Abstract

The source rocks of the Lower Cretaceous Thamama Group in east Abu Dhabi were identified by using wireline logs. This technique was applied to 33 wells which provided a well-sampled new regional pattern of source rock distribution and thickness. The Tharmama Group includes rich source rocks in the Aptian Shu'aiba intra-shelf basin facies and a moderate source rock potential in the dense layers, especially those in the basal part of the Nasr Formation. The reconstruction of the burial and thermal histories indicates that the mature Thamama kitchens are mainly located in the eastern part of Abu Dhabi, adjacent to the foredeep basin and reached optimum maturity levels starting in the Eocene. Westward migration from these kitchens is mainly lateral and updip toward the main Thamama producing fields in central Abu Dhabi. The conclusion that the hydrocarbons migrated laterally is supported by oil to source rock correlation and the vertical distribution of hydrocarbons in the reservoirs.

INTRODUCTION

The Lower Cretaceous Thamama Group of eastern Abu Dhabi (Figure 1) includes several important hydrocarbon reservoirs. This sequence was deposited on a carbonate platform and varies in thickness from 2,500 to 3,000 feet (ft). The overlying Middle Cretaceous Nahr Umr shale and the basal part of the Nasr Formation are regional seals (Figure 2). Local seals also occur as intercalated dense carbonate layers.

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