Table of Contents

Resistivity Methods
Introduction
Unfocused Resistivity Methods
Single Electrode Systems
Equivalent Circuit
Effect of Formation Resistivity
Volume of Investigation
Averaging within the Volume of Investigation
Position of the Return Electrode
Return Electrode Grounding Resistance
Multi-Electrode Systems
Normal Resistivity Devices
Empirical Method to Estimate Rt
Departure Curves
Lateral Resistivity Devices
General Expression for Resistivity Devices
Microresistivity Systems
Miscellaneous Resistivity Items
Surface Resistivity Methods
Focused Resistivity Methods
Focusing Electrode Devices, Omnidirectional
3-Electrode Guard Logs
7-Electrode Guard Logs
Shallow Investigating Guarded Electrode Device
Spherically Focused Systems
Radial Pseudo-Geometrical Factors
Sidewall Guarded Electrode Systems
Microlaterolog (MLL)
Proximity Log (PL)
Microspherically Focused Log (MSFL)
General Reduction Procedure
Induction Methods
Introduction
Principle
Conventional Induction Logs
Phasor Induction Systems
Array Induction Logs
Factors Affecting Induction Logs
Skin Effect
Bed Boundary Effects
Thin Bed Response
Dipping Beds
Net Bed Boundary Response
Data Reduction
Borehole Corrections
Adjacent Bed Correction
Invaded Zone Correction
Resistivity Log Interpretation
Introduction
The Archie Method
Values of the Cementation Exponent
The Ratio Method
The Rocky Mountain Method
The Migrated Hydrocarbon Method
Estimation of Permeability from Resistivity Gradient
Determination of the Diameter of Invasion
Reading "Tornado" Charts, Detail
Rt vs. ? Crossplot, The Pickett Plot
The Nonlinear (Hingle) Crossplot
The Movable Hydrocarbon Method
The FR,a vs. FR Method
The RW,a vs. RW Method
Non-Hydrocarbon Usage of Resistance and Resistivity
Spontaneous Potentials
Introduction
Principles
Physical Principles
Absorption or Shale Potential
The Electrochemical or Diffusion Potential
Effect of Ion Types
Thin Beds
Formation Water Resistivity, RW
Taking Ion Types into Consideration
The Effect of Shale
Direction of Deflection
Formation Resistivity Effects
The Static SP
Calculation of Salinity
Reduction of Data
Example
The Electrokinetic Component
Redox Component
Problems with SP Measurements
Resistance Component
Sensitivity to Motion
Electrodes Touching the Sidewall
Bimetallism
Improper Electrode Material
Methods of Determining RW and Use of RW Calculations
SP vs. RXO/Rt; the Ratio Method
Ionic Conduction
RW from Resistivity Values
The Use of RWa
The Dual Water Model
RW from RXO and Rt
Dunlap Multipliers
The SP Measurement in Fresh Water Sands
Natural Gamma Radiation
Introduction
Radiation from Formation Materials
Clays
Sands
Carbonates
Igneous and Metamorphic Materials
Fractures and Faults
Gross or Total Count Gamma Ray Systems
Ranges of Detection
Equilibrium
Volume of Investigation and Borehole Corrections
Calibrations
Uses
Volume of Clay/Shale Estimation, Vsh
Correlation
Lithology
Dead Time
Bed Boundary Effects
Thin Beds
Dipping Beds and Slant Holes
Grade Calculations
Fracture Detection
Tracers
Gamma Ray Spectroscopy
Introduction
Chemical and Geological Implications
System Types
Detectors
Single Window Systems
KUT Systems
MCA Systems
Monitoring Systems
Problems with Spectrographic Systems
Major Mineral Systems
Uraniferous Minerals Systems
Thorium Minerals
Potassium Minerals
General
Miscellaneous Effects
Spectrometric Ratios
Uses of Ratios
Crossplotting
Scattered Gamma Ray Methods
Introduction
Formation Density Logging
Source Energy Requirements
Operation
Example 1, The Mole Fraction Method
Example 2, The Molecular Mass Method
Downhole Tool Types
Omnidirectional Density Systems
Single Spacing Sidewall Systems
Mudcake Compensated Density Systems
Calibrations
Interference by Natural Gamma Radiation
Rock Type Identification
Example 3, Mineral Identification and Z/A Ratio
Porosity Calculations
Example 4, Porosity from Bulk Density
Coal Analysis
Scattered Gamma Ray Spectroscopy
Neutron Porosity Logging
Introduction
Physical Description
Operational Principles
Moderation
Reactions
Sources
Detectors
Systems Now in Use
Single Spacing Systems
Sidewall Neutron Porosity Systems
Borehole Compensated Systems
Neutron Porosity Measurements
Shale Correction
Rock Type Corrections
Borehole Corrections
Cased Hole Use
Calibration
Data Reduction
Depth of Investigation
Source-Detector Spacing
Interpretation Methods
Chlorine Logs
Neutron Activation Methods
Introduction
Types of Systems
Isotopic Sources
Neutron Generators
Detector Types
Action Within the Formation Material
Saturation Systems
Neutron Induced Gamma Ray Logs
Capture Spectra
Ratio Logs
Uranium Systems
Thermal Neutron Formation Temperature Logs
Acoustic Methods - Porosity
Introduction
Principles
Operation Principles of Downhole Acoustic Systems
Tool Configurations
Single Transmitter, Single Receiver Systems
Multiple Receiver Systems
Borehole Compensated Systems
Long Spacing Acoustic Systems
The Array Sonic System
Log Presentation
Effect of Gas and Road Noise
Full Wave Systems
Evaluation
Porosity Determinations
Mechanical Properties
Effects of Clay or Shale
Primary Porosity
Fractured Media
Porosity and Lithology Determinations
Analysis of Log, Figure 19-33
Determination of Permeability from Acoustic Logs
Cement Bond Logging
Determination of the Shear Wave Velocity using the Stoneley Mode
Formation Evaluation - Standard Methods
Introduction
Assumptions
Methods Available
Multiple Parameters
Scope
Research
New Information
Methods to be Used
Analysis Methods - Standard Measurements
Normalizing Data
Cuttings Lag
Identifying the Formation Sequence
Characteristic Signatures and Values
Target Zones
Visual Examination
Quantitative Analysis
Quantitative Porosity and Saturation
Reserve Calculation
Rock Type
Shale and Clay Content
MN Crossplot
The AK Crossplot
The MID Plot
Simultaneous Equation Method
Frequency Plots
Permeability
k Estimated from the Resistivity Gradient
k as a Function of Mineral Content
Formation Fluids
Formation Fluid Types
Formation Fluid Distribution
Formation Fluid Pressure
Structural Changes
Formation Rock Strength and Competence
Zone Extent
Redox Effects
Enhancement
Combinations
Other Methods
Index