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What is coal seam gas?

Coal seam gas is natural gas found in coal seams, formed as a by-product of the conversion of plant material to coal, and primarily consists of methane, which is an odourless, colourless gas. It is used in the same ways conventional gas is used to power hot water systems, heaters and for a wide range of industrial uses.

How do you decide on well location?

The location of our coal seam gas wells is flexible. We work with landholders to locate our wells and associated infrastructure to minimise impact to the landholder's current and future land uses. We are mindful of our impact on the neighbours and do everything possible to minimise any disturbance.

What is the process of entering into an access and compensation agreement?

If AGL is interested in placing a well on a property, the first thing we will do is to arrange a member of our Land and Approvals team to contact the landholder. The Land and Approvals team member will be the landholder’s key point of contact. Informal conversations will take place before any formal agreements need to be entered into. This will give the landholders time to ask any questions they have, including to our environmental, groundwater and technical specialists. This will also enable AGL to take into account any specific constraints or considerations the landholder may have, and discuss potential locations of infrastructure taking into account those matters.

How long will AGL be on my property?

The amount of time we are on your property will depend on the type of operation taking place. Your AGL Land and Approvals contact will be able to advise you of the specifics of your property. Production wells generally have a life span of 15-20 years. After that, AGL will decommission and rehabilitate the well site. The surface will look as good as or better than before operations began.

Will I receive compensation for AGL activities on my land?

AGL will compensate landholders for activities on their land. Compensation will depend on the value of the land, as well as the type of activity proposed to be undertaken.

What happens if a gate is left open?

AGL personnel and all contractors are inducted into each site and part of the induction includes any particulars regarding your property. The general rule for all personnel accessing private property is to leave the gate as you find it and any AGL person that does not follow this procedure will be subject to disciplinary action and any stock losses that arise will be compensated by AGL.

Will your operations cause subsidence on my land?

No. Previous work has demonstrated that AGL’s coal seam gas production activities do not cause measurable subsidence.

Will coal seam gas activities impact my groundwater?

The local geology of an area determines what impact (if any) might occur to shallow groundwater as a result of coal seam gas activities. In many of the areas that AGL operates the impact is expected to be negligible.

In addition to the natural geological conditions that exist, protection of shallow groundwater is established by having strict environmental management plans and groundwater monitoring plans and monitoring networks in place, constructing wells to best industry practice and monitoring well integrity, and containing and disposing all drilling and fracture stimulation fluid (where applicable).

Learn more about how AGL protects Gloucester's water.

How will the site be rehabilitated?

AGL works with landholders and farm managers to create a rehabilitation plan for their property. As no two properties are the same early consultation will take place to determine the best way forward for the rehabilitation. The aim is to get the land back to its original state or better in the quickest time possible through reseeding and monitoring.

Are the wells safe enough for my stock to be near them?

Production wells are fenced and cattle are unable to access the well.

Can I have access to environmental reports relating to my land?

Yes. If you would like them, AGL will provide you with copies of any environmental reports (such as groundwater studies) which are relevant to your property.

Will the community be kept informed throughout the project?

Yes. A thorough community engagement program will be prepared to ensure landholders and the community are informed throughout the duration of the project.

The community will be kept informed throughout the project via a number of communications mechanisms, including; community updates, fact sheets, letters, meetings, project website, and through the Community Consultative Committee (CCC).

What is seismic exploration?

Seismic surveys are a non-intrusive exploration method used to create a map of the structures beneath the Earth’s surface. The method sends sound waves into the Earth, where the different rock formations then reflect the waves back to the surface. The information is recorded over a period of time measured in seconds.

Geologists and geophysicists can then interpret this data to understand where possible petroleum reserves might be located, to identify areas that are unsuitable for coal seam gas exploration and to gain a regional understanding of the geology of the area.

What is a core hole?

