Green light for Inpex to carry out site surveys and drilling activities for CCS project off Australia

Inpex Browse E&P, a subsidiary of Japan’s oil and gas producer Inpex, has received a seal of approval from the country’s offshore regulator for an environment plan (EP), covering pre-drill site surveys, and the drilling and evaluation of two initial exploration wells off the coast of Australia.

Inpex Browse E&P, on behalf of Woodside and TotalEnergies as the Bonaparte Carbon Capture and Storage Assessment Joint Operating Agreement participants, was awarded GHG assessment permit G-7-AP in the Bonaparte Basin off northern Australia. The G-7-AP permit area is wholly located within Commonwealth waters to the north of the Joseph Bonaparte Gulf and approximately 100 km west of Darwin Harbour.

The National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) accepted Inpex’s environment plan in December 2023, covering pre-drill site surveys, and the drilling and evaluation of two initial exploration wells between 2023 and 2024. Inpex explains that up to three possible additional wells and associated pre-drill site surveys may also be drilled in an area of G-7-AP within the life of the EP.

Furthermore, the pre-drill site survey associated with the initial exploration drilling campaign will last for around 30 days and is provisionally expected to be conducted in early 2024 with the drilling activities scheduled to kick off in the first half of 2024. The scope of the surveys encompasses a multibeam echo sounder, side-scan sonar, magnetometer, sub-bottom profiling, seabed grab sampling, and one geotechnical borehole/or several piezo-cone penetrometer tests at each proposed well location.

The block, which contains the acreage awarded to the Inpex-led Bonaparte CCS Assessment JV, is located in the Bonaparte Basin off the northwestern coast of the Northern Territory of Australia, an area considered to be promising for geological storage of carbon dioxide in service of CCS activities. The water depth at this site ranges between approximately 30 and 75 meters.

Back in August 2022, Inpex underlined that Ichthys LNG would be a natural user of the CCS solution, seeking to reduce its GHG emissions by making use of carbon capture and storage opportunities. This project provides an opportunity to prove a large-scale carbon storage site for the Darwin-based, CCUS hub proposed by the government of the Northern Territory.

Inpex outlines that the drilling and evaluation activities for the initial exploration drilling campaign are expected to last for about 150 days for both wells and it is expected that the earliest start date will be in 2024. Once drilled to total depth, each well will undergo various evaluation techniques to assess reservoir parameters, which will include a water injectivity test and a vertical seismic profile (VSP).

According to the company, various other wireline formation evaluation techniques will also be completed. However, the activity described in this EP does not involve the injection of carbon dioxide (CO2), as the aim is to assess the suitability of potential reservoirs for future CO2 storage. Inpex will conduct drilling operations using either a jack-up or semi-submersible mobile offshore drilling unit (MODU).

A minimum of two support vessels will be needed to provide support for the drilling activity while personnel transfers to and from the MODU will be done by helicopter several times per week. These operations will occur 24 hours a day. The exact location of the proposed pre-drill site surveys and wells in G-7-AP is yet to be finalized, but will fall within the boundaries of the proposed project area, a small section of the broader GHG assessment permit where water depths range from around 75 m to 100 m.

At the end of the initial drilling and evaluation activities, Inpex confirms that both wells will be permanently plugged and abandoned with the conductor and casings cut below the sea floor (mudline) and all equipment removed. Any additional wells drilled during the life of this EP may remain in place for future use.