Maximising hydrocarbon recovery efficiency requires that production and injection wells be positioned to take full advantage of the natural directional flow characteristics of the reservoir.

Depositional grain fabrics and diagenetic processes in sandstones can cause 30% or more variation in horizontal permeability, with still larger differences between horizontal and vertical permeability.

Reliable information on 3-D permeability anisotropy in sandstone cores can now be obtained quickly and accurately by the MAGPORE method.

This uses anisotropy of magnetic susceptibility (AMS) analyses on plug samples whose pore networks are filled with a magnetic fluid, using a specialised technique.

The pore fabric is then re-oriented relative to North, by the paleomagnetic method.

Detailed comparisons between 3-D permeability anisotropy determinations using a Hassler cell system and pore fabrics determined by the MAGPORE technique have demonstrated that the maximum permeability direction can be accurately predicted from the preferred orientation of pore long axes.

In the example shown, the blue arrows represent the maximum permeability axis in a deep water sand reservoir, determined by Hassler cell measurements on oriented core samples.

Pore long axis orientations determined by MAGPORE measurements, are shown contoured. The mean pore long axis orientation corresponds with the maximum permeability direction.