Basics of Oil & Gas Log Analysis

John Doveton
Kansas Geological Survey


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Complete Document PDF (2.5mb)

Section 1 (PDF)
Resistivity logging

Vertical resolution and radius of investigation

Section 2 (PDF)
Porosity logging

Density log
Neutron log
Neutron - density log combination
Primary and secondary porosity

The Archie Equation

Formation factor - porosity relationships for sandstones
Formation factor - porosity relationships for carbonates
Resistivity index - saturation relationships

Section 3 (PDF)
Temperature and water resistivity

Estimation of formation temperature
Temperature correction of water resistivity

Example of Sw computation: Mississippian carbonate

Section 4 (PDF)

Digital log data
Example of Sw computation: Ordovician sandstone

Updated February 1999
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