Coring and Core Analysis

Instructors: Dr. Michael Myers & Dr. Lori Hathon

Discipline: Geoscience and Engineering

Course Duration: 5 days

Teaching Mode: In-person

Introduction: Formation evaluation of a hydrocarbon reservoir is key to the economic optimization of that reservoir. Coring and core analysis provide useful information needed to estimate the volume of hydrocarbons in place, permeability, and commerciality of the reservoir.

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

Course Description: This course is designed to equip the participants with knowledge of routine core analysis, special core analysis, geomechanical testing, and formation evaluation. This course presents topics such as standard and routine core analysis, core cleaning, mineralogy and diagenesis, potential for formation damage, special core analysis involving wettability, imbibition/drainage capillary pressure, mercury injection capillary pressure, and geomechanical testing.

Course Content:

Day 1: Introduction to Formation Evaluation

The role of a formation evaluation specialist is to evaluate hydrocarbon reservoirs and to provide the information needed for the economic optimization of that reservoir. The economics of a hydrocarbon reservoir are directly related to the volume of hydrocarbons in place (storage capacity), the production rate (a function of fluid pressure, reservoir geomechanical properties, and permeability), and the optimization of spending to produce the hydrocarbon reservoir.

1.1 – Primary Formation Properties of Interest

1.2 – Primary Formation Evaluation Tools

1.3 – Acquiring Core: Core Barrel Types and Uses

1.4 – Planning the Job

1.5 – Bit Considerations

1.6 – Avoiding Problems: Naturally Fractured Formations, Unconsolidated Sands

1.7 – Sidewall Operations

1.8 – Analytical Aspects of Sidewall Coring

1.9 – Standard Core Analysis Workflows – Core Gamma Ray, Core Slabbing

1.10 – Standard Core Analysis Workflows – Core Description, Core Orientation, and Sampling

1.11 – Routine Core Analysis - Introduction

1.12 – Exercises/Workshop

Day 2: Routine Core Analysis

Several factors including formation characteristics, type of coring equipment used, and results desired from analysis all play a part in what techniques are chosen for measurement.

2.1 – General Considerations – Analytical Speed vs Accuracy, Whole Core vs Core Plug Measurement

2.2 – Core Cleaning – Removing Hydrocarbons and Salts, Saturation Determination

2.3 – Porosity – Boyle’s Law and Archimedes’ Principle

2.4 – Permeability – Steady State, Unsteady State, Brine and Air Perm, Ambient and Reservoir Stress.

2.5 – Geological Analyses - Introduction

2.6 – Mineralogy and Diagenesis – XRD, FTIR, Thin Section, SEM

2.7 – Biostratigraphy, Chemostratigraphy, Natural Fracture Intensity

2.8 – Potential for Formation Damage – CEC, Fluid Sensitivity, Fines Migration, Sand Production

2.9 – Critical Partical Size, Low Salinity Flooding

2.10 – Exercises/Workshop

Day 3: Special Core Analysis

Special core analysis is distinguished from "routine (RCAL) core analysis" by including measurements of two-phase flow properties, determining relative permeability, capillary pressure, wettability, and electrical properties. Due to the time-consuming and costly character of SCAL measurements, routine core analysis (RCAL) data should be inspected thoroughly to select a representative subset of samples for SCAL.

3.1 – Wettability

3.2 – Imbibition/Drainage Capillary Pressure

3.2 – Mercury Injection Capillary Pressure

3.3 – Saturation Height Functions

3.4 – Formation Resistivity Factor

3.5 – Steady State Relative Permeability

3.6 – Unsteady State Relative Permeability

3.7 – Nuclear Magnetic Resonance (NMR)

3.8 – Exercises

Day 4 – Geomechanical Testing

Geomechanics describes how subsurface rocks deform or fail in response to changes in stress, pressure, and temperature. The determination of a reservoir’s mechanical properties is critical to reducing drilling risk and maximizing well and reservoir productivity.

4.1 – Stress Path and Sample Response

4.1 – Core Scratch Test

4.2 – Unconfined Strength Test

4.3 – Uniaxial (Zero Lateral Strain) Test – Pore Volume Compressibility

4.4 – Triaxial Test – Drained and Undrained, True Triaxial Test

4.5 – Multi-stage Triaxial Tests

4.6 – Seal Capacity – Threshold Entry Pressure Test

4.7 – Relative Tension Tests

4.8 – Acoustic Properties

4.9 – Exercises

Day 5: Integration and Quality Assurance

Core analysis provides the only direct and quantitative measurement of “intact” oil and gas reservoir properties. It should provide the foundation of formation evaluation for building static and dynamic reservoir models. However, it is estimated that approximately 70% of core analysis data are unfit for purpose as a consequence of ill-conceived test program design, lack of planning, poor laboratory practice, inadequate reporting standards and unrepresentative test samples or test conditions.

5.1 – Core/Log Integration

5.2 – How Good is My Porosity Data?

5.3 – I Work in Consolidated Formations, Why Do I Care About Pore Volume Compressibility?

5.4 – Why Do I Need to Look at Rocks?

5.5 – How Do I Upscale My Results?

5.6 – Exercises