Insights into the Unayzah Formation and the Basal Khuff Clastics in North Kuwait

Abstract

Abstract A continuous core of about 280 feet covering Basal Khuff Clastics, and the upper Unayzah Formation was cut in a North Kuwait well. The Unayzah Formation in the cored interval consists of four main lithologies. These include; 1) stacked normally graded braided fluvial coarse pebbly sandstones, 2) high angle cross bedded sandstone likely involves eolian reworking, 3) flood plain / distal alluvial fan red colour mudstones, and 4) dark colour mudstones and siltstones which were deposited in backswamp and marsh type settings. This latter facies locally contain impoverished palynofloral assemblages and the associated beds have indications of tidal influence. The Basal Khuff Clastics consist of 1) amalgamated sandstone, 2) bioturbated sandstone and siltstone, 3) heterolithic black carbonaceous shale with sandstone interbeds, and 4) interbedded sandstone, siltstone and dolomite facies. These sediments were deposited in coastal plain environments representing tide influenced channels, crevasse splay, interfluve, and coastal marsh / lagoon environments, prelude to the onset of a major transgression. With the exception of ?eolian sandstone, due to authigenic illitic clay development, compaction, and the quartz cementation the reservoir potential in these sediments is reduced. Based on the limited palynofloral information, age of these strata is most likely Kazanian to Tatarian.