Petroleum Systems Modeling of the Kwanza Salt Basin, Offshore Angola

Abstract

Petroleum systems modeling (PSM) is an important aspect of hydrocarbon resource assessment. Performing PSM at an early stage of the exploration cycle helps to reduce exploration risk. We aim to understand the charge, timing, and migration components of the Kwanza basin, offshore Angola. The basin is part of the Aptian salt basin formed by the opening of the South Atlantic during the breakup of the Gondwana supercontinent.

Our analysis involves interpreting 2D multiclient seismic data of various vintages and multiclient 3D anisotropic prestack-depth-imaged datasets that cover an extensive part of the Kwanza basin. The four regional 2D PSM transects of this study individually extend approximately 800 line kilometers from shallow water (<150 m) to ultradeep water (>4,000 m). An interpretation of 3D prestack-depth-imaged volumes provides full temporal, spatial, and physical relationships between burial history, lithologies, porosity and permeability characteristics, compaction, hydrodynamic effects, and paleoheat flow.

Regional horizon interpretation includes the seabed, Miocene, Eocene, Cretaceous, Albian, top salt, base salt, Barremian, Neocomian, and basement. The study involves a restoration of the structure through geologic time, with key focus on the presalt section.

The geology in the study area comprises both extensional and compressional domains. The extensional zone consists of raft zones with remnant salt pillows and welds. The compressional zone consists of salt diapirs, ridges, and shallow allochthon feeders connected to salt stock. Key trap styles in the postsalt includes salt-induced fault-bounded traps, salt-flank stratigraphic traps, and turtleback faulted structures. Presalt trap styles are mainly structural. Anticipated results from petroleum systems modeling will impact future exploration efforts and guide future seismic acquisition plans.

AAPG Datapages/Search and Discovery Article #90189 © 2014 AAPG Annual Convention and Exhibition, Houston, Texas, USA, April 6–9, 2014