ENERGY News' exclusive report just before Christmas that Wood Mackenzie analysis sees WA facing a 150 million standard cubic feet per day gas shortfall by 2021 should be "ringing alarm bells" within government, gas users say.

The report appeared to contradict the recent WA GSOO, prepared by the former Independent Market Operator, which forecasts excess supply in the market out to 2025.

In its base case scenario, supply is forecast to grow on average 2.4% per annum to 2025, reaching 1486TJ per day (1401MMcfpd). In the same scenario, demand is forecast to grow by only 0.1% pa, reaching 1083TJ/d (1021MMcfpd) by 2025.

While the GSOO - which guides government decision making on issues affecting the supply of gas to the domestic market - painted a rosy outlook of excess supply for the state, domestic gas users had already questioned its accuracy and findings, with particular concerns about the supply outlook beyond 2020.

Wood Mackenzie's revelation backed those concerns, with the firm's WA lead analyst Saul Kavonic telling Energy News that the significant gas supply shortfall from 2021 would be "painful" for domestic gas users.

"The key thing is that the shortage is there and we don't really have a line of sight to where that gas is going to come from," Kavonic said.

DomGas Alliance executive director Matt Brown said it was "beyond belief" that WA - a state rich in gas resources, enough to feed multiple multi-billion dollar LNG projects - should be struggling to provide enough gas for its own domestic security,

"We are deeply concerned that the unjustifiably optimistic outlook of the recent GSOO has lulled the government and others into a false sense of security," Brown said.

"The Alliance said at the time that the GSOO simply did not reflect the reality of the marketplace.

"It is now absolutely essential for there to be an independent review of the compilation of the GSOO so that the domestic gas users and the community can have clearer understanding of the domestic gas supply challenge facing our state.

"The danger here is that if the government is making decisions based on the GSOO outlook, it is likely to be making the wrong decisions."

When contacted by Energy News, a Department of State Development spokesperson said that while Wood Mackenzie was a credible analyst, forecasting gas demand and prices over long periods was uncertain.

The spokesperson pointed out that WA's Independent Market Operator's November 2015 GSOO considered that domestic gas supply would tighten after 2020, but the market was reasonably well supplied for the foreseeable future.

"Presently, demand has softened," the spokesperson said.

"The government is securing Western Australia's energy needs through its domestic gas policy, which requires LNG producers to reserve gas for the domestic market, ensure the gas can get to market, and market the gas.

"LNG exporters comply with the policy as a condition of project approval.

"[The Chevron-operated] Gorgon and Wheatstone domestic gas facilities under construction will supply 500 terajoules a day, equivalent to half current consumption. New domestic gas commitments for the North West Shelf contribute 100Tj a day."