Aritish oil major Tullow Oil (TLW) has struck black gold at its Enyenra-2A appraisal well, offshore Ghana, in what it hailed an "exceptional" result.

The well, located in the Deepwater Tano licence, encountered oil in excellent quality sandstone reservoirs, the FTSE 100 company said, and has confirmed that the Owo oil discovery - now renamed Enyenra - is a major light oil field.

Spanning seven kilometres south and down-dip of Owo-1, Tullow Oil drilled the well to a depth of 4,234 metres to appraise both the Upper and Lower Channels of the Enyenra oil field. Results revealed 21 metres of net oil pay in the Upper Channel and 11 metres of net oil pay in the Lower Channel.

Pressure data from the Upper Chanel also showed that the oil is in communication with the Owo-1 well, while oil pressures in the Lower Channel suggest it may also be in communication with the deeper pools seen in Owo-1 and its sidetrack, Tullow added.

"The discovery of oil this far down-dip in Enyenra-2A is an exceptional result," said exploration director Angus McCoss. "This represents a major step forward in the appraisal of the Enyenra-Tweneboa area and is highly encouraging for our target to declare commerciality later this year."

Once operations are complete, Tullow plans to suspend the well for later use, and said the Deepwater Millennium drillship will remain in the Deepwater Tano block to complete the drilling of the Tweneboa-4 well.

Meanwhile, the blue chip major will now turn its attention towards drilling the high-risk, high-impact Zaedyus prospect in French Guiana later this month.

Alejandro Demichelis, research analyst at Bank of America Merrill Lynch, said: "We believe this successful appraisal confirms the Enyenra/Tweneboa as a world-class field and pushes it closer to commercial stage.

"Reflecting the de-risking of the Enyenra field we raise our Net Asset Value estimate driven price objective by 60p to 1880p and reiterate our 'buy' rating on the stock."