* No meaningful flow rate measured due to mechanical issues
* Testing operations confirm 30 degree API gravity oil
* Say to sidetrack into the Catcher East area
* Premier Oil says Catcher reserves estimates unchanged
* EnCore shares falls 16 pct, Nautical falls 10 pct (Adds details)
BANGALORE, June 15 (Reuters) - Britain's EnCore Oil Plc EO.L and Nautical Petroleum NPE.L said test at Catcher well in the Central North Sea produced light oil but no meaningful flow rate could be measured due to some mechanical issues.
Shares of EnCore Oil were down 16 percent at 29.50 pence, while Nautical shares fell 10.4 percent to 133.5 pence at 1505 GMT on Tuesday on the London Stock Exchange.
“I don’t think it’s a negative announcement. But ... I would probably say that the expectations were for a flow rate and they did not get one, instead there were some problems encountered,” analyst David Hart of Westhouse Securities told Reuters.
The companies, which have a 15 percent stake each in the Catcher licence, said the tests resulted in light oil of 30 degree API gravity.
The companies would now sidetrack into the Catcher East area, where they expect to encounter additional hydrocarbon bearing reservoirs.
Separately, Premier Oil PLC PMO.L, which has a 35 percent stake in the licence, said the well would have likely flowed at a rate in excess of 7,500 barrels per day if not for the mechanical issues.
Premier also said its recoverable reserves range estimate of 25 million to 50 million barrels of oil for Catcher was unchanged.
Premier shares were up 4 pence at 1217 pence at 1505 GMT. (Reporting by Tresa Sherin Morera; Editing by Gopakumar Warrier)