OML123 is Addax Petroleum’s largest lease area as measured by reserves and production and is located offshore approximately 60 km south of the town of Calabar in the south-eastern part of Nigeria, in the Gulf of Guinea. It covers an area of 90,700 acres (367 km2) in water depths ranging from 3 to 40m.
Both Kita Marine and Adanga North Horst are located in the north sector of OML123 in around 10 m water depth. For the past couple of years, these two fields have been the key assets of OML123. Together, they have totalised more than 55% of OML 123 production and contain 40% of OML’s probable reserves among the lease’s producing fields in 2013 and 2014. These impressive contributions are, among other things, the results of two intensive and consecutive drilling campaigns.
The development of Kita Marine started in the summer of 2011. Prior to development, oil was proven in four reservoirs: P-6, P-7, I-2 and I-4. However, one of the key things that happened over the course of the development was the appraisal of other reservoirs: I-3, I-3.05, I-3.1 and I-3.2. As a result of the successful appraisal an additional 8 production wells were drilled that weren’t planned in the original development programme. In order to accommodate the increase in the number of wells, the Kita Marine B Platform was expanded to increase capacity from 12 slots to 16 slots, all of which were used.
The same rig used for the development of Kita Marine – Adriatic X, a jack-up owned by Shelf Drilling – was used for the development of Adanga North Horst from December 2013. In 2014 seven production wells – ADNH-16HST1, 17H, 18H, 19H, 20H, 21H, 22H – and three sidetracks – ADNH-10HST1, 12HST1, 15HST2 – were drilled based on the original Field Development Plan (FDP).
The FDP for Adanga North Horst was revised in May 2014 and proposed the drilling of 11 development wells in the P-0.5 and P-1 reservoirs, using the ADN-A platform already existing. The aim of this campaign is to recover an additional 12.6MMstb of oil that would otherwise not be produced. In addition, it proposed the drilling of pilot well to appraise an unpenetrated fault block and the first two wells based on the FDP phase 2, ADNH-24H and 23H were drilled.
Thanks to these two successive drilling campaigns and a continuous operation of the Adriatic-X drilling rig production levels of 50,000 bopd were experienced in OML123 last year. Peak daily production rates for Adanga North Horst were 12,407 bopd (1,000 more than the production rate of up to 11,100 bopd anticipated in the revised FDP) and 25,438 bopd for Kita Marine. At the end of 2014, Kita Marine was responsible for 34% and Adanga North Horst of 27% of OML123 production.
Generally, production from OML123 was also enhanced in 2014 thanks to the installation of two booster compressors, BC-1 (became operational in July 2013) and BC-2 (became operational in August 2014) providing more gas lift. Thanks to these and many other diverse efforts, OML123 attained the key milestone of having produced 300 MMbbls on 22 March 2014.