NAMIBIA: Shell Strikes Oil at Graff-1 Deepwater Wildcat

The National Petroleum Corporation of Namibia (NAMCOR), the Namibian state-owned oil company, and its partners, Shell Namibia Upstream B.V and Qatar Energy, are pleased to announce that the Graff-1 deep-water exploration well has made a discovery of light oil in both primary and secondary targets.

The Graff-1 well has proved a working petroleum system for light oil in the Orange Basin, offshore Namibia, 270 km from the town of Oranjemund. Drilling operations commenced in early December 2021 and were safely completed in early February 2022.

In the coming months, we will perform extensive laboratory analyses to gain a better understanding of the reservoir quality and potential flow rates achievable. Whilst we can learn a great deal from the results of Graff-1, we anticipate that further exploration activity, including a second exploration well, will be required to determine the size and recoverable potential of the identified hydrocarbons.

“We hope that this discovery puts to rest doubts about the hydrocarbon potential of Namibia and opens a new dawn in the country’s future prosperity” said Managing Director, Immanuel Mulunga of NAMCOR.

Global Petroleum believes that the Graff–1 discovery has positive implications for the Company’s PEL 94 licence, which is situated approx. 1,000km north of the Graff–1 discovery:

• The Graff–1 discovery clearly has the potential to underpin a new petroleum province offshore Namibia, which Global’s model predicts to extend to PEL 94, further north in the Walvis Basin.
• Graff–1 has demonstrated for the first time in the history of Namibian offshore exploration that valid hydrocarbon–bearing reservoirs with viable traps are present and that potentially commercial volumes of oil are capable of migrating into them. Both Marula – Global’s primary prospect in PEL 94 – and the Graff discovery are stratigraphic traps with late Cretaceous, deep water sandstone reservoirs.
• Both the Graff–1 discovery and Global’s prospects and leads in PEL 94 are interpreted by the Company to be sourced with oil from the Barremian–Aptian Kudu Shale. This source rock has been proven in the Orange Basin by wells previously drilled there. The Company’s work has demonstrated that the Aptian source rock is likely to be present and charging its prospects and leads in PEL 94 with oil.
• A major factor in field development economics are water depths and subsurface drilling depths, which are significantly less in PEL 94 compared to those at Graff–1 and at TotalEnergies’ Venus–1 well, currently being drilled. Global’s internal economic modelling concludes that its two primary prospects, Marula and Welwitschia Deep, would be robust economic projects in the event of successful exploration drilling.

Peter Hill, Global’s CEO, commented:

‘We would like to congratulate Shell and its partners on the drilling of the successful Graff–1 well. As the first potentially commercial oil discovery offshore Namibia, this is a significant event not only for Shell and its partners, but also for Namibia as a country. We note the apparent similarities between the Graff discovery and the prospectivity in our own licence, which is highly encouraging especially when combined with the strong economics of our prospects.‘

Total drilling depths in PEL 94 are much shallower than is the case for the Graff discovery, leading to significantly lower drilling and development costs should operations proceed to this stage. Water depths are approx. 1000 metres at both the Marula and Welwitschia Deep prospects in PEL 94, against approx. 2,000 metres at Graff–1. The depth to drill from seabed to the expected prospect depth is around 2,000 metres in PEL 94 compared to over 3000 metres at Graff–1.

Another IOC Tower Resources, with a net acreage position of 18,637 km2 is believed to be the third-largest net acreage position in the Namibian offshore, after Exxon and Eco Atlantic Oil & Gas also expressed optimism fuelled by Shell’s success. Tower’s Namibian Blocks, covering a gross area of 23,297 km2, are in the Northern area of Namibia’s offshore, in the Walvis basin which is closer to the border with Angola and the Namibe basin, approximately 950 kms away from Graff-1. While this is a considerable distance, certain conclusions can nevertheless be drawn that are relevant to our Namibian Blocks.

