The remote location and extensive HFR resources of the Cooper Basin, Australia, require large scale multi-well exploitation as the optimal means of development. There is estimated more than 1,000 km2 of granite with a temperature of greater than 250?C at 4,400m. A combination of overthrust stress conditions and overpressured fractures has resulted in extensive stimulations in horizontally oriented fracture systems during fluid injection (hydraulic stimulation). Additionally fracture systems stacked on each other have been stimulated independently with low connectivity in the vertical plane. This leads to the possibility of developing stimulated fracture systems that extend over many square kilometres, with many injection and production wells operating within the fracture systems.

A conceptual model based on the current understanding of the geology and fracture hydraulics was implemented using the commercial finite element software package FEMLABÆ and "in house" Q-con development of the package. In the model injection and production wells were spaced up to 1,000 m apart in triangular or square grid patterns. Flow in stimulated fracture zones in the depth range 4,200 m to 5,000 m was simulated for a triangular pattern of 43 wells and a square pattern of 41 wells with a total flow of 600 kg/second for the well field per fracture zone. With a 1,000 m well spacing the well field covers 31 km2 for the triangular pattern and 32 km2 for the square pattern. From the model were computed: pressure distribution, flow distribution pumping pressure, temperature decline over time, thermal power, and temperature distribution in the rock matrix. The modelling shows that for a 1,000 m well spacing the production well temperature decline will be approximately 12?C over 20 years. and 40?C over 50 years. The life of a power station would be greater than 50 years with this temperature decline.

On the basis of the model a scale-up program has been developed once the "proof of concept" Habanero doublet circulation testing has been completed. The initial scale-up will be a 7-well program producing 40 MWe.

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