By Tapan Panchal

LONDON--Oil and gas exploration company Tullow Oil PLC (TLW.LN) said Friday it has encountered water-bearing reservoirs in the Shimela-1 well in the South Omo Block, onshore Ethiopia.

The well encountered lacustrine and volcanic rocks including 100 meters of net sandstone reservoir within siltstones and claystones. The Exalo 205 rig drilled the well to a final depth of 1,940 meters and will now be moved to drill the Gardim-1 well in the south-eastern corner of the Chew Bahir basin, Ethiopia.

Tullow Oil operates the South Omo Block with 50% equity interest, Afica Oil Corp.(AOI.T) owns a 30% stake and Marathon Oil Ethiopia Limited B.V. owns 20% equity interest in the block.

Marathon Oil Ethiopia is a unit of Marathon Oil Corp. (MRO).

Shares of Tullow Oil on Thursday closed at 852 pence, valuing the company at 7.75 billion pounds ($13.08 billion).

Write to Tapan Panchal at tapan.panchal@wsj.com

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