Geophysical Mapping: Method Details
Printer Friendly Version  
41 of 48
Method Name: Technical logging
Method Type:   Borehole Methods
Assigned Problems:
+ Permafrost and ice detection Natural Hazards
+ Soil / rock quality Civil Engineering
0 Fractures Groundwater
0 Gravel, clay, limestone, salt exploration Natural Resources
0 Landslides Natural Hazards
   '+' = Technique applicable; '0' = Application possible/limited use
Principle:   Technical logs mainly support the analysis and interpretation of other logs or serve for checking the quality of the borehole and casing.
  • Caliper log: Records the borehole diameter; changes in borehole diameter are related to well construction, such as casing or drill-bit size, and to fracturing or caving along the borehole wall.
  • Cement bond log (CBL) / Acoustic cement bond log (ACBL): Testing the casing-cement-formation bond (interpretation of seismic-wave amplitudes)
  • Temperature log: Records the temperature
  • Borehole deviation / Directional log / Directional survey: Measurements of direction and inclination of a borehole (determination of borehole geometry)
  • Other techniques: Multifinger-caliper log: High-resolution measurements of the borehole cross-section
  • Casing collar log: Location and control of casing collars
Keywords:   Temperature; temperature gradient; caliper; diameter; casing; deviation; orientation
Prerequisites:   Temperature log should be usually measured as first log and downwards
Resolution:   Temperature log: Relative accuracy: 0.01 to 0.1 K; absolute accuracy 1 K or better
Caliper log: Absolute accuracy 1 mm
Expected Results:  
  • Measured parameter: Caliper log: Positions of one or several arms/ borehole diameter in cm; Temperature log: Temperature in K or C, gradient of temperature [K/m]; Cement bond log: Amplitudes of ultra-sonic waves; Borehole deviation: North-South / East-West deviation from the vertical / intended borehole direction in m
  • Data analysis: Logs: Measured parameter vs. depth in m
  • Interpretation: Geothermal gradient
Combination with other Methods:  
  • Required additional information: NA
  • Usefull additional information: NA
  • Independent additional information: NA
Operating Expense:  
  • Crew size: 1 - 2 persons
  • Acquisition speed: see ""Parameter to specify""
  • Processing: low
  • Equipment rental costs: high
Parameters to specify:  
  • Instrument type
  • Logging speed (4 - 8 m / min)
  • Logging speed temperature logging: normally less than 6 m / min
  • Diameter or radius for each caliper arm
QC Documents:  
  • Calibration data: last shop-calibration or on-site calibration
  • Around 20 m of repeated measurements
  • Borehole information (i.e., casing (type and length), diameter, deviation, fluid properties)
  • Complete headers
  • Field notes (e.g., all activities, effective time schedule, present personnel)
Products:  
  • Field logs (displayed using specified scales)
  • Composite logs
  • Interpretation
Printer Friendly Version