--> Abstract: Fracture Evaluation from Borehole Images in Low-Porosity Carbonate Reservoirs, Southeast Turkey, by M. Ozkanli and A. Tandircioglu; #90942 (1997).

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Abstract: Fracture Evaluation from Borehole Images in Low-Porosity Carbonate Reservoirs, Southeast Turkey

OZKANLI MEHMET AND AHMET TANDIRCIOGLU

Electrical and acoustic images but mostly electrical image logs (FMS, FMI) were recorded in several wells in southeast Turkey, over the past six years. These image data give an excellent indication of degree of fracturing, fracture porosity, intensity, fracture aperture, widths and orientation of the naturally fractured systems present within the reservoir units as well as the origin of fractures in relation to the local structural events.

Image data come from the Karakus, Cendere, Ozan Sungurlu, Tokaris and Ikizce fields of Southeastern Turkey. The main reservoir units are in the Cretaceous Mardin Group. Limestones in the Mardin Group are locally dolomitized and production is greatly influenced by the presence of fractures as the matrix porosity is generally less than 5%.

Fracture development controls the oil production from the low-porosity dolomite and limestone reservoirs of Cretaceous age. In the northern part of the study area, wells are drilled in the overthrust zone where the main fracture orientation is NNW-SSE direction which is parallel fault-related features. Fractures with different orientations are observed. Toward the south, tectonic activity decreased and fold-related fractures are observed dominantly. These fold-related fractures are present in Tokaris and Ikizce fields and show an orientation of NW-SE. In addition, horizontal drilling perpendicular to the fracture strike resulted in cutting the maximum number of fractures and increased production rates.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria