U.K.'s MMS ready to drill off Bulgaria

David Knott
London
[email protected]

Exploration in the Black Sea off Bulgaria has so far been disappointing, but a London independent reckons it has hot prospects.

Texaco Inc. as operator of Block 91-3 found gas with Galata-1 and Galata-2 wells drilled in 1993 and 1996, respectively (OGJ, May 17, 1993, p. 20).

Although both wells tested at more than 30 MMcfd, Texaco is rumored to be negotiating to sell the license. Then Balgarevo East-1 wildcat drilled on Block 91-2 in late 1996 by Enterprise Oil plc proved dry.

Yet MMS Petroleum plc is so optimistic about four prospects on nearby Block 91-1, known as Shabla and where it is operator, that it has already chosen a likely development concept and studied marketing options.

Steve Bottomley, geoscience manager at MMS, explains that Block 91-1 is bounded to the west by onshore Tulenovo oil field, developed by the Bulgarian state firm and which has yielded more than 20 million bbl of oil.

Bottomley is convinced two of the prospects in Shabla block are analogous to Tulenovo geology. Because Tulenovo is effectively a limestone cavern holding oil, he believes productivity in any Shabla finds would not be a problem: "Tulenovo wells have produced up to 2,000 b/d of 19? gravity oil."

Prospects

In a bid to attract farm-out partners, MMS has split the prospects into two groups of two, which are so different they are thought unlikely to be attractive to just one company.

K1 and E1 are low-risk shallow targets in early Cretaceous/late Jurassic and Eocene formations, respectively; T1 and D1 are higher-risk/reward prospects in deeper Triassic and Devonian layers.

Three inconclusive wells were drilled by previous western holders of the Shabla license. Bottomley said poor seismic was to blame.

MMS has acquired 850 line km of 2D seismic data over the northwestern part of Shabla and is tendering for a rig with a view to spudding a wildcat on K1 prospect in second quarter 1998.

MMS hopes to drill the K1 well with a local jack up for about $1 million and to follow this immediately with an appraisal well if a discovery is made. MMS will drill the K1 well whether or not a farm-out is arranged.

Development plans

K1 and E1 are thought large enough to have reserves of 45 and 25 million bbl of oil, respectively. Because the prospects are in 45 m of water and are expected to produce for only 5-10 years, MMS is thinking of development with "an extended well test."

Up to four subsea horizontal wells would be tied back through a tripod catenary mooring and loading system to a production, storage, and offloading ship.

MMS plans to transport the oil to a local refinery for processing on a tariff basis. Then it intends to sell the products through an association with a local trader.

The D1 and T1 prospects are even larger and in 75 m of water, said Bottomley: D1 could hold 1 tcf of gas, while T1 could hold 150 million bbl of oil. MMS hopes to find a farm-out partner to split the anticipated $4 million drilling costs.

John Small, managing director of MMS, said, "We'd be amazed if someone does not take up a 1 tcf prospect. Bulgaria is developing into a gas crossroads for the area, it is well placed for international, relatively hard currency markets, and Bulgarians are desperate for their own supply."