From Basalt to Skeletons – the 200 million-year history of the Namibian margin uncovered by new seismic data

Abstract

South of the prolific Angolan oil provinces and conjugate to the Southern Brasil margin, offshore Namibia could be the area focus for future exploration discoveries. The margin is adjacent to existing markets in South Africa such that hydrocarbon discoveries of significant quantity should prove to be commercial. Exploration offshore Namibia has yet to produce results as the expected potential remains elusive. Campaigns from the 1970s to 2000s have tested variety of plays from near shore shelfal carbonates to deep-water clastics. All exploration phases have approached the margin through the lens of the technologies and trends of the time, but only hydrocarbon discovery is the Kudu gas field discovered in 1973. More recent wells have successfully proven the constituent parts of a working petroleum system; mature source, reservoir, seal and trap; unfortunately the right combination to produce a large discovery and unlock a new petroleum province remains elusive. In order to understand the context of this margin it is important to see how the overall architecture of the Namibian offshore is fundamentally different from the provinces to the north and farther west in Brazil. On the West African margin the Walvis ridge is a significant boundary between the Cretaceous salt basins farther north and the more magmatic and clastic dominated systems further south. Thus, a different set of play concepts are required and are best understood within the regional setting of the margin. In 2014, ION acquired NamibiaSPAN, a 10,400 km survey of deep, long-offset, regional BasinSPAN seismic reflection lines covering the entire offshore Namibian margin from the shallow coastal waters to the abyssal plains (Figure 1). These data were acquired to intersect important wells and cross numerous basins, crustal domains and tectonic fabric. The objective of the survey was to image the full sedimentary and crustal section down to below the Moho. Several BasinSPAN surveys have been acquired across many of the world’s margins and prolific hydrocarbon provinces. This paper presents the PSTM data from the NamibiaSPAN survey. The PSDM data will be avail¬able in November 2015.