Activity - Minerva Cessation
Activity - Minerva Cessation
|Organisation||BHP Billiton Petroleum (Victoria) Pty Ltd|
|Activity types||Any other petroleum-related activity|
|Submission date||17 June, 2019|
|Acceptance date||24 December, 2019|
|Start date||Pending titleholder notification|
|Stop date||03 September, 2019|
Phone: 61 8 6321 4473
BHP Billiton Petroleum (Victoria) Pty Ltd (BHP) proposes to commence cessation phase activities at end of field life for the offshore Minerva gas field located in production licence VIC/L22 (Commonwealth waters), and the associated Minerva subsea pipeline (VIC/PL33), which runs from the Minerva wells to the boundary of the Victorian State Waters.
The Minerva gas field is located in the Otway Basin in 60 m of water and approximately 11 km southwest of the township of Port Campbell, Victoria. The gas field was discovered in March 1993, followed by the drilling of two exploration wells (Minerva-1 and Minerva-2A). Later that same year, the wells were plugged and suspended. Two production wells (Minerva-3 and Minerva-4) were drilled in late 2002 and the offshore and onshore pipeline was laid in 2003. The construction of the onshore gas plant was completed in December 2004, and the facilities were commissioned and commenced production in January 2005. Production of the field ceased in September 2019, and the Minerva-3 and Minerva-4 wells were subsequently suspended through valve closure on the wellheads.
The cessation phase and associated activities covered under the Environment Plan (EP) will continue for the remaining acceptability period of the EP (5 years), with ongoing management of the infrastructure in accordance with the currently approved Well Operations Management Plan (WOMP) and the Minerva Field Subsea Operations Offshore Pipeline Inspection Frequency Plan. The cessation activities within the scope of the EP include the following offshore activities:
• Subsea flowline disconnection/cutting and plugging;
• Subsea inspection/intervention activities on infrastructure (wellheads, flowlines, umbilical);
• Subsea inspection/intervention activities to support planning and preparation for a well plug and abandonment (P&A) campaign in accordance with the currently approved WOMP; and
• Environmental survey and monitoring.
The cessation phase has commenced with barrier testing and verification for production well isolation, and the flushing of the flowline. Near term, it is planned for the flowline system to be positively isolated from the hydrocarbon source, via jumper spool removal, to verify flushed condition and eliminate risk of future hydrocarbon contamination from the wells. Pressure retaining plugs will also be installed to provide an additional barrier for well integrity, prior to Well P&A. Cutting and plugging of the flowline is expected to take approximately one week and is currently planned for Quarter 1 of 2020. The cessation phase includes specific planned activities in preparation for future well P&A and field facilities decommissioning. Well P&A and field decommissioning activities will be the subject of future EP submissions.