There are two main types of well: exploration and production.
An exploration well helps us to understand the nature, size and commercial viability of a gas reserve, while a production well allows us to bring the gas to the surface.
A production well is drilled using a series of rigs that descend through the different layers of earth below ground.
Most of the production wells we have drilled to-date are between 300 and 800 metres deep and target gas trapped in the Walloon Coal Measures in the Surat Basin.
If there are several wells on a plot of land, they will normally be around 750 metres apart.
A well site
Normally, you can tell a well site because it includes the following items above ground: wellhead; separator; telemetry enclosure and antenna; connecting flow lines; flare stack; and hydraulic power unit.
A typical well site incorporates the following key items:
- Wellhead - provides a pressure seal to ensure the flow of gas and water is controlled.
- Hydraulic power unit - provides the hydraulic power to drive a pump at the bottom of a well.
- Remote telemetry unit - links the wellsite facilities to a control system for remote operation.
- Hole pump - dewaters the well so that the gas will flow to the surface.
- Separator - separates the gas and water that is produced from the well.
- Booster pump - drives produced water to water treatment plants.
- Solids disposal tank - safely collects and stores solids from the separator.
- Connecting flow lines - these pipes take the gas and water to processing facilities.
Our wells are designed in such a way that gas and water will travel directly from the extraction point inside the well to the surface without any connection with groundwater.
The gas and produced water is isolated from surrounding aquifers by one or two layers of steel casing, which is held in place with impermeable cement.