Learn more about onshore gas.

Useful information about conventional gas, coal seam and shale gas

What’s the difference between conventional, shale and coal seam gas extraction and what are the potential environmental, social and economic impacts and opportunities of these two extraction processes? Take a look at the short animations to find out.

Conventional gas

Unearthing conventional gas animation explores what conventional gas is, how it is extracted and some of the challenges involved.

[Music plays and CSIRO logo and text appears on a blue screen: Unearthing conventional gas, What is conventional gas, how is it extracted and what are some of the challenges involved?]

[Image changes to show a rotating 3D cross-section block of earth showing the different strata layers joined by a line to hexagons showing sea creatures and rocks on the left and text appears: Plant and animal matter such as plankton]

Narrator: Natural gas is mainly methane formed over millions of years from the breakdown of organic matter in rocks like shales and coals.

[Camera zooms in on the strata layers of the cross-section and arrows appear moving towards the top of the screen and then an inset image appears of rock and text appears beneath: Impermeable rock]

Over time gas can migrate up from the source rocks, either reaching the surface or becoming trapped under a layer of impermeable rock.

[Camera zooms out on the cross-section and the word “Sandstone” appears on one of the layers and then a square of permeable rock and text appears on the right of the cross-section: Conventional Gas Resource]

Conventional gas resources are trapped within layers of permeable rock like sandstone which allows liquid and gas to flow through making it possible to extract with conventional techniques.

[Image shows “Coal” and “Shale” labelled on the cross-section, and a square of less permeable rock and text appears on the right: Unconventional Gas Resource]

Unconventional gas resources are trapped within less permeable rocks such as shale or coal which need techniques like hydraulic fracturing or dewatering to extract the gas.

[Camera zooms in on the cross-section, and a line appears down the side through the layers and then the camera zooms in on the line to show the steel casing]

Once a gas reservoir is targeted and the well drilled, steel casing is cemented in place sealing the well bore from the surrounding environment.

[Image shows the gas moving to the surface of the cross-section and then a line appears joining the cross-section to a processing plant and then to a factory on the right]

Gas then flows to the surface where it’s collected and processed. Additional wells may be drilled to check the resource and increase production.

[Camera zooms in on the cross-section and shows a drilling site on the surface and then an inset swimming pool appears on the screen]

Conventional gas drilling uses around one to two megalitres of water, less than an Olympic sized swimming pool, depending on the well depth, diameter and geological conditions.

[Camera zooms in on the drilling area and then the image shows the drilling rig being removed and the top of the steel casing being capped with cement]

After all viable gas reserves are extracted wells are plugged with cement and capped to stop gas escaping.

[Camera zooms out on the cross-section again and a map of Australia appears on the right with a gold badge and a tick list covering part of it]

Australia’s gas extraction regulations are world leading and potential impacts must be managed appropriately.

[Camera zooms in on the cross-section and then the image shows a truck backing into the drilling area and then liquid spilling out of the back of the truck and seeping into the cross-section]

Some people are concerned about potential environment impacts of the industry, like possible surface and groundwater contamination from accidental surface spills or leaks of drilling fluids, waste water and by products. These could impact water for drinking or farming.

[Camera zooms out on the cross-section and it rotates in an anticlockwise direction]

Others are concerned about potential impacts of the industry’s greenhouse gas footprint and the changes to agricultural landscapes. As fewer gas wells are needed to extract conventional gas, than coal seam gas, a smaller surface area is disturbed.

[Camera zooms out and the cross-section disappears and then text appears: Research to inform decisions, Visit the CSIRO and GISERA websites for more information and latest research, www.csiro.au, gisera.csiro.au]

CSIRO’s research aims to better understand these impacts and ensure socially and environmentally responsible development.

[Music plays and the CSIRO logo and text appears: CSIRO, Big ideas start here]

Unearthing conventional gas

Coal seam gas

Unearthing coal seam gas animation provides an overview of the extraction process, from drilling the well to what happens to the extracted gas and water. Also explained are some potential impacts of coal seam gas development and the technique used to increase the rate of gas and water flow, known as hydraulic fracturing (fraccing).

