The entire Walvis Basin is significantly under-explored although the wells drilled to date have encountered multiple source rocks and reservoir intervals and, in a number of cases, hydrocarbon shows. Only eight wells have been drilled to date – by Norsk Hydro, Sasol, Ranger, HRT, Repsol and, most recently in 2018, by Tullow and Chariot. Of the wells drilled in the Walvis Basin, Geo regards the HRT operated Wingat-1 well as being the most significant in that liquid hydrocarbons were recovered from the Aptian interval, thus establishing for the first time that a source rock has charged oil into a trap in the Walvis Basin.

In 2017 Geo completed an infill 2D seismic program of 840km across the adjacent PEL0029 licence with particular focus on the primary prospect Gemsbok. The subsequent interpretation confirmed three prospective, very large, fault and dip-closed structures: Gemsbok, Lion (which can be sub-divided into Lion North and Lion South) and Dik-Dik.

Geo was encouraged enough to apply for Block 2011A to the east where similar plays are seen in the Welwitschia Deep structure, as well as other plays, which have been demonstrated elsewhere in the Walvis Basin. A Petroleum Agreement for this acreage was signed with the Namibian Government and our partners in September 2018 and the PEL0094 licence was subsequently issued. Geo has mapped 3D and 2D seismic across the basin and across this licence and confirmed that the source rock is present and is able to charge oil into  the significant portfolio of prospects and leads.

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Rich, oil-prone, Aptian-Barremian source rocks are present in Wingat-1, Murombe-1, Moosehead-1 and at Kudu, where it has sourced significant volumes (multiple tcfs) of gas. In addition to the oil at Wingat-1, trace oil was extracted from core in the Albian carbonate reservoir at 1911/15-1, migrant oil was sampled from Upper Cretaceous sandstones at 2012/13-1 and slicks detected by satellite have been noted to the north of the Gemsbok prospect in PEL0029. In PEL0094 a survey sampled gas from seabed cores, which was interpreted by the contractor to be at least partly generated from a deeply buried source rock. This suggests that, of the oil and gas generated by the Aptian source rock, some of the gas has leaked up through a large fault imaged on the seismic data that underlies these cores, whereas the oil has been trapped in the sub-surface. Also visible on the seismic in PEL0094 is a very large area of probable shallow gas above the aforementioned large fault and, whilst this will never be a commercial accumulation, it does, with the evidence of gas from the seabed cores, indicate a working source rock within PEL0094.

Specialist studies on the seismic and wells have enabled Geo to map the source rock with some confidence into PEL0094 and a petroleum systems modelling study has confirmed that not only is the source rock mature, but that it has generated oil that has migrated to and filled the prospects.

Albian-Aptian, shallow marine carbonate reservoirs, the main targets at Welwitschia Deep, Gemsbok, Lion and Dik Dik are present in the wells 1811/05-1 (Tapir South-1), 1911/15-1 and 1911/10-1, where the reservoir quality is good. This reservoir is mapped in large, dip and fault-closed structural traps in Global’s prospects. In the western part of PEL0094 the Welwitschia Deep prospect is already covered by 3D seismic data and Global’s interpretation of the data has confirmed this large prospect.

Further into the basinal areas the Albian is expected to be composed mainly of deep water mudstones and sandstones, which were proven as a new play type by Tullow’s Cormorant-1 well. Global’s model is that the play extends into the SE corner of PEL0094 and east of here in PEL0097 the Osprey prospect, with Albian sandstones as the prognosed reservoir, has been mapped by the operator.

Geo interprets the presence of Upper Cretaceous and Paleocene sandstone reservoirs in both PEL0094 and PEL0029. These sandstones have been intersected in most of the deep water wells offshore Namibia, including nearby wells 2012/13-1, 1911/15-1 and 1911/10-1. The reservoir quality is good and at 2012/13-1, to the SE of PEL0094, migrant oil was sampled from these sandstones.

Within the area of the 3D seismic data survey in PEL0094, the Marula prospect has been mapped with Upper Cretaceous sandstones in a distal pinchout trap. There is a strong amplitude anomaly whose edge conforms to structure down-dip, and this edge could be an oil-water contact. As such, Geo considers this to be the most attractive of its prospects. The forward plan is to work up existing data and other data yet to be licensed to showcase this potential, and then partner with a credible deep water operator to move the exploration of the two licences forward.

A summary of the play types in PEL0094 are shown in the figure below.