Increasing gas production

Oxair recently saw its project selected by the Australian Petroleum Production and Exploration Association as an Australian example of efforts to mitigate emissions in the upstream oil and gas sector.

Image credit: Quadrant Energy

Oxair teamed up with Quadrant Energy in a nitrogen generation project at Devil Creek, Western Australia in 2016. Quadrant Energy runs the Devil Creek Gas Plant as one of three natural gas processing hubs which supplies gas to the domestic gas market in Western Australia. Located near Karratha and with a capacity of 220Tj/d, it provides a reliable and independent supply of gas for Western Australia and has become a key supplier for many households.

For safety reasons, Quadrant’s gas plant processing system relies on all its pipelines being purged of air before the introduction of any natural gas into its plant. Previously it had relied on methane gas to do the purging with its associated non-green venting emissions. However, driven by the desire to reduce environmental emissions as well as achieve an increase in the quantity of marketable gas produced per annum, the significant investment in the plant has exceeded the objective of replacing the methane used in its purging process with nitrogen.

To achieve a constant and reliable supply of nitrogen for pipe purging, flare control, compressor operations and black start operations, Quadrant turned to Oxair to supply two containerised nitrogen systems installed on site – with spectacular results. Not only did the nitrogen generators help to create reduced vented emissions of 3.5 MtCO2-e per annum but an additional estimated 60TJ per annum of gas is now available to sell to the market – bringing added economic benefits to Quadrant.

One of the main reasons that Oxair’s systems were chosen was that its technology, using Air Products’ membranes for this particular application, is extremely reliable and stable. It also allows the end user to run the unit 24/7 with minimal interaction with the plant.

The units were built around Quadrant’s stringent specifications and then successfully integrated into its Distributed Control System (DCS). The two packages contained both the primary feed air and filtration as well as a nitrogen membrane system used to generate the controlled purity and flow of nitrogen required. The continuous rate of supply achieved during normal operations is now around 160 Sm3/hr.

In addition to the environmental benefits of onsite nitrogen generation, there are additional safety advantages of not having to transport nitrogen to site on demand. Previously, when nitrogen was needed there was a requirement to deliver it to site in quads at high pressure (250barg). Accessing this pressurised inventory posed safety risks to employees; mainly due to the use of temporary hoses, manual handling and bespoke pressure relief which was required. Having nitrogen generated at the plant itself has effectively eliminated all the risks previously incurred when moving nitrogen around.

Quadrant’s lead facilities engineer, Neil Halpin, comments, “We are delighted to find a local company that offers competitive pricing and are able to provide total technical compliance with QE specification and design criteria. Thanks to this project we have made financial gains with gas savings and have been able to offset our carbon footprint. Flare is now run exclusively with nitrogen as the purge gas. Working with Oxair was made easy for us by their good technical knowledge and ongoing support during performance testing of the packages. Quadrant view this project as a real positive for the organisation.”

Devil Creek commenced operations in December 2011, and today provides a reliable and independent supply of gas for Western Australia. In 2016, Quadrant Energy accounts for 22.3% of domestic gas production in Western Australia (84.8 petajoules), making it the state’s largest single domestic gas supplier.

Since engaging in its onsite nitrogen generation project with Oxair, Quadrant Energy has reported a USD342-million net profit in 2017, up from USD86-million the year before, putting the company in a strong position to capitalise on several growth opportunities. In addition, it can reassure the population of Western Australia that they can relax comfortably in their homes knowing they will be supplied with reliable, safe and greener energy for many years to come.


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