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Aurora back to work on Cohoe unit Unit would require seismic shoot and re-entry of existing well over next two years; Aurora looking for bypassed gas play By Eric Lidji For Petroleum News
Aurora Gas LLC is looking to form the Cohoe unit over leases in the Cook Inlet basin.
The proposed 7,707-acre onshore unit would cover two State of Alaska leases and one Cook Inlet Region Inc. lease near the Kenai Peninsula community of Kasilof.
The unit application, originally filed in August 2010, sat in limbo at the Department of Natural Resources’ Division of Oil and Gas for nearly a year, while officials waited for Aurora to submit a proposed unit agreement that included both the State of Alaska and CIRI as co-royalty owners.
Under Aurora’s proposed two-year plan of exploration, it must re-enter the Cohoe Unit No. 1 well or perform 3-D seismic over the area by the end of September or lose the unit.
Union Oil Co. of California drilled the Cohoe Unit No. 1 in 1973. Aurora must re-enter it to at least 10,000 feet, penetrating the Sterling, Beluga and Upper Tyonek formations.
By Sept. 30, 2012, Aurora must either re-enter the well or run the seismic program, whichever it didn’t do in the first year. It must apply for a PA, or Participating Area, by the end of 2012.
DNR is taking comments through July 25.
Thought to contain bypass play Sun Oil Co. first leased the Cohoe-area acreage in 1967, but farmed it out to Unocal in 1972. Unocal was formerly Union Oil, and is today owned by Chevron.
Unocal shot seismic over the area and drilled the Cohoe Unit No. 1 to a measured depth of 15,683 feet, but the companies ultimately terminated the leases in 1975.
A group of individual investors picked up the leases in a 2003 sale and Aurora acquired the acreage in early 2004, eventually adding a neighboring CIRI lease in 2006.
Because Unocal encountered gas en route to targeting a deeper oil deposit that proved unsuccessful, Aurora believes Cohoe could contain a “bypass play” worth exploring, Aurora President Scott Pfoff told Petroleum News last August.
“Like so many other wells drilled in the Cook Inlet, this well was drilled deeper, looking for oil and with heavier (drilling) mud,” Pfoff said. “We see evidence of bypassed gas pay, but testing was minimal and we suspect negatively impacted by mud invasion into the formation.”
Faced with a pending expiration of the leases last summer, Aurora filed paperwork to form the Cohoe unit and to drill a re-entry of the Cohoe Unit No.1 well, but at the time the company told Petroleum News it preferred to shoot seismic over the area first in order to determine whether the original well penetrated the top of the gas prospect.
But because Aurora needed its rig for operations on the west side of the Cook Inlet, it couldn’t begin drilling last fall.
Should Aurora ultimately drill, it is well positioned to develop Cohoe because the leases are close to existing regional infrastructure, including the Kenai-Kachemak Pipeline.
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