A Geological appreciation of Shaly Sands


William R. Almon
Cities Service Company

7th Formation Evaluation Symposium of the
Canadian Well Logging Society in Calgary, October 21, 22, 23 & 24, 1979



The analysis of “shaly” sands has long been a problem. Most approaches to this problem have made the basic assumption that the “shale” in the sandstone has the same basic properties as the shale beds associated with the sandstone units. This is not the case as the “shale” in most sandstones is a product of diagenesis rather than the depositional process. As a result it tends to be of different mineralogy from the associated detrital shales and to occur almost exclusively within the pore system of the sandstone.