Log Quality Control Typical Course Contents

  • Introduction
    • Basic Concepts.
    • Depth Control.
    • Anatomy of an Electric Log.
    • Tool Combinations.
    • Auxiliary Measurements.
    • Caliper.
    • Cable Tension.
    • Logging Speed.
  • Metrology
    • Metrology Elements.
    • Error Types.
    • Error Minimization.
    • Resolution and Accuracy.
    • Depth of Investigation.
    • Vertical Resolution.
    • Logging Tools Calibration Theory.
  • Gamma Ray and SP
    • Gamma Ray.
    • Applications.
    • Shaliness.
    • Spectral Gamma Ray.
    • Environmental Corrections.
    • Calibration.
    • Quality Control.
    • SP.
    • Applications.
    • Rw Determination.
    • Commonly Found Issues.
    • Quality Control.
  • Resistivity Tools
    • Resistivity Theory.
    • Invasion Profile.
    • Laterolog.
    • Environmental Effects.
    • Calibrations.
    • Log Quality Control.
    • Microlog.
    •  Microlaterolog.
    • Focused Spherical Log.
    • Calibrations.
    • Quality Control.
  • Conductivity Tools
    • Induction.
    • Physical Principles.
    • Geometrical Factor.
    • Array Induction.
    • Environmental Corrections.
    • Calibrations.
    • Log Quality Control.
    • Induction vs. Laterolog.
  • Nuclear Logging Tools
    • Nuclear Interaction Principles.
    • Density Tool.
    • Photoelectric Factor.
    • Environmental Effects.
    • Calibrations.
    • Log Quality Control.
    • Compensated Neutron Tool.
    • Environmental Effects.
    • Calibrations.
    • Log Quality Control.
    • Lithology Identification.
  • Sonic Tools
    • Compensated Sonic.
    • Long Spacing Sonic.
    • Sonic Porosity.
    • Wave Propagation.
    • Dipole Sonic.
    • Mechanical Properties.
    • Borehole Effects.
    • Quality Control.
  • Cement Evaluation Tools
    • Cementation.
    • Factors Affecting the Cement Quality.
    • CBL Principle.
    • Waveform Analysis.
    • VDL.
    • CBL-VDL Interpretation.
    • Eccentralization.
    • Bond Index.
    •  Ultrasonic Tools.
  • Image Logs
    • Dip Interpretation Theory.
    • Wellbore Images.
    • Image Processing and Interpretation.
    • Static and Dynamic Images.
    • Open, Closed and Induced Fractures.
    • Wellbore Stresses.
    • Ultrasonic Images.
  • Petrophysical Interpretation
    • Qualitative Interpretation.
    • Archie Equation.
    • Hingle & Pickett Plots.
    • Dual Water Model.
    • Other Saturation Equations.
    • Graphical Log Interpretation (Crossplots).
    • Thin Bed Interpretation Methodologies
    • Thomas Steiber.
    • Juhasz Equation.

Value Added Selling Typical Course Contents

  • Introduction
    • Types of Sales in the Oil Industry
    • Customer Objectives and XYZ Company Objectives– How to match them?
    • Sales Call Structure
  • Opportunity Management
    • Make Time Your Advantage
    • Sales Phases in the Opportunities Management Process
      • Phase 1: Corporate Account Profile
      • Phase 2: : Identifying a Compelling Event
      • Phase 3: Evaluation of Options
        • Determine Decision Criteria and Evaluation Model
        • Identifying Differentiators
        • Judging Alternatives Using the Evaluation Model
      • Phase 4: Negotiation
      • Phase 5: Implementation
      • Phase 6: Process Revision
  • Sales Communication Skills
    • Communication Process
    • Communication Channels
      • Body Language
      • Written Communication
      • Oral Communication
    • Active Listening
    • Discussion Skills
    • Delivering the Message
    • Managing Differences
    • Concluding the Conversation
    • Video: Effective Communication
  • Effective Presentations
    • The Presentation Elements
    • Learning Styles (Visual, Auditory, Kinesthetic)
    • Planning
    • Know your Audience
    • Verify Space and Logistics
    • Preparation
    • Research, Research, Research
    • Effective Utilization of Visual Aids
    • Anxiety Control
    • Get your Audience Involved
    • Homework: Prepare a Presentation for the Group
  • Social Profiling
    • Analytical, Amiable, Driver and Expressive
    • What is my Social Profile? è Test
    • Aligning with Customer Personality
  • Value Added Selling
    • Value Proposition Definition
      • Points of Differentiation
      • Points of Parity
      • Support Points
    • Finding XYZ Company´s Value Proposition
    • The Sales Call
    • Setting the Sales Call Objectives
    • Planning the Probing Strategy
    • Opening
    • Propose an Agenda
    • Acknowledge Customer Requirements
    • State the XYZ Company Unique Value Proposition
    • Checking for Acceptance
    • Probing to Uncover Customer Needs
    • Supporting Customer Needs
    • Closing
    • Pot Sales Call Analysis
    • Video: The sales Call
    • Role Play: Selling XYZ Company Services
  • Handling Objections
    • Getting to Yes
    • Customer Indifference
    • Overcoming Customer Indifference
    • Customer Skepticism
    • Overcoming Customer Skepticism
    • Misunderstanding
    • Overcoming Misunderstanding
    • Acknowledging XYZ Company Services Limitations
    • How to Overcome the Limitations
    • Role Play: Handling Objections
  • Successful Negotiations
    • Negotiation Style è Test
    • Types of Negotiation
    • The Negotiation Process
    • Situational Analysis
    • Strategic Questions
      • Can we Compete?
      • Can We Win?
      • It is Worth Winning?
    • Proposal Analysis
    • Negotiation Objective
    • Determine Negotiable and Non-Negotiable Points
    • Build Trades
    • Negotiation Strategy
    • Determining my  BATNA
    • Successful Negotiation Examples
    • Video: Successful Negotiations
    • Role Play: Selling Against the Competition
  • Negotiation Meeting
    • Objectives
    • Initial Position
    • Negotiating Ranges and Zone of Possible Agreement
    • XYZ Company Value Proposition
    • Checking for Acceptance
    • Review the Initial Offer
    • Negotiation Sequence
    • Address Non-Negotiable Issues
    • Handling the Customer’s Rejection of a First Trade
    • Ask for any Outstanding Issues
    • Summarize the Agreements
    • Closing
    • Review Next Steps


