The Oxnard Oil Field is a large oil field and is currently productive in and adjacent to the city of Oxnard, in Ventura County, California in the United States. Its conventional oil reserves are running low, with only about one percent of the original oil recoverable with the current technology remaining: 434,000 barrels (69,000 m 3 ) of the original 43.5 million. However, the reservoir includes a very large deposit of tar sands, ultra-heavy oils classified as unusual petroleum reserves, and potentially contains 400 million barrels (64,000,000 m 3 ) oil equivalent, if it becomes economically feasible to be extracted. Existing operators in the field include Tri-Valley Oil & amp; Gas Co., Anterra Energy Services, Inc., Chase Productions Co., and Occidental Petroleum through its subsidiary, Vintage Production. As of early 2009, there are 34 active wells in the field.
Video Oxnard Oil Field
Geographic settings
Oxnard Oil Field is one of several under the Oxnard Plains, an area largely protected by farmland with the communities of Ventura, Oxnard, and Camarillo that are separated by greenbelt. Around the oil field, agriculture remains dominant in land use, and oil wells, processing facilities, and related infrastructure are interspersed with fields grown with crops such as strawberries, broccoli and onions. Parts of the field, especially in the west, have been given to light industrial and commercial development when the Oxnard metropolitan area expands to the east. Highway 101 US limits the field to the north; California State Route 34 (Oxnard's East 5th Street) cuts it from east to west, and Rice Avenue cuts it from north to south. Most of the oil wells are currently active in the eastern part of the field, west of the intersection of 5th Street and Pleasant Valley Road. Several active wells remain west of Padi Avenue, and a group of well-directed drilling wells are grouped together on a drilling island near the northeast corner of the intersection of Rose Avenue and Wooley Road. The total productive area of ​​the projected field is 1,350 hectares (546 ha).
The climate in this region is the Mediterranean, with cool winters and rain and warm and no rainy summers, where the heat is moderated by the frequent clouds and low coastal fog of the morning. Annual rainfall is about 15 inches (380 mm), almost all in winter, and all in the form of rain. The mean annual temperature is 56 to 60 Â ° F (16 Â ° C); freeze is rare. Field altitudes range from about 40 to 60 feet (18 m) above sea level. Mostly flat, with a very soft slope in the south-southeast; drainage is along Revolon Slough to Calleguas Creek to Mugu Lagoon, and then to the Pacific Ocean.
Maps Oxnard Oil Field
Geology
The Oxnard field is within the Ventura Basin Region in southern California. Geologically, this area is part of the structural downwarp that occurred during the final Pliocene. Rocks in this region are all sediments and most of the ocean. The accumulation of oil, which exists predominantly in the province of Ventura, mainly occurs in the anticlinal arrangements modified by fractures; stratigraphy is also influential in creating traps for hydrocarbons. Where sedimentary rocks are high porosity sandstones, and their structure and stratigraphy allow trapped hydrocarbons in upward migration, oil fields are found.
Because the oil field is in the middle of a vast alluvial floodplain, there is no surface expression of the anticline structure that is able to withstand oil. Below the surface of alluvium, a series of relatively impermeable sedimentary units mask petroleum-bearing formations. Above are the Pleistocene formations of San Pedro and the Pleistocene-over Pliocene Santa Barbara; under that Pico Sands, the age of Pliocene, which contains a tar sand area; below it, separated by unconformity, the Monterey Formation, Miocene age, which also contains tar sand (Vaca Tar Sand); underneath it, again separated by unconformity, a relatively watertight Conejo-Topanga Formation, which limits the erroneous anticlinal structure containing middle-class oil about 6,500 feet (2,000 m) below the soil surface. This production horizon is called the "McInnes" pool, and is in the age-Oligocene Sespe Formation.
The Oxnard field contains a large amount of tar sands, a kind of asphalt categorized as unconventional oil deposits. The average depth below ground level of tar sand - both Vaca Sand and Pico Sand - is about 2,500 feet (760 m), and its thickness ranges from 0 to 600 feet (180 m), representing a total volume of 405,000 ft acres (500,000 3 m 3 ), equivalent to about 565 million barrels (89,800,000 m 3 ) of oil for both units, is it possible to recover their oil content. Only a fraction of this has been brought to the surface to date, although Tri-Valley Corporation is actively developing units by drilling horizontal wells through the sand and subjugating them to a cyclic steam process. According to Tri-Valley, several test wells have demonstrated a production rate of 1,000 barrels per day (160 m 3 /d), and can be brought online as soon as the steam generator and storage infrastructure are in place in the field.
