Different methods for shale volume determination

• Autorzy: Wandycz P.
• Konferencja: XVth International Conference of Young Geologists Her'lany 2014 : Międzybrodzie Żywieckie, Poland, May, 8th-10th 2014
• Języki publikacji: EN

Abstrakty

EN

One of the most important steps in well log analysis is proper evaluation of shaly formations. Clay minerals may cause a lot of problems with calculating porosity or water saturation (Jarzyna 1997). There are several different methods that allow us to determine the volume of shale in the geological formation. It is a fact that choosing correct technique is often a problem which many well log analysts must struggle with (Bassiouni 1994). This paper shows the results that interpreter might obtain using different types of methods for quantitative determination of shale content. 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. The first method for the determination of the shale volume was the Gamma Ray technique. This method allowed to calculate the amount of shale using only one log as an input (Ellis & Singer 2008). Both nonlinear and linear equations were applied to calculate the volume of shale. 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). 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). The results obtained with each technique were compared to each other and then combined together. The last step allowed to calculate the final volume of shale (Schlumberger 1998). Since each technique gave different results, and it was impossible to choose the correct one, the combination of methods had to be applied for the calculation of shale volume. The errors for every method have a tendency to increase, not to reduce, the apparent shale volume (Schlumberger 1998), therefore a "minimum combination" was applied, meaning that the minimum values of all the variables (calculated shale volumes) were used as an input. Results of the "minimum combination" method give the most probable information about the volume of the shales within the analyzed geological formation.

Słowa kluczowe

EN

clay minerals; porosity; water saturation

• Wydawca: Wydawnictwa AGH
• Czasopismo: Geology, Geophysics and Environment
• Rocznik: 2014
• Tom: Vol. 40, no. 1
• Strony: 140
• Opis fizyczny: Bibliogr. 5 poz.

Twórcy

autor

Wandycz P.

• AGH University of Science and Technology, Faculty of Geology, Geophysics and Environmental Protection, Department of Fossil Fuels, al. Mickiewicza 30, 30-059 Krakow, Poland

Bibliografia

• 1. Bassiouni Z., 1994. Theory, Measurements, and Interpretation of Well Logs. Society of Petroleum Engineers.
• 2. Ellis D. & Singer J., 2008. Well logging for Earth Scientists. Springer.
• 3. Jarzyna J., Bała M. & Zorski T., 1997. Metody geofizyki otworowej. Pomiary i interpretacja. Uczelniane Wydawnictwa Naukowo-Dydaktyczne AGH, Kraków.
• 4. Schlumberger, 1998: Log Interpretation Principles/Applications. Schlumberger Wireline & Testing, Texas.
• 5. Techlog interactive Suite, 2011. Schlumberger.