A seismically controlled seal breach in a major hydrocarbon province: A study from the Mauddud Formation in the Bahrah field, Kuwait.

Behbehani, Sayed, Hollis, Cathy , Holland, Greg, Singh, Parmjit and Edwards, Keith (2019) A seismically controlled seal breach in a major hydrocarbon province: A study from the Mauddud Formation in the Bahrah field, Kuwait. Marine and Petroleum Geology, 107 . pp. 255-277. DOI 10.1016/j.marpetgeo.2019.04.017.

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Abstract

The Mauddud Formation, a late Albian-aged carbonate oil reservoir, is one of the main oil
producers in Kuwait, however, it exhibits unreliable oil production from the Bahrah Field.
The Mauddud Formation in the Bahrah field is divided into two sub-structures by a series of
E-W faults and shows a slight degradation in oil quality (~5API) within the up-dip structure.
Intersections of the E-W faults with NW-SE faults are associated with deep-seated seismic
pipes, which culminate in pull-up features, creating the overlying sag-like features.
Additionally, the Mauddud Formation shows evidence of baroque (saddle) dolomite in
fracture cements and replacing clasts. Fluid inclusions within the baroque dolomite have
abnormally high salinity (>20 wt% NaCl eq), high homogenisation temperatures (up to
~100°C) and 3He/4He ratios ~0.3 times higher than atmospheric values. Taken together, this
seismic and petrographic evidence suggests that the Mauddud Formation experienced an
ingress of radiogenic, crustal fluids, potentially sourced from the basement. Seismic pipes, therefore, are interpreted to be the product of the upward movement of hydrothermal
fluids that breach seal rocks, causing oil to escape and subsequent calcite cementation. An
integrated map of a basement magnetic anomaly and current exhalative features on the
present-day surface shows evidence of a relationship with fault locations on the level of the Mauddud Formation that were rejuvenated and associated with the remigration of oil. This
study provides an exceptional example of a seal breach in one of the world’s most prolific
hydrocarbon provinces. It also indicates the importance of a multidisciplinary, multi-scale
approach extending from the basement to the surface in order to understand seal breach in
carbonate petroleum systems. The overall data is used to assess the main factors that effected the integrity of the seal when this latter is breached by hydrothermal fluids.

Document Type: Article
Keywords: seal breach, major hydrocarbon province, Mauddud Formation, Bahrah field, Kuwait
Refereed: Yes
Open Access Journal?: No
Publisher: Elsevier
Projects: Enrichment
Date Deposited: 11 Jun 2019 14:15
Last Modified: 31 Jan 2022 09:22
URI: https://oceanrep.geomar.de/id/eprint/46861

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