Oil and Gas

1. Explain the basic principles of conventional well logging tools.
2. Identify key log measurements and their geological significance.
3. Interpret mineralogy, lithology, facies, and depositional environments using combinations of well logs.
4. Recognize sequence stratigraphic markers, such as flooding surfaces.
5. Develop a correlation scheme using well log data to support geological modeling.
6. Apply log interpretations to guide well placement and reduce subsurface project risks.

1. Introduction to Well Logging and Basic Concepts

• Overview of Well Logging: Purpose and objectives of formation evaluation; acquisition methods (wireline and LWD); anatomy of a well log.
• Basic Geological Concepts: Porosity, permeability, and fluid distribution (water, oil, gas) in porous rocks.
• Log Measurements: Introduction to gamma ray (GR), spontaneous potential (SP), resistivity, density, neutron, and sonic logs.
• Exercises: Reading and identifying basic features of a well log (e.g., depth, scale, and log curves).

• Gamma Ray and Spontaneous Potential Logs:
  • GR: Principles, shale identification, and environmental corrections.
  • SP: Principles, applications for lithology, and water salinity estimation.
  • Quality control basics for GR and SP logs.
• Resistivity Logs:
  • Fundamentals of resistivity measurements; differences between induction and laterolog tools.
  • Using resistivity to identify fluid types (water vs. hydrocarbons).
  • Introduction to invasion effects and basic environmental corrections.
• Exercises: Interpreting GR and SP logs to identify shales and estimate lithology.

• Nuclear Porosity Logs:
  • Density and neutron logs: Basic principles and calibration.
  • Using density and neutron logs to estimate porosity.
  • Environmental effects and quality control.
• Sonic Logs:
  • Basics of sonic measurements and their use in porosity estimation.
  • Introduction to wave propagation and borehole effects.
• Lithology Identification:
  • Combining GR, density, neutron, and sonic logs to interpret lithology (sandstone, shale, limestone).
  • Introduction to crossplots (e.g., neutron-density) for lithology determination.
• Exercises: Calculating porosity and identifying lithology using density and neutron logs.

• Facies and Depositional Environments:
  • Using log shapes and trends to infer facies (e.g., fining-upward, coarsening-upward sequences).
  • Recognizing depositional environments (e.g., fluvial, deltaic, marine).
• Sequence Stratigraphic Markers:
  • Identifying flooding surfaces and other key markers using GR and resistivity logs.
  • Understanding log trends with depth to support sequence stratigraphy.
• Petrophysical Basics:
  • Introduction to Archie’s equation for water saturation.
  • Qualitative interpretation of fluid saturation and hydrocarbons.
• Exercises: Interpreting facies and depositional environments from log patterns.

• Well Correlation Principles:
  • Techniques for correlating logs across multiple wells.
  • Using log trends and markers to establish robust correlation schemes.
• Practical Exercise:
  • Correlation exercise using data from three wells to create a correlation scheme.
  • Interpreting lithology, facies, and sequence stratigraphic markers.
  • Deriving property inputs for geological modeling (e.g., porosity, lithology distribution).
• Applications to Subsurface Projects:
  • Guiding well placement using log interpretations.
  • Reducing risk and uncertainty in geological modeling.
• Wrap-Up: Review of key concepts, Q&A, and discussion of real-world applications.

This course is designed for early-career geoscientists, new-hire petrophysicists, technologists, and engineers seeking a foundational understanding of conventional well log interpretation.