Field Characterisation of Fractured Carbonate Reservoirs in NE Kurdistan, Northern Iraq

The High Altitude Folded Zone of the Zagros Mountains in Kurdistan, Northern Iraq provides an ideal analogue for characterising fracture networks in low matrix porosity and permeability reservoirs.

Detailed field mapping supported by structural field measurements, fracture mapping along 60 scanlines, microfracture descriptions and biostratigraphic dating has been undertaken on Jurassic, Cretaceous and Lower Tertiary carbonate reservoirs exposed in the deeply eroded anticlines of Bina Bawi, Surdash and Pir-i-Mugurun.

Relationships between fracture distributions and kinematics have been analysed with respect to the structural position within the folds, the presence of mesoscopic-scale faults, lithological facies zonation, mechanical layer thickness, age, depth of burial and timing of structuration.

Results show variations in fracture distributions and orientations along strike and position of the folds. Good correlation is demonstrated between normalised fracture frequencies and mechanical stratigraphies, distance to mesoscopic faults and distributions of lineaments on eroded crests of anticlines on ASTER Global Digital Elevation models. The superimposition of fracture parameters on to a sequential restoration along four dip sections reconstructs the timing of faulting and fracturing in the reservoirs into stages since the early initiation of the Arabian Foreland.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California