Anning and Somerville Gas Fields, UK

Anning and Somerville gas fields are located offshore UK in the Seaward production licence P2607. The licence is owned and operated by Australian oil and gas company Hartshead Resources.

License P2607 comprises five blocks in Quads 48 and 49 on the UK Continental Shelf in the Southern Gas Basin. It hosts several gas fields and exploration prospects with a combined gas resource base of around 0.8tcf.

The licence will be developed in three phases. Phase I will include the development of Anning and Somerville gas fields, which are estimated to hold 2P (proven and probable) reserves of 301.5 billion cubic feet of gas (bcf) (around 52 million barrels of oil equivalent).

In May 2022, the Phase I development Concept Select Report (CSR) was submitted to the North Sea Transition Authority (NSTA). The company received ‘Letter of No Objection’ on the development concept in July 2022.

The Phase I Front-End Engineering & Design (FEED) study and the gas export route are expected to be finalised during 2022/2023.

Hartshead aims to take the Final Investment Decision (FID) on the development in 2023 and achieve first gas in late 2024.

At peak, production from the Phase 1 development is expected to be 140Mmscf/d.

Anning and Somerville fields reserves

The Anning and Somerville gas fields have multiple well penetrations and 3D seismic coverage, with a history of production.

The Anning gas field is estimated to hold probable and proven gas reserves of 145bcf and 192,000 barrels of condensate.

The Somerville gas field is estimated to contain 156.5bcf of probable and proven gas reserves and 208,000 barrels of condensate.

At Anning, initial production from a historical single frac in the 49/17-14 well was 14 million metric standard cubic feet a day (Mmscf/d), while an initial production of more than 45Mmscf/d was recorded from the historical two fracs in well 49/17-12 at Somerville.

Anning and Somerville development plan

The development concept involves six production wells from two wireline capable Normally Unmanned Installation (NUI) platforms.

This will include three horizontal multi-frac wells and one NUI platform each at Anning and Somerville fields.

The NUI platforms are planned to be connected to Shell’s Corvette and Leman A platforms via a subsea pipeline for onward transport to Bacton gas terminal for processing.

Subsequently, the processed gas will be transported to the UK Gas National Transmission System.

Contractors involved

Subsea7-subsidiary Xodus Group secured a contract in June 2021 to provide surface geology and geophysics services for Phase I gas development.

Petrofac was selected for Pipelines, Facilities, Safety and Environmental services and Fraser Well Management for Well Construction evaluation. Hartshead onboarded Fenix Consulting to assist with the frac design.

Hartshead Resources appointed energy consultancy firm ERC Equipoise for an independent technical and commercial audit of the reserves and resources associated with the Phase I, II and III developments.

In June 2022, Hartshead announced an upgrade in the Contingent Resources of the Anning and Somerville gas fields to Reserves following the Phase I Development Plan audit by ERC Equipoise.

In the same month, LAB Energy Advisors was contracted to advise Hartshead Resources on industry partnering for its Phase I development.

Hartshead and Shell UK Exploration & Production signed an agreement in August 2022 to carry out the engineering study for a preferred offtake route and tie-in of Phase I gas field development to Shell’s infrastructure.

The study will help in determining the design and cost estimate for the tie-in of facilities as well as the necessary brownfield modifications. Energy services company Petrofac was contracted for the study.

In December 2022, Petrofac was also awarded the platforms Front-End Engineering Design (FEED) contract for the Anning and Somerville unmanned minimum facilities jackets and topsides; and the Subsea FEED contract for the interconnecting subsea pipelines.

UK-based consultancy TelosNRG was selected to support and advise Hartshead with the preparation of the Phase 1 field development plan.

In February 2023, GEOxyz UK won a contract to conduct a geophysical survey across the Anning and Somerville fields and inter-field pipeline locations. The Geo Ocean III vessel, a Dynamic Positioning (DP2) Multi-Disciplined Offshore Survey Vessel, is planned to be mobilised for the work during April 2023.

In the same month, Hartshead Resources also launched a pre-qualification process for the Platform and Jacket Engineering, Procurement, Installation and Commissioning (EPIC) contract for Anning and Somerville gas fields. The contract is expected to be awarded in the third quarter of 2023.

Licence P2607 details

Five blocks in the Seaward Licence P2607 were formally awarded to Hartshead Resources in January 2021 as part of the 32nd Offshore Licensing Round.

The blocks that were awarded to Hartshead are 48/15c, 49/6c, 49/11c, 49/12d and 49/17b.

The Anning and Somerville Gas Fields will be developed in the first of the three-phase development of the licence.

Phase II will include the development of Hodgkin and Lovelace fields with 2C contingent resources total of 139bcf, while Phase III will comprise 14 prospects and leads with unrisked 2U Prospective Resources of 344bcf.

In February 2023, the UK North Sea Transition Authority (NSTA) approved Hartshead Resources as Sub-Area Operator to License P2607.

Hartshead entered into a Farm-out Agreement (FOA) with RockRose Energy (RockRose) to divest 60% equity interest in License P2607 for a gross consideration of around A$196.3m. According to the Australian firm, the farm-out will provide a clear pathway to the full financing and subsequent development of South Basin Gas assets.

The completion of the transaction is subject to customary closing conditions including government approval. Hartshead will continue to remain the operator of the licence.