Borehole Geophysics for Coal Bed Methane Logging Programs

1
Borehole Geophysics for Coal Bed Methane Logging
Programs

• presented by
• Brian Peterson
• Century Geophysical Corporation
• 7517 E. Pine Street
• Tulsa, Oklahoma

2
Major Topics

• Introduction and Background
• Oil Field versus Slim Logging Tools
• Review of Density Tool Designs
• Other Common Log Types for Evaluation
• Common Log Responses and Examples
• Associated Problems and Cures
• Closing Remarks

3
Coal Bed Methane Logging Tools

• Standard Logs in Use Today
• Compensated Density Tools
• High Resolution Density Tools
• Compensated Neutron
• Temperature and Differential Temperature
• Various Resistivity Devices, including Focused
  and Induction
• Imaging Tools and Dipmeter
• Limiting Factors for Interpretation
• Limited Vertical Resolution of Standard Logs
• Core Comparison verses Log Comparison
• Gas Content Estimates Errors

4
Goals of Coalbed Methane Logging Program

• Identify Coal Seams and Determine Thickness
• Identify Possible Production Zones
• Determine Coal Quality from Log and Core Data
• Evaluate Cleat Permeability From Core Data and
  Correlate to Log Data
• Identify Other Possible Productive Formations and
  Evaluate SW

5
Typical Drilling Location in Wyoming
6
Coalbed Methane Areas
7
Typical Geophysical Logging Truck in Wyoming
8
STANDARD COAL SUITE - WYOMING

• NATURAL GAMMA
• CALIPER
• FOCUSED DENSITY
• RESISTIVITY

9
COMPENSATED DENSITY TOOL

• 1. Natural Gamma
• 2. Focused Resistivity and Temperature
• 3. Caliper
• 4. Far Detector
• 5. Near Detector
• 6. Source
• LENGTH 10 FEET
• DIAMETER 2.2 INCHS
• WEIGHT 65 LBS

10
Typical Coalbed Suite in Wyoming

• NATURAL GAMMA
• CALIPER
• SP
• DUAL RES.
• DENSITY POROSITY
• NEUTRON POROSITY

11
COALBED SUITE, COREHOLE

• NATURAL GAMMA
• INDUCTION RESISTIVITY
• DENSITY
• CONDUCTIVITY

12
STANDARD CDL LOG

• NATURAL GAMMA
• CALIPER
• CDL DENSITY
• DENSITY POROSITY
• COMPENSATION

13
EXPANDED CDL LOG

• NATURAL GAMMA
• CALIPER
• CDL DENSITY
• DENSITY POROSITY
• COMPENSATION

14
COMPENSATED DENSITY TOOL DESIGN

• CESIUM 137 SOURCE 2.0 CURIES
• SOURCE ENERGY LEVEL 662 KEV GAMMA RAY
• DETECTOR WINDOWS AT APPROXIMATELY 6 AND 12 INCHES
• FULL RESOLUTION 2 FEET

15
HIGH RESOLUTION TOOL DESIGN

• AMERICIUM 241 SOURCE 250 MILLICURIES
• SOURCE ENERGY LEVEL 60 KEV GAMMA RAY
• DETECTOR WINDOW AT 1.5 INCHES FROM SOURCE
• FULL RESOLUTION 3 INCHES

16
CDL LOG - THIN SEAM

• NATURAL GAMMA
• CALIPER
• CDL DENSITY
• DENSITY POROSITY
• COMPENSATION

17
HIGH - RES VS. CDL COMPARISON
18
CDL LOG - TEMPERATURE LOG - WATER FILLED

• NATURAL GAMMA
• CALIPER
• DELTA TEMP.
• TEMPERATURE
• CDL DENSITY
• COMPENSATION

19
HIGH - RES VS. CDL SHOWING SHALE PARTINGS
20
COAL QUALITY LOG - BASED ON DENSITY AND CORE DATA

• CALCULATED PARAMETERS INCLUDE
• PERCENT ASH
• PERCENT MOISTURE
• BTU

21
DENSITY AND ACOUSTIC TELEVIEWER - COAL SEQUENCE
22
Expanded CDL/Temp with Short Spaced Density
23
CDL and Temperature Air Filled Hole
24
CDL and Acoustic Televiewer
25
Coalbed Methane Logging Summary and Conclusion

• Utilization of Compensated Density Tools and
  Proper Interpretation of the Data can accurately
  Predict Coal Seam Thickness and Quality.
• High Resolution Tools have Good Application in
  Thin Seams and Partings, but Hole Size Problems
  must be addressed.
• Other Geophysical Data such as Gamma Ray,
  Temperature, and Resistivity have good
  applications to Coalbed Methane.