Energy Minister Peter Collier said the move would allow the development of a greater range of gas fields to supply the domestic market and would lead to greater competition among gas producers and to improved energy security.

The move was applauded by the Australian Petroleum Production & Exploration Association, which said the Gas Supply (Gas Quality Specifications) Act 2009 had brought the state's gas specifications closer into line with the Australian standard.

"Broadening the gas specification of the Dampier to Bunbury Natural Gas Pipeline means that more gas can be made available to supply the WA market, a move that will help secure long-term natural gas supplies for the state," APPEA WA director Tom Baddeley said.

Collier said the new legislation might render unsafe some pre-1980s gas appliances - such as gas cookers, heaters and hot water systems - if operated on leaner gas.

"To offset any inconvenience to consumers, a special program will be introduced before the leaner gas starts flowing to either service these appliances or replace them at no charge," he said.

"The gas rectification program will be funded by the producers who intend to supply gas with a leaner energy content, ensuring safety to residential consumers, schools and other institutions."