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Method Name: |
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Technical logging |
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Method Type: |
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Borehole Methods
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Assigned Problems: |
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Principle: |
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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
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Keywords: |
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Temperature; temperature gradient; caliper; diameter; casing; deviation; orientation |
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Prerequisites: |
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Temperature log should be usually measured as first log and downwards |
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Resolution: |
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Temperature log: Relative accuracy: 0.01 to 0.1 K; absolute accuracy 1 K or better
Caliper log: Absolute accuracy 1 mm
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Expected Results: |
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- 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
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Combination with other Methods: |
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- Required additional information: NA
- Usefull additional information: NA
- Independent additional information: NA
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Operating Expense: |
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- Crew size: 1 - 2 persons
- Acquisition speed: see ""Parameter to specify""
- Processing: low
- Equipment rental costs: high
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Parameters to specify: |
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- 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
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QC Documents: |
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- 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)
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Products: |
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- Field logs (displayed using specified scales)
- Composite logs
- Interpretation
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