Paleohighs role in cement sequences and hydrocarbon reservoirs

Category Sedimentology
Group GSI.IR
Location The 25 Symposium of Geosciences
Author M.A.Kavossi
Holding Date 01 July 2007

Paleohighs role in cement sequences and hydrocarbon reservoirs



   The upper Dalan Carbonates (Late Permian) consist of carbonate rocks and is an important gas reservoir in southwest Iran. Its lower contact with the Sarchahan Formation (Silurian) and upper contact with the Kangan Formation is unconformable. Detailed petrographic, core, geophysical logs and seismic line investigations led to recognition of several facies and facies group that were deposited on a carbonate ramp.

       Microscopic analysis indicates that paleohighs had controled diagenetic environments, diagenetic imprints and cement sequences. For instance in the upper carbonates of the Dalan Formation of Tabnak well (situated above the Razak basement fault) marine cements, vadose silt, dissolution, fresh water phreatic cements and dolomitization with vuggy porosity are widespread. Instead in Khalafani well which situated in a low between Razak and Hendourabi Highs, primary cements are rare but deep burial cements like anhydrite with poikilotopic fabric, pressure solution, pressure seams and stylolites are abundant. Paleohighs have an important role in subsequent diagenetic trends to originate porosity to allow hydrocarnon migrate into these porous horizons deposited on paleohighs.                                                                                                                      

tags: QAZVIN