More fact sheets and answers to frequently asked questions can be found on our assets’ project pages.
How do we explore for Coal Seam Gas (CSG)?
CSG exploration aims to identifyand evaluate a gas resource. The process begins by identifying prospects and leads through geological and geophysical desktop studies. Hydrocarbon accumulations are then identified through drilling core and stratigraphic holes. The potential size of the discovery is then evaluated, as is the gas discovery to see if enough gas will flow to warrant commercial production.
What is the life of a producing CSG well?
It is expected that a CSG well will be commercially viable for about 15 years. After that, AGL will plug and abandon the well then rehabilitate its site. The surface will look as good as or better than before operations began.
What are gas reserves?
Reserves are amounts of a gas that are considered tobe commercially producible by a specialised independent company . Once a well achieves a commercial gas flow the reserves can beestimated. The estimators form a view on how much gas is likely to be produced based on the characteristics of the reservoir and the flow, content and composition of the gas.
Reserve levels are assigned a probability:
- 1P or Proved reserves are those quantities that are estimated with reasonable certainty to be commercially recoverable;
- 2P or proved plus Probable reserves are those quantities that are estimated with equal certainty to be greater than or less than actual commercially recoverable quantities.
- 3P or Proved, plus Probable plus possible reserves are those quantities that are estimated with low certainty to be greater than actual commercially recoverable quantities.
2P reserves are the most accepted for reporting purposed in Australia.
How does Upstream Gas consult with the community?
As outlined in AGL’s Sustainability Report, AGL’s goal is to connect AGL’s business and the community in ways which make a genuine contribution, engage our people and strengthen our business. Each Upstream Gas project plan includes a community engagement strategy tailored to the local stakeholders for that project.
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 geothermal energy?
Geothermal energy is power extracted from heat stored in the earth. The temperature beneath the earth’s surface increases with depth. Due to volcanic activity or radioactive decay in some parts of the world, heat is closer to the earth’s surface.
Why was water pumped onto the ground during water bore drilling at Windermere?
Large inflows of groundwater were encountered during drilling at this site. Most (about 70%) was contained on site and in tanks. After assessing options to complete the bore, it was decided that the least risk to the environment was to complete the drilling quickly and to use the adjacent depression to contain the excess water. The water was contained on a small area of AGL’s property and there was no run off onto other properties or into drains. At no stage was there any threat to waterways.
The lack of available tankers and temporary storage facilities (both on and offsite) was the primary trigger to pump to land. An assessment of options and environmental risks was completed and it was decided that continuing to drill and to complete the monitoring bores program was the least impact option.
If drilling was stopped and water levels allowed to recover, an additional 400,000L (or more of slightly salt water) would have had to be pumped and removed from site the following week using a fleet of trucks (increased noise, traffic and safety issues).
Was the water disposed of in accordance with license conditions?
Yes - The bore drilling referred to related to AGL’s ongoing groundwater monitoring program and had nothing to do with drilling for CSG. This was about drilling a bore for water, not for CSG. The two drilling programs – for water monitoring and for CSG exploration – are very different and involve different techniques and machinery.
The groundwater brought to the surface during drilling was disposed of in accordance with our water bore license issued by the NSW Office of Water under the Water Act. This approval allows for disposal of water to land during construction, although AGL was proactive in tankering most of the water from the site.
How much water was disposed of on site, and how salty was it?
Most of the 400,000 litres generated during the drilling of the monitoring bores was tankered from the site. About 120,000 litres was pumped from the drill site into a low lying depression within the adjacent lucerne paddock. The groundwater salinities varied between 9,000EC and 10,600EC (approximately 5,800 to 6,900 ppm salt). AGL would describe this as “slightly salty” given that seawater is 55,000 EC (approximately 36,000ppm salt).
Did this pollute/contaminate water or soils?
The groundwater that was pumped was between 9000 and 10500 EC. All drill cuttings had settled before water was pumped to the depression. Water was contained in the depression and did not overflow to or impact any waterways. Shallow groundwater in the alluvium is more saline (at 19500 EC) so this ponded water did not impact underlying shallow groundwater (it may have in fact improved the quality).
Soils in the area of inundation would have an increased salt content but with irrigation and recent rain, these salts will migrate through the soil profile. Impacts to soils in this water logged area are expected to be temporary.
Samples from the recently constructed monitoring bores are currently in the laboratory for a full range of analysis.
Was any vegetation affected?
The pumping to the lucerne paddock did not cause any change to vegetation because the area where the water ponded was a depression with existing poor lucerne growth because of water logged soils. Lucerne is salt tolerant and there were no nearby trees.
What were the volumes of groundwater produced during drilling?
Some 400,000 L of groundwater were airlifted during drilling the four water monitoring bores. Some 280,000 L were tankered and removed from site to waste water plants for recycling. Just over 120,000L was pumped to the depression in the lucerne paddock.
What remedial activities have been completed?
The ponded area was allowed to dry out and the depression was tilled and reseeded in early September. The area is now regrown.
What happened with water from the Broke and Spring Mountain exploration activities?
Water generated during drilling programs at Broke and Spring Mountain was all contained in the drill pits and onsite tanks, and then transported offsite to waste water disposal facilities.
Water from the Broke flow testing program was captured in onsite tanks and taken to a wastewater facility in Sydney. At the end of the gas flow testing volumes reduced to less than 630 litres per day, which required about two truckloads per month.