Calvalley tests Kohlan, basement in Yemen

Calvalley Petroleum Inc., Calgary, has tested oil and gas-condensate from fractured granitic basement and gas-condensate from Jurassic Kohlan sands at its Qarn Qaymah-2 deep exploratory well in central Yemen’s Block 9 in the Masila basin.

By OGJ editors
HOUSTON, Feb. 15
-- Calvalley Petroleum Inc., Calgary, has tested oil and gas-condensate from fractured granitic basement and gas-condensate from Jurassic Kohlan sands at its Qarn Qaymah-2 deep exploratory well in central Yemen’s Block 9 in the Masila basin.

The well’s estimated hydrocarbon column exceeds 380 m in fractured granitic basement in a structure larger than 37 sq km. Production tests through 2-7/8-in. tubing yielded a natural flow of 43° gravity sweet crude, 55° gravity condensate, and associated gas at fluctuating rates that reached a maximum of 2,350 b/d of oil and condensate with no formation water.

A sustained rate could not be achieved due to excessive hydrostatic head (greater than 3,500 m), but management believes a sustainable rate can be attained with an electric submersible pump. A system is being designed.

Calvalley perforated the overlying Kohlan sands twice over a 13-m interval. After the first set of perforations were shot, the well flowed condensate-rich natural gas at an initial rate of up to 3.8 MMcfd. After several days, the rate dropped and stabilized at 350 Mcfd as the wellbore loaded with condensate.

The result of the first flow test indicated ineffective initial perforations and potential formation damage. Calvalley reperforated the Kohlan with mild acidization with marked improvement. The well flowed for an extended period at 2-3.5 MMcfd with 70 bbl/MMcf of condensate. Management believes further acidizing is warranted.

Kohlan sands in the Qarn Qaymah fairway display regional blanket sand characteristics with the fairway extending over 34 sq km of Block 9. Recent success by other operators in the area has a positive implication for both Kohlan and FGB potential, Calvalley said. TD is 3,975 m measured depth, and the basement was drilled at a 70° inclination.

Calvalley plans to drill four more deep wells on the same fairway in 2010.

At Ras Nowmah-1, an exploratory well between Hiswah and Al Roidhat fields, Calvalley cut 45 m of gross oil pay in high-quality reservoir rock including 35 m in the Cretaceous Qishn and 10 m in the Cretaceous Saar formation. Production casing was set, but a stuck downhole completion assembly awaits a fishing job in March. The first of two follow-up wells is to spud by the end of March.

Calvalley will abandon the Salmin-1 exploration well near the block’s western edge. The primary target, a seismically identified carbonate buildup prospect in the Jurassic Madbi formation, had nonreservoir quality rock, and 10 ft of Kohlan sand had moderate hydrocarbon shows.

Agreements are to be signed in February 2010 for the sale of blended crude from Block 9 through Block 51 to the Masila system in Block 14 for export. Trucking is to start in the third quarter of 2010, and engineering of a pipeline to replace the trucking will begin as soon as the agreements are signed.

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