Subsea engineering services provider Subsea7 has signed a contract worth up to $500 million with Turkish Petroleum Offshore (TP-OTC) for work at Türkiye's vast natural gas field in the Black Sea.

In a statement, Subsea7 said the size of the contract with the subsidiary of the Turkish Petroleum Corporation (TPAO) is estimated to be between $300 million and $500 million.

The agreement supplements a third-phase development deal for the Sakarya natural gas field signed between the two companies in August last year.

The Sakarya field is estimated to hold 710 billion cubic meters (bcm) of gas, discovered gradually between 2020 and 2022. Once fully developed, it is expected to meet roughly 30% of Türkiye's annual gas demand.

Türkiye completed the first phase in 2025, reaching 10 million cubic meters per day, enough to meet the needs of about 4 million households.

Production is expected to double this year as Türkiye's first floating gas production platform becomes operational. Output is targeted to reach four times today's level by 2028, potentially covering the needs of up to 17 million households.

In mid-May last year, Türkiye also announced a separate 75 bcm gas discovery in the Black Sea's Göktepe field.

Under the new contract with Subsea7, connections will be constructed between the Göktepe field and the third-phase floating production facility.

The scope includes engineering, procurement, construction and installation of approximately 20 kilometers (12.43 miles) of flexibles, 120 kilometers of umbilicals, a rigid production riser and associated subsea equipment in water depths of 2,200 meters (7,215 feet).

Offshore activities are expected in 2027 and 2028.

"We are proud to continue to support TP-OTC in their ambitions in the Black Sea with the development of the Goktepe field, which will enable increased production through the Sakarya Phase 3 facilities and support Türkiye's gas needs," said David Bertin, senior vice president of Subsea7's Global Project Centre – East.