San Miguelito Oil Field
Encyclopedia
The San Miguelito Oil Field is a large and currently productive oil field
in the hills northwest of the city of Ventura
in southern California
in the United States. The field is close to the coastline, with U.S. Highway 101 running past at the base of the hills, and is sandwiched between the larger Ventura Oil Field
to the east and the Rincon Oil Field
, which is partially offshore, to the north and northwest. Discovered in 1931, and with about 7 million barrels of oil remaining out of its original 125 million, it ranks 44th in the state by size, and at the beginning of 2009 had 61 producing oil wells, all operated by Vintage Production California LLC, a subsidiary of Occidental Petroleum
. p. 63, 165
and the offshore Dos Cuadras field
, and to the east the much larger Ventura Oil Field
. Total productive area of the field, projected to the surface, encompasses about 940 acres (3.8 km²), about one and a half square miles. On the coast between Ventura and Carpinteria
, the stretch known locally as "the Rincon", the hills rise steeply from the shore, with the coastal U.S. Highway 101 occupying much of the narrow strip between the beach and the sharply rising hills. A cluster of seaside homes is on the ocean side of Highway 101 at Solimar Beach (marked as "Dulah" on the USGS topographic map of the area). One of the field's pumpjacks is visible on the mountain side of the highway, at sea level, just north of the Solimar Beach exit; almost all the other oil wells are out of the line of sight from any public road, as are the other oilfield structures (tank farms, processing units, and others).
The predominant vegetation in the hills is chaparral
and coastal sage scrub. Terrain on the hills is steep, and the unpaved access roads make numerous switchbacks. Some of the hillsides are bare where landslides have stripped them, and the terrain in this area is unusually prone to landslides.
Climate in the area is Mediterranean
, with cool, rainy winters and mild, dry summers, cooled by morning coastal clouds. Elevations on the field range from sea level to over 1200 feet (365.8 m) on the highest ridgetops. Runoff from the oil field is west and southwest down ephemeral, seasonal drainages into the Pacific Ocean.
, bounded on the north by the Grubb Thrust Fault, where the fault has pushed another closed anticline above the end of the Ventura Anticline. Petroleum-bearing units are sands of Pliocene
and Miocene
age, and are given numerical designations increasing with depth: 1st Grubb, 2nd Grubb, down to 5th Grubb (as well as an additional "Grubb D" zone for units lower than 5th Grubb). These units are present on either side of the fault, but are offset by about 4,000 vertical feet. It is a deep reservoir, with the uppermost producing unit at an average depth of 6800 feet (2,072.6 m) below ground surface, and the lowest over 14000 feet (4,267.2 m) deep. The California Department of Conservation groups together the Grubb 1-3 zones, Grubb 4-5 zones, Grubb D (Deep) zones as three distinct producing horizons.DOGGR 2009, p. 101.
The oil is medium-grade with an API gravity
of 31 in the first four Grubb zones, 25 in the 5th.
was discovered in 1919, it was not until 1931 that prospectors thought of searching for oil near the western end of the Ventura Anticline, where the borehole had to reach a considerable depth before finding oil. The discovery well for the field was the Continental Oil Co. "Grubb No. 1", which reached 7623 feet (2,323.5 m) below ground surface, drilling from a ridgeline about a half mile from the ocean, about 800 feet (243.8 m) above sea level. It flowed over 600 barrels a day, and development of the field began.
In 1944 the 2nd Grubb Zone was discovered, and in 1950, the 3rd Grubb. Peak production from the field was in 1951 at 4.5 million barrels of oil. Further zones were discovered, with the 4th Grubb coming online in 1970, and the 5th Grubb in 1979. By 1983, the deepest well was already producing from 14752 feet (4,496.4 m).
In order to increase reservoir pressure, several waterflooding projects have been undertaken on the field, commencing in 1955. Most of the water injection has been done in the Grubb 1-3 zones; only one waterflood well was active as of 2009 in Grubb 4-5, with 31 in Grubb 1-3.
In 1993, Vintage Petroleum
acquired both the San Miguelito and adjacent Rincon
fields from Mobil, Conoco
, and Santa Fe Energy. To improve operational efficiency, Vintage combined the two adjacent oil fields into a single operating unit. Occidental Petroleum acquired Vintage in 2006, retaining their name and making them a wholly owned subsidiary, and still operates the Rincon and San Miguelito fields under the Vintage banner.
