Big Foot discovery takes giant step

Chevron’s Walker Ridge sidetrack drilled to 24,434 feet, confirms Gulf of Mexico deepwater oil find; confirms discovery

Ray Tyson

For Petroleum News

Chevron’s Big Foot discovery continues to evolve into a first-rate deepwater Gulf of Mexico oil play. The company’s latest appraisal well confirmed the same approximately 300 feet of net pay initially found in the discovery well on Walker Ridge Block 29.

The appraisal well was sidetracked to a total vertical depth of 24,434 feet, Big Foot operator Chevron said July 26, adding that the well was drilled into a target roughly one-half mile north and “significantly downdip” of the discovery well.

“This sidetrack encountered the same pay intervals as seen in the discovery well,” the company said. “Further appraisal drilling will be conducted, the timing of which is still under consideration.”

Walker Ridge Block 29 is located about 225 miles south of New Orleans, La., and is situated in approximately 5,000 feet of water.

Chevron owns a 60 percent working interest in Big Foot. Anadarko Petroleum has a 15 percent interest in the prospect, while Plains Exploration & Production Co. and Shell each hold a 12.5 percent stake in Big Foot.

“Big Foot is potentially a very, very large discovery,” Chris Oynes, Gulf regional director for the U.S. Minerals Management Service, said in early May at the Offshore Technology Conference in Houston, Texas.

Big Foot followed Knotty Head

Bob Daniels, Anadarko’s senior vice president in charge of exploration and production, noted in January that “coming on the heels of … the Knotty Head discovery, the Big Foot discovery further validates the extensive middle-to-lower Miocene play we are aggressively pursuing within the foldbelt area.”

Last year Anadarko hit on three of four exploration wells in the foldbelt, including the company’s 100 percent owned Genghis Khan discovery in a water depth of 4,300 feet on Green Canyon Block 652.

Like Big Foot, the initial Knotty Head exploration well turned up about 300 feet of net oil pay. However, appraisal drilling increased the estimated pay to around 600 feet, potentially ranking Knotty Head among the largest oil finds ever in deepwater Gulf of Mexico.

“This discovery follows a string of Gulf of Mexico discoveries that is a result of executing our focused, high-impact exploration program,” Paul Siegele, vice president of Chevron’s Gulf of Mexico deepwater business unit, said of Big Foot.