The wider HQ diameter portion of the well had been successfully drilled to 1442m and secured with steel casing. Drilling had now restarted with smaller diameter NQ coring, with the well currently at a depth of 1590m.

First-pass temperature logging, performed after the HQ casing had been put in place, indicated the rate of temperature increase was in line with the company’s original target expectations to produce economical viable electricity generation, that being resource temperatures of 200 degrees Celsius or more at about 3.5km depth.

Petratherm said absolute determination of the temperature gradient would occur once drilling had ceased and the well had had time to reach thermal equilibrium with the surrounding rock strata, about three weeks after drilling operations ceased. This was expected to occur around mid-July.

The company said rocks encountered so far indicated that satisfactory insulating properties existed, giving encouragement for the continuation of the well beyond the initial nominal depth of 1500m.

This final stage of drilling was being undertaken to more accurately determine thermal conductivities and hence temperature gradient profiles of particular rock strata.

That information together with other geological data would be used should Petratherm proceed with its first geothermal production well at Paralana.