The innovative use of helicopters to conduct 3D seismic surveys onshore has only two precedents - on the environmentally sensitive Barrow Island and in the mountainous terrain over the Taranaki Basin in New Zealand.

The move follows Empire's success last year at Gingin West-1 and Red Gully-1 in EP 389, which showed 3D seismic was crucial to unlocking the hydrocarbon potential of the highly faulted Perth Basin.

Empire managing director Craig Marshall told Energy News Premium the heli-seismic survey could be done more quickly and also produced data of much better quality compared to conventional 3D surveys.

"The environmental impact is substantially less with the heli-seismic, which uses a small explosive charge rather than taking in vibrating trucks," he said.

"We fly in a little drilling rig with the helicopter, drill a small vertical well and put the charge in and we leap across from one shot point to the next - we're not driving in a vehicle.

"These charges are small. You won't even see any dirt flying out of the hole.

"As soon as you finish, each charge hole is rehabilitated and that's it.

"You don't need to recultivate the lines, revegetate or anything.

"We'll be doing that whole seismic survey by helicopter."

Marshall said small explosive charges also provided "seriously good quality data. Each profile is going to give surface velocity as well as deeper imaging".

The heli-seismic survey in EP 389 was planned to take place in about the third quarter of the year, which is when he expected to have all environmental and landowner approvals in hand.

A botanical survey of the target area has already been completed.

"The government likes it because it is less invasive. It leaves much less of a footprint," Marshall said.

"Then we have the safety plan to complete and of course to take landowners through the plan and educate them about what we're proposing."

The survey will provide an extension of the 3D data used to make the Gingin West and Red Gully discoveries and it is expected to define the locations for proposed wells Wannamal-1, Gingin-4 and Gingin-5, as well as some other prospects.

"We would like to drill more than one well," he said.

"We would like to increase our exploration in the Perth Basin by drilling back-to-back wells and recording seismic similarly.

"The seismic crew that conducts the 3D survey in EP 389 will most likely also be used to conduct surveys in our newly awarded permits in the south."

Marshall said the Gingin West and Red Gully discoveries would mean Empire's future was firmly focused on the Perth Basin.

"We have sold our Canning Basin assets into Key," he said.

"We will probably do something else with our Carnarvon assets, so Empire will become purely focused on the Perth Basin.

"Within the permit where we have the two discoveries, there's almost a lifetime's work within that permit.

"It's a big permit and we have a trend there of over 60 kilometres of prospects to drill.

"We have over 10 permits and in excess of five million acres of permit under tenure on Perth Basin alone.

"These days, once you have a discovery I think you better focus on where you have had success and develop that. I believe that's what shareholders want."

First sales of gas and condensate from Red Gully and Gingin West are expected in the third quarter of this year.

It will be the first revenue Empire has earned from the Perth Basin since it began exploring in the area in 1996 (although not its maiden revenue, which came from the sale of small volumes of oil from Rough Range in the Carnarvon Basin, which was shut in several years ago).

It's a major milestone for the company and a vindication of its long-held faith in the Gingin field, a Jurassic discovery by WAPET in the 1960s but shut in a few years later when WAPET discovered the Dongarra gas field.

Gingin was viewed almost universally by industry as a tight gas field without commercial potential but Empire held a different view.

"When we started back in 1996, it was written in various papers and perpetuated that the Gingin reservoirs were tight," Marshall said.

"We didn't take that on board, we said these sands in Gingin-1 have flowed for 18 months at a maximum rate at 5 million cubic feet of gas per day from the Lower Cattamarra measures.

"That's not tight gas. And it was deeper and potentially not as good a reservoir as the sands we were targeting withun Gingin West and Red Gully.

"I don't think people were able to see the opportunity but now we've demonstrated that."

The big breakthrough came when 3D seismic over the Gingin West structure showed there were also deeper playes in the Jurassic Lower Cattamarra reservoirs.

The same play type in Permian rocks was well understood as a prolific source of oil and gas in the northern Perth Basin, giving rise to such fields as Dongarra, Jingemia, Hovea and Beharra Springs.

"We're starting to understand this Jurassic play more and more and as we record seismic we keep finding prospects. It's definitely encouraging," he said.

"In this particular area, if you spend the money to record the 3D seismic - and it's not cheap, you will substantially reduce your risk.

"If you can find a closed structure in the Perth basin, the likelihood of finding hydrocarbon in it is high.

"If you can find a four-way dip anticline, you have really reduced your risk.

"These are rare but Gingin West is one such feature."

Marshall said Empire was finally getting it tight but he believed it could do better.

"We've drilled the lowest risk stuff, not necessarily the biggest prospects," he said.

"Now we will start drilling some of the bigger prospects and the bigger prizes."

Empire currently estimates potential recoverable gas of 30 billion cubic feet and associated condensate for the two discovery wells.

Marshall has stated the areas around the wells have potential for another 200Bcf of recoverable gas and another 9-10 million barrels of recoverable condensate.

These are big numbers for any junior explorer and possibly just the start for Empire as it gears up to lift the pace of discovery and development.