Petrophysical interpretation and fluid substitution modelling of the upper shallow marine sandstone reservoirs in the Bredasdorp Basin, offshore South Africa
Abstract
The fluid substitution method is used for predicting elastic properties of reservoir rocks and their dependence on pore fluid
and porosity. This method makes it possible to predict changes in elastic response of a rock saturation with different fluids.
This study focused on the Upper Shallow Marine sandstone reservoirs of five selected wells (MM1, MM2, MM3, MM4, and
MM5) in the Bredasdorp Basin, offshore South Africa. The integration of petrophysics and rock physics (Gassmann fluid
substitution) was applied to the upper shallow marine sandstone reservoirs for reservoir characterisation. The objective of
the study was to calculate the volume of clay, porosity, water saturation, permeability, and hydrocarbon saturation, and the
application of the Gassmann fluid substitution modelling to determine the effect of different pore fluids (brine, oil, and gas)
on acoustic properties (compressional velocity, shear velocity, and density) using rock frame properties.