Cymric Oil Field
The Cymric Oil Field is a large oil field in Kern County, California in the United States. While only the 14th-largest oil field in California in total size, in terms of total remaining reserves it ranks fifth, with the equivalent of over 119 million barrels (18,900,000 m3) still in the ground. Production at Cymric has been increasing faster than at any other California oil field.
The Cymric field is in the Temblor Valley, along the west side of State Route 33, between that highway and the Temblor Range. It is north of the town of McKittrick, which is at the junction of State Route 58 and 33. The field is approximately 11 miles (18 km) long, from northwest to southeast, and up to two miles (3 km) across, including several smaller discontiguous areas which are considered geologically to be part of the main field. Elevations on the field range from approximately 600 to 1,000 feet (300 m).
Adjacent to the Cymric Field on the south are the smaller fields of McKittrick, Belgian Anticline and Railroad Gap, and on the east, along Route 33, is the small Monument Junction field. The enormous South Belridge Field, one of the largest in California, begins about one mile (1.6 km) northeast of Cymric's northernmost extent.
The local climate is arid to semi-arid, and the predominant native groundcover is grassland and low scrub. In many areas of active oil field development, almost all vegetation has been removed.
Most of the oil in the Cymric field is in a sandstone formation known as the Tulare, which is divided into three units: the Tulare I, II, and Amnicola. All are of age. The Tulare formation was created mainly in a braided stream and fan delta depositional environment, while the depositional characteristics of the Amnicola suggest a lacustrine (lake) environment, as well as braided stream. These kinds of rocks have high porosity (around 35%) but low permeability, allowing considerable oil to accumulate in the formation, while a combination of structural and stratigraphic traps keep the oil from migrating further upward. Throughout the history of the field, these upper units have been the most productive, and they were also the first to be discovered, in 1909.
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