1. Initial conclusions

The most important point is that the Graff-1 well demonstrates conclusively the potential for source rocks in the Namibian offshore to have been buried sufficiently to generate light oil in substantial quantities. In the past, this had been open to question, as the only potentially commercial reservoir previously encountered in the Namibian offshore had been the Kudu gas discovery, and the Lower Cretaceous source rock at Wingat-1 (about 250 kilometres to the South of our Namibian Blocks) had produced light oil but until now no substantial oil-charged reservoir was found. The result at Graff-1 therefore reduces the risk of all leads which may rely on similar source rocks, even though each source rock carries its own characteristics and the risks of migration, charge and reservoir are also unique to each case.

The Graff-1 well also would appear to indicate, if the press reports are correct, that the slope channel system with a stratigraphic trap has enabled successful migration of oil into a potentially commercial scale reservoir, which is encouraging for further plays of the same type in both Namibia and South Africa.

2. Tower’s Namibian Blocks

This key conclusion is relevant to our Namibian Blocks because our license area contains a large number of prospects and leads in the Cretaceous turbidites (sandstones) and also in the Albian carbonates and early Cretaceous clastics; and the license area also contains stratigraphic intervals that correlate with regional Lower Cretaceous source rocks which are buried at a sufficient depth to put them in the light oil window. We now have confirmation that these source rocks are potentially capable of producing oil in quantities required to charge substantial reservoirs.

We note that the two wells drilled by Norsk Hydro in the mid-1990s in the Tower block 1911 already penetrated both Upper Cretaceous turbidites and Albian carbonates, with well 1911/15-1 recovering light oil from Albian carbonates, as well as penetrating three source rock intervals including one in the Upper Cretaceous (which is oil-prone, but not mature) and two Lower Cretaceous intervals. In addition to the oil potential from the marine source rocks encountered in the Lower Cretaceous, the oil actually recovered from well 1911/15-1 appears to be from deeper Lacustrine sources, also thought to be Lower Cretaceous, which are clearly mature.

As previously announced, our Namibian Blocks contain two giant structures (identified on the map on our website at the link below as Alpha and Gamma) and four other substantial leads in the Dolphin Graben (identified on the same map as leads A, B, C and D), each of which contain multiple stacked reservoirs including Albian carbonates and Upper Cretaceous turbidites. Both Alpha and Gamma are interpreted as giant 4-way dip closured structures with billion-barrel potential. The Dolphin Graben Leads A, B C & D, all of which are located directly adjacent to areas with mature source rocks, are each estimated to hold between 250-686 million barrels of prospective resources (arithmetically summed gross, unrisked, Pmean), based on Tower’s own initial unaudited estimates.

In addition to the structural plays identified above, Tower has also identified significant prospectivity in stratigraphic plays within the Cretaceous and Palaeogene intervals, with potential for deep-water turbidite reservoirs interbedded with mature source rocks.

These various plays include leads in the slope channel system and the base of slope/fan setting, similar to Graff and Venus respectively, although we do not yet have enough information to say how closely analogous individual structures may be.

3. Next steps

Tower has already been conducting basin modelling to support technical evaluation of the leads identified to date as part of the work programme for the Initial Exploration Period for PEL 96. We are now moving forward with more detailed and focused geological and geophysical analysis aiming to high-grade areas for further seismic data acquisition, and we will also be looking out for further information regarding Graff and Venus as and when it becomes available. Once this work is complete, we will acquire new 3D seismic data over the most promising leads/prospects in line with our work programme.

Jeremy Asher, Tower’s Chairman and CEO, commented:

‘We are delighted by the Graff-1 discovery, for the Republic of Namibia and our partners at Namcor, and also for the greater confidence that this discovery gives us in our own Namibian Blocks. As Immanuel Mulunga, Managing Director of Namcor, has said, this should put to rest any remaining doubts about the hydrocarbon potential of Namibia. We hope that this discovery will bring prosperity to Namibia, and that the further exploration and appraisal activity it generates will also reduce costs and provide further insights to assist all of us exploring in the area.’