Dcpositional and diagenctic fades relationships, khuff-C reservoir, eastern Saudi Arabia

الملخص EN

The Khuff Formation represents the earliest record of major carbonate sedimen- tation in the Arabian Gulf region which was initiated by a widespread Late Permian transgres- sion of the Tethys Sea over the Arabian Foreland.

The sediments comprise a carbonate-evapo- rite sequence which has been divided into four major depositional cycles correctable with worldwide Upper Permian Cycles.

Porosity distribution is controlled by the degree of diagenesis.

The diagenctic changes which affect porosity in the Khuff-C seem to have taken place in the early history of the sediments, in- cluding dolomitization.

leaching and dissolution, and cementation.

Penecontemporaneous dolomitization and early diagenetic replacement of the sediments by dolomite are probably the key processes that enhanced the Khuff-C porosity development, but porosities in the Khuff-C have most likely been enhanced by dissolution of calcite as well.

On the contrary, porosities were destroyed by emplacement of equant calcite and anhydrite cements.

A conceptual model has been developed for explaining the diagenetic process in the study area.

In this model, some very low relief "topographic highs” were formed and were occasion- ally subaerially exposed.

The fresh water lenses developed on these highs controlled diagenesis of the sediments.