This crossplot displays shale volumes calculated from the gamma ray log. Linear and non-linear equations are presented.
Inputs are highlighted in yellow and outputs are color coded, based on the equation used. Enter the average gamma ray log value over the interval of interest, as well as gamma ray log values for clean (no shale) and shale (completely shale) intervals. The linear output is known as the gamma ray index, which is used as input to the non-linear equations.
Data points associated with output values are plotted on the cross plot for reference and are also color coded.
References
Bush, Robert, E., and Mardock, E.S., "The Quantitative Application of Radioactivity Logs." Petroleum Transactions AIME, Volume 192, 1950: 191-198.
Bhuyan and Passey, "Clay Estimation from GR and Neutron-Density Porosity Logs." SPWLA, Thirty-Fifth Annual Logging Symposium, 1994, papper DDD.
Clavier, C., Hoyle, W., and Meunier, D., "Qunatitative Interpretation of Thermal Neutron Decay Time Logs: Part I Fundamentals and Techniques." Journal of Petroleum Technology Volume 23, Number 6, 1971: 743-755.
Heslop, A., "Gamma-ray Log Response of Shaly Sandstones." The Log Analyst Volume 15, Number 5, 1974: 16-24.
Katahara, K.W., "Gamm Ray Log Response In Shaly Sand." The Log Analyst Volume 36, Number 4, 1995: 50-55.
Larionov, V.V., "Borehole Radiometry." Book Published in Russian Language, Moscow, 1969.
Poupon, A., and Gaymard, R., "The Evaluation of Clay Content from Logs." The Log Analyst Volume 11, Number 6, November - December 1970: 18-25.
Stieber, S.J., "Pulsed Neutron Capture Log Evaluation: Louisiana Gulf Coast." American Institute of Mining, Metallurgical and Petroleum Engineers, 1970, SPE 2961.