Abstract
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.