Great Bear Petroleum has started drilling the first of its ambitious three-well programme on Alaska’s North Slope, targeting conventional and unconventional reserves from the Shublik and Kingak shale formations.

Off the exploration radar the past few years, Great Bear chief executive Ed Duncan said the small independent has been forging ahead behind the scenes evaluating the results of its two-well 2012 drilling programme and acquiring nearly 500 square miles (1295 square kilometres) of 3D seismic in 2013.

The results from its Alcor 1 and Merak 1 wells confirmed its pre-drill expectations, prompting Great Bear to revise its fairway mapping to reflect new observations.

“We focused on understanding the retained phase of the liquid hydrocarbons in the reservoir. We tested our regional thermal maturity model in Alcor and Merak and collected data that would allow us to better understand retained phase in rock mechanics,” said Duncan. Both Alcor and Merak were drilled on Great Bear’s 75%-owned lease shared with Halliburton.

“The drilling this year is meant to confirm the phase prediction fairway mapping we have and that, coupled with the 3D, should unlock a path forward on the unconventional space, particularly in the Shublik,” said Duncan.

Alaska’s Department of Natural Resources approved Great Bear’s winter exploration programme in early January and drilling of the Alkaid 1 well — located on its Halliburton-shared lease — was scheduled to begin on 28 January.

Subsequent wells will include the Talitha 2 on wholly-owned acreage recently acquired in the state’s November 2014 lease sale, and Phecda 1, also on its Halliburton-shared holding.

Drilling will be carried out using the Nabors 106 AC rig and is scheduled to be complete by 30 April.

The three wells are located immediately west of the Dalton Highway beginning about 19 miles (30 kilometres) south of Deadhorse and following the same route as the Trans-Alaska Pipeline System (TAPS).

To date Great Bear has spent in excess of $150 million, said Duncan, who declined to comment on the costs associated with the current drilling programme, and an additional 170 square miles of 3D currently being shot. “We’re spending a lot of money. This will be by far and away the most financially exposed investment that we’ve made in the four years that we’ve been active on the Slope,” said Duncan of the privately-held company.

Although the goal from the onset was to target conventional oil from the Shublik formation the results from its initial drilling programme revealed “huge” unconventional gas deposits.

Duncan said the gas will be used to generate electricity for its operations, but selling it as liquefied natural gas for export or re-injecting it for pressure maintenance will be considered.

“We have a portfolio of conventional prospects that are inter­woven within the unconventional. It is really exciting for us because they’re regionally proven plays on the North Slope,” he said.

“Based on the evidence of the seismic and hopefully confirmed with drilling over the next few months this portfolio will also facilitate regional development of the unconventional.

“From the beginning, the scale of what we set out to do is legacy class — it’s a generational scale exploration and development programme.

“We’re going to test some play concepts in the unconventional space that, if successful, will mean this project will be going on 30 years from now.”