If you believe that for most of you this will be a very easy question to answer, think it twice, most people will answer something like this:

That is easy!!! Density, neutron & sonic, some others that are a little more technical will include Nuclear Magnetic Resonance as well.

Let me inform you that they have it all wrong and I will explain the reasons right now.

Density Tool Basics

Density tools uses a chemical gamma ray source and two or three gamma ray detectors. The source emits gamma ray which interact with the formation atoms trough several nuclear physics mechanisms being the main ones Compton scattering and photoelectric absorption.

Density Tool


Gamma rays will lose energy during these interactions and the number of gamma rays returning to the detector will depend on the number of electrons present, the electron density, RHOe.

The electron density can be related to the bulk density (RHOB) of the minerals by a simple equation:

RHOe = RHOB ( 2 Z/A )

Where Z is the atomic number (number of electrons per atom) and A is the atomic weight.

The assumption made in the interpretation is that:

Z/A = 0.5

This is very close for most elements commonly encountered, except hydrogen which has little effect on the measurement (as it only has 1 electron). Therefore we can assume that RHOe =  RHOB.

This is not 100% correct, equations have been developed that relates electron density to formation density and those are the ones applied on the different density tools in the market. Therefore, density tool as it names indicates measures density, in order to calculate porosity, you need to know the  lithology and then you can calculate it using the formula:

PHI = (RHOB – RHOma)/(RHOma – RHOf)

Where RHOma is the equivalent matrix density, RHOf is the fluid density (mud filtrate) and RHOB  is formation density determined by the tool readings.

Neutron Tool Basics

To talk about the mechanism used by neutron tools to determine porosity, we need to define a parameter know as Hydrogen Index.

Hydrogen Index is the quantity of hydrogen per unit volume, fresh water is defined as having a Hydrogen Index of 1, oil has a Hydrogen Index which is slightly less than that of water, the Hydrogen Index of gas is a much smaller than that of water, this is what causes the very well-known density-neutron crossover.

Neutron tools use a chemical or electrical neutron source and 2 to 3 detectors, the neutrons emitted by the source will interact with formation atoms, they will be slowed down from their initial “fast” state by collisions with the formation nuclei. At each collision there is some energy lost by the neutron.

The principal element involved in the slowing down is Hydrogen, because it is close in size to the neutron, this is why the tool measures the Hydrogen Index.

Neutron detector counts are then converted to porosity using a transform which is a mixture of theoretical and experimental work, these transform will give different porosity values according to the lithology.

Therefore, neutron tools measure Hydrogen Index and convert its measured counts to porosity depending on the formation matrix, so they do NOT measure porosity.

Sonic Tools Basics

Sonic tools use a minimum of two acoustic transmitters and four receivers. The tools create an acoustic signal and measure how long it takes to pass through a rock. By simply measuring this time we get an indication of the formation properties.

The main property measured by the tool is the slowness, that is defined as the time needed for the acoustic signal to travel 1 foot in the formation.

Formation porosity can be determined with sonic tools using the following formula:

Where Dma is the equivalent matrix slowness, Df is the fluid slowness and DT is slowness determined by the tool readings.

Therefore, sonic tools do not measure porosity, they do measure slowness and we calculate porosity using equations, furthermore sonic tools do not “see” secondary porosity, on the contrary density and neutron allow to calculate total porosity.

Nuclear Magnetic Resonance Basics

Nuclear Magnetic Resonance tools use the same principles of medical MRI in a different way, instead of having the subject of investigation (a human) in the middle of the instrument, in this case the instrument is inside the borehole so the subject of investigation (formation) is all around the tool.

An NMR tool can directly measure the density of hydrogen nuclei in reservoir fluids. Because the density of hydrogen nuclei present in water is known, data from an NMR tool can be directly converted to an apparent water-filled porosity. This conversion can be done without knowledge of the matrix, so it provides a lithology independent total porosity.



Tool physics is pretty complicated and outside the reach of this article, you can learn more about NMR on any of my courses.

What is really important to know here is that NMR measurement depends on Hydrogen Nuclei, so it is somehow dependent of the Hydrogen Index, thus we can say that it does not measures porosity but it allows to calculate it as with the other 3 types of tools we talked about before.

So as you should be able to realize now, there is not a single wireline tool that can “measure” porosity although there are several tools that allow us to determine it.

If you want to learn more about petrophysics and the fascinating relationships between formation lithologies and their fluid contents in the reservoir, take a look at some of my courses offered by Applied Stratigraphix:

Basic Well Log Analysis

Advanced Well Log Analysis

Log Quality Control and Petrophysics

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