On opposing sides of the Atlantic Ocean lie the Kwanza-Campos conjugate pair – exploration hotspots, remarkably similar, with a rich history of drilling successes and remaining running room for yet-to-find resources. Modern 3D data acquisition reveals tantalizing similarities between the two basins and the learnings from each can be utilized to advance the identification of their additional exploration potential.
The comparison and identification of petroleum system elements of the Campos and Kwanza basins, as published in the May edition of First Break, illustrates to explorers the potential that exists on each side of the South Atlantic.
Translating Analogies from One Basin to the Other Fuels Exploration Opportunities
While asymmetry is evident in South Atlantic conjugates such as the Santos-Namibe pairing, the Kwanza-Campos salt basin conjugates show remarkable symmetry in structural style and scale, both in the rift architecture as well as in the post-salt passive margin sequences.
Modern GeoStreamer data reveal clear architectural symmetry in the Campos-Kwanza conjugate basins through four geological domains based on salt geometry and the structural style of post-salt sediments.
Both basins exhibit near mirror images of highly effective proven source and reservoir systems at least through until Cenomanian-Turonian times, when fully separated basin conditions were established. Despite the differences in more recent basin history, the impact of the common underlying geology can be applied similarly to reservoir systems in the Late Cretaceous and Tertiary sections in both conjugate basins.
Exploring New Frontiers in Campos Basin
Exploration success in the Campos Basin is well established and is now moving to emerging frontier areas, chasing the continuation of the presalt play in deepwater Santos. In the deep-water Campos, sag and syn-rift reservoir potential is seen in base-salt and fault-related traps, with access to the Barremian-Aptian source kitchens, as proven in the conjugate deep-water Kwanza.
To date in the basin, the dominant reservoirs are turbidites found in the post-salt section. Pre-salt reservoirs have primarily been drilled in shallow waters, though the success of deepwater presalt carbonate reservoirs in the Santos Basin show the potential for further exploration.
Revisiting the Proven Yet Overlooked Kwanza Basin
The improved imaging of basement structure, syn-rift, and sag-phase megasequences in conjunction with a review of the Kwanza well results and analogous systems from the Campos Basin, has enabled the petroleum potential of the Kwanza shelf area to be reassessed.
Historical shelfal exploration in the Kwanza Basin focused on the post-salt section, with secondary targets in the pre-salt. The wells drilled in the 1980s were all drilled on 2D seismic data which struggled to clearly image the presalt section. Despite this, both pre- and post-salt discoveries were made, and several hydrocarbon system elements were proven. The revisiting of these proven hydrocarbon systems with new GeoStreamer seismic data has enabled improved pre-salt imaging, basin framework definition, and further identification of exploration potential.
Considering the exploration success in the Campos Basin, petroleum system analogies can be extended to the Kwanza Basin for the post-salt. Likewise, discoveries made in the presalt of the Kwanza Basin prove the hydrocarbon system, and these analogies could be translated to the deep-water Campos.
Upcoming Licensing Rounds Will Unlock Remaining Potential
New data provides coverage for upcoming licensing rounds. In addition to the Angola MegaSurvey, the PGS ANG Kwanza Shelf 3D GeoStreamer survey delivers key data for the Angola 2021 offshore bid round with excellent imaging of the pre-salt structures and syn-rift/sag-phase sediments, ideal for prospect identification and analysis.
Although details of the Campos Basin presalt play elements are at present unconfirmed in the deepwater, the recent 1-BRSA-1377-RJS Urissane presalt oil discovery made by Petrobras and partners in block C-M-411 provides further encouragement for the play extending into the deepwater 17th Bid Round areas of the Campos Basin.