Borehole image logs provide accurate, orientated dip information used to interpret structural geometry and depositional environments, as well as present day in situ stress directions and geomechanical properties of the rocks drilled. Despite these advantages over standard logging techniques, borehole images are underutilised within ground investigation. Using data from the Glasgow Geothermal Observatory - a test case for shallow mine geothermal heating, this study demonstrates the use of image logs to better constrain ground models and provide valuable information on fault and fracture characteristics, contamination pathways and void detection; conditions which are difficult to assess using data from drilling, standard wireline logging and core. Analysis of the borehole image logs reveal the structural dip of the bedding planes, fault and fracture orientations, maximum horizontal stress (SHmax) trends and geomechanical property variations of the rocks encountered. Coal seams are easily identifiable within the images, with evidence of mine workings including void spaces with steeply inclined, sporadically faulted beds with noticeable offsets above. This study highlights how data from image logs can better constrain rock mass properties as well as provide vital data to aid in the engineering assessment of anthropogenic and geological hazards.
Pettigrew et al. (Thu,) studied this question.