Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Geophysics

The clastic shallow section in the Nile delta is characterized by mild velocity variations. The relationship between the expected velocity reduction in the gas reservoir rocks and the encompassing shale is responsible for lithology contrast, predictable to a particular AVO-class. In class-3AVO the bright spot is a result of great reduction of velocity increase due to differences between high velocity encompassing shale and relatively low velocity reservoir sand. The class-3AVO characterizes a strong seismic amplitude appearance in the full stack section and with similar characteristic view of AVO analysis and interpretation. In addition to the strong amplitude, there are different DHI features related to the gas occurrence. These features are analyzed to achieve and deliver a successful exploratory well. The analysis of one of the unsuccessful cases clarifies the importance of the workflow that works for exploring types of anomalies in the Nile delta. The anomalies are drilled mainly based on an explicit high amplitude anomaly with local flat spot, but without taking into consideration the extent of DHI characteristics, inherent to gas occurrence in the Nile delta. Authors investigate all the features related to this unproven case in the form of a post-mortem and compare it with proven existing discoveries, to know the possible reason of unsuccessful DHI anomalies in the Nile delta. Where the exploration of the deep target is expensive with different risk parameters in all petroleum system elements, the absence of well data and the contradiction between some of the available data types make the analysis of the different petroleum system elements very hard, these contradictions are partly removed by the deep analysis of the available data and modelling of the absent data, the results of these studies are confirmed by the new discoveries in the nearby areas

Issued also as CD