The junior explorer said the previously calculated mean gas-in-place for the Overston Structure was 57 billion cubic feet, but an independent report by MBA Petroleum Consultants has increased this figure to 137 bcf.

However, Sunshine said potentially economic flow rates have not been measured and so MBA is unable to assign a proved and probable gas reserve. "Based on future testing and other new well results, appropriate proved and probable reserves can then be assigned to the field," said Sunshine Gas company secretary, Chris Blamey.

In other company news, the company has terminated an agreement which would have seen it purchase 19.9 million options in Sydney Gas in exchange for issuing 15 million Sunshine Gas shares and 7.5 million options to corporate entities Mandolin Pty Ltd and Mangalore Nominees.

With Sunshine's share price increasing from 11c in late December to be currently trading at 23c, the company said it was not appropriate to proceed with the transaction as the corporate entities involved in the deal are associated with John and Jeremy Towner, both current directors of Sunshine Gas.