A core hole is a hole drilled to take a core sample of coal and its surrounding geology. A core hole is typically 10 centimetres in diameter and can vary in depth from 300 metres to 1,500 metres, depending on the depth of the targeted coal seams. A piece of core sample is typically five to six centimetres in diameter and sectioned into one metre lengths. Once core samples have been collected, they undergo a variety of tests to understand the rock, coal and gas properties including the amount and type of gas contained within the coal. Other tests including down hole logging and analysis is also undertaken to provide geophysical information.

How is a core hole drilled?

An area of approximately 60 by 60 metres is usually required for drilling core holes. The process used for drilling is similar to that used for domestic and irrigation bores, but at a larger scale.

A drill rig is needed to extract the core samples. Different rock structures dictate how quickly a core hole can be drilled, but typically the drill rig will be on site for up to eight weeks.

Core holes are lined with steel casing cemented to the side of the hole, both for safety reasons and to isolate any aquifers that are intersected during the drilling process.

Once the core sampling and testing is complete, the well is backfilled, or plugged, and cemented all the way to the surface. A marker is placed at least two metres below ground level to mark the top of the well. The site is then remediated to its original state or as prescribed by the landholder.

What is a stratigraphic hole?

This involves drilling exploration holes to retrieve and test drill cuttings and complete subsequent down hole logging and analysis. The holes are typically designed to provide geological, permeability and gas composition data.

Stratigraphic holes are generally cemented, plugged and abandoned in accordance with requirements, and then rehabilitated, unless the holes are needed for further exploration testing.

An instrument called a piezometer may be installed into the hole for ongoing data collection and the hole may be capped and suspended for future testing work.

What is an exploration test well?

A test well is a gas well used to investigate the potential gas reserves in an area. It is used to measure the flow of gas and the volume of water produced from the targeted coal seam. A well is drilled down to the coal seam of interest. The well is fully cased with steel and concrete. The casing is perforated at the coal seam to allow the flow of water and gas from the seam.

A test well generally operates for several months to collect the necessary data. Once the testing is complete the well may be removed and the site rehabilitated or it may remain in place to allow for testing of other coal seams.

What happens when a coal seam is hydraulically fractured?

When hydraulic fracturing a coal seam, a fluid (the “fracture fluid”) is injected into the seam at pressures high enough to widen the existing fractures in the coal. Sand is then pumped in to hold the fracture open, which creates a better path for gas and water to flow out of the coal seam and back to the surface.

Typically for AGL’s operations, fractures are millimetres wide and extend for tens of metres into the coal seam. The process is carefully managed so that there is minimal impact on the rock layers above and below the coal seam.

What is a fracture fluid?

The ingredients used to make up a fracture fluid are determined by the specific characteristics of the target coal seam, such as the ability for water or gas to flow through the coal (permeability), the number of coal seams, and the coal formation’s thickness, and stress or mechanical properties of the coal. The fluid used also depends on the desired length and direction of the fracture. Learn more about AGL's hydraulic fracturing activities.

The fracture fluid is designed to have a certain viscosity or fluid thickness. A low viscosity fluid, like water, tends to flow more easily and faster; while a high viscosity fluid, like honey, tends to flow less easily and slower.

Most fracture fluids used by AGL are simply sand and water. Sometimes small amounts (usually less than 2 percent of the total volume) of commonly-used household chemicals are added to prevent bacterial growth, to make it easier to pump the fracture fluid into the coal seam, and to thicken the fluid so that less water is needed to carry the sand into the fracture.

Are the fracture fluids used in coal seam gas wells safe?

Yes. The chemicals used are highly diluted when injected into the coal seam and are then further diluted by the naturally occurring water in the coal seam.

No BTEX chemicals (Benzene, Toluene, Ethylbenzene and Xylenes) are used or have ever been used by AGL in any of its fracturing fluids. Any chemicals used must be disclosed to, and are assessed for safety by, government agencies during the application process and before the hydraulic fracture operation takes place. Under the recently announced NSW Code of Practice for Coal Seam Gas Fracture Stimulation, full disclosure is required of all additives used for fracturing in NSW. A human health and ecological risk assessment is conducted for every fracture fluid and its constituents must confirm that the use of a fracture fluid is of minimal risk before being used.

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