Before petroleum-related exploration can begin, steps must be taken to ensure all proposed activities are performed ethically and are environmentally rehabilitated at the activity(s) conclusion.
Exploration
All petroleum companies must engage with landholders about the possible impacts of exploration. Once consultation and engagement with landholders has taken place for a discussed exploration activity, both the landholder and the company can then negotiate a ‘land access agreement’.
The main steps in exploration and possible impacts on the land include the following:
Studies and data processing
Activity: Data from the Department of Energy, Mines, Industry Regulation and Safety (DEMIRS) Geological Survey WA will help to identify areas with the best potential for exploration work.
Existing seismic data is processed by computers to gain extra knowledge about the rocks underground.
Impacts: No impact on the community or the environment.
Airborne surveys
Activity: Airborne surveys are carried out by fixed wing aircraft or helicopters flying approximately 300 metres above the ground. In the aircraft, computers take readings of the earth’s magnetic and gravity signals. This gives the petroleum companies information about the potential for further studies.
Impacts: Short term noise but no significant impacts.
On-ground surveys
Activity: There are several different types of on-ground surveys. Some use handheld instruments to take readings or small samples. The most common on-ground survey is a seismic survey. This type of survey uses trucks with vibrator pads to send small sound waves deep below the ground. These waves bounce back from the rock to be picked up by sensitive microphones placed on the ground. The recordings create two-dimensional or three-dimensional pictures of the underground geology.
Impacts: The surveys using handheld instruments have no significant impact on the land.
Seismic surveys can be conducted from existing roads and tracks, but often require clearing of vegetation needed for equipment and vehicles. The path of any proposed seismic lines can be changed to protect heritage sites. These surveys can require teams of up to 50 workers, housed in temporary accommodation. Seismic survey areas are rehabilitated once the survey work is finished.
Drilling a petroleum exploration well
Activity: Exploration drilling for oil and gas can be approximately four kilometres deep into layers of rock. If the exploration program finds a petroleum resource, testing for the quality and amount of oil and/or gas in the well is required. Test results will help the company decide whether the discovery has any commercial potential.
Impacts: Drilling for exploration can take several months and can extend as wide as 155m and as long as 185m. Petroleum wells are designed and constructed according to strict safety, engineering and environmental standards, which are checked by the department. When drilling is finished, the well is made safe and the area is rehabilitated. If the well is to be used later, a two-metre-high well-head structure known as a ‘Christmas tree’ will be erected to allow for controlled production.
Discovery of petroleum
When resources are discovered, the petroleum company needs to establish the most efficient course of resource development. The company is required to make a ‘declaration of location’ to the department before applying for a production license. Further exploration is permitted in the permit area. The production licence application requires comprehensive assessment before commercial operations can be approved.
Rehabilitation
Most land disturbed by petroleum operations is rehabilitated once exploration work has concluded. The structures are removed, and the land is replanted with native vegetation. The only exceptions are drill sites which might be used in future production. These are kept and maintained until production starts.
Key facts
- A land access agreement must be in place before exploration can start.
- Some types of exploration work have little impact on the land.
- Petroleum companies can plan where activities take place to make sure heritage sites are protected.
- For every petroleum activity, an environment plan and a safety plan must be submitted to the department for assessment and approval.
Phone: (08) 9222 3333
Exploration is the basis for a successful petroleum industry. This information sheet explains some of the activities undertaken
