Sedimentological interpretation of the Albian Nahr Umr Formation in the United Arab Emirates

Abstract

In the United Arab Emirates, the Nahr Umr Formation (Albian) comprises a series of varicoloured shales, siltstones and mudstones, with increasing carbonate content toward the northern United Arab Emirates. The percentage of clay minerals in the shale ranges from 62% to 73%, while the non-clay fraction 50 is dominated by calcite, quartz and traces of dolomite, feldspar pyrite, glauconite and phosphate. The formation ranges in thickness from 63 to 220 m (200–700 ft) and forms an excellent cap rock to the major Aptian 5030 reservoirs. Geochemical studies indicate that the shales have no oil or gas generating potential; the total organic carbon content ranges from a low of 0.20% to a high of 0.50%. These sediments were deposited in a shallow marine to distal offshore shelf setting.