Oxnard Oil Field facts for kids
The Oxnard Oil Field is a large area where oil is found underground. It's located near the city of Oxnard in Ventura County, California, USA. This oil field is still active today.
Most of the easily reachable oil from this field has already been used up. But there's a huge amount of a different kind of oil here called "tar sands." This is a very thick, heavy oil that is harder to get out of the ground. Companies like Tri-Valley Oil & Gas Co. and Occidental Petroleum (through its Vintage Production company) work here. In 2009, there were 34 active oil wells in the field.
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Where is the Oxnard Oil Field?
The Oxnard Oil Field is one of several oil fields under the Oxnard Plain. This area is mostly farmland, with cities like Ventura, Oxnard, and Camarillo nearby.
You'll see oil wells and equipment mixed in with fields of strawberries, broccoli, and onions. Some parts of the field, especially to the west, are now used for businesses as Oxnard grows.
Major roads like U.S. Route 101 and California State Route 34 cross the field. Most active oil wells are in the eastern part. Some wells use a special method called directional drilling. This allows many wells to be drilled from one spot on the surface. The total area of the field is about 1,350 acres.
Climate and Land
The weather here is like the Mediterranean. Winters are cool and rainy, while summers are warm and dry. Coastal fog often keeps summer days from getting too hot.
About 15 inches of rain fall each year, mostly in winter. Freezing temperatures are rare. The land is mostly flat, about 40 to 60 feet above sea level. Water drains into Revolon Slough, then to Calleguas Creek, and finally to the Pacific Ocean.
What's Under the Ground?
The Oxnard field is in a geological area called the Ventura Basin. This area sank down a long time ago. The rocks here are mostly sedimentary, formed from layers of sand and mud.
Oil usually collects in underground traps. These traps are often formed by folded rocks (called anticlines) or by cracks in the earth (faults). If the rocks are sandy and porous, oil can get trapped there.
Oil and Tar Sands
Even though the surface is flat, deep underground there are folded rock layers that hold oil. Layers of rock like the San Pedro and Santa Barbara formations are on top. Below them are the Pico Sands, which contain areas of "tar sands." Even deeper, the Monterey Formation also has tar sands.
The main oil-producing layer is called the "McInnes" pool. It's about 6,500 feet below the surface. This oil is lighter and easier to get out.
The Oxnard field has a lot of tar sands. This is a very thick, sticky form of oil called bitumen. It's considered an "unconventional" oil source because it's so hard to extract. The tar sands are about 2,500 feet deep and can be up to 600 feet thick.
Companies like Tri-Valley Corporation are trying new ways to get this thick oil out. They drill horizontal wells and use a method called cyclic steam. This involves injecting steam into the ground to heat the tar sands, making the oil thinner and easier to pump. Some test wells have shown good results.
The oil from the deeper layers is good quality. But the oil from the tar sands is very heavy and has a lot of sulfur.
History and How Oil is Produced
The Oxnard Oil Field was discovered in January 1937 by Vaca Oil Exploration Co. They found tar sands about 2,800 feet deep. Even though the oil was very thick, they were able to produce about 50 barrels of oil per day. Later that year, they found more tar sands deeper down.
Over time, drillers found even deeper oil layers with lighter oil. In the 1950s, the McInnes, Lucas, and Livingston pools were discovered. These produced better quality oil. In the 1960s, a method called Waterflooding was used. This involves injecting water into the oil layers to push the oil towards the wells.
Most of the wells in these deeper layers were eventually closed when they ran out of easily recoverable oil. Some wells were kept open to inject wastewater back into the ground. This is better for the environment than releasing the water on the surface. In 2008, only two wells were still active in the deep McInnes layer. All the others were in the shallower tar sands.
Bringing Wells Back to Life
Sometimes, oil companies go out of business, and their wells are left unused. These are called "orphan wells." Under California rules, other companies can take over and restart these wells.
In 2008, Tri-Valley Oil & Gas Company took over 20 wells that were no longer active. They started working on these wells to bring them back into production.
Oil from the Oxnard field is sent to the Oxnard Refinery. This small refinery processes about 2,800 barrels of oil per day. It also processes oil from the West Montalvo Oil Field, which is located west of the Oxnard field.
Images for kids
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The Oxnard Oil Field in Ventura County, California. Other oil fields are shown in dark gray.
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Oxnard Refinery, an oil processing facility. Oil from the Oxnard field and the Montalvo field comes here.
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Detail of the Oxnard field, showing its location near Ventura and Oxnard. Yellow dots show active oil wells in 2008.
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Oil storage tank next to Tri-Valley's operations center.
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Oil wells, tanks, and a burn-off flame. Agriculture irrigation pipes are in the front.
