According to Bloomberg, the United States oil giant owns 37.5% stakes in two of the blocks - T/32P and T/35P - and 50% of T/36P.

Santos as operator owns stakes of identical proportions to Chevron, while Mitsui holds 25% of T/32P and T/35P.

Interested investors must sign a confidentiality agreement to gain access to a data room in Chevron's Perth office, accessed via Schlumberger's energy-marketing website.

Last year, Santos shot more than 2000km of 2D seismic in the Sorell, which is being interpreted and analysed.

This is in addition to another 3680km of 2D seismic acquired in previous years.

Drilling could start in 2008-09.

While its mapping has identified multiple trap types, Santos has focused on large structural traps that could hold the volumes needed for frontier economics.

The basin is one of Australia's least explored regions.

Only two exploration wells have been drilled so far - Esso's Clam-1 in 1969 off the northwest tip of Tasmania, which was dry, and Amoco's Cape Sorell-1 off Strahan in 1982, which found live oil shows in sediments below 3000m.

Santos' exploration team says geological studies indicate the working petroleum systems that have led to exploration success in the eastern Otway Basin are likely to extend southwards into the Sorell.

Play fairway mapping has identified areas with the potential for mature source rocks capable of expelling oil and gas into quality reservoirs.