Unearthing conventional gas

What is conventional gas, how is it extracted and what are 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.

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Unearthing conventional gas – GISERA video