* Owo-1 well encounters two oil bearing zones
* Well to be side-tracked to establish size of oil field
* Plans to accelerate its drilling appraisal programme
* In advanced talks with partners about procuring a new rig
* Shares rise as much as 5.9 pct (Adds detail)
By Sarah Young
LONDON, July 26 (Reuters) - Tullow Oil (TLW.L), Europe's largest independent oil explorer by market value, said on Monday it had found a major new oil field off the coast of Ghana, raising hopes of further discoveries off West Africa.
Shares in Tullow (TLW.I) jumped as much as 5.9 percent to 1,249 pence before falling back to 1,221 at 0854 GMT, after it announced its Owo-1 exploration well had struck oil.
London-based Tullow said the well, drilled in the deepwater Tano licence, intersected a significant column of excellent quality light oil. Wells in the Tano area have yielded a string of discoveries including the Jubilee field, establishing Ghana as a country with significant oil reserves.
"The oils and reservoir qualities here are similar to Jubilee. We've made a substantial discovery here," Tullow's exploration director Angus McCoss told Reuters by telephone.
"It continues the success of Tullow's equitorial exploration campaign in West Africa... we're very well-exposed to the upside in this play."
The well encountered 53 metres of oil pay in two zones of high quality reservoir sandstones, with pressure data indicating the two zones were part of the same accumulation of oil.
Tullow also has positions in the Atlantic Ocean off the coast of Cote d'Ivoire, Liberia and Sierra Leone and is planning to drill a number of wells on its licences in these countries in the next twelve months.
Oriel Securities analyst Richard Rose said the Owo-1 result was "unequivocally positive" and provided encouragement over the potential of the neighbouring Tweneboa area.
Tullow found the Tweneboa oil field in January, building on the 2007 find at Jubilee, which will turn Ghana into an oil producer when it starts pumping later this year. [ID:nLDE60K08B]
Tullow said it would begin its appraisal of the Owo field straight away by side-tracking the well to the east of the discovery to help establish the size of the reservoir.
McCoss said Tullow planned to complete the side-track in mid-August, at which point it would update its current reserves estimates.
"Whilst further appraisal work is required to assess the volumetrics of Owo, confidence around achieving the P10 upside of 1.4 billion barrels of oil equivalent has increased significantly," analysts at Bank of America Merrill Lynch said, referring to an industry measure of reserves which have at least a 10 percent certainty of being produced.
Tullow, which owns a 49.95 percent stake in the Tano licence, said the Owo find meant it was going to speed up its appraisal plan and would drill more wells than first planned.
Discussions were at an advanced stage between Tullow and its partners in the licence, who include privately-held U.S. firm Kosmos Energy and U.S. oil producer Anadarko Petroleum (APC.N), about procuring another rig, McCoss said.
"The market for the rigs is obviously better for us now than it was several months ago," McCoss said, referring to the U.S. deepwater oil drilling moratorium issued in the wake of BP's oil spill in the Gulf of Mexico. [ID:nN12269656]
After completing the side-track, the rig will drill another exploration well, Onyina-1, which sits between Jubilee and Owo.
(Editing by Lin Noueihed)