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Lecture Presentations
PGE368Fall 2003 Semester
October 21, and 23, 2003
Principles of Density Logging and Interpretation
Carlos Torres-Verdín, Ph.D.Assistant Professor
Objectives:
• To understand the physical principles behind the operation of density logging tools,
• To understand the principles behind the interpretation of density and PEF logs, and
• To understand the importance of environmental corrections applied to density and PEF borehole measurements.
Complementary Reading Assignment:
1. Bassiouni, Z., 1994, Theory, Measurement, and Interpretation of Well Logs, Chapter 8: “Gamma Ray Absorption Logs.”
2. Ellis, Darwin, 2003, Tutorial on Active Gamma-Ray Log Principles and Interpretation: Petrophysics.
Bulk Density Logging
Neutron Logging
Sonic Logging
Electrical Resistivity of Rocks
Electrical Resistivity Tools:Induction and Laterolog
Course Plan, II
Saturation
Invasion
Active NuclearLogging
Porosity
GasLithology
Invasion
CoreData
Density
Density: Influence of Porosity and Saturation
Density: Typical Range of Values
Density: Typical Range of Values
Density: Typical Range of Values
Density: Influence of Porosity and Saturation
Density-Porosity Relationship
Density LogAnd
EstimatedPorosity
Radioactive Sources
Nuclear Logging Methods
Density Measurements: Active Gamma-Ray Interactions
Density Logging
Measurement Principle
MEASUREMENT PRINCIPLE: Active Gamma-Ray Interaction with Porous Media
Measurements in the
Borehole
Density and Gamma-Ray Count Rate
Typical Borehole Tool Configuration
250 cm 200 150 100 50 0 cm
80 cm
80 cm
40 cm30 cm 20 cm
60 cm
5 cm 2 cm 0 cm
INDUCTION LOG
LATEROLOG
NEUTRONGAMMA RAY
DENSITY
SONICMICRO RESISTIVITY
MICROLOGDIPMETER
DEPTH OF INVESTIGATION
RES
OLU
TIO
NRESISTIVITY
RADIOACTIVITY
RESISTIVITY
ACOUSTIC
Logging Tools
Measurement Principle
Mechanisms of Gamma Ray Absorption
Photoelectric Effect
Compton Scattering
Pair Production
Gamma Ray Sensor
Gamma Ray Detection Process
Litho-DensityLog
(PEF + Density)
Gamma Ray Detector Count Rate
Gamma RayBasics
Gamma RayAbsorption
Bulk Density and Electron Density
Bulk Density and Electron Density
Bulk Density and Electron Density(Molecules and Minerals)
Typical Values
Statistics of Gamma Ray Count
Absorption Properties
Photoelectric Effect
Pe for Minerals
Typical Values
Th/K-Pe Cross-Plot
Compton Effect
SingleDetector
Tool
Tool Calibration: Single Detector
Mudcake Correction: Single Detector
Dual-Detector Tool Configuration
Dual Detector:Density
Response
Dual Detector:Mudcake
Thickness Effect
Dual Detector:MudcakeDensity
Response
CompensatedDensity:
Spine and RibsPlot
Porosity and Mineralogy
SUMMARY: Gamma-Ray Interactions
Acknowledgements
• Baker Atlas
• Schlumberger
