A team from Australia, New Zealand, the USA and Korea have gathered at the Nirranda site to assess the ways carbon dioxide is trapped permanently in rock formations during deep geological storage.

The stage two works are part of research into carbon capture and storage technologies, which are aimed at making deep cuts in global carbon dioxide emissions.

"Over the past two years, the Otway Project has demonstrated that we can safely store and monitor geologically stored carbon dioxide," said Dr Peter Cook, Chief Executive of the CRC for Greenhouse Gas Technologies, which is leading the international team.

"In this new research we will be injecting carbon dioxide and water and then extracting it to determine how much gas is trapped in the tiny rock pores and how much is dissolved in formation water.

"Both these mechanisms are believed to be important in trapping carbon dioxide permanently underground."

By using the instrument array to measure pressure, temperature and tracer gas concentrations, scientists will get field measurements of the amount of carbon dioxide securely stored by these methods.

A system which allows samples to be taken from the reservoir 1400 metres underground, known as a U-tube system, is also part of the instrument package.

"We used the U-tube system during Stage 1 of the Otway Project and found it immensely useful," said Dr Barry Freifeld, from Lawrence Berkeley National Laboratory in California.

"The system enables us to chemically analyse samples of water and dissolved gas direct from the reservoir, at original pressure. We can see precisely what's going on underground."