Introduction to Well Logging

Instructors: Dr. Michael Myers & Dr. Lori Hathon

Discipline: Multi-discipline

Course Duration: 5 days (Aug 12-16, 2024)

Teaching: In-person

Introduction: The primary function of a petrophysicist is to ensure that the right operational decisions are made during drilling, completions, and well-testing. Data gathered thereafter forms the necessary parameters required to build an accurate static and dynamic model for reservoir simulations. The Advanced well-logging course prepares the participant for improved understanding and knowledge of formation evaluation through well-logging.

Who Should Attend: Petropysicists, geoscientists, reservoir engineers, production engineers/technologists, asset managers, log analysts, and technical professionals.

Course Description: This is a comprehensive and up-to-date course designed to equip participants with knowledge of logging environment and mudlogging, permeable zone logs, Resistivity logs, porosity logs, and integration.

Course Content:

Day 1: The Logging Environment and Mudlogging

The primary functions of a petrophysicist are to ensure that the right operational decisions are made during drilling and testing a well—from data gathering, completion, and testing—and thereafter to provide the necessary parameters to enable an accurate static and dynamic model of the reservoir to be constructed.

1.1 – Formation Evaluation Introduction

1.2 – The Logging Environment

1.3 – The Undisturbed Reservoir: Rock and Fluid Properties

1.4 – The Ideal Borehole Model

1.5 – Caliper Logs

1.6 – Mud Types

1.7 – Invasion

1.8 – Formation Temperature

1.9 – Mud Logging – Sensor Types and Measurements Recorded

1.10 – Factors Influencing Rate of Penetration – Normalized Drilling Rate

1.11 – Lag Time

1.12 – Exercises/Workshop

Day 2: Permeable Zone Logs

Lithological determination from wireline logs is often done by sophisticated computer programs, but basic quick-look interpretation can be made by visual inspection of appropriate logs. The boundary between permeable and non-permeable zones are typically identified by the SP and Gamma Ray logs.

2.1 – Spontaneous Potential

2.2 – Electrochemical Potential – Membrane Potential (Esh) and Diffusion Potential (Ed)

2.3 – Electrokinetic Potential – Streaming Potentials (Emc, Esb)

2.4 – Total Potential – Static SP

2.5 – Shape of the SP Curve

2.6 – Rw from SP

2.7 – Gamma Ray Logs

2.8 – Sources of Natural Gamma Ray

2.9 – Calculating the Shale Index

2.10 – Exercises/Workshop

Day 3: Resistivity Logs

In the oil and gas industry, resistivity is measured in newly drilled wells. The measurement of formation resistivity is used to define the water, oil, and gas contained within the pore space of the formations penetrated by the well. Calculations are made using measured physical and electrical properties of the formations to determine hydrocarbon saturation.

3.1 – Generic Electrical Measurement

3.2 – Deriving the Radial Geometric Factor for a Simple System

3.2 – The Normal Array

3.3 – The Lateral Array

3.4 – Induction Logs

3.5 – Laterologs

3.6 – Using Tornado Charts to obtain Rt, Rxo, di

3.7 – Electrical Anisotropy

3.8 – Exercises

Day 4: Porosity Logs

Three open hole logs are commonly used to evaluate porosity. While none of these logs measures porosity directly, the porosity can be calculated based on theoretical or empirical considerations. The measurements obtained from these logs are not only dependent on the porosity but are also dependent on other rock properties

4.1 – The Compensated Density Log

4.1 – Density Corrections – The Spine and Ribs Plot

4.2 – The Litho-Density Log (Pe)

4.3 – The Compensated and Dual Energy Neutron Logs

4.4 – Environmental Corrections and the Gas Effect

4.5 – Density/Neutron Cross Plots

4.6 – Compensated Acoustic and Long Spaced Acoustic Logs

4.7 – Porosity from the Acoustic Log – Wyllie Time Average, Gassmann, Local Transforms

4.8 – Secondary Porosity from the Acoustic Log in Carbonates

4.9 – Exercises

Day 5: Integration

Water saturation (Sw) determination is the most challenging of petrophysical calculations and is used to quantify its more important complement, the hydrocarbon saturation (1 – Sw). Complexities arise because several independent approaches can be used to calculate Sw. The complication is that often, if not typically, these different approaches lead to somewhat different Sw values that may equate to considerable differences in the original oil-in-place (OOIP) or original gas-in-place (OGIP) volumes.

5.1 – Quick Scan Evaluation Techniques

5.2 – The Rwa method, Pickett Plots, Hingle Plots

5.3 – Carbonate Petrophysics

5.4 – Pore Combination Modeling

5.5 – Exercises