NEAG JG Surprising Results and their Effects on Hydrocarbon Potentiality and Prospects Ranking (Case Study: Lower Cretaceous Bahariya Reservoirs in NEAG JG Field, Abu-Gharadig Basin, Western Desert)

This case study from Bahariya reservoirs in Neag JG serves as a valuable learning lesson for hydrocarbon explorations in any field affected by erosional unconformity surfaces. The objective of this study is to show the new results found by the authors on the top of lower Bahariya reservoirs in Neag JG, knowing that Neag JG is highly affected by the upper cretaceous uplifting and erosion phases of the Syrian arc system. The area of interest includes two wells penetrated good quality lower Bahariya reservoirs. Well 1X (NEAG JG J2-1), situated in a down-dip structure, encountered two hydrocarbon bearing intervals within lower Bahariya separated by an intra-formational seal, Conversely, well 2X (NEAG JG C5-1), drilled in a distinct structure shallower than Well 1X, yielded water. A comprehensive analysis incorporating the tectonic and stratigraphic activities happened on the top of Lower Bahariya reservoirs and their potential effects were conducted through high-resolution geological, geophysical, and petrophysical methodologies to elucidate the discrepancy: why well 1X exhibited hydrocarbon presence while well 2X did not. The results were a little bit surprising and interesting, as detailed geological investigations revealed that Well 2X, which yielded water, encountered approximately 100 meters of unfamiliar log responses above the reservoir when compared to all offset wells in Neag-5, JG, and JD fields. This anomalous section is interpreted as comprising slumped materials eroded and transported from adjacent higher elevations, subsequently deposited atop the erosional unconformity surface. This process was responsible for decreasing the top seal quality of the lower Bahariya reservoirs in the up-dip structure. Substantiating this interpretation, bio-stratigraphic analyses conducted on both wells, alongside its identification in seismic sections, provided corroborative evidence. Following the findings of this study, the top seal emerges as the primary risk factor and must be thoroughly evaluated during the prospect assessment within similar fields encountering erosional unconformity surfaces and affected by the Syrian-Arc system.