An official field development plan drawn up last year for Dart Energy's disputed coal-bed methane project at Airth, near Falkirk, says it will be allowed to release up to five tonnes of gas per day for safety reasons.
The Australian company will also be able to burn off gas in flares "on an emergency basis".
Dart has applied for planning permission to sink 22 wells at 14 sites to extract up to 60 billion cubic feet of methane at Airth.
The application has prompted more than 1500 objections, has been delayed by local authorities and is now being considered by the Scottish Government.
Last week, Falkirk Council agreed to urge the Government to hold a public inquiry into the plans.
Extracts from the draft 2012 field development plan for Airth have been released to the campaign group, Frack Off Scotland, by the Scottish Environment Protection Agency and the Department of Energy & Climate Change in London after appeals under freedom of information law.
"This licence to vent potentially massive amounts of methane is another reason unconventional gas is such an environmental disaster," said Ed Pybus from Frack Off Scotland.
Dart pointed out that controlled venting of methane was sometimes required to ensure safe operation and maintenance.
"Consent for this would be considered at the appropriate time by the regulator following assessment of requirements and impact," said a company spokesman.
"This consent, in line with industry standards, describes a limit and it would be highly misleading to imply that this could be a routine occurrence."