern end, overlooking Santa Barbara harbor.[4][5]

Climate in the area is Mediterranean, with mild, sometimes rainy winters and dry summers, with the temperature moderated by ocean breezes and a morning marine layer. Freezes are extremely rare. Mean annual temperature is approximately 60 °F (16 °C), and the growing season is year-round.[6]

Numerous other oil fields exist within the region. The Summerland Oil Field, location of the world's first offshore oil wells into the ocean, is about seven miles (11 km) to the east of the field; the large Ellwood Oil Field is about ten miles (16 km) to the west. Approximately seven miles to the southeast in the Santa Barbara Channel is the Dos Cuadras Oil Field, source of the 1969 Santa Barbara oil spill.[7]

Geology

The structure of the Mesa field is relatively simple. Oil was trapped in two anticlinal structures in a band of the porous Miocene-age Vaqueros Sandstone formation, at a depth of between 2,000 and 2,500 feet (760 m). The two oil accumulations were about two-thirds of a mile apart horizontally, and around the same depth. Trapping the oil was the overlying impermeable Rincon Shale, also of Miocene age, and above that unit is the Monterey Formation. A thin layer of Pleistocene sediments known as the Santa Barbara Formation lies between the Monterey and ground surface. Underneath the Vaqueros formation and separated by an unconformity is the Oligocene-age Sespe Formation; no oil has been found in or beneath this unit, even though one well had been drilled into it to a total depth of over 10,000 feet (3,000 m).[8] The Sespe and Vaqueros Formations together form the second-most-prolific oil-producing unit in Southern California.[9]

Oil from the Mesa field was medium to heavy. Early reports give a value of 17 to 18 degrees Baumé;[10] the California Department of Natural Resources reports the same oil as having API gravity of 20 to 24. Sulfur content was 0.45 percent.[11] As its quality was relatively low, it was mainly used for fuel oil, road oil and asphalt.[10]

Wells rarely produced for long, and a common experience of operators was fast production when the well first hit the oil-bearing sandstone, followed by swift decline, with late production mostly water.[12] The overall structure of the field was imperfectly understood, with some wells producing poorly near to better producers; some geologists attributed such discrepancies to faulting not visible in well cores, and others to impermeable sand lenses in the Vaqueros. Total recoverable oil was limited since oil appeared only in one relatively thin rock formation, and even the more productive wells became uneconomic to operate within a few years of their drilling.[13]

History, production, and operations

Notes

References

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