Prospect Validation Using Geological Expression in a Gas Discovery, Offshore Mozambique

Abstract

This study attempts to gain a better insight into the controls on an under-saturated gas discovery, offshore Mozambique, using Geological Expression techniques such as High Definition Frequency Decomposition (HDFD) and multi-attribute classifications with synthetic wedge modelling being used to better understand the results. HDFD highlights known hydrocarbon bearing sands as high magnitudes and shows that structural processes are dominant in controlling their distribution. Observations from the Chaos divided by Envelope attribute lead to gas chimney interpretations and show that faults may be acting as migration pathways for hydrocarbons into and out of the reservoir. The Interactive Facies Classification tool confirms preconceived ideas of a later stage inversion, shows potential deposition fairways and sand-sand juxtaposition across faults confirming that faults are not acting as baffles to fluid flow. Finally synthetic wedge modelling of the reservoir provides an explanation for similar colour responses of the HDFD RGB blend above and below the gas-water contact. We observe that, even though thickness is a dominant controlling factor on the colours in the RGB blend, pore fill plays a role and allows a single stratigraphic layer to be divided based on it. These techniques aided in better understanding and risking the reservoir