Expanding under WA: the Mondarra Gas Storage Facility

The Mondarra facility is an underground gas storage facility located in the Perth Basin near Dongara, which interconnects with both the Parmelia Gas Pipeline (PGP) and the Dampier to Bunbury Natural Gas Pipeline (DBNGP).

The facility stores gas in the depleted Mondarra gas reservoir, which was discovered by West Australian Petroleum in 1968, and produced 26 PJ of gas from 1972-94 through the Mondarra-1 well.

In 1994, the reservoir was converted into a gas storage facility. This was purchased together with the PGP in 1997 by CMS Energy Corporation, before ownership of both assets was transferred to APA in 2004 as part of the company’s acquisition of CMS’ assets.

Expanding for gas demand

The Mondarra facility, which currently has two functioning injection/production wells and compression facilities, is available to any gas shipper requiring storage. It was upgraded to improve performance in 2003, and in 2006-07, APA expanded the facility’s capacity by drilling an additional well and upgrading its compression facilities. The current expansion project is required due to increased customer demand for storage services.

Project plans

The next phase of the expansion project, which is expected to cost over $150 million, will involve two additional injection/production wells, as well as new compression facilities, pipeline interconnects and treatment plants.

At present, the Mondarra facility can receive gas from both the PGP and DBNGP, but can only deliver gas into the PGP. The expansion will include pipe work to allow delivery into the DBNGP, enabling shippers to use either pipeline to deliver gas downstream from the Mondarra facility.

The expansion is also expected to increase the current commercial storage capacity level of 3 PJ of gas by five times to 15 PJ, subject to final drilling results.

“At current average rates of peak gas demand in Perth, this storage capacity could keep Perth homes and businesses supplied with energy for over a month,” said APA Head of Commercial and General Manager WA Steve Lewis.

A significant increase in the daily injection and withdrawal rates into and out of the facility will be another result of the expansion, with the current 15 TJ/d injection and withdrawal rates to increase to rates of 70 TJ/d for injection and 150 TJ/d for withdrawal.

“The facility will ensure peak gas supply, and provide backup gas supply, mitigating short-term supply risk such as pipeline or gas plant failure,” added Mr Lewis. “It will provide a cost-effective service to WA gas shippers, enabling them to better manage their upstream gas supply contracts with downstream market demand fluctuations.”

Market confidence

Verve Energy, the WA government-owned electricity generator, has entered into a long-term foundation contract with APA, committing to a substantial part of the Mondarra facility’s increased capacity. APA is in discussions with other major gas industry utilities in WA for additional gas storage services from the expansion project.

Engineering and procurement work has commenced, with completion of the expanded capacity scheduled for first quarter calendar year 2013. The Mondarra facility will continue to operate its existing contracted storage services during the expansion period.

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