Exploration Technique: Caliper Log
|Exploration Technique Information|
|Exploration Group:||Downhole Techniques|
|Exploration Sub Group:||Well Log Techniques|
|Parent Exploration Technique:||Well Log Techniques|
|Information Provided by Technique|
|Low-End Estimate (USD):|| 0.4040 centUSD |
4.0e-10 TUSD / foot
|Median Estimate (USD):|| 0.7878 centUSD |
7.8e-10 TUSD / foot
|High-End Estimate (USD):|| 3.00300 centUSD |
3.0e-9 TUSD / foot
|Low-End Estimate:|| 0.35 days9.582478e-4 years |
0.0115 months / job
|Median Estimate:|| 0.46 days0.00126 years |
0.0151 months / job
|High-End Estimate:|| 0.69 days0.00189 years |
0.0227 months / job
|Cost/Time Dependency:||Depth, Temp, Resolution|
A caliper log provides a representation of the diameter of a borehole along its depth. Wellbores are usually irregular in diameter, it is important to have a tool such as the caliper log that measures diameter at multiple locations. The drilling engineer will use the caliper measurement as a qualitative indication of both the condition of the wellbore and the degree to which the mud system has maintained hole stability. This is also critical information when calculating the cement volume when the casing is cemented. Caliper logs can also give some indication of formation types and whether or not the rocks are hard and compact or loose gravel.
The geophysical/well logging service company conducts the down hole logging operation and produces both digital and hard copy logs. The Drilling contractor trips the drill pipe and bit and conditions the well bore for logging.
Caliper logs are usually measured mechanically, with only a few using ultrasonic devices which provide full azimuthal coverage with high resolution. The tools measure diameter at a specific chord across the well.
A single axis caliper provides a single diameter at a specific chord across the borehole. A multi-axis caliper has multiple arms and can measure the diameter of the well bore in multiple locations simultaneously. This provides useful information as to the shape of the borehole and when run in conjunction with a orientation tool can give understanding to the stress orientation.
An unstable well bore (sluffing, wash outs, etc) can be of concern in any well logging operation. In extreme condition, the loss of the logging tool down hole could possibly result in the loss of the hole and would require premature abandonment or the necessity to side track to complete the well drilling operation.
Well logging is a standard operation associated with the drilling permit approval and is included in the down hole analysis of the drilling program.
|Page||Area||Activity Start Date||Activity End Date||Reference Material|
|Caliper Log At Valles Caldera - Redondo Geothermal Area (Rowley, Et Al., 1987)||Valles Caldera - Redondo Geothermal Area||1984||1984|