Obaiyed Field: A Major Challenge for Hydrocarbon Exploration in the Western Desert of Egypt

By

 Asem Mahmoud¹, Mohamed El-Saadany¹, Ahmed N. El-Barkooky², Adel R. Moustafa³, Mohamed Saad¹

(1) BAPETCO, Cairo, Egypt (2) Cairo University, Cairo, Egypt (3) Ain Shams University, Cairo, Egypt

 Obaiyed is the largest Jurassic gas/condensate field in the northern Western Desert of Egypt. It represents a combination trap on the western flank of the Matruh basin; a NNE trending Jurassic-Early Cretaceous rift that was inverted in the Late Cretaceous - Early Tertiary. The field lies within the up-dip side of a large easterly-tilted half graben. It produces from Bathonian sandstone unconformably overlying pre-rift Paleozoic sequences. Integrated analysis of borehole and seismic data helped outline the 3D geometry of the field and define the seismic signature of the Paleozoic - Mesozoic unconformity.

Predicting the reservoir distribution above this unconformity is a challenge for exploration and development of the field. Understanding the paleogeography and tectonostratigraphy of the area as part of the Matruh Basin is inevitable for constructing a predictive depositional model of this reservoir. This task is further challenged by the inversion overprinting the original paleo-relief.

Three main tectonic trends controlled the deposition of the early rift clastics. These are rift-parallel NNE faults forming depositional compartments, a few ENE faults, and WNW pre-rift shear zones. The fault-bounded corridors acted as estuarine embayments with amplified tidal energy. Coarse Pebbly sandstone was deposited proximal to paleo-highs and on the hanging walls of main active faults. Muddy sediments dominated the central and outer reaches of these embayments and fluvial influx supplied sands to them.

Does Obaiyed represent a unique play in the northern Western Desert? Alternatively, it might provide a hydrocarbon exploration analogue for other similar settings.