Interview: Alexander Mould
What needs to be done to ensure the development of the Tweneboa, Enyenra and Ntomme (TEN) fields remains on schedule?
As you probably know, the project is being developed in phases. The oil system has been completely commissioned, and we achieved TEN first oil on August 18, 2016. First gas is expected in early 2017. One key outstanding issue is the gas sales agreement between GNPC and the TEN joint-venture partners. This should be completed by the end of the year. Also, further development work such as water and gas injection systems will continue. The construction and tie-in agreement for the TEN and Jubilee gas pipelines has been signed. GNPC owns the TEN pipeline, while Ghana Gas owns the Jubilee pipeline, both of which have been laid. In the first quarter of 2017 the commissioning of the gas pipeline will be completed for gas from the TEN field to flow to power plants in Takoradi. This pipeline interconnection should minimise disruption in the volume of gas provided to Atuabo in the event that Jubilee goes offline.
How will the success of the TEN and Jubilee fields help deliver increased levels of production?
Jubilee currently produces more than 100,000 barrels per day (bpd) of oil, and about 140m standard cu feet per day (scfd) of gas. Part of this gas is reinjected to provide pressure support to the reservoir for optimum production. GNPC’s agreement with the field’s partners – including the operator, Tullow Oil – is to reinject up to 30%, while around 5m-10m scfd is consumed on the floating production storage and offloading (FPSO) vessel. The result of this is that we have access to around 80m scfd, which is significant for power generation in Ghana’s Western Corridor and a major contribution to gas sufficiency in the country. However, one constraint is gas production issues at the FPSO Kwame Nkrumah vessel. Another constraint is the Atuabo plant, which has a nameplate capacity of 150m scfd of raw gas before the liquids are removed, thus resulting in 142m-143m scfd of dry gas. Despite the six-week temporary shutdown of the Jubilee FPSO in March and April of 2016, the field produces about 100,000 bpd of oil and between 140m and 150m scfd, with a gas-to-oil ratio of 1400-1500:1.
The output of the TEN field is also important for the country’s production volumes. TEN produces an additional 30m scfd. As per the plan of development, TEN’s non-associated gas can arrive up to 12 months after first oil – that is August 2017 – although this timeline is now being accelerated by GNPC. The de-bottlenecking of the Atuabo plant – a programme executed with GNPC’s subsidiary, Ghana Gas – will serve to increase the amount of gas processed there. The TEN field is expected to provide an estimated 80,000 bpd of oil at its peak.
What work can be expected to assist the FPSO Kwame Nkrumah vessel at Jubilee?
Preventing the FPSO’s turret from rotating prosed a challenge at the beginning of 2016 and is expected to cost the Jubilee partnership over $120m per year, but we are working with our partners to resolve it permanently. The immediate response, locking the turret bearing in place, has been completed. The next phase will take place over the course of the first quarter of 2017, when a temporary mooring system will be put in place, securing the vessel’s aft to the floor of the sea.
A permanent solution will be discussed in November and should be approved by December 2016, with two options currently on the table – either taking the vessel out to a shipyard to fix the bearing in the turret, or introducing a permanent spread mooring system, which would require a different discharge mechanism, possibly a catenary floating shallow-water buoy about 2 km away from the vessel. This would take about 18 to 24 months to complete.
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