Vertical-Horizontal Permeability Relationships in Stress and Non Stress Sensitive Reservoirs

Abstract

One of the important petrophysical parameter in reservoir description is the permeability distribution in a given reservoir. It is well known that most reservoir are heterogeneous in nature and homogeneous ones been the few exceptions. Therefore, most reservoirs exist with different degree of permeability anisotropy and reservoir heterogeneity.

In stress sensitive reservoirs, permeability does not only vary spatially but also varies temporally due to the changes in effective stress distribution resulting from pressure drawdown around a producing well and the reservoir pressure distribution due to production and injection processes.

This work investigates the relationship between vertical and horizontal permeability in stress and non-stress sensitive reservoirs. Various petrophysical properties were calculated from core and log data gotten from both stress and non-stress sensitive formations. New correlations between vertical and horizontal permeability were then developed for the zones that were analyzed, with each zone representing different formation types. The correlations show that there is a log-log linear relationship between vertical and horizontal permeability for the different zones and that these correlations are affected by the shaliness of each zone, and the number of flow units in each zone.