First oil flowed from the Tweneboa, Enyenra, Ntomme (TEN) fields offshore Ghana, to the FPSO Prof. John Evans Atta Mills in August 2016. This milestone was reached on time and on budget three years after the Plan of Development was approved by the Government of Ghana in May 2013.
In March 2009, the Eirik Raude rig successfully drilled the Tweneboa-1 wildcat well in the Deepwater Tano licence, around 20 km west of Tullow’s Jubilee field and some 45 km offshore from the Ghana mainland. This initial discovery was followed up by a series of further successful appraisal and exploration wells which resulted in the discovery of the Tweneboa-Enyenra-Ntomme (TEN) field.
Developing the TEN fields
In May 2013, The Ghana Minister of Energy approved the Plan of Development for the field and Tullow commenced with its second major operated deep water development project in Ghana. Similar to Jubilee, the development includes the use of an FPSO which has a facility production capacity of 80,000 bopd which will be tied in to subsea infrastructure across the field. The vessel was converted in Singapore and in September 2015, the vessel was officially named ‘FPSO Prof. John Evans Atta Mills’, after the late Ghanaian president who oversaw First Oil from Ghana’s Jubilee Field in 2010. The FPSO sailed away from Singapore to Ghana on 23 January 2016.
The FPSO arrived in Ghana in early March 2016 where it was moored to the seabed before being connected to the risers and subsea infrastructure.
First oil was achieved on time and on budget in August 2016, three years after the Plan of Development was approved by the Government of Ghana.
In April 2015, the Special Chamber of the International Tribunal of the Law of the Sea (ITLOS) ordered a number of provisional measures which both Ghana and Côte d’Ivoire were required to comply with; including ‘no new drilling’ until ITLOS gave its decision on the maritime boundary dispute. The TEN field therefore started up with 11 of the planned 24 wells and no new wells could be drilled until after the ITLOS ruling.
On 23 September 2017, the International Tribunal for the Law of the Sea (ITLOS) made its decision with regard to the maritime boundary dispute between Ghana and Côte d’Ivoire. The new maritime boundary, as determined by the tribunal, does not affect the TEN fields.
Return to drilling
Following the ITLOS ruling,Tullow subsequently received notification from the Government of Ghana to recommence drilling in the TEN fields and a multi-year incremental drilling programme started in 2018, seeking to ramp up production from the TEN fields to utilise the full capacity of the FPSO and sustain this over a number of years.
Tullow has two rigs operating in Ghana, the Maersk Venturer since March 2018 and the Stena Forth which commenced operation in October 2018. These rigs are allowing simultaneous drilling and completion activity across the TEN and Jubilee fields. The drilling programme is running to plan with four production wells and two water injector wells expected to be completed by the end of the year and gross production across both fields expected to increase to around 180,000 bopd in early 2019.
The TEN fields performed well in 2018, with gross production averaging 64,500 bopd (net: 30,400 bopd) reflecting good results from the drilling programme. The first additional Ntomme well, NT05-P, was successfully drilled in the first half of the year and started producing in August 2018. A second new producer, EN10-P, is currently being completed and is expected to be online in February.
Tullow expects 2019 gross oil production from the TEN fields to average around 83,000 bopd (net: 39,000 bopd). Tullow is confident of this growth in production following strong performance in 2018, good results from recently drilled wells in both the Ntomme and Enyenra fields and production testing that has seen the TEN FPSO deliver in excess of its design capacity. The forecast includes a two-week shutdown of the TEN FPSO for routine maintenance which is currently scheduled for the second quarter of 2019. Gross gas production is expected to be around 2,100 boepd (net: 1,000 boepd).