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.
The Stena Forth and Maersk Venturer drillships have been working in tandem on Ghana drilling and completion operations throughout the first half of the year with four wells drilled and three wells completed. The Stena Forth drillship has now left Ghana to commence drilling in Guyana. The Maersk Venturer will remain in Ghana and will complete the ongoing Enyenra-14 production well, a Jubilee producer and an Enyenra water-injector, before switching to drilling operations for the remainder of the year.
The TEN fields have produced 61,500 bopd gross (net: 29,000 bopd) in the first half of 2019. This was lower than expected due to a delay in completing the Enyenra-10 production well in the first quarter. This well has now been brought on stream and has been producing oil in line with expectations. In the second quarter of 2019, the TEN fields produced in line with expectations and the FPSO was shut down for 11 days for planned routine maintenance which was completed successfully. Tullow has also completed 4D seismic acquisition around the TEN fields to identify areas for future drilling, and this data will be ready for interpretation later in 2019.
As previously disclosed in June, mechanical issues have been encountered with the completion of the Enyenra-14 well. It was not possible to fully resolve these issues and a decision was taken to suspend the well and move the rig to the next Jubilee completion while next steps are considered. Accordingly, Tullow has reduced its TEN gross full year production forecast to around 63,500 bopd (net: 30,000 bopd).
Over the first half of the year, Tullow averaged 300 boepd of gas production from the TEN fields. The Group expects to average 1,000 boepd of gas production for the full year.