Photo: Prelude FLNG; Source: Shell

Shell seeking approval for development drilling on gas project off Australia

Shell Australia, a subsidiary of oil major Shell, has submitted an environment plan (EP) to the country’s offshore regulator for development drilling on the Crux natural gas field, off the coast of Western Australia.

The National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) confirmed that Shell submitted this environment plan on 29 July 2022, proposing to undertake the Crux development drilling programme – inclusive of drilling template and docking pile installation – as the first significant infield activity planned to occur to support the execution of the Crux development within production licence AC/L10.

The Shell-operated Crux development, which was sanctioned in May 2022, is located in Commonwealth waters in the northern Browse Basin, 190 kilometres offshore northwest Australia and 620 km northeast of Broome, in approximately 165 metres of water depth.

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According to Shell, the Crux gas field has been identified as a source of backfill gas to the existing Prelude Floating Liquefied Natural Gas (FLNG) facility. As a result, Crux will have the capacity to supply the Prelude FLNG facility with up to 550 million standard cubic feet of gas per day (mmscfd).

Furthermore, the development of this project will consist of a platform operated remotely from Prelude while five wells are expected to be drilled initially. Moreover, an export pipeline will connect the platform to Prelude, which is around 160 kilometres southwest of Crux. Shell anticipates the construction to start in 2022 with the first gas expected in 2027.

Crux development concept overview; Source: Shell
Crux development concept overview; Source: Shell

The project is being progressed by the Crux joint venture which comprises Shell Australia as the operator and SGH Energy as its joint venture partner. The first environmental approval for Crux was the Crux Offshore Project Proposal (OPP), which was accepted in August 2020 by NOPSEMA.

Shell’s recently submitted EP covers the drilling template and docking pile installation; drilling using a semi-submersible MODU; the operation of in-field support vessels and helicopters required to support drilling activities; the operation of remotely operated vehicles (ROVs); and well suspension and contingent sidetrack and/or plugging and abandonment activities.

As specified by Shell, the drilling template installation is the first activity that will be undertaken in relation to this EP and is currently proposed to take place in the second quarter of 2023, approximately three months ahead of the MODU arrival. Shell elaborated that the drilling template installation campaign is nominally scheduled to occur over a one-month period.

Drilling activities are going to start following the MODU arrival. These operations are planned to take approximately ten months, with an additional ten-month contingency drilling period. Upon completion of the drilling campaign, Shell underscored that the wells will be temporarily suspended, and subsequent well completion activities will be undertaken following the topside installation.

Source: Shell
Source: Shell

Moreover, the docking pile guides and docking piles will be installed following the suspension of the wells and the sail away of the MODU, based on this EP. While this installation is planned to be completed during a one-week campaign, weather constraints and subsurface conditions may see this extending over a one-month period.

Shell pointed out that this EP will remain active following the drilling campaign while the wells are temporarily suspended, which is planned to be approximately 21 months.

When it comes to other activities related to the Crux development, it is worth noting that NOPSEMA recently started the assessment of Shell’s environmental plan for the Crux seabed survey campaign.

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As reported at the time, the aim of this is to investigate sub-seabed geological conditions to understand conditions at the proposed pipeline pipelay initiation and the Pipeline End Manifold (PLEM) locations for the Crux pipeline.