STRUCTURAL MODELING OF THE CRETACEOUS DERDERE AND KARABABA RESERVOIRS IN THE CEMBERLITAS OIL FIELD, SOUTHEASTERN TURKEY

The Adiyaman region is located in the frontal belt of the southeastern Anatolia fold and thrust belt in Turkey. The region is the northwestern continuation of the Zagros fold-thrust belt and contains several small-to-medium size oil fields. These oil fields are characterized by structural traps located in East-West trending anticlinal structures along the frontal belt. One of these oil fields is the Cemberlitas Oil-Field which produce from fractured and dolomitized reservoirs of the Karababa and the Derdere formations of the Cretaceous Mardin Group carbonates.

We have delineated the structural geometry and evolution of the Cemberlitas Anticline and the reservoir characteristics in the Cemberlitas oil field based on our interpretation of available 2-D seismic reflection profiles, conventional wire-line well log data, and check shot surveys. Our preliminary interpretations suggest that the production in the oil field is from the hanging wall anticlines within the blind leading imbricate thrust system caused by Cretaceous break-forward sequence of thrusting which involves Karababa and Derdere formations. Within the study area we have found thrust faults branching from a low angle detachment surface in a break forward sequence of thrusting which is suggested by the high angle of dip on the northernmost thrust fault and a low angle of dip on the southernmost thrust fault. We have also observed the presence of high-angle Cretaceous normal faults to the south of the leading-edge thrust of the Cretaceous contractional structures. These normal faults were most likely formed during the Cretaceous subduction due to flexural bending of the subducting slab. They have also affected Carbonate facies development in the Derdere and Karababa reservoirs.