Decommissioning and Rehabilitation Project

Mitsui E&P Australia (MEPAU) is undertaking well site decommissioning activities in the Shire of Irwin as part of a campaign to rehabilitate well sites which are no longer in use. Decommissioning is an established industry practice undertaken at the end of a well’s life using a decommissioning plan approved by the government regulator.

Well decommissioning involves environmentally sound and safe isolation of the well. Typical steps of the process include removing any production tubing, isolating productive formations from other formations by installing cement plugs at several intervals, pressure testing of the cement plugs, cutting off the well head below ground level, removing remaining surface equipment and facilities and rehabilitating the site to an agreed end use.

Approximately 80 wells are included on the project schedule, which may take up to five years to complete. Most of these sites are on cleared agricultural land. MEPAU is using local services and supplies whenever practical.

Landowners and nearby residents are being consulted prior to activities starting at each well site.

Regulatory approvals for the decommissioning project are in progress. Approved environmental management measures to minimise any potential impacts include; dust suppression, noise, traffic and waste management and weed and dieback management. Chemicals used during the decommissioning process are included in the Environment Plan Summary.

Environmental Plan

Download the Onshore North Perth Basin Well Intervention Activities Environment Plan Summary (PDF 1mb).

Denison 3D Seismic Survey

Denison 3D Seismic Survey

The Denison 3D Seismic Survey was the most complicated survey ever done in Australia at the time. Find out more about what was involved in the Denison 3D Seismic Survey.

Care and Maintenance

Care and Maintenance

When a facility is not being used, it’s put into care and maintenance. Read more about Care and Maintenance.

What we do at Mitsui E&P Australia

What we do

We are actively exploring, appraising, developing and producing oil and gas in a number of locations in the north Perth Basin. Read more about what we do

Planning projects at Mitsui E&P Australia


Before anything can happen we need to plan carefully. Read more about the planning process.

Exploration and appraisal


We look for gas, and when we find it we figure out if it’s worth pursuing further. Find out more about our exploration and appraisal process.

Development at Mitsui


Once we’ve confirmed a well is commercially viable we get ready to put it into production. Read more about the development process.


Production of gas at AWE


During the production phase we extract gas from the well and sell it. Find out more about the production process.