Geophysical Mapping: Method Details Printer Friendly Version   Method Name: Borehole imaging, Structure logging Method Type:   Borehole Methods Assigned Problems: + Building stability Buildings and Structures + Cavity detection Civil Engineering + Depth of Overburden-bedrock interface Civil Engineering + Fractures Groundwater + Ice thickness Natural Hazards + Permafrost and ice detection Natural Hazards + Quality / Thickness of concrete Buildings and Structures + Quality and thickness (Natural resources) Natural Resources + Soil / rock quality Civil Engineering 0 Characteristics of hazardous waste Hazardous Waste 0 Contaminant plumes Hazardous Waste 0 Earthquakes / paleoseismology Natural Hazards 0 Foundations of ancient structures Buildings and Structures 0 Groundwater table Groundwater 0 Heat mining Natural Resources 0 Host sediments, hydogeological settings Hazardous Waste 0 Landslides Natural Hazards 0 Porosity / Permeability Groundwater 0 Quality / Thickness of aquifer/aquitard Groundwater    '+' = Technique applicable; '0' = Application possible/limited use Principle:   Imaging the borehole wall with television logs (colour optical image), acoustic borehole televiewer (BHTV: acoustic televiewer) (colored image of the reflected amplitudes) or electrical imaging (colored image of resistivity). Keywords:   Seisviewer; circumferential borehole imaging (CBIL); borehole televiewer (BHTV); formation microImager; Formation MicroScanner (FMS) Prerequisites:   Fluid filled borehole (exception: borehole television / optical scanner) Television log: optic transparent borehole fluid Smooth borehole wall is favourable Excentric or oval boreholes should be avoided Suspended particles in the fluid may scatter seismic waves and degrade the acoustic imaging Acoustic televiewer: maximum borehole diameter is about 20 cm Seismic velocity in the borehole fluid should be lower than in the surrounding rock Resolution:   Instrument dependent (logging speed) Acoustic televiewer: about 2 cm or smaller The depth of investigation is limited to the borehole-wall surface Expected Results:   Measured parameter: optical or coloured images of the borehole wall (real-time) Data analysis: colors represent the amplitude values Interpretation: Identification of fractures; fracture width and orientation; direction of tectonical stress Combination with other Methods:   Required additional information other loggings; cores Related add-on information: combination of borehole imaging techniques (e.g. resistivity imager and acoustic televiewer); caliper log Independent additional information: other logs; cores Operating Expense:   Crew size:2 persons Acquisition speed: logging speed 1.2 - 2.5 m / min Processing: expensive Equipment rental costs: high Parameters to specify:   Instrument type Sampling rate (digital device) Logging speed (1.2 - 2.5 m / min) Properties of borehole filling fluids QC Documents:   Calibration data: last laboratory-calibration and on-site calibration Around 20 m of repeated measurements Borehole information (i.e., casing type, length, diameter, deviation, fluid properties) Complete headers Field notes (e.g., all activities, effective time schedule, present personnel) Products:   Pictures of the borehole wall Statistical presentation (3-D or planar view) or the structural data Results of acoustic borehole televiewer Results of electromagnetic imaging Field logs (displayed using specified scales) Interpretation Printer Friendly Version