Oil field
An oil field is a region with an abundance of oil wells extracting petroleum from below ground. Because the oil reservoirs typically extend over a large area, possibly several hundred kilometres across, full exploitation entails multiple wells scattered across the area...
in the hills northwest of the city of Ventura
Ventura, California
Ventura is the county seat of Ventura County, California, United States, incorporated in 1866. The population was 106,433 at the 2010 census, up from 100,916 at the 2000 census. Ventura is accessible via U.S...
in southern California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
in the United States. The field is close to the coastline, with U.S. Highway 101 running past at the base of the hills, and is sandwiched between the larger Ventura Oil Field
Ventura Oil Field
The Ventura Oil Field is a large and currently productive oil field in the hills immediately north of the city of Ventura in southern California in the United States. It is bisected by California State Route 33, the freeway connecting Ventura to Ojai, and is about eight miles long by two across,...
to the east and the Rincon Oil Field
Rincon Oil Field
The Rincon Oil Field is a large oil field on the coast of southern California, about ten miles northwest of the city of Ventura, and about 20 miles east-southeast of the city of Santa Barbara. It is the westernmost onshore field in a series of three fields which follow the Ventura Anticline, an...
, which is partially offshore, to the north and northwest. Discovered in 1931, and with about 7 million barrels of oil remaining out of its original 125 million, it ranks 44th in the state by size, and at the beginning of 2009 had 61 producing oil wells, all operated by Vintage Production California LLC, a subsidiary of Occidental Petroleum
Occidental Petroleum
Occidental Petroleum Corporation is a California-based oil and gas exploration and production company with operations in the United States, the Middle East, North Africa, and South America...
. p. 63, 165
Setting
The oil field is one of several following the east-west trend of the Transverse Ranges: to the west is the Rincon Oil FieldRincon Oil Field
The Rincon Oil Field is a large oil field on the coast of southern California, about ten miles northwest of the city of Ventura, and about 20 miles east-southeast of the city of Santa Barbara. It is the westernmost onshore field in a series of three fields which follow the Ventura Anticline, an...
and the offshore Dos Cuadras field
Dos Cuadras Offshore Oil Field
The Dos Cuadras Offshore Oil Field is a large oil and gas field underneath the Santa Barbara Channel about eight miles southeast of Santa Barbara, California. Discovered in 1968, and with a cumulative production of over 260 million barrels of oil, it is the 24th-largest oil field within California...
, and to the east the much larger Ventura Oil Field
Ventura Oil Field
The Ventura Oil Field is a large and currently productive oil field in the hills immediately north of the city of Ventura in southern California in the United States. It is bisected by California State Route 33, the freeway connecting Ventura to Ojai, and is about eight miles long by two across,...
. Total productive area of the field, projected to the surface, encompasses about 940 acres (3.8 km²), about one and a half square miles. On the coast between Ventura and Carpinteria
Carpinteria, California
Carpinteria is a small oceanside city located in southeastern Santa Barbara County, California, east of Santa Barbara and northwest of Ventura. The population was 13,040 at the 2010 census, down from 14,194 at the 2000 census....
, the stretch known locally as "the Rincon", the hills rise steeply from the shore, with the coastal U.S. Highway 101 occupying much of the narrow strip between the beach and the sharply rising hills. A cluster of seaside homes is on the ocean side of Highway 101 at Solimar Beach (marked as "Dulah" on the USGS topographic map of the area). One of the field's pumpjacks is visible on the mountain side of the highway, at sea level, just north of the Solimar Beach exit; almost all the other oil wells are out of the line of sight from any public road, as are the other oilfield structures (tank farms, processing units, and others).
The predominant vegetation in the hills is chaparral
Chaparral
Chaparral is a shrubland or heathland plant community found primarily in the U.S. state of California and in the northern portion of the Baja California peninsula, Mexico...
and coastal sage scrub. Terrain on the hills is steep, and the unpaved access roads make numerous switchbacks. Some of the hillsides are bare where landslides have stripped them, and the terrain in this area is unusually prone to landslides.
Climate in the area is Mediterranean
Mediterranean climate
A Mediterranean climate is the climate typical of most of the lands in the Mediterranean Basin, and is a particular variety of subtropical climate...
