Estimation of shale volume using a combination of the three porosity logs

An equation was developed for evaluating the volume of shale using standard porosity logs such as neutron, density and acoustic logs. The equation is written in terms of several parameters that are readily available from well-log measurements. This equation, which takes into consideration the effect of matrix, fluid and shale parameters, applies reasonably well for many shaly formations independent of the distribution of shales. The results demonstrate the applicability of the equation to well-log interpretation as a procedure for computing shale volume in shaly sand sedimentary sections. Three key advantages of the proposed equation are: (1) it incorporates several parameters that directly or indirectly affect the determination of shale in one equation, (2) it integrates the three porosity tools for a more accurate determination, and (3) it works well in hydrocarbon-bearing formations and where radioactive material other than shale is present. Successful application of the equation to shaly sand reservoirs is illustrated by analyses of samples from the Gulf of Suez. (C) 2003 Elsevier B.V. All rights reserved.