Ethane value chain optimisation: insights from gas and LPG production in Bass Strait

When fields decline and approach end of life, gas producers must manage both changing production conditions and evolving market dynamics, challenging traditional approaches to optimisation. ExxonMobil Australia has delivered value enhancement through an integrated molecule management approach across its Longford and Long Island Point (LIP) facilities, while continuing to invest in gas developments and infrastructure upgrades. Historically, most of the ethane extracted offshore was recovered at Longford and purified at LIP for sale. Following the 2024 shutdown of a major ethane customer, a 42-MW power generation facility was commissioned at LIP to provide an alternative utilisation pathway. Operating within the dynamic Australian East Coast Gas Market, where value optimisation can be driven by the value per ethane molecule, or in additional gas deliverability, ExxonMobil recognised the potential value gain in being able to redirect additional ethane into the sales gas stream. At Longford, targeted improvements to fractionation performance and challenging norms (‘constraint busting’) achieved a 60% reduction in ethane recovery without any loss of higher value natural gas liquid molecules allowing for an increase in the out-the-gate value of these molecules. At LIP, the reduction in ethane enabled the bypassing of heritage ethane treating systems, eliminating safety risks associated with this footprint and driving significant reductions in emissions and maintenance cost.