Effect of the Geological Situation of the Late Jurassic-Early Cretaceous Period of the Region between the Upper and Lower Zab Rivers on the Oil Potential of the Najmah Formation-North Iraq

Abstract

To determine the location of the faults and the extent of their impact, a comparison made between
the subsurface sections of the upper regions to determine the sites of the faults and their impact as:
• The Fault Z1 is determined by the location of the upper Zab River, Fault Z2, was represents the
Lower Zab River and the Fault Z3, extending northwest southeast and is located between the well
sites of Zab-1 and Quwer-2. This fault fragmented of the inter Zab rivers area into two secondary
blocks, the Western sub-block and a Eastern sub-block, where this was 500 meters lower than the
first one and forming a good Structural trap.
The effect of those Normal faults (1Z, 2Z, 3Z), was perfectly limited on the Late Jurassic-Early
Cretaceous boundary. Which revealed that the reservoir unit (Najmah formation), was exposed to

the surface and the cap rocks have been eroded by the Neocomian uplift, and lading to escape of the
light hydrocarbon components while the heavy bituminous stained the lithofacies and plugged their
porosity