Santos WA Northwest Pty Ltd (Santos) proposes to drill up to 8 wells (2 exploration and up to 6 appraisal) across two operational areas located in permit areas WA-437-P and WA-438-P, within the Bedout Basin on the North West Shelf (NWS).
The two operational areas are wholly within offshore Commonwealth waters in water depths of approximately 65 to 93m. The closest operational area is approximately 35 km north from the nearest shoreline (Bedout Island), 76 km from the closest mainland point (De Grey River-mouth) and 125 km from Port Hedland.
The drilling activity will be carried out using a jack-up mobile offshore drilling unit (MODU). A Petroleum Safety Zone (PSZ) of 500 m radius will be established around each well location in
accordance with the OPGGS Act and be removed once the MODU leaves the area. A 5-year EP validity period is being sought, and the EP assumes drilling activities can take place at any time over that 5 year period.
A summary of activities included in the EP are:
+ MODU and vessel movement and commissioning activities (e.g., equipment testing, tank flushing)
+ deployment and recovery of jack-up legs
+ riserless drilling
+ drilling with a closed-circulating fluid system
+ installing casing strings
+ operation of a blow-out preventer (BOP)
+ drilling using water-based drilling fluid systems
+ use of lost circulation materials (LCM)
+ cementing
+ use and discharge of chemicals and additives for drilling, evaluation, testing and abandonment activities
+ well evaluation, including logging-while-drilling, wireline logging, hydrocarbon sampling, vertical seismic profiling (VSP) and coring
+ well testing (sampling, clean up, and flaring)
+ permanent abandonment (P&A) activities
+ side-track drilling, re-drilling sections and re-spud
+ general MODU operations including MODU refuelling, the use of support vessels, helicopters and remotely operated vehicles (ROV).
Activities are scheduled to commence in Q4 2021. However, the timing of subsequent activities has not been finalised. Drilling is expected to take approximately 35 to 80 days per well and activities will be conducted 24 hours per day, seven days per week. It is possible that the Activity duration may increase if technical difficulties or interruptions are encountered (e.g., equipment failures, weather, etc). It is envisaged that well activities are conducted over multiple campaigns; i.e., a MODU arriving to drill one or more wells in a period between two and six months, after which the MODU leaves the operational area.
The MODU may be supported by up to four vessels. The support vessels are yet to be confirmed. The vessels will be either stationary or operating at slow speeds while undertaking activities within the operational area including:
+ Towing the MODU;
+ Holding MODU position while pinning the rig;
+ Standby operations;
+ Delivering supplies; and
+ Back loading surplus chemicals, equipment and waste for delivery to shore.
The activity will also be supported by ROV and helicopter operations used primarily for crew change and medevac, and occasionally equipment/material transfers. Helicopter flights will typically occur a minimum of three times a week, dependent on the progress of the drilling program and logistical constraints.
