PETROLEUM AND HOT DRY ROCK: TWO TYPES OF ENERGY SHARING COMMONALITIES

Abstract

The Cooper Basin is the largest gas-producing basin in Australia and hosts a huge volume of natural gas in low permeability (known as 'tight gas') sandstone formations. Hydraulic fracture treatments, based on 'opening mode' fracture mechanics, are routinely carried out to unlock tight gas and to accelerate its recovery. Information regarding insitu stresses and natural fractures is required for successful fracture treatments. However, hydraulic fracturing is still often problematic, in part due to the relatively high insitu stresses and temperatures in the region. A vast amount of Hot Dry Rock (HDR) geothermal energy resources exists in granites below the sedimentary rocks in the Cooper Basin. Exploitation of HDR requires the same drilling and completion technologies as used in the petroleum industry. Hydraulic fracturing is also necessary for HDR reservoir creation, and requires characterisation of insitu stresses and natural fractures, as does tight gas production. It has been realised that the mechanism for reservoir stimulation in granitic rocks is proppant free shear dilation that is related to 'sliding mode' fracture mechanics. Furthermore, seismic imaging of hydraulic fracture propagation is well established in the HDR industry. These two technologies, developed in HDR, may have potential application to the petroleum industry for tight gas production. The geographic proximity of tight gas and HDR geothermal energy in the Cooper Basin and common exploitation technologies should justify close collaboration between the petroleum industry and HDR researchers.