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. Since start-up, Tullow has managed production from the existing 11 wells in a prudent and sustainable manner.
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 will start this year, 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 secured the Maersk Venturer rig which is expected to start drilling late in Febraury 2018. The rig will be used across the TEN and Jubilee fields and has been contracted for up to four years with early termination provisions. The first well planned is an Ntomme production well in the TEN fields. Work is ongoing to finalise the sequence of further wells to optimise output from both the Jubilee and TEN fields.
The TEN fields performed well in 2017 with gross production exceeding initial guidance, averaging 56,000 bopd (net: 26,400 bopd). This strong performance was as a result of production and water injection optimisation which continues to be effective and the field has performed consistently above 70,000 bopd for the last three months.
Tullow expects 2018 gross oil production from the TEN fields to average 64,000 bopd (net: 30,200 bopd). During the year, the rig schedule and timing of drilling and completion operations will be optimised, providing upside potential to this initial estimate.
In the last quarter of 2017, Tullow signed the TEN Associated Gas (TAG) Gas Sales Agreement with the Ghana National Petroleum Corporation and Tullow anticipates the start of gas sales from TEN in the first half of 2018. Gross gas sales equivalent to 4,200 boepd (net: 2,000 boepd) have been forecast for the year.