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- Title
SEDIMENTARY RESPONSE TO SALT RELATED TECTONICS AND ITS HAZARDS IN A HYDROCARBON FIELD, KWANZA BASIN, ANGOLA.
- Authors
Anyiam, O. A.; Jolly, B. A.; Harry, S. M.
- Abstract
The presence of extensive Aptian salt basin underlying the south Atlantic passive margin has in so many ways influenced the pattern of tectonics and its sedimentary response during the Cretaceous. Aptian salt in the Kwanza Basin was deposited in two sub-basins separated by a margin-parallel chain of platforms on which salt is either small or absent. Salt withdrawal and dissolution during the mid - Cretaceous led to the formation of a series of north-south trending salt ridges and associated depocentres that provided, and controlled the accommodation space for the deposition of marine sediments. The post-salt marine deposition was controlled by the subsidence of sediment packages into synforms between salt walls initiated by extension of the underlying Aptian salt. Thermal subsidence was locally enhanced by halokinesis in the vicinity of the salt horizon, creating sediment down-building which led to the initiation of prominent salt domes. These thick salt-bearing successions in the basin form sealing hydrocarbon traps with abnormally high fluid pressures (AHFP). Forecasting of AHFP in evaporates is difficult due to the absence of transition zones in salts. Such poor pressure forecast and risk evaluation in an oil field can result in well kicks and subsequent blow-outs. Better seismic imaging and interpretation of the subsurface reduces the risk of possible blow-out hazard in such hydrocarbon field.
- Publication
Petroleum & Coal, 2019, Vol 61, Issue 2, p332
- ISSN
1335-3055
- Publication type
Academic Journal