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Crude oil resources in the state was discovered and produced in the southern part of the Gulf Coastal Plain of south Arkansas, which includes the following ten counties: Ashley, Union, Ouachita, Columbia, Nevada, Hempstead, Bradley, Calhoun, Lafayette, and Miller. Historically, most of the oil production has been in Union, Lafayette, Columbia, and Ouachita counties. These four counties have been responsible for more than eighty-five percent of the oil produced in Arkansas.
History of Discovery and Exploration
The first Arkansas well that yielded sufficient quantities of oil was the Hunter No. 1 that was drilled in April 16, 1920 near Stephens, in Ouachita County. A few days later, gas was discovered in the northern part of the present El Dorado field in Union County by the Constantin Oil and Refining Company. On January 10, 1921, oil was discovered in the S. T. Busey well (below) in the same field. The S.T. Busey well marked the beginning of commercial oil production in Arkansas (1).
|Historic photograph of the S.T. Busey well that marked the beginning of south Arkansas oil production in 1921. (Photo courtesy of the Arkansas Natural Resources Museum, Smackover, Arkansas)
|Historic photograph of the Smith-McClerkin No. 1 well drilled in Columbia County in 1941. (Photo courtesy of Arkansas Natural Resources Museum, Smackover, Arkansas).|
Although most of crude oil was extracted from stripper wells that produced less than 10 barrels per day in the south Arkansas, Arkansas has two giant oil-producing fields. The Smackover field, discovered in 1922, produced 603,691,313 barrels of crude oil as of January 1, 2014. The Magnolia field, discovered in 1938, produced 172,561,255 barrels as of January 1, 2014.
|Photograph of a modern oil well pumping unit and tank battery commonly used in south Arkansas oil fields. (Photo courtesy of Arkansas Natural Resources Museum, Smackover, Arkansas)|
In south Arkansas, several wells have been drilled to depths exceeding 16,000 feet. An exploratory well in Hempstead County was drilled to 17,349 feet. Elsewhere, an exploratory well in Ashley County was drilled to a depth of 16,611 feet. There are several oil wells which produce from a depth exceeding 11,000 feet along the southern border of Arkansas in Lafayette County.
General Petroleum Geology
Upper Jurassic (Oxfordian) Smackover lime mudstones are the major source rock in south Arkansas. The reservoir rocks in this region are widely distributed in the sandstones and limestones of Cretaceous and Jurassic sections.
Production Data and Reserves
From 1920 to 2013, 1,870,030,073 barrels of oil have been produced in Arkansas. Annual production data for 2013, which is compiled from 352 fields in south Arkansas, is 6,686,243 barrels of oil and 11,108,536 MCF of gas. (2)
The oil and condensate reserves as of January 1, 1998, are estimated to be 210,173,106 barrels while the gas reserves associated with the oil and condensate are estimated to be 511,659,605 MCF. (3) The crude oil proved reserves (proved reserves is a technical term for how much we are reasonably sure is still in the ground, waiting to be extracted) in Arkansas are estimated to be about 40 million barrels in 2013. (4)
(1) Spooner, W.C., Oil and gas geology of the Gulf Coastal Plain in Arkansas, Arkansas Geological Survey Bulletin 2, 1935, p.140-141.
(2) Annual report of production, 2006, Arkansas Oil and Gas Commission.
(3) Annual oil and gas report, 1997, Arkansas Oil and Gas Commission.
(4) Energy Information Administration website