Regional Play Concepts of the Namibian Margin: New Mega-Regional Seismic Data Offer Insights Into New Petroleum Plays

Abstract

Abstract

The Namibian margin lies south of the prolific Angolan oil provinces and conjugate to the petroleum discoveries within the Brazilian margin, yet a large discovery along this margin remains elusive. Various plays have been tested from near shore shelfal carbonates to deep water clastics, with the Kudu gas field, discovered in 1973, being the only proven reserves. Recent wells have derisked constituent parts of a working petroleum system but the right combination for a large accumulation remains undiscovered. The architecture of the Namibian margin is fundamentally different from that of provinces further north and west in Brazil due to the Walvis Ridge creating a tectonic barrier between the Cretaceous salt basins to the north and the magma-rich and clastic dominated systems to the south. Analysis of regional seismic profiles combined with a comprehensive understanding of the tectonic history of the region may unlock both the future potential of these key plays and their reason for failure to date. As a result a different set of plays concepts are necessary which require understanding of the regional setting.

Integrated interpretation of seismic data allows for the entire Namibian margin, from north of the Walvis Ridge to the Orange Basin in the south, to be understood within regional larger context. The depth imaged (40km) seismic data provide integrated models for margin formation (continental breakup and margin subsidence) and interpretation of depositional systems through time. These observations and models underpin the analysis of a regional petroleum system for the entire margin to reduce uncertainty in exploration of commercial hydrocarbons.

Failure analysis of wells offshore Namibia shows prediction of reservoir presence and quality to be a principle risk factor in exploration. We present a regional play-based exploration framework developed to improve understanding of potential play concepts; both tested and untested, and to further recognize the relationship with the South American conjugate margin. Furthermore, enhanced understanding and imaging of the deep syn-rift and early post-rift sediments has allowed for regional petroleum systems modelling within the tectonic framework.

We present an integrated tectonic, structural and depositional framework for the Namibian margin enhancing understanding of the petroleum potential through interpretation of a mega-regional, trans-crustal seismic reflection survey.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016