Chevron strikes oil more than 6 miles below sea level

Chevron struck oil in a well drilled more than 6 miles deep in a new field off the coast of Louisiana, the company said Monday.

Operating in 6,000 feet of water, Chevron drilled through a thick underground salt layer to find oil at a depth of 31,866 feet below sea level.

The well found 400 feet of net oil pay. Feet of net pay is a measurement used by oil companies to gauge the vertical thickness of the hydrocarbon-bearing area found in an exploration well.

The so-called Coronado prospect is located more than 190 miles south of Louisiana and is a part of a region dubbed the Lower Tertiary Trend, which is especially challenging to drill in because a thick underground salt layer makes seismic scans challenging to read.

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“The Coronado discovery continues our string of exploration successes in the Lower Tertiary Trend, where Chevron is advancing multiple projects,” Gary Luquette, president of Chevron’s

North America exploration and production division, said in a statement. “It also highlights the importance of the deepwater Gulf of Mexico as a source of domestic energy for the United States.”

A Chevron oil discovery in the Gulf of Mexico was drilled in more than 6,000 feet of water and at a total depth of 31,866 feet. (Graphic: Chevron)
A Chevron oil discovery in the Gulf of Mexico was drilled in more than 6,000 feet of water and at a total depth of 31,866 feet. (Graphic: Chevron)

The Gulf of Mexico is one of Chevron’s primary worldwide focal points for its exploration and production program. The San Ramon, Calif.-based company started running a test well in February at another ultradeep-water location there, which produced at a high rate of 13,000 barrels per day.

The successful exploration effort announced Monday was Chevron’s second attempt to drill into the Coronado prospect after a 2011 attempt was abandoned. Drilling then was stopped because of “adverse drilling conditions in the shallow section of the wellbore,” said Russell Johnson, a spokesman for Chevron.

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The company began its second attempt there in mid-2012, eventually reaching a total depth equal to the height of 22 Empire State Buildings, Chevron said.

Chevron holds a 40 percent stake in the well, with other owners including ConocoPhillips, with a share of 35 percent; Anadarko Petroleum Corp, with a 15 percent holding; and Venari Offshore LLC, with 10 percent.

Drilling through thick salt layers is especially challenging because of the difficulty in analyzing data and also because of the operations of ships that drill for miles underground, where they encounter extreme pressures and temperatures.

The cost of operating an ultradeepwater drillship to work in those conditions can exceed $600,000 per day.