Integrated structural, sedimentological and diagenetic evaluation of hydrothermal dolomite, Cretaceous - Eocene, Hammam Faraun Fault block, Gulf of Suez

Jesal Hirani
University of Manchester, School of Earth, Atmospheric and Environmental Sciences Manchester, United Kingdom
[email protected]

The distribution of diagenetic bodies, such as dolomite, in carbonate reservoirs is critical to understanding the distribution of porosity and permeability in these reservoirs. Study of the Hammam Faraun Fault Block (Sinai, Egypt) and its footwall crest will allow the integration of the depositional, structural and diagenetic evolution of the fault block. This will determine if dolomitisation of the Eocene Thebes Formation, a remobilised carbonate succession, is either facies or fracture controlled, or a combination of the two. The Thebes Formation was deposited in a deep marine slope environment, with the remobilised carbonate units preserved within a background of pelagic lime wackestones.

This study will integrate multiscale sedimentological and structural data, with field-scale diagenetic observations in order to map dolomite body geometry. The Eocene Thebes Formation is partially dolomitised. The aim is to describe the texture of the dolomite, determine the timing of dolomitisation, the source of diagenetic fluids, and the mechanism for replacement of the host limestone. This will be achieved using petrography and a variety of geochemical analyses including electron microprobe, stable isotope and fluid inclusion analysis to fingerprint the replacive and cement phases.

The data collected in this project will help understand controls on dolomitisation within a rift setting. It will allow us to generate rules that can help predict the extent of dolomitisation and the size and shape of dolomite bodies, by understanding the interplay of fluid reactivity, depositional and structural controls on diagenesis. This would be vital in predicting reservoir quality in the subsurface.

AAPG Search and Discovery Article #90157©2012 AAPG Foundation 2012 Grants-in-Aid Projects