But the association has not advised against the transaction and is urging shareholders to carefully consider their own circumstances. The takeover, being effected through a scheme of arrangement, requires 75 per cent support of the votes cast by November 14. Data from NZOG today shows shareholders who have voted so far are split on the deal.
"It is important that retail shareholders vote their shares," the association says.
"It is likely that some shareholders will remain unhappy with the offer amount whereas others, perhaps with shorter-term horizons and recognising the low trading liquidity in NZOG, may be inclined to accept."
NZOG shares last traded at 72 cents and are near a 22-month high. The initial offer was a 25 per cent premium to the market price on July 9 and the latest offer is almost 50 per cent higher.
Today the company said about 40 per cent of the shares held by minority investors had been voted as of last night.
Of those, about 48.4 per cent were cast against the transaction, 40 per cent were in favour and 12.2 per cent were being left to the discretion of proxy holders. OGOG can't vote on the transaction.
NZOG has a small stake in the Kupe gas field and, through subsidiary Cue Energy Resources, a small stake in the Maari oil field and production interests in Indonesia. It also owns half the Barque exploration permit off the Oamaru coast and has a 15 per cent stake in the Ironbark prospect off north-western Australia where partner BP plans to drill late 2020. Cue, half-owned by NZOG, also has a 21.5 per cent stake in Ironbark.
Many of the complaints about the offer relate to the treatment of the firm's exploration assets, particularly a 5 per cent probability ascribed to the chances of Ironbark – a potentially 15 trillion cubic feet gas resource – being commercially developed.
While the odds of a discovery are better, there are many undeveloped gas discoveries in Australia's greater north-west shelf.
Last month, the Takeovers Panel asked NZOG to clarify two aspects of the information provided on Ironbark, which the company did.
But it stopped short of finding the original advice was misleading and said most of the complaints appeared to reflect honest and reasonable differences of opinion.