“Duva is the first discovery to be developed in the Agat Formation, and we’re hoping for additional discoveries and developments in the same formation,” said Kalmar Ilstad – Director of licence management in the Norwegian Petroleum Directorate.
Duva is the name of one of the 9 daughters of the sea gods Ægir and Ran.
Discovered through drilling 36/7-4 (Cara) in 2016, GDF Suez with partners Spring Energy and Idemitsu Petroleum proved a 50 m gas column and 60 m oil column in a stratigraphic pinch-out trap (known as the Cara discovery at the time) of Agat Fm sandstones.
Reservoir quality ranges from very good in the top section to good in the lower section and a formation test showed very good production and flow properties. In 2017, Engie increased the estimated recoverable reserves for Cara to be 56 – 94 MMboe. The current operator Neptune Energy expects to recover 71 MMboe.
Read about the mineralogy of the Agat sands in the Duva discovery here.
The Duva field has been developed with a four-slot subsea template and tied back to the Gjøa platform only 6 km to the west. The field has three production wells; two oil producers and one gas producer, with the possibility of another oil well. The expected production time on Duva is 13 years.
Drilling the 36/7-4 well was preceded by a first attempt to find hydrocarbons in the same structure. Well 36/7-3 was drilled just downdip of the Duva discovery in 2002, and found the Agat sandstones water wet. Based on the well results, there was doubt on whether the Agat sands did pinch-out in an easterly direction. Also, no traces of oil migration were found. In that light, it must be seen as a courageous decision to push ahead and drill the 36/7-4 well 14 years later. It is partly for that reason that the partnership won the Exploration Innovation Prize in 2019.
On the radar for years
The Agat Fm has been on the exploration radar for years. For instance, Saga proved gas in the 35/3-2 well in 1980, but the well-chosen name “Agat discovery” has been stranded since. More recently, Equinor drilled the Presto prospect in Agat Fm sandstones through drilling well 36/1-3 in 2019, targeting 160 MMboe of recoverable resources. Unfortunately, the well wasn’t a case of “Hey Presto” and it was abandoned dry.
Havhest
In a company exploration presentation, Cairn Energy in 2018 proposed to drill the Havhest prospect, which probably has a lot of similarities to the Duva field. Recoverable resources in Havhest were estimated to be 58 MMboe according to the UK-based operator. Will Havhest ever be drilled in a push to firm up more Agat Fm resources? Not by Cairn, as they decided to sell their Norwegian acreage in 2019. Since then, licence PL828 was relinquished by Neptune and Sval in May this year. However, if it was Kalmar Ilstad to decide, it still may, especially if Duva performs well!
HENK KOMBRINK
