168 / 2015-09-02 11:48:18

An inversion of reservoir properties based on a concurrent model approach

Rock physics,Petrophysics

It is a common understanding that the decision to continue with any oil and/or gas well completion project is based on the existence of an economically viable pay zone. This necessitates the need for a continuous optimization of reservoir characterization in order to preserve success in management decisions. During reservoir characterization process, Incorporating lithology and fluid mixtures in rock physics models so as to estimate rock properties is a challenging task because it leads to an underdetermined system of rock physics equations, which necessitate the application of complex mathematics. The possibility of overcoming this difficulty can be achieved when the number of unknowns in the equation are reduced. This paper made its contribution by making use of an additional petrophysical link, the one between porosity and clay content which is common on a dispersed shale environment. To achieve its goal, firstly, a rock physics model was established, and then the reservoir was delineated through a combination of P-wave impedance and poisson’s ratio. In the reservoir, total porosity and clay content were inverted based on P-wave impedance by applying the rock physics model that relates P-wave impedance to porosity and clay content, alongside the established petrophysical link between total porosity and clay content. The result was found to be consistent on the well log scale. Uniquely, a good match was obtained when the methodology was repeated on an up-scaled well log data, thereby presenting its behavior on the seismic scale.