The present Nile delta area covers approximately 60,000 sq km. Fields in this area provide two-thirds of the gas production in Egypt. Geological knowledge of the Nile delta is still limited because of insufficient subsurface data. Gas is generated and accumulates at stratigraphic levels ranging from the lower Miocene to the lower Pliocene. The highest levels of organic maturation in the Neogene-Quaternary section are in the northern part of the onshore area, such as in the Abu Madi well, and in the eastern part of the offshore area, such as in the El Temsah well, where gas reservoirs occur in the lower Pliocene sandstones (Abu Madi Formation), and in the underlying Sidi Salem Formation and lower Miocene rocks. Here, the Sidi Salem Formation is probably generative, having n R[o] of approximately 0.65%, LOM (levels of organic metamorphism) of 9.5 to 9.7, and TTI (time-temperature index) of 9.7 to 15.2. By contrast, a different thermal history clearly existed in the western and eastern parts of the onshore area, such as in the Monaga and Damanhur wells, where the organic maturities are significantly lower than maturities elsewhere in the basin (R[o] = 0.38 and 0.29%, respectively).

The predicted maturities obtained by using the LOM method seem to fit much closer to the observed maturities than the predicted maturities obtained by using the Lopatin TTI method.