Hydrocarbon Type Discrimination Using AVO analysis, Sama Field, Offshore, Nile Delta, Egypt

Abstract

Sama field is one of the rare fields in the offshore Nile Delta which contain two types of hydrocarbons; gas and oil. Although Sama field is covered by a state-of the art high density, long offset 3D dataset, the differentiation between several fluid types using the conventional stacked dataset is a big challenge. Although different fluids discrimination is difficult using post-stack seismic data, pre-stack seismic data can be the best tool of doing it. The reason can be attributed to the different amplitude change with offset behavior for each fluid type. The main aim is to find a way to map out the different reservoirs, in order to help in calculating the HIIP (Hydrocarbon Initial in Place) volumes and for optimizing the development plan. Rock physics modeling is needed to understand the AVO behaviors of oil and gas sands of the field. This understanding can be coupled with the pre-stack seismic data to produce AVO-classified seismic volumes. Hence, reservoirs of different fluid types can be identified and mapped across the study area. Rock physics modeling suggested that gas sand exhibits class 3 AVO response; however oil sand has a class 2 AVO behavior. Pre-stack seismic data needed some conditioning before the AVO classification. The conditioning workflow included; frequency filtering, time alignments and amplitudes balancing. Finally AVO-classified seismic volumes have been produced, which enabled the lateral tracking of the different reservoir bodies away from the well. The integration of pre-stack seismic data and the understanding the AVO behavior of different fluids allows precise delineation for the different reservoirs, Which in turn promotes a better chance of success for further future development plan.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015