Lithology

Our methods require a stable, calibrated measure of lithology. Standard logs will not work:

GR: The Gamma Ray log measures radioactivity, which comes dominantly from the K (potassium) in shales. This gives a qualitative view of shale content, but not quantitative, because different clays contain different K content.

SP: The Spontaneous Potential log measure voltage from surface to logging point. This gives a qualitative view of shale content, but not quantitative, because formation waters or drilling fluids can change salinity between zones.

NDPOR: The crossplot of Neutron Porosity against Density Porosity gives a semi-quantitative view of shale content, but it is not available in many wells.

Lithfrac Curve: We construct a Lithfrac curve from one of the above curves, via a proprietary calibration process. The units are percent. This percentage is a key input to many calculations that are crucial to our methods.