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State modifies Tarn participating area Changes add several areas bound for contraction; ConocoPhillips applies for seismic permits over Kuparuk River unit Eric Lidji Petroleum News
The state approved a modification of the Tarn participating area on Jan. 23.
Under the decision, the Tarn PA expands at its northern border, shrinks at its eastern border and keeps three pieces of acreage originally bound for automatic contraction.
The Tarn PA covers 10,345 acres in the southwest corner of the Kuparuk River unit.
ConocoPhillips, operator of the participating area, maintains a 55 percent working interest in the Tarn PA, with BP holding 39 percent, Union Oil Company of California (Chevron) holding nearly 5 percent and ExxonMobil holding less than 1 percent.
With the modification, the Tarn PA now includes a new rectangular block covering the southern half of section 13, township 10N, range 7E, Umiat Meridian, within ADL 380051 and the southwestern quarter of 18-T10N-R8E, UM, within ADL 25603.
But the participating area loses a rectangular strip covering the eastern halves of sections 19 and 30, T10N-R7E, UM, within ADL 25603 and ADL 25608.
The state Division of Oil and Gas said modifying the Tarn PA would increase oil production and minimize the chance of duplicating facilities at Kuparuk.
Decision pushes back contraction for three areas The Tarn PA was formed in 1998 and contracted five years later.
As part of the 2003 decision, the state marked three “expansion areas” for further contraction unless ConocoPhillips drilled four wells by deadlines in July 2005 and July 2006.
These expansion areas are in the southeastern corner of the participating area.
Area 1 covers the western halves of sections 19 and 30, T10N-R7E within ADL 25603 and ADL 25608. Area 2 includes the southeastern corner of 25-T10N-R7E within ADL 380053. Area 3 is the southeastern quarter of section 35 and the southwestern quarter of section 36 in T10N-R7E within ADL 380053.
The four delineation wells were designed to prove whether the three expansion areas should be included in the Tarn PA, but while ConocoPhillips drilled near the expansion areas, it did not drill in the expansion areas.
Upon request from the company, these deadlines were extended to July 2007.
In June, the company asked the state to once again push back the contraction date, to include the three expansion areas into the Tarn PA and to add additional acreage along the northern border.
Productive field is slowing down Exploration at Tarn began with the Bermuda No. 1 well drilled in 1991 and the Tarn No. 1 well drilled the following year.
Using data from a seismic survey conducted in early 1996, ConocoPhillips drilled four delineation wells in the winter of 1996 and 1997, finding a Brookian oil reservoir. The company gathered additional seismic data over the following two winters.
According to state figures from July 2007, the field is believed to contain 41 million barrels of remaining recoverable oil reserves and 50 billion cubic feet of remaining recoverable natural gas reserves.
The Kuparuk River unit was expanded in July 1998 and the Tarn PA formed. By the end of 2006, ConocoPhillips had drilled 45 wells from two drill sites at Tarn.
Through November 2007, the field had produced 85.5 million barrels of oil, making it the second-most productive participating area in the Kuparuk River unit.
Production at the Tarn oil field peaked in 2003 at 33,842 barrels per day. The field currently produces just less than 15,000 bpd.
Over the past two years, ConocoPhillips has drilled 10 development wells at Tarn trying to hit parts of the reservoir previously thought to be uneconomic. In the 2007 plan of development for the field, ConocoPhillips proposed continued infill drilling.
According to the Division of Oil and Gas, Veritas DGC Land Inc. applied for a state permit to acquire 200 square miles of 3-D seismic survey for ConocoPhillips over the Tarn field this winter.
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