The quality of the oil from the lower pool is good and the medium of gravity, at 24 to 38 API, while the oil of tar sand is very heavy and of poor quality, with extremely high sulfur content - gravity API 7, viscosity from 28,000 to 33,000 sentipoise, sulfur between 5 and 7.5 weight percent.
History, production and operations
The field was discovered in January 1937 by Vaca Oil Exploration Co., which was drilled into tar sand about 2,800 feet (850 m) below ground level. Apart from the very heavy oil deposits in the production formation, they named after their company - Pliocene "Vaca" Tar Sand - they were able to produce about 50 barrels per day (7.9 m 3 /d). In May of the same year they discovered tar sands in the underlying Monterey Formation from which they were able to produce about 90 barrels (14 m 3 ) of oil per day.
More adventurous drillers find deeper yielding horizons with lighter oils. In 1953 and 1954, McInnes, Lucas, and Livingston pools were brought online, producing 24 gravity API APIs, 32 and 25-36 respectively. The operation of waterflooding in these deeper dams in the 1960s helped production, but most of the wells on the horizon were abandoned because of the last economically extractable oil; some remain as drainage wells, as it is usually economically and environmentally better to re-enter waste water into an outdated container than to maintain and release it on the surface. In 2008 only two wells were active in the McInnes reservoir; all others are in shallow tar sand.
Under the adoption rules of California Department of Conservation, Tri-Valley Oil & amp; Gas Company acquired 20 wells previously operated by GEO Petroleum, Inc., which filed for Chapter 11 bankruptcy protection in 1998. Wells was declared abandoned by the State - usually because of the dispersal of operators - was open for adoption and reconstruction under "orphaned well, with written approval from the owners of mineral rights over property and the Department of Oil, Natural Gas and Geothermal Resources In 2008 Tri-Valley began to re-develop these wells and bring them back to production.
The oil produced at the entrance to an oil refinery (2,800-barrel (450 m), belongs to Tenby, Inc., in an unincorporated area south of Fifth Street near the eastern city limits of Oxnard.The refinery also processes oil from the West Montalvo field on the beach west of the Oxnard field.
Oilfield waste
Anterra operates the only commercial facility that discharges oilfield waste through injection wells in the area. In 1998, Anadime Energy Services Inc. applied for permission from the county of Ventura to operate a commercial dump in 1933 E. Wooley Road near the Oxnard city limits. This Canadian company receives waste from other oil field operators, mostly saltwater, and injects thousands of feet to the ground. This permission held by Anterra will expire in 2018 and commercial oil disposal sites on farms are no longer permitted by county zoning laws. The regional Supervisory Council abolished such use on farms two years after the 1998 license was issued. They also reject the zoning change by 2015 which will allow the expansion of facilities citing many places in open spaces and industrial zones where oilfield disposal sites are allowed. They are not convinced by the testimony that Ventura County, as the country's third largest oil-producing region, needs to allow saltwater to be effectively and cheaply dumped. Anterra can still apply to continue operations at the current level when the permit expires. The Santa Clara Wastewater Facility, founded in 1959 about 2 miles (3.2 km) southwest of Santa Paula, can also receive the waste but has no injection well on site.
References
- California Oil and Gas Field, Volumes I, II and III . Vol. I (1998), Vol. II (1992), Vol. III (1982). California Conservation Department, Oil, Gas and Geothermal Resources Division (DOGGR). 1.472 pp. Ventura oil field information p. 572-574. PDF files are available on CD from www.consrv.ca.gov.
- California Conservation Department, Oil and Gas Statistics, Annual Report, December 31, 2008.
- Keller, Margaret. Ventura Basin Province , US Geological Survey Digital Data Packages, DDS-30, Release 2, one CD-ROM, 19p. maps, numbers, and support tables. Available here
Note
Source of the article : Wikipedia
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