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Drilling transforms Shenzi Appraisal well uncovers 1,250 feet gross hydrocarbons, 500 feet net pay Petroleum News
Based on results from its first appraisal well the Shenzi prospect in the deepwater Gulf of Mexico appears to contain far more oil than the initial exploratory well indicated. It also can be ranked among the more robust discoveries in the Green Canyon-Atwater Valley area in terms of sheer pay thickness.
The Shenzi-2 appraisal well, operated from the drillship CR Luigs in 4,238 feet of water and drilled to a total depth of 25,000 feet, “significantly extended the scale of the oil accumulation discovered by Shenzi-1,” Phil Aiken, chief executive officer for Shenzi operator BHP Billiton, said Nov. 12.
BHP said the appraisal well penetrated 1,250 feet of gross hydrocarbon column with about 500 feet of net oil pay, compared to a much smaller 465-foot column with 140 feet of net encountered in the Shenzi-1 discovery well.
Located on Green Canyon Block 653 about two miles southwest of Shenzi-1, the appraisal well uncovered net pay roughly equivalent to other major discoveries in the region, including BHP's own Neptune prospect in nearby Atwater Valley. It's also on par with Unocal's recent St. Malo discovery southwest of Shenzi in Walker Ridge. Confirmed prolific nature of Atwater Shenzi-2 also reconfirmed the prolific nature of the Atwater Fold Belt trend, which produced Neptune and other major deepwater fields, including blockbusters Atlantis and Mad Dog.
In fact, the four-block Shenzi prospect is located just north of the BP-operated Atlantis oil field, scheduled to come on stream in 2006 with platform capacity of 150,000 barrels per day.
Mad Dog is set to come on line in 2005 with facility capacity of 80,000 barrels per day.
Despite its obvious candidacy as a tie-back to Atlantis, Shenzi may be able to stand on its own feet. “The field looks appreciably larger and increases the potential for a stand-alone development,” a spokesman for BHP said. Sidetrack needed Because a sidetrack off Shenzi-2 will be required to size the field, BHP was reluctant to discuss reserve estimates, something the company says it generally does only after a field is sanctioned for development.
“While further appraisal drilling will be required to fully define the reserve size, we will be working with our partners to begin studying possible development options,” BHP's Aiken said.
However, a spokesman for Shenzi partner Amerada Hess said that for now Hess “probably would not be uncomfortable” with industry speculation that Shenzi may contain 250 to 500 million barrels of oil.
“But we need to do additional drilling to further evaluate the prospect,” he cautioned. BP and Hess each hold 28% interest In addition to being field operator, BHP has a 44 percent stake in Shenzi. Hess and BP each hold a 28 percent interest in the field. BHP also holds a 23.9 percent interest in Mad Dog, a 44 percent interest in Atlantis and operates Neptune with a 35 percent stake.
The company also is participating in the Puma exploration well currently being drilled just west of Mad Dog.
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