The Australian offshore regulator, NOPSEMA, has issued directives to SGH Energy concerning its shut-in Longtom gas field offshore Victoria. The field has been non-producing for 11 years following an electrical failure in the control umbilical, which also resulted in the loss of continuous well barrier monitoring for the Longtom-3H and Longtom-4H wells. NOPSEMA stated this extended shutdown without restoring monitoring or installing downhole mechanical barriers represents an erosion of industry standards and a potential regulatory non-compliance.

Regulatory Directives and Compliance

NOPSEMA has identified a minor external leak from the Longtom-3H Christmas tree, estimated at 0.246 cubic metres per day, observed since 2023. The regulator has ordered SGH to halt this leak by the end of March and to assess the barrier conditions of the Longtom-3H and -4H wells. Subsequently, by 30 April, SGH must submit a technical study evaluating the wells' suitability for future service, including estimates of remaining structural integrity and an updated design basis. The company must also outline detailed designs for downhole suspension and permanent abandonment for each well. Furthermore, NOPSEMA has mandated the reinstatement of continuous well integrity monitoring for the Longtom wells by no later than 30 October 2027. An SGH spokesperson confirmed the company will comply with the order, with actions already underway.

Field History and Future Plans

The Longtom field, in Production Licence VIC/L29, began production in 2009, with gas transported via the Patricia Baleen pipeline to the Orbost processing plant. Production ceased in 2013 after an electrical fault in the offshore umbilical caused a loss of communication and an unplanned shutdown. Well and pipeline valves were closed, and a campaign in early 2017 confirmed the status of subsea facilities and rectified the electrical connection to Longtom-3. Looking ahead, SGH has commenced planning to resume gas production, potentially from 2028 onwards. A future subsea well, Longtom-5, may be developed and tied back to existing infrastructure. Any redevelopment involving drilling and tie-in activities will require a new Environment Plan. The field, discovered in 1995, had proven reserves of 268 billion cubic feet of gas and 2.8 million barrels of condensate, with potential for increased volumes from nearby prospects.