GEOLOGICAL FRAMEWORK OF JURASSIC SEQUENCES, EAST TIBA SUB-BASIN, NORTH WESTERN DESERT, EGYPT

Abstract

In 2014 and for the first time in East Tiba Sub-Basin exploration history, gas and condensates were tested at commercial rate from the Aalenian Middle Jurassic sandstone reservoir in SH-4well, Shahd/Shahd SE oil fields. This encouraging Jurassic gas discovery gave the initiative to evaluate the Jurassic geological system in the area in order to determine its hydrocarbon potentiality for further exploration and development activities. The present study revealed that, the area has been subjected to multi-phases tectonic history and had significant effects on the Jurassic sedimentary sequences. Sea level changes induced by tectonics resulted in the deposition of the deltaic complex of the Middle Jurassic Khatatba coal-bearing shales and sandstone reservoir, in addition to the alternating marine sandstones and carbonates of Wadi El Natrun Formation. The hydrocarbon-bearing sandstones are found to be related to the middle interval of Wadi El Natrun Formation that could be correlated stratigraphically with the Middle Jurassic Aalenian sandstone of Gebel Maghara surface outcrop. A 3D reprocessed PSDM seismic cube has been used, in addition to the well log data, to produce the Middle Jurassic Wadi El Natrun structural map, as it represents a good seismic marker allover the Tiba Sub-Basin. It is concluded that, the complexity of the deeper Jurassic structural configuration, the quality of the seismic data, the combined stratigraphic and structural prospective traps, the magnitude of the Jurassic fault throws, the terminations of these faults below the younger Cretaceous structural trends and sealing capacity are the critical factors for hydrocarbon generation and entrapment.