Intra-Disciplinary Data Integration to Reduce Subsurface Uncertainty, Oligocene Reservoir Delineation and Characterization; Atoll Field, Offshore Nile Delta

Abstract Subsurface uncertainty related to data challenges is one of the main obstacles faces both frontier basins exploration, and mature fields early production. This technical piece of work offers a case study on how geological well data integration can tackle the data limitations and its subsequent uncertainty in both exploration and development aspects of a large gas field producing more than 60% of PhPC's gas and showing remarkable exploration potential, Atoll field still one of the game changers gas discoveries that unlocked Oligocene reservoir systems offshore Nile Delta over the last decade. As the first Oligocene producing field in the off-shore East Nile Delta, Atoll field is of significant high potentiality, but combined with several subsurface ambiguities and uncertainties. Due to the initial poor seismic image, limited acquired well data from few well penetrations, in addition to the complex heterogeneous nature of turbidities reservoir systems; Reservoir delineation and characterization are true challenges reflected in understanding controls on GIIP, connectivity, reservoir geometries, quality and productivity. Those challenges have been tackled successfully through the early production scheme phase of the field and hence continues to support further field development and reservoir management decisions. Integrated with the recently acquired high end seismic acquisition technology of (Ocean bottom nodes) OBN; Cutting samples discerption, thin section semi-quantitative analysis, sidewall cores, and well-log data were integrated to extend facies and facies associations interpreted from image log (OBMI) available for one of the wells to the others. That was followed by delineating the depositional cycles and architecture elements throughout the wells. In parallel the scanning electron Microscope (SEM) and X ray diffraction (XRD) analysis from both drilling cuttings and sidewall cores (SWC) were integrated to build the diagenetic model for reservoir quality. The study resulted in solving the ambiguity around the depositional setting in the penetrated area, predictive understanding of the reservoir geometry, thickness, and connectivity. Additionally, uncovered the reasons behind the well's chock plugging during production. Further inter-disciplinary integration is planned to extend/interpolate the crystalized understanding laterally to support Atoll development theme, and vertically to support the Exploration one.