About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract

AAPG Bulletin, V. 97, No. 7 (July 2013), P. 11811207.

Copyright copy2013. The American Association of Petroleum Geologists. All rights reserved.

DOI:10.1306/11011212076

Linking process, dimension, texture, and geochemistry in dolomite geobodies: A case study from Wadi Mistal (northern Oman)

Veerle Vandeginste,1 Cedric M. John,2 Tina van de Flierdt,3 John W. Cosgrove4

1Department of Earth Science and Engineering, Imperial College London, SW7 2BP, London, United Kingdom; v.vandeginste@imperial.ac.uk
2Department of Earth Science and Engineering, Imperial College London, SW7 2BP, London, United Kingdom; cedric.john@imperial.ac.uk
3Department of Earth Science and Engineering, Imperial College London, SW7 2BP, London, United Kingdom; tina.vandeflierdt@imperial.ac.uk
4Department of Earth Science and Engineering, Imperial College London, SW7 2BP London, United Kingdom; j.cosgrove@imperial.ac.uk

ABSTRACT

Understanding the distribution and geometry of reservoir geobodies is crucial for net-to-gross estimates and to model subsurface flow. This article focuses on the process of dolomitization and resulting geometry of diagenetic geobodies in an outcrop of Jurassic host rocks from northern Oman. Field and petrographic data show that a first phase of stratabound dolomite is crosscut by a second phase of fault-related dolomite. The stratabound dolomite geobodies are laterally continuous for at least several hundreds of meters (sim1000 ft) and probably regionally and are one-half meter (1.6 ft) thick. Based on petrography and geochemistry, a process of seepage reflux of mesosaline or hypersaline fluids during the early stages of burial diagenesis is proposed for the formation of the stratabound dolomite. In contrast, the fault-related dolomite geobodies are trending along a fault that can be followed for at least 100 m (328 ft) and vary in width from a few tens of centimeters to as much as 10 m (sim1–33 ft). Petrography, geochemistry, and high homogenization temperature of fluid inclusions all point to the formation of the dolomite along a normal fault under deep burial conditions during the Middle to Late Cretaceous. The high 87Sr/86Sr ratio in the dolomite and the high salinity measured in fluid inclusions indicate that the dolomitizing fluids are deep basinal brines that interacted with crystalline basement. The dolomitization styles have an impact on the dimension, texture, and geochemistry of the different dolomite geobodies, and a modified classification scheme (compared to the one from Jung and Aigner, 2012) is proposed to incorporate diagenetic geobodies in future reservoir modeling.

Pay-Per-View Purchase Options

The article is available through a document delivery service. Explain these Purchase Options.

Protected Document: $10
Internal PDF Document: $14
Open PDF Document: $24

AAPG Member?

Please login with your Members Only username and password.

Members of AAPG receive access to the full AAPG Bulletin Archives as part of their membership through the AAPG Members Only program. For more information, contact the AAPG Membership Department at members@aapg.org.