Clay Mineralogy of the Khabour and Akkas Formations, Akkas Field, Western Iraq: Implications for Reservoir Characterization and Paleoclimatic Conditions

Clastic sedimentation dominates the early Paleozoic succession in subsurface section from the Akkas-1 well, west Iraq. Mineralogical investigation has revealed that the main clay components include, illite, chlorite, kaolinite and mixed layer illite/smectite, whereas, the non-clay fractions include quartz, feldspar and calcite. The clay minerals exist in both detrital and authigenic forms and in different morphologies either as scattered or filling fractures and cavities in both sandstones and shale units which may impact on reservoir characteristics of the studied rocks. Presence of these clay minerals also reflects an arid-humid paleoclimatic conditions during which these minerals were formed in addition to effect of post depositional diagenetic processes.