Searcher is reprocessing 3D data with CGG on trend with the Pluto, Io-Jansz and Wheatstone fields in the Carnarvon Basin, using new technology to enhance imaging of the Jurassic and Triassic plays.

 

Chevron Australia's general manager, asset development Gerry Flaherty recently said there were "a lot of plays" below the main existing 3600m exploration window.

 

Searcher's geoscience manager, Josh Thorp, confirmed to Energy News that his company's work was targeting the Triassic play in that area, which has been opened up since Quadrant Energy and Carnarvon Petroleum made the play-opening Phoenix South discovery in once-discounted Triassic reservoirs within the Bedout Sub-basin.

 

"We're trying to look at existing plays and try to image them better as they were poorly imaged previously, then look at the plays below that as well," Thorp said.

 

He said that compared to other basins in the world, the Carnarvon, Browse and Bedout areas were "definitely underexplored if you look at then number of wells drilled". 

 

"There's a lot of prospectivity out there, it's just trying to understand it in terms of the seismic data, and costs are usually an issue for operators to drill wells," he said.

 

"Seismic costs are pretty similar worldwide but getting to actually drill and test the lower plays [provide challenges for operators]."

 

The revolution underway is around deghosting and pre-stack depth migration, which Thorp described as "an evolution of all the processing algorithms and the seismic acquisition techniques together". 

 

"There's no one silver bullet, you just need to do good geoscience the whole way through," he said.

 

"There has also been a very gradual industry shift between true integration of the geology and the geophysics."

 

While 5-7 years ago there was a clear delineation between geophysics departments or seismic processing and geology, Thorp said he said the Australian industry is now seeing a much greater interaction with geoscientists.

 

"It's a culmination of a corporate culture change and technology improvements that have really started to unlock new plays and new ideas in the Carnarvon Basin, and really Australia-wide," Thorp said.

 

"There have been some small evolutions on some seismic technologies and some bigger ones in others, and really once you bring the whole basket of technologies together it can make really big differences."

 

Deghosting is trying to compensate for one of the effects of towing a seismic streamer underwater, while PSDM is where the collaboration between geoscientists and geophysicists comes in.

 

"You have one reflection coming up from the seabed, another coming down from the sea surface, and the latter is not really ‘real', so you're trying to remove that in a geophysically plausible manner, and that makes a big difference," Thorp said.

 

"The pre-stack depth migration is really where you see the integration of the geoscience and geophysics departments; that's trying to understand and create a ‘true earth' model that you fit your seismic data to, so you can really improve your understanding of the imaging."

 

Unique challenges 

 

Thorp said Australia has many unique challenges, especially in terms of seismic data, that are elsewhere in the world, so industry has had to adapt technology from around the world to the local problems. 

 

This is why there can be a lag in technology developments, as local industry tries to understand how to apply it in Australia; but there have already been some successes.

 

"Basically the geology is very different from, say, the Gulf of Mexico, with very different problems," Thorp said. 

 

"Essentially they have big salt domes and we have carbonate layers, and those are very different problems, geophysically speaking."