NZOG invested up to $150 million in Pike River Coal's West Coast mine but it could be up to a year before it knows how much of that money can be recovered.
An explosion in the coal mine on November 19 left 29 men dead and eventually led to the Pike River company asking to be put into receivership by NZOG.
"As a shareholder, we are in the same position as the thousands of other Pike River Coal shareholders, big and small," NZOG chief executive David Salisbury said yesterday.
Pike River had been suspended from trading and the value of NZOG's shareholding was "very uncertain".
"Our shareholding may have some value - and we are working to address that - but shareholders are at the end of the line when it comes to getting something back on their investment."
Despite the loss to be reported for the six months ended December, NZOG's balance sheet remained strong, Mr Salisbury said.
The company remained focused on growing its oil and gas business and increasing shareholder value.
A comprehensive inspection of the Kupe production station was successfully carried out in November.
The Kupe gas and oil field continued to perform strongly, he said.
Like Kupe, the Tui area oil fields received a benefit from oil prices that hit two-year highs during the three months ended December.
Despite the three week shut-down at Kupe, and a shorter shut-down at Tui for some process improvements, the two fields combined provided NZOG with $16.7 million in revenue for the quarter.
In the exploration portfolio, NZOG had built a dominant position in the relatively lightly explored northern offshore Taranaki Basin, with large holdings in three adjoining permits, Mr Salisbury said.
In the southern Taranaki offshore basin, the Kaupokonui prospect was "drill-ready" and NZOG was looking at drilling options.
To increase those options, NZOG had applied for a six-month extension to the date for making a "drill or drop" decision and continue with its farm-out activities, he said
Quarterly update
• December quarter operating revenue was $16.7 million.
• 753,000 shares bought and subsequently cancelled under a share buy-back scheme, costing $857,000.
• At December 31, NZOG's cash balance was the equivalent of $111.8 million.
