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Chevron confirms Tahiti reserve At 400 to 500 million barrels discovery among largest in Gulf of Mexico Petroleum News Houston Staff
ChevronTexaco has confirmed a range of 400 to 500 million barrels of reserves for its deepwater Tahiti prospect, ranking it among the largest-ever oil discoveries in the Gulf of Mexico.
And just a dozen miles west of Tahiti, a prospect called Constitution was declared a success following appraisal drilling by operator Kerr-McGee. The company also confirmed its Hornet discovery northeast of Tahiti.
ChevronTexaco’s estimate for Tahiti was verified by results from two appraisal wells released April 22, one of which is said to have encountered an amazing 1,000 feet of net pay in high-quality sandstone.
The company said the two-well appraisal program confirmed that the reservoirs in Tahiti “are well developed and correlate” over a three-mile distance. It characterized the prospect as “one of the most significant net pay accumulations in the history of the deepwater Gulf of Mexico.”
Nevertheless, operator ChevronTexaco apparently is not quite ready to launch development at Tahiti on behalf of itself and partners EnCana and Shell.
“Considerable work is still ahead to evaluate the results of these wells and to screen development alternatives to optimize value,” said Dave O’Reilly, ChevronTexaco’s chairman and chief executive officer.
Production test planned A production test of the discovery well is planned for the first quarter of 2004, the company said, adding that appraisal drilling also is continuing at the prospect.
The Tahiti appraisal wells, located on Green Canyon blocks 596 and 640, about 190 miles southwest of New Orleans, Louisiana, were drilled in just over 4,000 feet of water. The wells were drilled simultaneously using deepwater rigs Glomar Explorer and the Transocean Deep Seas, and each drilled a vertical well with a sidetrack, the company said.
The initial 400-to 500 million-barrel estimate for Tahiti was announced in June 2002, soon after the discovery. ChevronTexaco has a 58 percent working interest in Tahiti. EnCana holds a 25 percent stake and Shell a 17 percent stake.
Exploration and production independent Kerr-McGee declined to discuss reserve estimates for deepwater fields Constitution and Hornet, also located in the prolific Green Canyon region of the Central Gulf.
“Further appraisal work is ongoing to determine the full resource ranges and the optimum potential development solutions for these fields,” said Luke Corbett, Kerr-McGee’s chairman and chief executive officer.
But he said the company was “very encouraged by the confirmation of these two fields” through appraisal drilling. However, the fields have not yet been deemed commercial, a company spokeswoman said. Second Constitution well being sidetracked Constitution is located in 5,000 feet of water on Green Canyon Block 680. Hornet is situated in 3,800 feet of water on Green Canyon Block 379. Both fields are 100 percent owned by Kerr-McGee.
The company said discovery of the Constitution field was confirmed by a second successful well, located in a separate fault block. The pay sands are high-quality oil reservoirs, the company added, with porosity of 25 percent to 30 percent and API gravity oil greater than 30 degrees.
The initial well, drilled to a depth of 13,727 feet, encountered more than 100 feet of net pay. The second well, located about 4,000 feet northwest of the initial exploratory well and drilled to a depth of 15,213 feet, encountered about 375 feet of net oil pay in the same Plio-Pleistocene sands.
The second Constitution well is currently being sidetracked down-dip 1,650 feet to test additional potential deeper reservoirs, Kerr-McGee said.
The Hornet field was confirmed after an appraisal well encountered more than 275 feet of net pay in Plio-Pleistocene sands, the company said, adding that the well is being sidetracked about 2,300 feet into Green Canyon Block 335 “to better define the aerial extent of the reservoirs.”
Kerr-McGee said high quality oil and gas sands were confirmed on both the northeast and northwest flank of Hornet, with porosity ranging from 23-to 30 percent.
Separately, Kerr-McGee said the RunfortheRoses exploratory well on Green Canyon Block 735 was plugged and abandoned. Costs incurred on the well through March 31 will be included in the company’s 2003 first-quarter expense, which is now estimated in the range of $140-to $145 million, the company said. Kerr-McGee held a 50 percent interest in the prospect.
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