The Kurdistan Region, including the study area, is presently considered an
important hydrocarbon province. The broad and box-shaped anticlines in the area are indeed structures for accommodating hydrocarbons. The sealing capacity of associated
thrusts must be considered carefully in these folds. Some associated faults in the adjacent
anticlines to the study area (e. g. in Atrush Field; west to the Akre Anticline) exhibit
trapping efficiency within the Jurassic and Triassic systems (Shamaran petroleum corp,
2012). Thus, the same efficiency is expected from most thrusts in the area. However, the
lithology of the sedimentary units in both hanging wall and footwall has a role in the
trapping efficiency of the thrusts. For instance, the Jurassic and Triassic units in the
footwall block of the thrust in the southern limb of the Perat Anticline are facing the
Triassic units (probably the Kurra China and Baluti Shale Formation) in the hanging wall
(Figure 4-5).
The anhydrite and shale in the Triassic units may seal the Triassic and
Jurassic petroleum systems in the footwall. The younger Cretaceous system has been
exposed to the surface due to uplift and erosion of Cenozoic units, which seal the
Cretaceous system. This exposure led to seepage of the Cretaceous petroleum system
through tertiary migration, as evidenced through bitumen seepage around these anticlines.
Seepages are not detected along linear trends above thrusts or blind thrusts. This suggests
that there is a chance of for these thrusts to seal hydrocarbons at deeper level in the
sedimentary cover.
Folds in the area have grown laterally or they formed from linkage of separate
segment. The fold growth and fold segments (i.e. location of linkage and lateral extension
of fold segments) were affected by the distribution of the transversal basement faults in
the area. Thus, traps within a single fold may be segmented via lateral growth of the fold
and/ or influence of the basement faults.
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