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Last updated: 12 Feb 2014

Key statistics

2013 Exploration and appraisal wells 2013 Success rate
17 88%

Tullow has a one-third interest in each of four licences in the Lake Albert Rift Basin. Operating responsibilities within the basin are divided between the Partners: Total operates EA-1 and EA-1A; Tullow operates EA-2; and CNOOC Limited operates the Kingfisher Production Licence.

Since the first discovery was made at Mputa-1 in 2006, Tullow has drilled over 50 wells in Uganda. Durimg 2013, operational activities have focused on completing numerous appraisal wells and flow tests with results achieving or exceeding expectations. These included the Waraga-3 well which discovered 93 metres of net oil pay, the largest pay tally since the start of the campaign, and the Jobi-6 well which successfully tested horizontal drilling techniques, resulting in enhanced well productivity. In addition, a 352 sq km 3D seismic acquisition across EA1 continues with over half of the programme now completed. These successful activities continue to support our estimates of gross recoverable resources of around 1.7 billion barrels of oil.

The largest discovery in the basin to date is Jobi-Rii (formally called Buffalo-Giraffe), in EA-1 which has a continuous oil column of 140 metres and very high quality sandstone reservoirs. The scale of the discoveries in the Butiaba area has confirmed the Group's view that this is a major hydrocarbon province in its own right within the Lake Albert Rift Basin.

In EA-3, the Kingfisher-3 appraisal well was completed in December 2008, having encountered up to 40 metres of oil bearing sands confirming Kingfisher to be a highly productive field. In February 2009, the Kingfisher-3 well was successfully sidetracked for use as a future producer and this completed the initial appraisal drilling programme for the field.

After encountering borehole instability when drilling the high-impact Ngassa prospect in EA- 2 in early 2008, a new location for Ngassa-2 was identified to reduce the operational complexity of the well trajectory. In August 2009, the Ngassa-2 well reached a total depth of 3,392 meters and encountered 7 meters of net oil pay. Pressure data indicates the potential for a significant oil column down-dip, which could fill the entire 150 sq km closure. Ngassa has the potential to be the largest discovery in the basin, with further appraisal work required to understand the full extent of the discovery.

The Ngara-1 discovery in August 2009 was the last well in a Butiaba EA-2 campaign. The drilling and seismic data was then integrated with the FTG survey. Kasamene-2 was announced as a successful appraisal well in January 2010, supporting the development proposal for the field. This was followed by Kasamene-3 and Kasamene-3A in April 2010. In total, 10 wells were drilled in 2010 utilising 2 land rigs, including wells to trial development drilling techniques in EA-2.

Drilling operations in the Lake Albert Rift Basin continued in 2011. In EA-1, Tullow made an important discovery with the Jobi-East 1 well in June 2011 which encountered 20 metres of hydrocarbon bearing reservoir. Following this discovery, Tullow drilled the Jobi-2 appraisal well in the north of the Jobi-Rii field in July 2011 and confirmed the northward extension of this exciting discovery. Elsewhere in EA-1, Tullow drilled the Mpyo-3 well in June 2011 which confirmed the reservoir sands to be good quality with viscous oil, similar to that encountered in the shallower oil bearing zone of Mpyo-1. In the Total Operated Block 1, one out of four wildcat wells at the end of 2012 successfully encountered hydrocarbons.

Tullow then drilled the Gunya-A well in July 2011, which made a discovery in an undrilled fault block downdip of the Mpyo field. Appraisal drilling on the Jobi-East discovery commenced with Jobi-East-5 in August 2011 and Jobi-East-2 in September 2011. Jobi-East-5 provided valuable data for regional reservoir mapping but was drilled just outside the closure of the field. Jobi-East-2 successfully extended the field five kilometres north. In 2012 a significant appraisal and testing campaign commenced in the block. This campaign will include over 20 appraisal wells, extensive well-testing and 3D seismic acquisition on the Mpyo, Gunya, Ngiri, Jobi-Rii and Jobi-East discoveries over the course of 2012 and 2013. This campaign has commenced with the drilling of the first of three wells on the Jobi-Rii field, the flow testing of Ngiri-2 at rates up to 1,200 bopd and the drilling of the first of five wells on the Ngiri field.

In EA-2, three successful appraisal wells, Nsoga-2, Kigogole-6 and Ngege-2, were drilled and an extensive 3D seismic campaign covering the Kasamene, Ngiri, Nsoga and Kigogole discoveries was completed. The data recovered is of high quality and is currently being interpreted. In October 2011, Tullow received confirmation of the continuation of the appraisal periods for Kasamene, Wahrindi, Kigogole, Nsoga, Ngege and Ngara for an additional year where further testing was carried out. Appraisal drilling and testing activities in the Kigogole/Nsoga/Ngege/Ngara (KNNN) area commenced in 2012 and continue on schedule. The Ngege-3, 4, 5 and 6 wells are all now complete and the Ngege-7 appraisal well is expected to be completed shortly. The successful Ngege-6 well was the first slant well drilled in Uganda and provided valuable experience for future production drilling. The Ngege appraisal wells have all encountered hydrocarbons and enabled improved delineation of this field which covers an area of approximately 50 sq km.

In the Kanywataba licence in the southern part of the Lake Albert Rift Basin, the Kanywataba-1 exploration well commenced drilling in May 2012 and the results of drilling, wireline logging and sampling show that the reservoir is water bearing. This wildcat well was drilled 20 km from the nearest well control on an outlier prospect. This was the last exploration well in the southern part of the basin with this exploration licence expiring in August 2012

The Ngassa discovery, which extends beneath Lake Albert, has been written off due to offshore appraisal and development being currently uneconomic. 

18 Month Exploration & Appraisal Programme