Northern Perth Basin | Southern Perth Basin
The Perth Basin is a long and deep sedimentary basin that extends for about 700km along the southwestern margin of Western Australia. The basin is up to 15km deep and overlies Archean and Proterozoic gneissic basement. The Basin supports a large proportion of Western Australia’s population and major industries and consequently contains excellent power infrastructure to support geothermal development.
The northern part of the Perth Basin is situated in the Mid West region which is host to a number of large iron ore mines and major projects poised for development.
The Perth Basin consists of alternating sequences of sandstone, shale, coal seams and other sedimentary units. The lower units in the Basin are predominantly shale, while the upper parts have considerably more sandstone. This distribution of lithologies is ideally suited to geothermal formation as the lower shales will act as a thermal blanket, trapping in heat from depth. This will assist Hot Rock development in the gneissic basement and will concentrate heat in intervening sandstone aquifers.
The Basin has undergone extensive oil and gas exploration. Down-hole temperature measurements recorded during this exploration provide a good understanding of the distribution of heat and enables geothermal potential to be assessed. The presence of high temperatures in localised areas demonstrate that there is extremely good potential for the Basin to host viable geothermal resources.
New World Energy has undertaken a detailed geoscientific study of the Perth Basin to assess its geothermal potential and to target areas with the best geothermal resources.
Northern Perth Basin
New World Energy has acquired eight Geothermal Exploration Permits in the northern Perth Basin. These were targeted using the parameters discussed above and cover the highest defined geothermal gradient areas in the Perth Basin (Chopra & Holgate, 2007).
Importantly, all of the permits in the northern Perth Basin are close to existing and proposed transmission lines.
The southern-most block of five permits (Woodada-Jurien project) encompasses the entire Woodada gas field owned by AWE Limited. Eastern parts of the project, in the vicinity of the gas field are prospective for both Hot Aquifer and Hot Rock resources, while western parts are predominantly prospective for Hot Rock resources due to the shallower depth tobasement across the Beagle Ridge.
The northern three permits (Dongara project) partially cover the Dongara gas field owned by AWE Limited. Because the basement shallows to the north and it is exposed at surface northeast of Greenough, the relatively thin sedimentary succession is unlikely to host water that is hot enough for electricity production. However, the high geothermal gradients suggest that there is good potential for Hot Rock resources to occur in the basement in this region.
|Jurien-Woodada Geothermal Resource Statement
In October 2009 Hot Dry Rocks Pty Ltd undertook an initial resource estimate at New World Energy’s Jurien-Woodada project (GEP’s 15, 16, 19, 20 and 21) based on information from 14 historical petroleum wells that it used to constrain 3D temperature modeling. This resulted in an Inferred Geothermal Resource estimate totaling 120,000 petajoules (thermal) from a Hot Aquifer resource play with a total estimated reservoir volume of 433km2. A summary of the key findings of the full technical report dated 30 October 2009 is presented below.
| This resource estimate was based on the following assumptions and parameters:
- cut-off temperature of 125°C;
- base temperature of 70°C;
- model base of 5,000m;
- proposed use of the geothermal resource for electricity generation via air-cooled Organic Rankine Cycle binary power plant generator;
- resource temperatures inferred from conductive heat flow models constrained by 14 surface heat flow values;
- the stated resource does not include any additional heat that might conduct into the reservoir volume during production;
- the stated resource assumes that advective or convective processes transfer no significant heat; and
- that the average proportion of fluid in the reservoir is 5% and that the heat is stored in both the matrix of the reservoir rock and contained fluid.
Southern Perth Basin
New World Energy’s single permit in the southern Perth Basin is located at Binningup, approximately 120km south of Perth.
Although the area has undergone considerably less petroleum and gas exploration than the northern Perth Basin, the area contains a basement ridge (Harvey Ridge), which is a similar geological feature to that which hosts the high geothermal gradients in the northern Perth Basin.
New World Energy is particularly interested in the permit due to the unique market opportunities that exist within its bounds. The permit contains the site of the proposed Binningup Desalination plant, which will require about 100MW of electricity powered entirely by renewable energy.
The permit also contains the Kemerton Industrial Park which is set to be a major heavy industrial area for southwestern Australia. The permit is ideally situated for the supply of electricity and/or hot water for use by industries in the park.
New World Energy plans to assess the geothermal potential of the permit in the context of the local markets and opportunities.