oa Sedimentology and Exploration Potential of the Haima Supergroup from the Eastern Flank of the Ghaba Salt Basin in Central Oman

In Central Oman the Early Palaeozoic Haima Supergroup contains important clastic reservoirs charged<br>by hydrocarbons from the underlying Huqf Supergroup. CCED (Oman) and partner, Tethys Oil, are<br>exploring on the eastern flank of the Ghaba Salt Basin. The Amin, Miqrat, Al Bashair and Barik<br>Formations in the lower part of the Haima Supergroup form part of their exploration portfolio.<br>Recent heavy oil discoveries have been made in the Amin and Miqrat clastics as well as newly<br>discovered light oil in the underlying Huqf carbonates.<br>We report on new data on the Amin to Barik Formations which have emerged as a result of the recent<br>drilling and on a linked outcrop-based program in the nearby Huqf inlier.<br>The Huqf inlier is a 10,000 km2 area of outcropping Cretaceous to Neoproterozoic sediments. Here, the<br>Amin Formation at the base of the Haima comprises coarse lithic sandstones and chert conglomerates<br>that were deposited as in channel bars on a west facing continental braid plain. A marine flooding<br>surface in the upper part of the Amin Formation terminates continental sedimentation. Thereafter all<br>Haima sediments were deposited in marginal marine to fully marine settings.<br>Contrary to previous suggestions no evidence for primary aeolian sand deposition has been found.<br>Instead marine incursion during upper Amin times resulted in flooding of the continental braid plain<br>and a shore-fringing mixed clastic-carbonate tidal flat developed upon which the fine clastics of the<br>Miqrat Formation were deposited. The tidal flat interpretation is based on the occurrence of<br>channelling, convolute bedding and starved wave ripples, on the overall fine grained nature of the<br>sediment and on the ubiquitous presence of dewatering structures and carbonate mud.<br>Highly porous large scale cross bedded sandstones occur within the Miqrat Formation in the outcrop<br>belt. Based on the evidence for marine deposition these sandstones are believed to represent subtidal<br>straight crested dunes.<br>Marine influence increases upwards into the Al Bashair Formation with oolitic limestones interbedded<br>with the fine clastics. The Barik Formation represents progradation of deltaic sands out over this marine basin.<br>These revisions to the stratigraphy and palaeoenvironmental interpretations of the Haima Supergroup<br>have provided a better framework for east flank exploration in Central Oman and for prediction of the<br>geometry of potential clastic reservoirs in the target formations.