Online Journal for E&P Geoscientists

Shalaby, Mohamed R.^*1; Hakimi, Mohammed H.¹; Abdullah, Wan H.¹
(1) Geology, University of Malaya, Kuala Lumpur, Malaysia.

The Shoushan Basin is an important hydrocarbon province in the northern Western Desert, Egypt, but the origin of the hydrocarbons is not fully understood. The Middle Jurassic Khatatba Formation has an important hydrocarbon potentiality where a complete petroleum system has been identified. It is also considered as a giant gas condensate container in the study area. The Khatatba Formation composed mainly of sandstone and organic-rich shales interbeds, deposited in a deltaic to shallow marine environments. The source rock succession of Khatatba Formation composed mainly of organic-rich shales and mudstones. Marine organic matter is the main source input for the Khatatba shales. This has been identified based on organic petrological studies and from the n-alkane distributions. Organic-rich shales with excellent potential to generate mainly gas and oil and most of generated hydrocarbons were expelled into sandstones within the Khatatba Formation. The Khatatba sandstones were recognized to have good reservoir quality and represent the main producing reservoir rocks. Good reservoir quality occurs in a high energy fluvial deltaic environment, with no inhibiting authigenic clays or diagenetic problems. Shallow marine carbonates of the Masajid Formation overlying the top of the Khatatba Formation and provide an excellent seal of Jurassic reservoirs in most parts of Shoushan Basin.

In this study the results of Khatatba source rock have been integrated with the results of basin modeling to improve our understanding of burial history and timing of hydrocarbon generation. Based on basin modeling analysis, Thermal and burial history models indicate that the Jurassic source rocks entered the mature to late mature stage for hydrocarbon generation in the Late Cretaceous to Tertiary. Hydrocarbon generation began in the Late Cretaceous and maximum rates of oil with significant gas have been generated during the early Tertiary (Paleogene). The peak gas generation occurred during the late Tertiary (Neogene). On the basis of the hydrocarbon generation modeling, one can deduce the time of hydrocarbon migration after expulsion. It is believed that hydrocarbon migration in the study area has continued approximately since Tertiary time.