Cement Bond Log
From Open Energy Information
Exploration Technique: Cement Bond Log
IntroductionUse in Geothermal ExplorationRelated TechniquesField ProceduresEnvironmental Mitigation MeasuresData Access and AcquisitionBest PracticesPotential PitfallsNEPA Analysis
|Exploration Technique Information|
|Exploration Group:||Downhole Techniques|
|Exploration Sub Group:||Well Log Techniques|
|Parent Exploration Technique:||Acoustic Logs|
|Information Provided by Technique|
|Low-End Estimate (USD):|| 0.850.85 TUSD |
85 centUSD / foot
|Median Estimate (USD):|| 1.251.25 TUSD |
125 centUSD / foot
|High-End Estimate (USD):|| 3.003 TUSD |
300 centUSD / 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|
Cement-bond logging usually employs a single receiver to obtain information on the quality of the bond between casing and cement and between cement and borehole wall. Most cement-bond logs are a measurement only of the amplitude of the early arriving casing signal. Although a small amount of the total acoustic energy may be received from the rock when the casing is free to vibrate, the formation signal usually is not detectable. The detection of channeling through cement in the annular space is one of the main objectives of cement-bond logging. The fundamental principle is that the acoustic signal will be more attenuated in the presence of cement than if the casing were uncemented.
A cement bond log can be done to test the integrity of a geothermal exploration well.
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.
Cement bond logs are required to evaluate the isolation and protection of usable mineral resources, ground water aquifers. This protection an isolation is generally required in federally approved wells to a depth of 2,000' in non geothermal wells. Geothermal wells are cemented behined each casing string.
A circuit is employed to convert the difference in time of arrival of the P-wave at the two detectors to transit time (t) in ms/ft.
Analysis and interpretation of a cement bond log is necessary to assure integrity of the cement job, and if an adequate bond is not present throughout the interval the drilling contractor will be required to place plugs and perforate the casing and squeeze cement (perf and squeeze) into the zone. A cement bond log is required to determine whether the perf and squeeze was effective.
Even expert analysis of a cement-bond logs will not always locate all channels through the cement accurately.
Well logging is a standard operation associated with the drilling permit approval and is included in the down hole analysis of the drilling program. A cement bond log is required to determine whether there is an adequate bond between the casing and well bore. if the analysis of the cement bond logs indicates that the seal is not adequate the drilling contractor will be required to per and squeeze the zone prior to continuing operations.
No exploration activities found.