COMBINING GEOPHYSICAL AND WELL DATA FOR IDENTIFYING BEST WELL LOCATIONS

Geoelectric and well data are combined and used to delineate ''best'' well location areas. The best location is selected based on a compromi se solution for two conflicting objectives: (1) maximum well yield (i. e., maximum sustainable pumping rate); and (2) maximum wellhead protec tion (i.e., maximum total travel time related to a fixed setback dista nce). The methodology combines hydraulic conductivities and layer thic knesses obtained from well logs, well-performance tests, and geoelectr ic measurements to estimate and map well yield and travel time. Hydrau lic conductivities, layer thicknesses, and the estimated yields and to tal travel times are considered as spatially correlated random variabl es. Expected value and 75% reliability maps are developed for yield an d total travel time. The best well location areas are identified based on a trade-off map that is calculated as a combination of the yield a nd travel time maps. The relative importance of well yield versus well head protection is incorporated in the trade-off relationship. The met hodology is illustrated for a study area located near Ashland, Nebrask a.