"We’re in the final stages of construction and commissioning on Curtis Island, and the upstream parts of the project … are complete," he said.
"If you think back to four or five years ago there were a lot of sceptics that this could ever be done – even one single project let alone three.
"It’s very satisfying to see QGC exporting cargoes, soon to be followed by ourselves (Santos) and Australia Pacific LNG."
Mr Brown said the sector had managed to overcome many hurdles to make the projects a reality.
"This is the first time in Australia’s history that a significant oil and gas resource has been located directly underneath a very significant intensive agricultural and farming area," he said.
"That has required a lot of change over the last few years, and to do it at the scale and the pace that we’ve all collectively done has meant that we’ve had to really push the boundaries of how fast people can digest that change.
"Queensland has done that extremely well through a variety of agencies and through the commitment and bipartisan support of the State Government.
"This sector is an important one … to put Queensland on the map as a reliable supplier of LNG.
"When all three of these plants are up and running reliably, safely and efficiently, we will then underpin our reputation in the marketplace as a reliable and safe provider of LNG to world markets.
"This amount of infrastructure installed in Queensland sets Queensland up for a very rosy future."
Also speaking at the event, QGC Managing Director, Mitch Ingram said: "We delivered our first LNG in December 2014 and that was a key milestone for us at QGC but also for the industry."
"It really proved that natural gas from coal seam to LNG is a viable proposition," he said.
"Since then we’ve had 16 cargoes.
"Our emphasis now really is on transitioning from the project world – which we’ve been in for quite a few years – to safe, sustainable and efficient operations."
Australia Pacific LNG Chief Executive Officer, Page Maxson said: "On Curtis Island, we’re a few months away from starting up later this year."
"But upstream we’re actually already in full scale operations," he said.
"We’ve worked a lot together to share learnings, to share best practices, really for the benefit of Queensland and the community."