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Uinta Uteland Butte, Mahogany zones yield oil

Bill Barrett Corp., Denver, is adding oil production in the Uinta basin from the Uteland Butte and shallower Mahogany members of the Eocene Green River formation in its Blacktail Ridge and Lake Canyon areas.

The company has completed four horizontal Uteland Butte wells and is testing oil from the Mahogany through a vertical well.

Peak 24-hr initial rates for the first four horizontal Uteland Butte wells have averaged in excess of 1,000 b/d of oil equivalent per day. The first two are producing as or better than expected. The third flowed and pumped an average 707 boe/d its first 30 days and had a peak 24-hr IP rate of 1,330 boe/d. The fourth, on production 21 days, has averaged 596 boe/d and had a peak IP rate of 863 boe/d.

The third well had 15 frac stages in a 3,400-ft lateral at 5,850 ft, and the fourth well had 15 stages in a 3,200-ft leg at 5,900 ft.

It is too early to figure estimate ultimate recoveries, the company said. Barrett has 55.8% working interest in the first four wells and plans to drill a total of seven horizontal Uteland Butte wells by the end of 2011.

Meanwhile, Barrett completed a vertical test well into the Mahogany formation to 5,500 ft with 245 ft of core. Core tests in the Mahogany formation were positive, and the well is recovering oil. The company is permitting two more vertical test wells it expects to drill in mid-2012.

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