The last step allowed to calculate the final volume of shale (Schlumberger 1998). The results obtained with each technique were compared to each other and then combined together. The third and the last method for calculating the volume of shale in Borehole A-1 was Resistivity technique, with deep resistivity log (Schlumberger 1998).
#Techlog geophysics equations manual
The second technique used is the Neutron-Density Method (Techlog Manual 2011), where two logs were used as an input data source, Neutron Porosity log (NPHI) and Bulk Density (RHOB). Both nonlinear and linear equations were applied to calculate the volume of shale.
This method allowed to calculate the amount of shale using only one log as an input (Ellis & Singer 2008). The first method for the determination of the shale volume was the Gamma Ray technique. Well logs used for the calculation of the shale volume come from Borehole A-1, which is located in west central Poland in Greater Poland Voivodeship. This paper shows the results that interpreter might obtain using different types of methods for quantitative determination of shale content. It is a fact that choosing correct technique is often a problem which many well log analysts must struggle with (Bassiouni 1994). There are several different methods that allow us to determine the volume of shale in the geological formation. Clay minerals may cause a lot of problems with calculating porosity or water saturation (Jarzyna 1997). One of the most important steps in well log analysis is proper evaluation of shaly formations.
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