The Cairns office will close by the end of the year as InterOil relocates core functions to support expanding operations in PNG.
InterOil said the decision to increase capacity in PNG came as it finalised its agreement with French supermajor Total S.A.
The company agreed to sell Total a gross 61.3% interest in Petroleum Retention License 15 which contains the Elk-Antelope gas fields in the Gulf Province of PNG.
Work on the Total agreement, including the buy-out of minority interests, is scheduled to be completed by the end of the quarter.
InterOil CEO Dr Michael Hession said the relocation of core functions would put resources where they are most needed.
"PNG is our base, and where all our activities are, including exploration, refining, and distribution - and, of course, the LNG project," he said.
"It makes sense to focus our workforce there."
InterOil has also begun a new round of drilling as part of its exploration activities across almost four million acres in PNG.
The company plans to drill up to eight wells in the next 12-15 months, with the drilling of each well expected to take about three months.
About 1100 people are working in the field on the seismic program and preparation for drilling operations.
An additional 300 people will be employed when drilling operations get underway.
Meanwhile, stocks on Wall Street have risen after the release of positive US growth data.
Fourth-quarter gross domestic product increased at a rate of 3.2%, while initial jobless claims for last week rose slightly.
The S&P 500 climbed 1.1%, while the Dow Jones Industrial Average gained 0.7%.
The NASDAQ increased more than 1.7% thanks to a more than 14% jump in Facebook shares, after the company released earnings.
Singapore Tapis crude closed at $US115.40 a barrel overnight, compared to $114.77 at the end of last week.
London Metal Exchange cash copper closed at $7135.50 a tonne overnight, compared to the price of $7211 at the end of last week.
By the same comparison, LME spot nickel's overnight price was $13,756/t, down $684 or 4.7% from last week's price of $14,440.
Spot gold was trading at about $1270 an ounce in the past 30 minutes, from the price of $1243 last Friday.