Log Derived Shale Distribution in Sandstone and Its Effect Upon Porosity, Water Saturation and Permeability


E. C. Thomas,
Shell Development Company

6th Formation Evaluation Symposium of the
Canadian Well Logging Society in Calgary, October 24, 25 & 26, 1977



A shale volume parameter derived from the response of the gamma ray log in shaly sands is often used to correct the responses of other logs for the effects of the shale. However, no dis- tinction is usually made as to the shale distri- bution, i.e., laminated or dispersed. Vie show that these two distributions involve different gamma ray responses and that a gamma ray versus porosity crossplot can be used to determine snale distribution, sand porosity and shale fraction.