Property Modelling in a Carbonate Field with Complex Diagenesis, an Example from the Kangan and Dalan Formations, Iran

Daniel Berge Sollien¹*, Ali Asghar Taghavi², Arild Eliassen¹, Joanna Garland³, Jens Halvor Rolfsnes¹, Torgrim Jacobsen¹, Tore Amund Svånå¹, and Stephen Neville Ehrenberg^1
1StatoilHydro, Norway
²Reslab Integration, Norway
³Cambridge Carbonates Ltd, UK
*[email protected]

Detailed studies of the sedimentology, sequence stratigraphy and diagenesis were conducted on the Permian-Triassic Kangan and Dalan formations of Iran. The objective was to reveal links between sequence stratigraphy, depositional and diagenetic processes. The identified relationships and the methodology used to distribute reservoir properties in a geocellular model is the focus of this presentation. Detailed descriptions of depositional facies and the depositional stacking pattern were followed by characterisation of diagenetic facies. The dataset consisted of more than 800 m of core and more than 800 thin sections from three wells penetrating the Kangan and Dalan formations. The analysis showed that the reservoir quality varies according to depositional facies and is extensively modified by diagenetic processes. However, the diagenetic processes can, to a certain extent, be related to the sequence stratigraphy and depositional facies. The trends are not unique and other controls must be applied when reservoir properties are to be distributed. These controls need to be obtained from standard log suites, because cores are available from only a limited number of wells. In order to model the 3-D distribution of reservoir properties, the modelling work has focused on capturing the spatial distribution of both depositional and diagenetic facies. The depositional facies have been modelled using high-frequency cycle-specific conceptual models. For the distribution of diagenetic facies, a novel approach using trends from calculated volume fractions of calcite, dolomite and anhydrite was used. Alternative geocellular models will be presented and differences between these discussed. Flow simulations have been performed, and the results were used to identify key sensitivities and controls.

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain