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 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 secured the Maersk Venturer rig which started drilling late in March 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. Tullow has also contracted a second rig, the Stena Forth, for an initial three-well campaign from October 2018 with flexible extension options. This additional rig capacity will enable Tullow to carry out simultaneous drilling and completion activity, allowing the tie-in of new wells to be brought forward.
The first additional Ntomme well (Nt-05P) was successfully drilled in the first half of the year and is expected to start production in August 2018. A second well is expected to be completed around the end of the year and start production in early 2019, at which time Tullow expects to be able to increase gross production to around 80,000 bopd. The TEN FPSO has previously been tested at rates in excess of the 80,000 bopd design capacity and the vessel’s ability to produce above this design capacity for long-term operations will be tested in 2019 as further wells come on stream.
The TEN fields performed well in the first half of 2018, with gross production averaging 65,100 bopd (net: 30,700 bopd). Due to this strong performance in the first half of the year, Tullow has increased its gross full year production forecast for TEN to around 65,500 bopd (net: 30,900 bopd).
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 third quarter of 2018. Gross gas sales equivalent of around 2,300 boepd (net: 1,100 boepd) have been forecast for the year.