Geochemical evaluation of the karstified Bangestan reservoirs in the Dezful Embayment, SW Iran
Roshanak Sonei
University of Calgary, Department of Geoscience
Calgary, Alberta, Canada T2N 1N4
[email protected]
Geochemical composition of carbonate sediments are in equilibrium with the contemporaneous sea-water composition in the absence of considerable biotic fractionation. However, in carbonate sediments, diagenetic imprints may have considerable effects on primary sediments textures, mineralogy, reservoir quality and finally geochemical characters. Depending on some factors including primary (depositional) sediments characteristics, governing climate and diagenetic history, geochemical composition of carbonates has been altered by post-depositional overprints.
Stable isotopes and trace elements analyses can be used as a good tool to measure the extent of these alterations. Coupled imprints of tropical climate and recurring emersions had considerable effects on Middle-Upper Cretaceous carbonate reservoirs of the SW Iran (Dezful Embayment), and Middle East region. Petrographic studies (from core to thin section scales) and geochemical analyses (stable isotopes and trace elements) were carried out on 478 samples from five giant and supergiant oilfields in these embayment to reveal the main diagenetic alterations of these karstified carbonate sequences. Variations in δ18O and δ13C compositions and trace elements (Mn, Fe and Sr) concentrations are useful diagenetic indicators that resulted in classification of studied intervals into diagenetic classes according to their meteoric diagenetic features, intensities and developments.
AAPG Search and Discovery Article #90157©2012 AAPG Foundation 2012 Grants-in-Aid Projects