Oil-shale resources of the Mahogany Zone in eastern Uinta Basin, Uintah County, Utah

7 Introduction 8 Memorandum of understanding 8 Proj ect personnel 8 Acknowledgments 9 Study area 9 Previous investigations 10 Geologic setting 10 Green River Formation 12 Mahogany oil-shale zone 12 Oil-shale resources of the Mahogany zone......... 13 Other mineral resources in the study area 15 Methodology 17 Base map and acreage calculations 17 Well data 18 Shale-oil analyses 18 Evaluation of density and sonic logs 24 Estimating shale-oil content from geophysical logs 25 Geostatistics 38 Data used in analysis of oil-shale resources..... 38 Variogram modeling 39 Adjusting for drift 41 Testing the validity of the fitted variogram-drift model 44 Criteria to judge acceptability of the variogram-drift model 44 Results of cross-validation 45 Tract-by-tract estimation of geological variables 47 Kriging of resource estimates 47 Kriging of thickness and depth 51 Evaluation of oil-shale resources. 56 Relation between thickness and grade of oil shale 56 Estimated error of resources 58 Recommendations 62 References 59 Appendix A 62