Sakarya gas field is located within the 7,000km² block AR/TPO/KD/C26-C27-D26-D27 in the ultra-deep waters in the western Black Sea, approximately 175km offshore Eregli, Turkey.

Turkish Petroleum (TPAO), the state-owned oil and gas company, holds 100% interest in the block and will develop the field. TPAO is in talks with the State Oil Company of the Azerbaijan Republic (SOCAR) to collaborate for the development and production of the Sakarya gas field.

The development is expected to meet approximately 30% of the domestic natural gas demand. First production from the field is anticipated in the first quarter (Q1) of 2023.

Sakarya gas field discovery details

TPAO discovered the Sakarya gas field by drilling the Tuna-1 ultra-deepwater exploration well using its sixth-generation ultra-deepwater drillship Fatih, in August 2020.

Tuna-1 was drilled at a water depth of 2,115m to reach a depth of 4,525m in the Black Sea. The well intercepted more than 100m of the natural gas-bearing reservoir in Pliocene and Miocene sandstone formations.

The field was estimated to hold potential natural gas reserves of 320 billion cubic meters (bcm)/11 trillion cubic feet (tcf)) of lean gas, which is considered the largest gas reserves discovered in the Turkish Exclusive Economic Zone as well as in the Black Sea.

The company made a second discovery in the lower sections of Tuna-1, which increased the potential reserve estimate to 405bcm (14.3tcf) of lean gas in October 2020. The discovery was found at a depth of 4,775m in 2,117m of water where an additional 30m of gas play was encountered in the reservoir in sandstones of the early-Pliocene to late-Miocene era.

Further, the drilling of the exploratory well Amasra-1 in the northern Sakarya gas field by Fatih drillship discovered 135bcm gas in June 2021, increasing the cumulative natural gas reserves of the field to 540bcm.

The natural gas was intercepted at three levels between 3,000m and 4,775m in the Pliocene to Miocene-era sandstone formations.

Appraisal details

The successful exploration drilling at the Sakarya gas field encouraged the company to conduct field appraisal and acquisition of the three-dimensional (3D) seismic data in the block utilising state-of-the-art technology.

A total of ten appraisal wells have been planned in the first phase of the project. The drilling of appraisal wells Turkali-1, Turkali-2, Turkali-3 and Turkali-4 was carried out by Fatih, while Kanuni, TPAO’s another sixth-generation drillship, will perform the well completion operations and boreholes testing.

Located approximately 4km to the northwest of Tuna-1, Turkali-1 well was drilled to a total depth of 3,920m, while Turkali-2 was completed at a drilling depth of 3,950m. The project is expected to produce up to 20bcm of natural gas a year, satisfying almost half of Turkey’s gas requirements, upon the completion of phase one appraisal programme.

TPAO completed the 3D seismic exploration operations over an 11,000km2 area at Sakarya gas field, using Barbaros Hayreddin Paşa seismic vessel, and moved to the interpretation stage in July 2021.

Sakarya gas field development details

TPAO will drill up to 40 production wells at Sakarya by 2028, of which ten wells of 2km diameter each will be completed by 2023 in the first phase of development. The ten wells are expected to together deliver ten million cubic meters (Mcm) of natural gas a day.

The second phase will involve the development of the remaining wells with a combined production of 40Mcm a day between 2023 and 2028.

The Sakarya gas field will be developed with two units, a subsea natural gas production system, and an onshore natural gas processing facility within the Filyos Industrial Zone in Zonguldak province of Turkey.

A pipeline of approximately 155km length will be laid at a depth of 2,000m in the seabed to connect the two units. The pipeline will transport the produced gas to the onshore facility for processing. The processed gas will reach the national gas network through Turkey’s Petroleum Pipeline Company (BOTAS).

Contractors involved

The consortium of Subsea 7 and Schlumberger received the engineering, procurement, construction, and installation (EPCI) contract for the Sakarya field development in October 2021.

The contractual scope includes the installation of subsea production systems (SPS), subsea umbilicals, risers and flowlines (SURF), tie-in connections, associated subsea equipment, laying of 170km of gas export pipeline and monoethylene glycol injection pipeline as well as the development of an onshore early production facility.

Norwegian geophysical services company Shearwater GeoServices conducted a 2,000km² 3D seismic survey in the Sakarya area as part of its 6,200km² programme in 2019.

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