Comparative Tertiary petroleum geology of the Gulf Coast, Niger, and Beaufort‐Mackenzie delta areas

• Published in: Geological Journal
• Main Author: Curtis, Doris M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1986
• Subjects: Canada; Mackenzie Delta; Alaska
• Online Access: http://dx.doi.org/10.1002/gj.3350210303; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fgj.3350210303; https://onlinelibrary.wiley.com/doi/pdf/10.1002/gj.3350210303

Abstract Oil and gas are produced from Tertiary sandstone reservoirs in deltaic and related depositional systems in the Gulf Coast (U.S.), Niger (Africa), and Beaufort‐Mackenzie (Canada‐Alaska) basins. In each area there is an orderly, predictable interrelationship of sedimentation, stratigraphy, depositional environment, and structure, with the characteristics, ages, and distribution of producing trends. In comparing and contrasting the three areas, it is apparent that they have many essential aspects in common, resulting from the fact that they are relatively young, subsiding paralic basins on 'Atlantic type' or passive margins. They contain thick accumulations of deltaic terrigenous sediments that have prograded in regressive basin‐filling sequences as the basins subsided. Therefore each has a vertical gross lithologic sequence with shale at the base, overlain by interbedded sandstones and shales, overlain by massive sandstones. The vertical sequence is repeated laterally from the basin landward. In each basin the stratigraphic units of the sequences thicken basinward across a series of normal, listric, down‐to‐the‐basin syndepositional faults, with which are associated 'rollover' anticlines which form traps. Trapping associated with diapiric structures is also characteristic of all three areas. Although similarities among these areas is striking, significant differences are related to their different geologic settings and geologic histories. For example, the presence of salt in the Gulf Coast basin has resulted in a wide variety of salt dome‐related trapping mechanisms in addition to the shale diapirs and roll‐over anticlines common to all three areas. Pre‐Tertiary tectonic settings, different in each case, control basin configurations and affect structural trends. Vertical and lateral differences in depositional systems and sequences, as well as variations in delta morphology and sandstone geometries, result from variations in ratios of rates of deposition to rates of subsidence. The framework for the ...