, with cool, rainy winters and mild, dry summers, cooled by morning coastal clouds. Elevations on the field range from sea level to over 1200 feet (365.8 m) on the highest ridgetops. Runoff from the oil field is west and southwest down ephemeral, seasonal drainages into the Pacific Ocean.
Geology
The San Miguelito field is an accumulation of oil along the westernmost portion of the Ventura AnticlineAnticline
In structural geology, an anticline is a fold that is convex up and has its oldest beds at its core. The term is not to be confused with antiform, which is a purely descriptive term for any fold that is convex up. Therefore if age relationships In structural geology, an anticline is a fold that is...
, bounded on the north by the Grubb Thrust Fault, where the fault has pushed another closed anticline above the end of the Ventura Anticline. Petroleum-bearing units are sands of Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
and Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
age, and are given numerical designations increasing with depth: 1st Grubb, 2nd Grubb, down to 5th Grubb (as well as an additional "Grubb D" zone for units lower than 5th Grubb). These units are present on either side of the fault, but are offset by about 4,000 vertical feet. It is a deep reservoir, with the uppermost producing unit at an average depth of 6800 feet (2,072.6 m) below ground surface, and the lowest over 14000 feet (4,267.2 m) deep. The California Department of Conservation groups together the Grubb 1-3 zones, Grubb 4-5 zones, Grubb D (Deep) zones as three distinct producing horizons.DOGGR 2009, p. 101.
The oil is medium-grade with an API gravity
API gravity
The American Petroleum Institute gravity, or API gravity, is a measure of how heavy or light a petroleum liquid is compared to water. If its API gravity is greater than 10, it is lighter and floats on water; if less than 10, it is heavier and sinks...
of 31 in the first four Grubb zones, 25 in the 5th.
History, production and operations
While the adjacent large Ventura Avenue oil fieldVentura Oil Field
The Ventura Oil Field is a large and currently productive oil field in the hills immediately north of the city of Ventura in southern California in the United States. It is bisected by California State Route 33, the freeway connecting Ventura to Ojai, and is about eight miles long by two across,...
was discovered in 1919, it was not until 1931 that prospectors thought of searching for oil near the western end of the Ventura Anticline, where the borehole had to reach a considerable depth before finding oil. The discovery well for the field was the Continental Oil Co. "Grubb No. 1", which reached 7623 feet (2,323.5 m) below ground surface, drilling from a ridgeline about a half mile from the ocean, about 800 feet (243.8 m) above sea level. It flowed over 600 barrels a day, and development of the field began.
In 1944 the 2nd Grubb Zone was discovered, and in 1950, the 3rd Grubb. Peak production from the field was in 1951 at 4.5 million barrels of oil. Further zones were discovered, with the 4th Grubb coming online in 1970, and the 5th Grubb in 1979. By 1983, the deepest well was already producing from 14752 feet (4,496.4 m).
In order to increase reservoir pressure, several waterflooding projects have been undertaken on the field, commencing in 1955. Most of the water injection has been done in the Grubb 1-3 zones; only one waterflood well was active as of 2009 in Grubb 4-5, with 31 in Grubb 1-3.
In 1993, Vintage Petroleum
Occidental Petroleum
Occidental Petroleum Corporation is a California-based oil and gas exploration and production company with operations in the United States, the Middle East, North Africa, and South America...
acquired both the San Miguelito and adjacent Rincon
Rincon Oil Field
The Rincon Oil Field is a large oil field on the coast of southern California, about ten miles northwest of the city of Ventura, and about 20 miles east-southeast of the city of Santa Barbara. It is the westernmost onshore field in a series of three fields which follow the Ventura Anticline, an...
fields from Mobil, Conoco
Conoco Inc.
Conoco Inc. was an American oil company founded in 1875 as the Continental Oil and Transportation Company. It is now a brand of gasoline and service station in the United States which belongs to the ConocoPhillips Company...
, and Santa Fe Energy. To improve operational efficiency, Vintage combined the two adjacent oil fields into a single operating unit. Occidental Petroleum acquired Vintage in 2006, retaining their name and making them a wholly owned subsidiary, and still operates the Rincon and San Miguelito fields under the Vintage banner.