Ukraine-focused oil and gas firm Cadogan Petroleum lost almost 30% of its market value on Wednesday morning after giving an update on the ongoing drilling and well testing programme on the Pokrovska and Zagoryanska gas fields in eastern Ukraine. Logging of the Pokrovska 1 well indicated it to be water bearing and as a result the zone was plugged off to enable testing of the overlying V24/V25 interval, which log data indicates is gas bearing. Also, testing on the secondary target V23/V24 at the Zagoryanska 1 well proved to be non-productive. The well was recompleted in the primary V18/V19 target and perforated. Drilling on the Pokrovska 2a location, where the main objective is the Upper Visean section in a different part of the Pokrovska licence, is planned to begin this month. A coiled tubing unit is being mobilised to Zagoryanska 1 to continue the testing program on the V18/V19 interval, the firm said. An extensive work over and testing programme on the other wells on the Zagoryanska license will continue into next year. The share price 29% to 35.5p by 09:13.NR