Two of the energy industry’s most prominent players have formalized a significant new chapter in deepwater collaboration. INEOS Energy and Shell Offshore Inc., a subsidiary of Shell plc, have signed an agreement to jointly invest in exploration and development opportunities in the Gulf of America, anchoring their partnership around one of the region’s most strategically positioned production assets — the Appomattox platform.
The announcement, made on 5 May 2026, signals a decisive move by both companies to capitalise on proven deepwater infrastructure and accelerate the unlocking of high-margin barrels in one of the world’s most prolific offshore energy basins.
A 21% Stake and a Shared Vision
At the heart of the agreement is INEOS Energy’s acquisition of a 21% working interest in a portfolio of Shell upstream assets — a stake consistent with its existing ownership in the Appomattox production hub, the Rydberg tieback, the Nashville discovery, and the Mattox pipeline. The financial terms of the transaction were not disclosed.
The partnership targets both exploration and development opportunities situated within tieback distance of the Appomattox platform — a world-class deepwater facility located in the Gulf of America that has become the operational anchor for an expanding cluster of subsea assets.
David Bucknall, Chief Executive of INEOS Energy, underscored the disciplined rationale underpinning the deal: “We are focusing on areas close to existing infrastructure where we can move quickly, control costs and unlock new production. This is disciplined growth targeting exploration, shared risk and returns.”
Key Assets in the Frame
The agreement identifies several high-priority assets as initial targets for investment:
Fort Sumter DiscoveryThe flagship asset in the deal is the Fort Sumter discovery — a deepwater well situated in Mississippi Canyon Block 566. Though a final investment decision has yet to be reached, Shell’s initial estimates place recoverable resources in excess of 125 million barrels of oil equivalent (MMboe), making it one of the more significant unappraised finds in the Gulf of America. Development as a tieback to Appomattox would allow both companies to leverage existing pipeline infrastructure and processing capacity, dramatically reducing capital expenditure and time to first production.
Sisco Exploration WellAlongside Fort Sumter, the alliance covers drilling of the Sisco exploration well — a prospect that further extends the footprint of the Appomattox hub into undeveloped territory.
Additional Exploration WellA third exploration well is planned for drilling by 2030, reflecting the long-term ambition of the partnership to systematically evaluate and de-risk prospective resources across the agreed portfolio.
Building on a Proven Track Record
The new agreement is the latest in a series of collaborative steps between INEOS Energy and Shell in the Gulf of America, and it builds on a foundation that has already delivered tangible results.
Rydberg — the first tieback to Appomattox — came online in the first quarter of 2024, with a capacity of 16,000 barrels of oil equivalent per day (boed) and proven and probable (2P) reserves of approximately 38 MMboe. Dover, the second tieback, followed in 2025, delivering production of up to 20,000 boed and estimated 2P reserves of 44.5 million boe.
Perhaps most notably, 2025 also saw INEOS Energy achieve what the company described as its “first successful exploration well in the region” — the Nashville discovery. Drilled more than five miles beneath the seabed, the well confirmed high-quality oil in one of the Gulf’s most promising deepwater formations. Further technical assessment is now underway to quantify the full scale of the find, and Nashville is already planned as the next tieback to Appomattox.
INEOS stated that the new agreement “builds on a state-of-the-art facility, integrating the early production assets of Appomattox and Rydberg with existing pipeline infrastructure to deliver high-margin barrels.”
Strategic Context: Disciplined Growth in a Competitive Basin
For INEOS Energy, the Gulf of America partnership forms a core pillar of a broader international growth strategy. The company maintains established positions in the UK Continental Shelf, Eagle Ford in South Texas, and offshore Denmark — and views its deepwater Gulf footprint as a key platform for value creation as the global energy system continues to evolve.
For Shell, the Appomattox hub sits at the centre of its Gulf of America operations. As of 2025, Shell operates 10 production hubs across the basin — including Auger, Enchilada/Salsa, Mars, Olympus, Perdido, Stones, Ursa, Vito, and Whale — cementing its position as the leading deepwater producer in the region.
The tieback model adopted by both companies reflects a broader industry trend: extending the productive life of existing infrastructure by tying in new subsea discoveries rather than constructing standalone facilities. This approach compresses development timelines, reduces capital intensity, and optimises returns — particularly important in a period of heightened cost discipline across the sector.
INEOS Energy is the upstream oil and gas and energy trading arm of INEOS Group, one of the world’s largest privately owned petrochemical companies. Operating across the United Kingdom, the United States, and Denmark, INEOS Energy produces and trades oil, natural gas, liquefied natural gas (LNG), and carbon credits. The company manages its portfolio with a focus on operational excellence — taking on assets and optimising them to run more safely, reliably, and efficiently. INEOS Energy is also a world leader in Carbon Capture and Storage (CCS), through its flagship project in Denmark, and holds a strategic investment in HydrogenOne Capital, the London Stock Exchange-listed clean hydrogen fund. Its growth strategy centres on acquiring further oil and gas assets, expanding into LNG and new energies, and developing its CCS capabilities to establish a long-term, commercially viable business aligned with a net-zero pathway by 2050.
Shell Offshore Inc. is the primary subsidiary through which Shell plc manages its upstream exploration and production operations in the United States. A pioneer in deepwater energy development, Shell made history in 1978 when it became the first company in the world to produce oil in water depths exceeding 1,000 feet, with the installation of its Cognac platform in the Gulf of America. That milestone marked the beginning of more than four decades of deepwater innovation. Today, Shell Offshore Inc. is the leading deepwater producer in the Gulf of America, operating 10 production hubs across the basin. The company’s deepwater portfolio spans some of the most technically complex and commercially significant assets in the global offshore industry, and its operations play a critical role in Shell plc’s broader strategy of progressing energy security while advancing the energy transition.
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