Sedimentological characterisation and sequence stratigraphy of the lowermost Lekhwair deposits of the southern Tethys (Early Cretaceous, Onshore Abu Dhabi)

Aurelie Bonin

While the Kharaib and Shuaiba carbonate hydrocarbon reservoirs of UAE benefit from numerous investigations enabling the establishment of a relatively accurate biostratigraphical framework and the characterisation of the sedimentological, depositional and sequence stratigraphical context, the lowermost Lekhwair deposits remain poorly known and are rarely the topic of publications. These Valanginian/Hauterivian(?) (Alsharan and Nairn, 1986; Granier, 2000) carbonates are studied in the onshore Abu Dhabi area where they host hydrocarbon accumulations within clean shallow inner ramp deposits. These clean carbonates alternate with non-reservoir units comprising clay/organic matterprone carbonates thought to have been deposited in distal settings (e.g. Hassan and Wada, 1981) and commonly picked as maximum flooding surfaces (e.g. Sharland, 2001; Strohmenger et al., 2006). However, until now it has not been possible to confirm or refute these interpretations due to the lack of petrographical samples within these non-reservoir rocks, which are usually discarded due to their negligible reservoir potential.

This work consists of the establishment of the sedimentological framework of the lowermost Lekhwair Formation of an onshore Abu Dhabi area based on the detailed sedimentological descriptions from four cored wells and the analyses of petrographical samples. A facies analysis has been carried out which has resulted in the reconstruction of the depositional environments. The integration of key surfaces characterised in core, marked sedimentological changes and core-calibrated openhole log data have helped in the interpretation of a sequence stratigraphic framework across both the reservoir and non-reservoir units.

 Jeong, J, Kang, J and Bonin, A. (2016) Sedimentological characterisation and sequence stratigraphy of the lowermost Lekhwair deposits of the southern Tethys (Early Cretaceous, Onshore Abu Dhabi). Paper presented at the Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, 7-10th November, 2016.

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Sedimentological characterisation and sequence stratigraphy of the lowermost Lekhwair deposits of the southern Tethys (Early Cretaceous, Onshore Abu Dhabi)

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