Effect of Shaliness on Log Response

$10.00

Walter Johnson

Shaly Sand Seminar
Part 1

1978

Abstract

In 1942, Archie found that the resistivity of a mixture of quartz grains plus brine (Ro) divided by the resistivity of the brine (Rw) equalled grains plus brine (Ro) divided by the resistivity of the brine (Rw) equalled a constant which he called ‘F’. In the years that followed Archie’s paper, a constant which he called ‘F’. In the years that followed Archie’s paper, researchers dealing with shaly sands noted that the ratio of Ro to Rw did not researchers dealing with shaly sands noted that the ratio of Ro to Rw did not always equal the straight line relationship predicted by the Archie’s always equal the straight line relationship predicted by the Archie’s equation (Figure 1). This divergence was especially prominent when the form- equation (Figure 1). This divergence was especially prominent when the form ation water was of a high resistivity. The apparent decrease in Ro was attri- ation water was of a high resistivity. The apparent decrease in Ro was attri buted to the fact that clays in the matrix of the rock contributed positive buted to the fact that clays in the matrix of the rock contributed positive ions to the brine.