Tullow Oil plc announced today that the Tweneboa-2 exploratory appraisal well, being drilled some 6 km southeast of the Tweneboa-1 discovery, offshore Ghana, established that Tweneboa is a major oil and gas-condensate field.

"Results of drilling, wireline logs and samples of reservoir fluids establish that Tweneboa is a major oil and gas-condensate field,"the company reported.

Tullow (49.95%) operates the Deepwater Tano licence and is partnered by Kosmos Energy (18%), Anadarko Petroleum (18%), Sabre Oil & Gas (4.05%) and the Ghana National Petroleum Corporation (GNPC) (10% carried interest). 

Commenting today, Angus McCoss, Exploration Director, said: "Tweneboa-2 was a bold step-out which has successfully proven the significant extent of a major new oil and gas-condensate field offshore Ghana. Such an achievement provides a very good start to our exciting 2010 Equatorial Atlantic campaign. We look forward to further appraising this discovery later in the year."

Tullow has interests in two exploration licences offshore Ghana - - Deepwater Tano and West Cape Three Points.

Both blocks lie in deep water and in 2007 two successful exploration wells located a substantial discovery, which straddles the boundary between the two blocks, known as the Jubilee field.

Tullow says that in February 2008 the Odum prospect in the West Cape Three Points block was drilled, discovering the second oil field in Tullow Ghanaian acreage. Following the successful Odum-2 appraisal well in December 2009 the field, which is 13 km from the Jubilee field is on track towards a commercial development and could be tied-back to future infrastructure.

In March 2009, a further potentially significant discovery was made at Tweneboa-1. A highly pressured light hydrocarbon was discovered with seismic and pressure data indicating that the field could cover 200 sq km with an upside potential of 1.4 billion barrels. Appraisal of the field began in December 2009 when the Tweneboa-2 well commenced drilling.

The FT reported on Tuesday that Tullow, the fourth-largest listed UK oil company has exercised pre-emptive rights to scoop up Heritage Oil's assets in Uganda - - - knocking Eni of Italy's nose out of joint in the process - -  for a cool $1.5bn (£826m). This now gives it a dominating presence in the oil fields around Lake Albert although by farming out development it neutralises any whiff of monopoly, something the Ugandans are understandably keen to avoid.