[Music plays and text appears: Unearthing coal seam gas – What is coal seam gas, how is it extracted and what are some of the challenges involved?]
[Image appears of a farmland landscape on the surface of a cross section of land. Camera zooms down the cross section of land to a map of Australia and text appears: 1997 over Queensland]
Narrator: Coal seam gas has been part of Australia’s energy mix since it was first produced in Queensland in 1997, and development of the resource has been steadily increasing since then.

[A blue coal seam line appears on the rotating cross section of land and text appears: Coal seam]

Coal seam gas is mainly methane found within coal deposits trapped underground by water pressure.

[A line appears on the cross section of land moving through the rock to the coal seam and text appears: Surface, 300 m, 1000 m and Aquifer Aquitard]

To access the gas, a well is drilled – anywhere from 300 to 1000 metres deep through various layers of rock – to the coal seam.

[Camera zooms in on the well in the cross section of land and then a small block pops out of the side to show the cement and steel casing of the well]

To protect groundwater from being contaminated the well is lined with cement and steel casings.
[Camera zooms down to show water in the coal seam, text appears: Formation Water]

Water already in the coal seam is pumped out to release the trapped gas.

[Text appears: Hydraulic Fracturing and camera zooms in on well shaft to show perforations in well shaft]

If water and gas don’t flow freely, hydraulic fracturing, also known as fracking, may be used to increase the rate of flow. Hydraulic fracturing involves perforating the casing at different levels along the well, to gain access to the coal.
[Image shows water moving down the well shaft and into the coal seam. A single water drop appears and text appears: 1% chemical additives, 99% water & proppant]

Water containing chemical additives is pumped under high pressure down the well, opening up existing fractures and creating new ones.

[Camera zooms in on the coal seam to show sand in the water and then zooms out to show the well shaft and the water and sand moving up the well shaft]

Proppant, such as sand is then added to the water that flows through to the fractures. The sand keeps the cracks open allowing the gas to flow to the well and up to the surface.

[Camera zooms up the well shaft to the well head at the surface. Image shows the well head with a truck and a pumping station. Text appears: Produced Water = hydraulic fracturing fluid + formation water]

Produced water and gas are pumped to the surface, and separated at the well head.

[Camera zooms out to reveal the whole cross section of land with arrows pointing left to three hexagons showing what happens to the gas and arrows pointing right to six hexagons to show what happens to the water]
The extracted gas is processed and transported for domestic and international use. Produced water is treated to remove salts and other chemicals and then either re-used or disposed of according to state government regulations.

[Camera zooms in on the cross section of land again and shows the well. Image appears of a cube of the Aquifer and Aquitard layer: text appears: On one cube Aquifer and the other cube Aquitard . Over decades and thousands of years
A source of concern is that hydraulic fracturing fluids may leave the coal seam and enter fresh water aquifers, which are layers of porous permeable rock that allow water to flow through easily.

This risk is reduced by layers of rock with low permeability, known as aquitards, which limit water flow and can act as a barrier.

[Camera zooms back to surface of cross section of land and image shows a truck with fluid spilling from the rear]

Contamination of groundwater is more likely to occur as a result of accidental surface spills or leaks of produced water and hydraulic fracturing fluids.

[Camera zooms out to show the coal seam and the layers either side. Text appears to label the layers: Aquifer, Aquitard, Coal Seam, Aquitard, Aquifer]

Another impact is the lowering of water levels in aquifers. Removing large amounts of water from the coal seam decreases the water pressure within the rock layer containing coal deposits. Water in the aquifers can then move towards the coal seam. Just how fast and far this happens depends on the type of and connectivity between the aquifers and aquitards.

[Camera zooms up the well shaft to the surface again and then zooms in on a chimney spewing flame]

[Camera zooms out to show the cross section of land]

Other potential environmental impacts include the industry’s greenhouse gas footprint, fragmenting of local habitat, changes to agricultural landscapes and rural communities.
[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’]
CSIRO is conducting research to better understand the impacts of coal seam gas development and develop sound technologies and practices to ensure socially and environmentally responsible development.
[CSIRO logo and text appears: Big ideas start here, www.csiro.au]

Unearthing coal seam gas

Shale gas

Unearthing shale gas animation provides an overview of the extraction process, from drilling the well to what happens to the extracted gas. Some potential impacts of shale gas development and the technique used to increase the rate of gas and water flow, known as hydraulic fracturing (fraccing) are also explained.

[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

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