The company reported it had reached its total depth of 1983m, when “mud cap drilling was stopped to perform a wiper trip”, and was in the process of performing the second drill stem test for gas and gas condensate.

Elk-1 will be flowed to clean up water and drilling mud lost while drilling, after which the open-hole section from 1640m to 1983m will be flowed for “an extended time at a steady rate”, then shut-in for a pressure build-up period twice as long as the flow period.

A day into the flow period the well was at 2000psi flowing pressure on a 42/64 choke at a very respectable rate of 19.3MMcfd and “appears to be continuing to clean up”.

Testing of Elk-1 was expected to take about three weeks.

The Elk discovery was announced in May and is InterOil’s first commercial success.

Chief executive Phil Mulacek had previously described Elk-1 as a huge well with the potential to kick-start the company’s plans to develop a liquefied natural gas plant in the country.

InterOil owns the only petroleum refinery in the country, the Napa Napa refinery, in Port Moresby.