Location of the Tuna-1 gas discovery in the western Black Sea, offshore Turkey. © NVentures.In Turkey the state oil and gas firm TPAO has announced a major gas discovery at Tuna-1 in the western Black Sea. The firm was drilling in 2,115m water depth on the Sakarya licence (Blocks C26, C27, D26 and D27) between July and August 2020. TPAO claim the discovery shows potential for an impressive 11.3 Tcf of lean gas (in-place), which would be the largest-ever gas discovery in the Black Sea and make Turkey self-sufficient in gas over the next decades.
Given plans for further drilling in this area, along with a major campaign offshore southern Turkey and Cyprus, the country could swing the pendulum towards having major influence over the gas export and transit policies of eastern and southern Europe and North Africa, a role Ankara appears to be very enthusiastic about. As Greece struggles to make important strides on their deepwater acreage (Repsol, Total and ExxonMobil are either being restrained or showing restraint in kicking off their campaigns offshore Greece and Crete), Turkey, Israel and Egypt will vie for dominance in supplying an ever-richer gas mix into the heated European markets.
The Tuna-1 discovery well penetrated over 100m gas column in Mio-Pliocene sandstones, trapped in a major fan system probably draped over a broad compression ridge, 60 km from the Domino gas discovery in the Romanian sector of the Black Sea. TPAO will appraise it with blockwide 3D seismic ahead of drilling, aiming for first gas in 2023.
Turkey has the longest coastline on the Black Sea and controls the largest offshore portion of the Exclusive Economic Zone. Since 2004 the state NOC has sponsored over 50,000 km of 2D and 14,000 km2 3D as operator or JV partner. In 2013 TPAO mobilised the Leiv Eiriksson drillship after OMV and ExxonMobil discovered gas at Domino in the Bulgarian sector. Only now, with a state-owned drillship Fatih, have they been able to venture beyond 2,000m water depth and test deeper Miocene targets. TPAO have said previously they believe the Turkish sector of the Black Sea can hold up to 53 Tcfg (GEO ExPro Vol. 10, No. 1, 2013), leaving Ukraine, Georgia, Romania and Bulgaria to catch up.
