Tectonic Controls on Triassic Stratigraphy and Hydrocarbon Prospectivity in Kuwait

Riyasat Husain*, Abdul Aziz Sajer, Nadia Al-Zabout, Ahmad Rabie, Mohammed K. Iqbal, and Dabeer A. Khan
KOC
*[email protected]

The Triassic System in Kuwait comprises ramp carbonates, anhydrites and clastics deposited in supra-tidal to inter-tidal settings. The N-S trending Kuwait Arch with flanking basins (offshore Kuwait in the east and Dibdibba Trough in the west) exercised control on deposition and preservation of Triassic strata and prospectivity. The Triassic encompasses the Upper Khuff, Sudair, Jilh and Minjur formations. The Upper Khuff consists of carbonates, which grade into argillaceous dolomites in the Sudair Formation. An additional dolomudstone-prone unit, provisionally named as Kra Al Maru Formation, is preserved locally between the Sudair and Jilh formations in the Dibdibba Trough. The Jilh Formation is evaporitic, divided by intra-formational salt. The thickness of the Lower Jilh decreases over the Kuwait Arch, whereas the Upper Jilh and Minjur formations thicken to the southeast with increased clastic influx. The tectono-stratigraphic imprint represents re-activation of structural grain inherited from Hercynian and older tectonism. Upper Khuff, Sudair, Kra Al Maru and Lower Jilh are influenced by uplift of the Kuwait Arch. Jilh Salt represents a major interface at the onset of tectonic inversion. The Upper Jilh and Minjur formations are influenced by southeasterly slope and clastic influx from the south. The Triassic sediments over the Kuwait Arch have diagenetically degraded reservoir properties. Evaporites and dolomudstones with fracture-related reservoir development in western Kuwait and shallow- to open-marine carbonates with conventional reservoirs east of the arch are prospective. Recent exploration wells have established flow to surface of sweet gas and gas condensate from Kra Al Maru. The Minjur Formation is prospective in the south where sandstone inter-beds have improved reservoir characteristics.

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain