CAPITAL: Sofia

MONETARY UNIT: Lev

REFINING CAPACITY: 324,000 b/cd

OIL PRODUCTION: 800 b/d

OIL RESERVES: 15 million bbl

GAS RESERVES: 170 bcf

Exploration off Bulgaria in the Black Sea had been disappointing through 1997, but London independent MMS Petroleum plc believed it had good prospects.

Texaco Inc. as operator of Block 91-3 found gas with the 1 Galata and 2 Galata wells drilled in 1993 and 1996, respectively. Both wells tested at more than 30 MMcfd. Then the 1 Balgarevo East wildcat drilled on Block 91-2 late in 1996 by Enterprise Oil plc proved dry.

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

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

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

Upstream development

In a bid to attract farmout partners, MMS split the prospects into two groups of two, which were so different they were thought unlikely to be attractive to just one company.

K1 and E1 were low-risk shallow targets in early Cretaceous/late Jurassic and Eocene formations, respectively; T1 and D1 were 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 acquired 850 line km of 2D seismic data over the northwestern part of Shabla and at yearend 1997 was tendering for a rig with a view to spudding a wildcat on the K1 prospect in second quarter 1998.

MMS hoped 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 was made. MMS planned to drill the K1 well whether or not a farmout was arranged.

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

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

MMS would move the oil to a local refinery for processing on a tariff basis. Then it intended to sell the products through an association with a local trader.

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