interpretation of wireline logs can be significantly improved by a quantitative knowledge of the rock mineralogy in the formation. the knowledge may be obtained from core analysis. alternatively, wireline well logs may be used to derive minerals from measurements of chemical elemental analysis logs. the elements must be combined to form minerals in a unique manner from modeling the core elements and mineralogy to truly reflect the core-derived mineralogy. once the element-mineral model is obtained for the tight gas sand (tgs) environment, the mineralogy may be combined with other logs such as resistivity, nuclear magnetic resonance, electromagnetic logs, density, neutron, and acoustic logs to calculate water saturation, porosity, permeability and stress profiles to be used in fracture modeling studies. the primary focus of the gri report is to provide a mineral-based log interpretation model that is transferable from well to well in the tight gas sand environments of the travis peak, and cotton valley formations of texas and the frontier formation of wyoming. the gri/tgs mineral model that resulted from the study, provides better estimates of reserves, producibility and stress profiles in tight gas sands