Following positive reservoir tests and a power plant deal with Origin Energy, hot rocks pioneer, Geodynamics, raised $5m last week through a share placement to put working funds into stage two of its Cooper Basin geothermal project.

Meanwhile, after successfully spinning off its uranium assets into Curnamona Energy last month, mining company Havilah Resources also announced its entry into geothermal energy.

Havilah said its substantial land position south of Lake Frome in South Australia covers an area of buried granite with the potential for geothermal energy. Havilah's preliminary exploration work will involve gravity surveying followed by deeper drilling of geothermal target zones to identify reliable heat flow measurements. The company said that if results were positive it expected future exploration to follow the same course as Geodynamic's Cooper Basin project.

Another hot rocks player, Green Rock Energy (formerly Mokuti Mining), finalised its name change and its acquisition of Perilya Geothermal Energy and Green Rock Energy's blocks in the Olympic Dam area of South Australia, covering 2,700 square kilometres.

Green Rock plans to start drilling the first of up to four 1.5 to 2 kilometre-deep test holes in the next couple of months. The cored drill holes will better define the temperature and rock properties at depth and the top of the geothermal energy anomaly, the company said.

Drill core and measurements collected from the drill holes will let Green Rock refine the drilling location of the first deep geothermal energy well. Depending on the success of these four holes, the company intends to drill its first geothermal energy well in 2006.

Meanwhile Minotaur Resources spin-off Petratherm has won a $140,000 South Australian Government "Plan For Accelerating Exploration" (PACE) grant to support the drilling of an evaluation well at its Callabonna prospect.

Drilling is to begin in about two weeks, according to Petratherm.

"The well, to be called Yerila-1, is named after the granite of the same name which outcrops just 40 kilometres south-west of the drilling site and is one of the highest heat producing granites known – over 20 times more than normal granites," the company said.

Yerila-1 will be drilled to a depth of about one kilometre depth, passing through an artesian aquifer modelled at 620 metres, and then penetrating into the interpreted Cooper Basin equivalent strata below. Data collected from the well will enable calculation of inherent stress characteristics and a temperature gradient profile.

On completing the Callabonna program, the rig will be moved to the Paralana-1 site in permit GEL178 to complete the Paralana geothermal evaluation well to 600m.

"Paralana-1 was spudded in mid January but encountered unstable hole conditions and was halted at 306 metres," Petratherm said.

Temperature gradient data gathered from the geothermal evaluation wells at Callabonna and Paralana will be used to determine whether significant geothermal resources exist at these sites.

But the only company with a current known resource is Geodynamics, and managing director Bertus De Graaf said converting the resource to reserves was the main focus of the game.