Quality Control and Validation of Detailed Logging Data from Slim Boreholes

Abstract

Borehole geophysical logging data can provide a direct link between results of large scale geophysical methods and core sample analysis. Also the in situ measurement data will focus the measured response to actual location and to the specific lithology, or overprint of alteration or deformation. This way the logging data serves as unique means to explain and control the results from a large variety of different views and scales, ranging from airborne and ground level mapping to seismic reflection surveys and electromagnetic soundings. The actual parameter information used in model interpretations is only accessible by borehole methods. Further to this, the comparison of different parameters and geological background information can lead to better understanding of processes involved in the subsurface. The presentation deals with practices of quality control and validation of slim hole logging data using different geological and sampling control data. The work includes the sample controlled conversion of measurement data to meaningful physical properties, depth matching of the data to a very good location accuracy, and computing of derivative parameters. Example data set has been produced in site characterization project of Posiva for spent nuclear fuel geological disposal in Finland.