Shale gas
[Music plays and text appears: Unearthing shale gas. What is shale gas, how is it extracted and what are some of the challenges involved?]
[Image changes to show a computer generated cross-section of land with the shale rock level labelled]
Narrator: Shale gas is mainly methane trapped within shale rock layers at depths greater than 1.500 metres.
Australia’s shale gas industry is largely in the exploration phase. This involves drilling vertical and horizontal wells and hydraulically fracturing, or fraccing, the shale rock to see if gas can be produced economically.
[Image changes to show the drilling lines appearing on the computer generate cross-section of land, with markers at both 1,500 and 3,000 metres deep]
When in the production phase, wells are drilled anywhere from 1,500 to 3,000 metres deep, through various layers of rock to access the shale.
To protect groundwater from contamination the well is lined with cement and steel casings.
[Camera zooms in on the well and shows the cement and steel casings]
Horizontal drilling is a technique used to maximise shale gas recovery and minimise surface impacts.
[Image changes to show a line appearing underground on the computer generated cross-section, labelled Horizontal Drilling]
Before gas production can start hydraulic fracturing needs to occur.
[Camera zooms in on the on the section labelled Hydraulic Fracturing]
This involves perforating along the horizontal portion of the well to gain access to the shale rock.
Water containing chemical additives is pumped under high pressure to open up existing fractures and create new ones within the shale rock.
[Image changes to show water running through the fracture. Camera zooms in on a drop of watered labelled 1 % chemical additives and 99 % water proppant]
Proppant, such as sand is then added to the water that flows through to the fractures.
[Camera zooms in on the sand moving through the water in the fracture]
The sand keeps the cracks open allowing the gas to flow to the well and up to the surface.
[Image changes to show the process being repeated and new fractures appearing]
This process is repeated several times within the horizontal portion of the well, with each fracturing stage separated by a plug. At the end of the hydraulic fracturing process the plugs are removed and production can start.
[Camera pans up the computer generated image to reveal the well head where a truck and equipment can be seen extracting the water and gas]
Shale gas and any produced water flow to the well and are pumped to the surface and separated at the well head.
Extracted gas is processed and transported for domestic and/or international use.
[Diagrams of the process appear on screen beginning at the cross-section of land where the shale is extracted, moving to a Gas compressor station (cleaning and compression), with two arrows off that box showing a Domestic use box and Export box]
The produced water is treated, then either used in future hydraulic fracturing jobs, or disposed of in accordance to state government regulations.
[Diagrams of the process appear on screen beginning at the cross-section of land, moving to a Water treatment box and then to a Re-use or disposal in accordance to state government regulations box]
A source of concern is the amount of water used in the hydraulic fracturing process.
[Image changes back to show the computer generated cross-section of land with text: 20 Megalitres – eight Olympic pools appear on top of the text]
An average of 20 mega litres of water can be used per well, which would fill about eight average Olympic sized swimming pools.
Another possible impact is groundwater contamination from accidental surface spills or leaks of produced water and hydraulic fracturing fluids.
[Image changes to show the truck reversing and a spill can be seen coming from under the truck]
Other potential environmental impacts include the industry’s greenhouse gas footprint, fragmenting of local habitat and changes to rural communities.
[Camera pans out on the computer generated cross-section of land]
CSIRO is conducting research to better understand the impacts of shale gas development and develop sound technologies and practices to ensure socially and environmentally responsible development.
[Text appears: Research to inform decisions. Visit the CSIRO and GISERA websites for more information and latest research. www.csiro.au, www.gisera.org.au]
[Music plays and CSIRO logo appears with text: Big ideas start here www.csiro.au]
Unearthing shale gas – GISERA video