EOG Resources Australia Block WA-488 Pty Ltd (‘EOG’) is the titleholder of permit WA-488-P, located in Commonwealth waters of the Joseph Bonaparte Gulf (JBG) off the northern Western Australian (WA) coastline.
EOG proposes to undertake geophysical and geotechnical (G&G) investigations within an activity area located 163 km offshore from nearest WA coastline and 73 km from the Northern Territory (NT) coastline. The activity is referred to as the Beehive Pre-Drill Seabed Assessment (‘PDSA’).
The purpose of the PDSA is to assess and characterise the seabed for risk mitigation and geohazard identification and to evaluate the seabed and sub-seabed conditions to support a jack-up Mobile Offshore Drilling Unit (MODU) that will be used to drill the Beehive-1 exploration well, as well as provide data for potential future wellsite placement.
The PDSA area covers an area of 340 km2 and occurs in water depths ranging from 35 metres (m) to 50 m. The G&G investigations will be acquired in two phases, as follows:
• Geophysical investigations – this area is likely to be restricted to an area of 9 km by 6 km
(54 km2) within the PDSA activity area. This investigation will be undertaken prior to the geotechnical investigation.
• Geotechnical investigation area – this area is likely to be restricted to an area of 3 km by 2 km (6 km2) within the PDSA activity area. The geotechnical investigation will be conducted following the completion of the geophysical investigation.
The activity is scheduled to be completed between April 2022 and August 2022, with the exact timing within this time window dependent on the receipt of environmental approvals, vessel/equipment availability and fair sea state conditions suitable for the activity. The activity is estimated to take up to 4-6 weeks in total to complete, although this is dependent on the exact methods and technologies used as well as weather conditions at the time.
The geophysical investigations are designed to support jack-up MODU leg penetration calculations and detect hazards on or below the seabed so that they can be avoided when determining the placement of the MODU. The geophysical investigations will collect data for assessment of water depths, seabed topography, seabed and shallow sub-seabed conditions and identification of obstructions on the seabed. The proposed techniques may include the following:
• Multi-beam echo sounder (MBES);
• Side scan sonar (SSS);
• Sub-bottom profiling (SBP);
• Magnetometer; and
• 2D shallow seismic (using either a mini airgun, small bubble pulser or small sparker system).
Geotechnical investigation methods collect detailed information on the physical properties of the seabed and the underlying shallow sediments to build up a picture of the local geology of the activity area. This is to determine the load bearing properties of the seabed sediments at potential MODU spud can locations and also to validate the results of the geophysical investigations. The proposed techniques will include some of the following:
• Grab sampling;
• Coring (vibrocoring, box coring, piston (or gravity) coring);
• Piezo Cone Penetrometer Test (PCPT); and
• Borehole sampling.
