During the development phase the gas company builds the infrastructure necessary for a fully producing gas field.

This includes connecting existing appraisal wells, drilling any additional production wells, building a production facility, and building flowlines and pipelines to transport the gas to market.

Sometimes the gas company can take advantage of existing infrastructure. For example, the Parmelia Gas Pipeline was built in 1971, and all gas produced from Waitsia – Stage 1 until 2020 has travelled to Perth via that pipeline.

This meant during initial Stage 1 development, Mitsui E&P Australia (MEPAU) only needed to install flowlines to connect two new wells to the existing production facility, which was already connected to the Parmelia Gas Pipeline.

As part of the Waitsia Stage 1 expansion project, MEPAU is constructing a new pipeline to the nearby Dampier to Bunbury Natural Gas Pipeline. This pipeline would also be used for the new Waitsia gas production facility, which is part of the proposed Stage 2 development.

Recent appraisal well examples include Waitsia-02, Waitsia-03, and Waitsia-04.

MEPAU stage 1 expansion

Waitsia Gas Project - Stage 1 Expansion

Waitsia Stage 1 Expansion began in January 2020. Find out about Waitsia Stage 1 Expansion.

Waitsia Gas Project - Stage 2

The proposed Waitsia Stage 2 project is nearing the end of the design phase and regulatory approvals are being sought. Find out about Waitsia Stage 2.

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 northern Perth Basin. Read more about what we do


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


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.


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

Decommissioning and Rehabilitation

When the exploration or production activity has finished it’s time to clean up. Read more about how we decommission and rehabilitate a well and its surrounding area.


The Northern Perth Basin

The Northern Perth Basin is a prolific oil and gas producing area covering a large portion of the Mid West region of Western Australia. The town of Dongara, located approximately 360km north of Perth, is the regional economic hub for a number of industries, including oil and gas.