The South Akçakoca Sub-Basin (SASB) Gas Field Development Project is a shallow water offshore conventional gas field located offshore Turkiye.
One of first and largest natural gas development projects, the SASB is owned by Trillion Energy (previously Park Place Energy) (49%) and Turkish National Petroleum (TPAO) (51%).
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Trillion Energy had an 36.25% interest in the project when it acquired an additional 12.25% interest of Foinavon Evergy in February 2018, becoming 49% owner of the project.
SASB consists of 23 shallow water wells, four offshore platforms, pipelines, and Cayagzi Onshore Gas Processing Plant with a cost of more than $600m (100% interest).
The project fields have produced more than 43 billion cubic feet (bcf) of conventional natural gas since its initial development in 2007.
SASB Location
The SASB Gas Field Development Project is located in the southwestern Black Sea. The block size of the License is 12,387 hectares (ha).
The subsea reservoirs lie at subsea depths ranging from 1,100m to 1,800m. The wells lie in less than 100m depth.
SASB Gas Field History
Initially, the SASB Gas Field commenced operation between 2007 and 2011. It produced 41.66bcf of gas till June 2020, an average of 4.166bcf per well.
The field is developed in phases. A forecast for the total economic recovery showed 5.814bcf of gas per well for the 10 production wells drilled during Phases 1 and 2.
In 2011, the production from both phases peaked at approximately 6.5bcf of gas per year. In June 2020, the wells from both phases produced approximately 40 million cubic feet (mcf) of gas annually.
The project produces gas from the Eocene-age sandstone reservoirs.
Phase 1 consisted of partial development of the nearer shore Ayazli (discovered in 2004), Dogu Ayazli (discovered in 2006), and Akkaya (discovered in 2005) fields.
These fields commenced production in 2007. In Phase 1, 17 wells were drilled to an average depth of 1,500m.
Phase 2 consisted of the deepwater Akcakoca field discovered in 2006. This phase commenced production in 2011. In Phase 2, six wells were drilled, and one platform was constructed.
For both phases, an 82% success rate was achieved in drilling the wells and finding gas based on the 3-D seismic data.
SASB Well Drilling Details
The drilling preparation work using the Saturn drilling rig for the first two shallow water development wells at SASB commenced in July 2021.
The $9m drilling project or the Saturn Project took over two months to complete and targeted the Alapli and Bayhanli wells. Both well’s drill stem tested more than 7mmcf/d of gas.
The Saturn Project was followed by the drilling of three deeper water wells by the Uranus drilling rig.
Uranus drilled the first deeper water well at the Akçakoca platform in September 2022. Three directional wells were drilled and one recompletion of the existing well from the platform was conducted within six months.
The first gas was produced from the three directional wells in early November 2022. The recompletion of the Akçakoca-3 natural gas well commenced in November 2022 and took 12 days to complete.
The Akçakoca-3 well commenced production in March 2011 and produced 9.78bcf (100% interest) of gas till November 2022. It was producing 3.3mmcf/d of gas after recompletion.
In November 2022, Uranus drilled the West Akçakoca-1 well to a depth of 1,000m followed by Guluc-2.
Trillion announced an increase in the development program from 17 to 20 wells (three additional side-track wells). The South Akçakoca-2 well was drilled as a side-track in 2022.
To obtain a detailed and accurate mapping of gas reservoir units, a 3D seismic reprocessing project was conducted by Trillion. The project commenced in January 2023.
The Guluc-2 well was drilled to a depth of 3,910m by Uranus and the preliminary gas indications were announced in February 2023.
The indications show 73m of potential natural gas pay within 14 separate sands in the Akcakoca Member (SASB production zone) and more than 9m thick three sand gas reservoirs.
The West Akcakoca-1 well was drilled by Uranus to a total measured depth of 3,839m and the preliminary results were announced in March 2023, suggesting 55m of natural gas pay within six sands in the Akcakoca Member.
The flow test of the West Akcakoca-1 well’s two lower D sand layers showed a total of 7m of natural gas pay in March 2023. Following the results, the well commenced production with 5.9mmcf/d of gas.
The flow test results of the Guluc-2 well were announced by Trillion in March 2023 peaking at 16.35mmcf/d of gas. The well commenced production with an initial production rate of 6mmcf/d of gas.
In April 2023, Uranus spudded the Bayhanli-2 well (2P reserves of 4.2bcf) reaching a total measured depth of 3,400m. The flow test results encountered a combined rate of 11.9mmcf/d of gas.
Uranus spudded the Alapli-2 well in June 2023 and tested at a combined rate of more than 7mmcf/d of gas.
The well was drilled to a total measured depth of 3,258m, indicating more than 40m of natural gas pay within 6 separate sands in the Akcakoca Member.
The flow test results showed a combined flow rate of 11.9mmcf/d of gas.
Trillion recompleted the West Akcakoca-1 in June 2023 with an increased gas production to 5.3mmcf/d at the field.
Trillion announced the commencement of the operations program at the project in May 2024. The program will occur over two months and will be conducted in phases.
The program will involve seven or eight wells at the SASB Field, including all six wells drilled or completed in 2023 and historically older wells which experienced water loading issues.
As of July 2024, the total production from the Akcakoca platform is 7.3mmcf/d (100% interest), including the West Akcakoca-1, Guluc-2, and South Akcakoca-2 wells.
SASB Gas Field Development Project Details
Trillion Energy is redeveloping SASB with a 17+/- well program. The program commenced in September 2022.
The development program comprises four phases: A, B, C, and D. In Phase A ($37m), six new wells were drilled, completed, and produced (2P reserves).
Phase B ($25m) comprises 9-10 workovers for 2024 with a target to drill five development wells and one stratigraphic well. 10 additional drilling locations have been selected for the development of the project.
Phase C is planned to explore stratigraphic and channel prospects and Phase D is planned to include tie-ins for production and off-block exploration near the licence area. Currently, land acquisition is pending.
A total of 8 million cubic feet of gas per day (mmcf/d) of production is forecasted for the end of 2024.
SASB Project Contractors
Grup Servicii Petroliere (GSP) Offshore signed an offshore drilling services agreement for 2022-23 with Trillion Energy in May 2022 for the gas field.
The work scope included drilling five wells using the GSP Uranus jack-up drilling rig. The Saturn drilling rig (GSP Saturn) was delivered by GSP Offshore.
A Memorandum of Understanding (MoU) was signed by Trillion and GSP for drilling services at the field in February 2022.
Under the MoU, Uranus drilled five new wells and two recompletions at the project in seven months. Uranus has a service rate of $95,000 per day.
Schlumberger (SLB) signed a purchase order with Trillion Energy in February 2022 to deliver well engineering design services and drilling support for new well drilling operations at the field.
The scope of work included the design and engineering of well directional trajectories, drilling mud programs, offset analysis, casing needs, directional tools etc.
The initial engineering and planning services were delivered by SLB in quarter 2 of 2022.
Oil and Gas Hunter was retained by Trillion Energy in April 2021 to conduct a geophysical analysis of the project for discovering new gas resources and deeper gas potential in the exploration area.
GLJ Petroleum Consultants prepared an independent petroleum resource evaluation, effective June 2020, for six prospects on the project.
The 3D seismic survey of the project area was conducted by WesternGeco in 2004.
