|2013 Exploration and appraisal wells
||2013 Success rate
In 2008, Tullow achieved a 100% exploration and appraisal success rate from its five Ghanaian wells. Mahogany-2, Hyedua-2 and Mahogany-3 were all drilled within the Greater Jubilee Area. Flow tests at Mahogany-2 and Hyedua-2 confirmed the reservoir was highly productive with good lateral connectivity.
In 2009, a two well appraisal programme at Mahogany-4 and Mahogany Deep-2 in the Mahogany area, southeast of the Jubilee Unit Area (JUA), identified further prospectivity. The JUA is considered to have a gross resource base of 500 mmbo (P90) through a most likely 700 mmbo (P50) to an upside of 1,000 mmbo (P10). This resource base will be developed in several phases, of which Phase 1 is now complete with initial production having commenced in November 2010. The Dahoma-1 well was drilled 11km south of Mahogany-3 and the result, announced in April 2010, was Tullow's first unsuccessful well in Ghana but was followed by the successful Mahogany-5 well in June 2010.
In 2009, Tullow continued its 100% exploration and appraisal success rate in Ghana with the discovery of Tweneboa, a significant highly-pressured light hydrocarbon accumulation. Further appraisal of the 200 sq km Greater Tweneboa Area was carried at towards the end of 2009 and in January 2010 the Tweneboa-2 well result was announced. This was followed by the succesful Tweneboa-3 and Tweneboa-3 sidetrack wells in January 2011. To further appraise the extent of the Greater Tweneboa area, the Owo-1 well was drilled approximately 6km west of the Tweneboa-1 well and in July 2010 it was announced that the well encountered 53m of net oil pay in 2 zones of high quality stacked reservoir sandstones. In September 2010, the result of the Owo-1 sidetrack confirmed an additional 16m of net oil pay in the lower part of the same channel system. Pressure data indicates that this oil pay is in communication with the reservoirs penetrated in the Owo-1 well and confirms at least 69 metres of total net oil pay in a substantial gross oil column of 200 metres. Beneath the Owo oil field, 13 metres of net condensate pay was also discovered, with an additional 6 metres of net gas pay logged in the deepest sand encountered.
The E&A programme continued in January 2011, with the drilling of the Tweneboa-3 well comprising two deviated exploratory boreholes drilled into the Ntomme prospect which was proven to be a material and separate gas-condensate accumulation. In March 2011, Tullow announced that the Enyenra-2A well successfully proved that light oil bearing reservoir is in communication with the Owo-1 sands over 7km away. In December 2011, Tullow re-drilled the Owo-1 discovery well, to allow testing and coring. To determine the level of reservoir connectivity and well deliverability, the well was flow tested. The lower channel was tested at a rate of approximately 10,000 bopd, and a commingled rate for the two upper channels was approximately 12,000 bopd. The pressure response will be monitored by pressure gauges deployed in the Enyenra-2A and Enyenra-3A wells, located to the south and north respectively.
Appraisal of the Ntomme accumulation commenced in early 2012 with the drilling of the Ntomme-2A well, located over four kilometres south of Tweneboa-3. This exploratory appraisal well successfully discovered high quality oil bearing reservoirs, below the Ntomme gas-condensate accumulation. The Enyenra-4A well result was announced in March 2012, intersecting 32 metres of net oil pay. Pressure data from the oil leg has demonstrated that the oil is in static communication with the oil seen in the other wells in the field and indicate a continuous oil column of approximately 600m.
In 2011, Tullow continued its exploratory drilling activity in Ghana, drilling the Teak-1, Teak-2, Teak-3, Banda, Akasa-1 and Makore-1 wells in the West Cape Three Points licence, operated by Kosmos. The Teak-1 well drilled in February 2011 encountered a thick tally of oil and gas pay, and the Teak-2 well drilled in March 2011 tested the fault block between the Teak-1 discovery and the Jubilee field, where it penetrated a gas reservoir that may represent a gas cap to the Jubilee field. The Teak-3 well was drilled in November 2011 and confirmed the northern extension of the Teak discovery, across a major fault. Teak-4 was uncessful in encountering hydrocarbons.
In the Deepwater Tano licence operated by Tullow, the final prospects have been drilled out. Of these final wells, Wawa-1, discovered 33m of oil and gas condensate up-dip from the TEN oil and gas-condensate fields. The second, Okure-1, was unsuccessful in discovering commercial hydrocarbons. The final well, Sapele-1, immediately southwest of the Jubilee field, was also unsuccessful in encountering commercial hydrocarbons.
On 25 July 2011, Tullow completed the acquisition of EO Group Limited for $305m. This acquisition, with an effective date of 1 December 2010, will increase Tullow's interest in the West Cape Three Points licence offshore Ghana by 3.5% to 26.4% and increase the Group's interest in the Jubilee field, which Tullow operates, by 1.75% to 36.5%. Following a redetermination of the Jubilee Unit Area, Tullow currently holds a 35.48% equity in licence.
18 month Exploration & Appraisal Programme