US shale pioneer Continental Resources Inc and Colombia’s Geopark Ltd were among bidders for Argentina’s largest offering of exploration licences in more than a decade in the country’s booming oil fields.

The auction is being carried out by Gas y Petroleo del Neuquén SA, or GyP, the provincial oil company in Neuquén, which is home to the lion’s share of acreage known as the Vaca Muerta and owns the mineral resources below ground.

Continental bid for six blocks in partnership with Phoenix Global Resources Plc, a unit of global trading house Mercuria Energy Group Ltd. Geopark bid for two blocks, according to a statement from GyP.

It’s the biggest single offering of drilling areas by Neuquén since 2010. Fifteen blocks are up for grabs at a time when production in the Vaca Muerta is growing quickly and foreign operators are taking note.

Billionaire wildcatter Harold Hamm’s Continental became the first US shale independent to take a chance on Argentina at the turn of the year, while Mercuria and Geopark have been expanding in its Patagonian shale basin. Supermajor Chevron Corp is also increasing its presence, but didn’t bid.

Provincial officials opened the bids on Wednesday and are expected to announce winners before the end of the year.

“This initiative is fully aligned with Neuquén Province’s strategy to unlock the value of our oil and gas resources,” GyP President Guillermo Savasta said in the statement.

Neuquén is seeking to capitalise on growing interest in the Vaca Muerta as the best drilling acreage runs out in the Permian Basin in Texas and some US shale companies consider migrating. That explains why Neuquén Governor Rolando Figueroa announced the auction last May in Houston.

US tech billionaire Peter Thiel even recently reported a sizeable stake in Argentine shale driller Vista Energy SAB, adding even more visibility to the region’s development.

Still, in a sign that oil drillers will be picky about what blocks they go after, only eight of the 15 received bids.

The most attractive areas include Corralera Northwest and Northeast, Ernesto Diaz, Senior Vice-President for Latin America at Rystad Energy, said on LinkedIn. Continental-Phoenix and Geopark bid for both.

For its part, GyP will take an equity stake of 10 percent to 20 percent in whatever blocks get awarded.

by Jonathan Gilbert, Bloomberg