Aptian unconformity characteristics and their controlling role on petroleum reservoirs in the South Gabon Basin

doi:10.3969/j.issn.1006-6535.2025.06.004

Abstract

Abstract: During the Early Cretaceous Aptian,widespread regional unconformities formed along the mid-South Atlantic rift basins, acting as major hydrocarbon migration pathways.With the South Gabon Basin in West Africa as an example, using seismic, drilling, reservoir data analysis was made on the types, structures and spatial distribution of Aptian unconformities to study their control on petroleum accumulation.Results showed that above and below the unconformity,overlaying anticlines(thrust-related folds)and relict erosional structures developed,respectively.Vertically,a dual-layer structure existed:the upper layer consisted of widely distributed water-conducting sandstones with good properties,high sand fractions and effective sealing by overlying salt, serving as long-distance hydrocarbon migration pathways;the lower layer of semi-weathered sandstones and rapidly varying shales lacked thick weathered clay caps and could not act as effective lateral conduits.These characteristics led to formation of structural-stratigraphic composite petroleum traps in the interior sag,overthrust anticline traps in the central uplift,and faulted traps in the outer sag.This study provides valuable insight for exploration in South Atlantic rift basins.

Key words: South Gabon Basin, unconformity, migration pathway, overthrust anticline, composite petroleum trap

CLC Number:

TE122.2

LI Haibin, HUANG Jianliang, REN Yan. Aptian unconformity characteristics and their controlling role on petroleum reservoirs in the South Gabon Basin[J]. Special Oil & Gas Reservoirs, 2025, 32(6): 33-39.

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