From Vienna (MT): A deepwater wildcat is underway in Bulgaria’s Black Sea sector which could open up a whole new play, according to OMV’s exploration chief.

The inland sea’s deepwater oil and gas potential, in addition to its location and proven history of shallow-water shelf discoveries and production projects, makes it a true ‘frontier’ area, OMV’s veep for global exploration told EAGE delegates at a session focused fully on the Black Sea region.

The 6th Generation DP3 drillship Noble Globetrotter II is currently drilling Bulgaria’s first ever deepwater exploration wildcat targeting the Polshkov-1 gas prospect. The potential significance of a further discovery, to follow up two previous deepwater gas finds made in recent years offshore Romania, was flagged up by Ingram, whose company is a partner in the Polshkov well being drilled in the Khan Asparuh block: “It’s a potential play opener,” he said.

Multi-well deep campaign

Operator Total, partnered by OMV and Repsol, spudded the Polshkov-1 well using the Noble Globetrotter II last month.

Located approximately 80 km offshore, the drillship is expected to drill several wells in this campaign over the next few months. Total and its partners signed the exploration contract for the license in August 2012, with the 14,220-sq. km block featuring water depths ranging from 100-2,000 meters. The probe is being drilled in around 200 meters of water. Seismic data acquisition was completed in early 2014. Total holds a 40% stake as operator with OMV and Repsol each with 30%.

Ingram reminded the audience of other previous deepwater successes in the western Black Sea offshore Romania, one of which is operated by an OMV Petrom-ExxonMobil joint venture. The first discovery, Domino, was made in early 2012 in the Neptun Deep block in a water depth of 900 meters. ExxonMobil was the operator for the well which targeted a Miocene gas target, with each company holding a 50% stake.

Ingram said: “We drilled seven wells between 2014 and 2016 using the Ocean Endeavour semisubmersible rig, and gas was encountered in most of those wells.”

Estimates for Domino and the surrounding area are currently put at a cautious 1.5-3 Tcf of recoverable gas, with the companies now examining potential economic development options. He also highlighted the deepwater Sile-1 well drilled by Shell and TPAO of Turkey in block 3920 in the Turkish sector last year, and which also used the Noble Globetrotter II drillship for the job. That probe was drilled 100 km offshore in 2,093 meters of water, and its results are still being evaluated.

Another speaker, Gabriel Ionescu of OMV Petrom, gave further detail on the emerging play trend, adding that a total of 10 deepwater wells have been drilled offshore Romania alone since the Domino discovery.

The other largest deepwater gas discovery there was made late last year by a Lukoil-led consortium, with the Lira-1X find in the Trident block some 170 km offshore in a water depth of around 700 meters. Lukoil has a 72% share in the find, with its partners being PanAtlantic Petroleum (18%) and Societatea Nationale de Gaze Naturale Romgaz (10%). According to preliminary analysis the well hit a production interval 46 meters thick, and further appraisal drilling is planned.

Technical challenges

Jose Martin Banon of Repsol, who was moderating the session, highlighted the region’s technical and operational challenges, stressing that advances in completion technologies, 4-D seismic, high-pressure drilling technologies, extended reach drilling and a deeper understanding of the Black Sea’s pressure and fluid systems would play key roles in future discoveries and development projects in the basin.

But out of a total of 424 wells drilled in the Black Sea since the late 1940s, the success rate up to today is an impressive 26.6%, he told the audience. “That’s from 399 wells drilled from the shelf, and only 25 wells drilled in more than 200 meters of water. From this there are 57 fields in total, 20 of which are producing. There is room for additional discoveries in the deep water, with more than 80% of the area not yet explored! And gas will be very likely,” he concluded.

OMV’s Ingram drew an analogy with what has happened so far in the Eastern Mediterranean, where the deepwater there was at a similar exploration stage with some large gas accumulations found offshore Israel and Egypt, he said. “We need to allocate resources to keep exploring the Black Sea. But it’s an ongoing challenge in this environment.”

Offshore