About Shale Gas
- Shale gas is natural gas produced from shale (source) rock.
- A clean form of energy produced form shale formations, usually 2-3km below ground level.
- Produced by a process known as hydraulic fracture stimulation (fraccing) – injecting water and sand solution (99.5% on average) and some chemicals at high pressure into the shale rock formations to create small microscopic fracture networks in the rock through which gas can flow.
- Shale gas first commercially extracted in 1821, with hydraulic fracture stimulation first commercially employed in 1947.
- Shale production in the USA has rapidly increased as technology continues to improve; it is an emerging industry in Australia.
How does shale gas production differ from coal seam gas production?
Shale gas is located in rocks 2-3 kilometres below the surface, far below surface aquifers. Coal seam gas in located in coal beds close to the surface.
What is hydraulic fracture stimulation
- Shale reservoirs have very low rock permeability which makes it very difficult for gas or oil to flow.
- Hydraulic fracture stimulation involves pumping (typically) water and sand, with 0.5% additives down the well at high pressure. This creates a network of microscopic cracks in the rock, and the pumped sand (called proppant) helps to ‘prop’ or hold the cracks open so that the natural gas can flow out the well.
- Hydraulic fracture stimulation has been used on over one million producing wells worldwide, and operators now fracture up to 35,000 wells per year.
- Both conventional and unconventional wells are fracced, to assist in hydrocarbon flow to surface.
Development of Shale Gas
- One exploration well or one multi-well pad requires the temporary clearing of 2-3 hectares.
- Horizontal wells allow production from up to 5km2 from a single well pad.
- Multiple wells are required for a successful commercial development.
Shale gas potential in Australia
- Many conventional oil and gas plays are mature – energy future value depends on unconventional discoveries.
- Potentially a large shale gas resource.
- Development timeline governed by prospectivity, commercial and economic drivers, and regulatory matters (approvals processes, environmental, native title, etc).