Jadestone Energy (Eagle) Pty Ltd (Jadestone Energy) plans to drill development well H6 in permit area AC/L7 in the Montara Field. The development well Skua-12 in permit area AC/L8 in the Skua Field, and workovers of H3 and Skua-10 within permit AC/L7 and AC/L8, are included in the drilling program as contingencies.
The Montara Field lies approximately 690 km (373 nautical miles) east of Darwin in a water depth of approximately 80 m (LAT), 621 km (334 nautical miles) NNE of Broome and 147 km (79 nautical miles) from Ashmore Reef in Commonwealth waters of the Timor Sea.
The drilling and workover activities are scheduled to commence during Q2 of 2020 and are likely to last for a period of approximately 150 days in total, however timings are subject to weather, drilling vessel availability and operational efficiency. Therefore, this EP validity period is from June 2020 to June 2021.
The workover plans for H3 and Skua-10, and well designs for H6 and Skua-12 will be finalised in the Well Operations Management Plans (WOMP), which are to be accepted by NOPSEMA prior to commencement of drilling. The H3 and SKUA 10 workover is estimated to take 20 days each, drilling of the Montara H6 well is estimated to take 80 days and drilling of SKUA 12 is estimated to take 50 days.
The MODU will be a ‘jack up’ drilling MODU towed to the drilling sites by two or three support vessels. The Skua-12 site is an undisturbed site approximately 20 km from the Montara WHP and the Skua-10 site is an existing well, while the H6 development well and H3 workover will be undertaken when the MODU is positioned alongside the Montara WHP. The MODU will cantilever the drill floor over the WHP to allow positioning the MODU’s drill centre over the H6 and H3 slots.
Operational discharges will be:
• Cement - used to form permanent barriers and fix casings in place. It may also be used to seal a lost circulation zone, and when abandoning the well. The majority of cement will remain downhole although minor volumes will be discharged at the mudline at the seabed surface, and at sea surface.
• Drilling fluids and cuttings - A drilling fluid program will be developed and drilling fluids will be water-based muds (WBM) only. All cuttings will be discharged overboard at sea surface or just below via a discharge pipe.
Chemical selection will be guided by the Offshore Chemical Notification System (OCNS) and the Jadestone Energy Chemical Selection Evaluation and Approval Procedure.
Support for the drilling activities will be provided by three support vessels which will operate out of Darwin. Support vessels will supply equipment, bulk chemicals, liquid drilling fluids, diesel fuels etc. to the drilling MODU. Each vessel will have approximately 10–20 POB and MARPOL compliant sewage and bilge systems.
Helicopter support will be provided by Babcock and will be based at Mungalalu–Truscott air base to support the MODU.
