--> Sequence Stratigraphy of Triassic Jilh Formation in Kuwait, Husain, Riyasat; Sajer, Abdul Aziz; Al-Ammar, Nada; Khan, Dabeer A.; Rabie, Ahmed; Iqbal, Mohammed K., #90100 (2009)

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Sequence Stratigraphy of Triassic Jilh Formation in Kuwait

Husain, Riyasat1
 Sajer, Abdul Aziz1
 Al-Ammar, Nada1
 Khan, Dabeer A.1
 Rabie, Ahmed1
 Iqbal, Mohammed K.1

1Exploration Group, Kuwait Oil Company, Ahmadi, Kuwait.

The Late to Middle Triassic Jilh Formation is a part of post-rift tectono-stratigraphic cycle coinciding with passive rift subsidence around Arabia in the wake of opening of Neo- Tethys during early Late Permian. The formation is a major arid climate sabkha system with restricted shelf evaporites and dolomites. It is an emerging exploration target in Arabian Gulf with numerous hydrocarbon occurrences reported from Kuwait, Saudi Arabia and Iraq. The formation was studied to establish the sequence stratigraphic framework to better constrain the spatial and stratigraphic distribution of depositional facies. Several significant stratigraphic surfaces were picked and correlated based on the detailed core descriptions, the biostratigraphic analysis, isotopic data, wireline logs and stratigraphic stacking patterns. Six unconformity bound depositional sequences (JS6 through to JS1) were defined within the formation. A sub regional layer of halite and anhydrite within the Jilh Formation marks a major interface across which lithofacies and thickness patterns are distinctly different and divides the formation into lower and upper Jilh. The Lower Jilh is dominated by sabkha and hypersaline facies and is made up of four depositional sequences (JS6 through to JS3). Each sequence is comprised of a transgressive and a highstand systems tract. The sequences are characterized by shales, carbonates and evaporites arranged in shoaling upward parasequences ranging from a few feet to tens of feet in thickness. Depositional and diagenetic patterns of these sequences are controlled by the north trending Kuwait Arch. These sequences are thickest in the western Kuwait and thin or disappear on the crest of the Kuwait Arch. The upper Jilh, on the other hand, shows gradual increase in clastic sediments upwards in the section and is constituted by two depositional sequences (JS1 to JS2). The lower sequence of this unit is more or less uniformly distributed within Kuwait while the upper sequence is thickest with higher clastic ratios in the southern part of Kuwait. It appears Kuwait Arch was not active during the deposition of the upper Jilh sequences and southeasterly basinal slope was the major influence on the deposition in the upper Jilh. This improved understanding of the sequence stratigraphic framework, depositional architecture and its linkage to the tectonics can be utilized in a predictive manner to open up new exploration opportunities.

AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil