N496 Advanced Special Core Analysis

Course Facts

Course Code:
N496
Duration:
5 days
Type:
Classroom
CEU:
4.0 Continuing Education Units
PDH:
40 Professional Development Hours
Certificate:
Certificate Issued Upon Completion

Summary

The course is intended to be a comprehensive introduction to the most widely used special core analysis measurements (that is measurements that are routinely made in a commercial core analysis laboratory). The course discusses both the measurements and the way the data is subsequently used in static and dynamic modelling.

Duration and Training Method

This is a five-day classroom course. Lectures supported by exercises of varying complexity. Lectures will make extensive use of real data to illustrate how SCAL has been used successfully. Where-ever possible the exercises will be based on real data as well. All exercises can be completed using calculators and graphs but they can also be completed in excel and access to a PC would enhance learning.

On completion of the course participants will
  1. Understand the purpose of electrical parameters, capillary pressure curves and relative permeabilities.
  2. Quality control the different measurements and assess how representative they are.
  3. Propose saturation parameters for input to a petrophysical model (including low and high-side realisations).
  4. Define excess conductivity and using appropriate measurements, incorporate it into a shaly-sand interpretation. Assess whether a shaly-sand equation is necessary.
  5. Understand what controls the shape of a capillary pressure curve and model individual curves with a curve fit.
  6. Use a set of capillary pressure curves to build a saturation-height function.
  7. Understand the concept of Wettability and how SCAL measurements relate to it.
  8. Understand the concepts of Relative and Effective permeability.
  9. Understand the difference and advantages/disadvantages of steady and unsteady state relative permeability measurements. Fit curves to raw data using Corey exponents.
  10. Integrate saturation-height functions with relative permeability curves to predict water cut in the transition zone.
Day 1: Introduction & Objectives of the Course.

Cores and Coring

  • History.
  • Coring equipment.
  • Biography of a core: from reservoir to laboratory.
  • Comparing Logs and Cores.
  • Preparation for measurements: plugging, cleaning and drying.

Special Core Analysis.

  • What is SCAL?
  • Purpose
  • Sample Selection.
  • Designing a Program: constraints.

Description of the Measurements.

  • Electrical properties (a,m and n)
  • Excess conductivity.
  • Capillary Pressure.
  • Relative Permeability.
  • Wettability.
  • Others: NMR, residual gas saturation, compressibility.

Day 2: Electrical Measurements

Summary of Day 1.

  • The Archie Equation.
  • Pickett plots and the Cementation Exponent (m).
  • Saturation Exponent (n)

Saturation Model.

  • Objective.
  • Selecting m,n values for the model.
  • Variable m models.
  • Uncertainty analysis.

 

Excess Conductivity.

  • Definition and Consequences.
  • Hill and Millburn’s experiments.
  • Cation Exchange Capacity and its relation to Excess Conductivity.
  • C0-Cw measurement.
  • 3 ‘Wet Chemistry’ methods.

Shaly-SandModels.

  • Waxman-Smits Method.
  • When should a Shaly-sand method be used?
  • Other Shaly-sand equations
  • Health Warning.

Day 3: Capillary Pressure and Saturation-Height Modelling.

Summary of Day 2

  • Fluid Distribution in Porous Rocks.
  • The Saturation-Height Function (SHF).
  • Applications of the SHF
  • Derivation of the SHF.

Capillary Pressure.

  • Capillary Rise.
  • Capillary Pressure.
  • Capillary Effects in Real Rocks.

Wettability

  • Interfacial Tension (IFT)
  • Wettability and Contact Angle.
  • Oil Wetness.

Fluid Distribution.

  • Buoyancy vs. Capillary Forces.

Capillary Pressure Curves.

  • Porous Plate.
  • Centrifuge.
  • MICP and Pore Size distribution.
  • Qualitative Information from Pc curves.

Developing a Saturation Height Function.

  • Data Collation and QC.
  • Selecting a Function.
  • Curve Fitting.
  • Accounting for Changes in Rock and Fluid Properties.
  • Comparison to Log Analysis and other data.

Elaborations

  • Imbibition and Residual Oil.
  • EOR.

Day 4 & 5: Review

Summary of Day 3.

Wettability Index.

  • Contact Angle (re-visited)
  • USBM Method
  • Amott Method
  • Interpreting the WI.

Relative Permeability.

  • Absolute and Effective permeability.
  • End Point Saturations and Effective Permeability.
  • Relative Permeability.
  • Permeability to Water.

Relative Permeability Curves.

  • Steady State Method.
  • Unsteady State Method.
  • Corey Exponent.

Interpreting Relative Permeability

  • Producing from the Transition Zone.
  • Consequences for Fluid Sampling.
  • Basin Centre Gas.

Conclusion

  • Is SCAL really necessary?
  • Alternatives to SCAL and Value of Information.

Who should attend

The course is really designed for anyone who is involved with building static and dynamic reservoir models whether as a geologist, petrophysicist or reservoir engineer. Familiarity with basic petroleum geology and engineering is assumed. Students should be able to define the basic petrophysical properties: porosity, permeability and saturation and understand how these relate to in-place volumes and how they are measured in routine core analysis. A basic knowledge of depletion mechanisms would also be helpful.

Special Core Analysis produces numerical data and understanding the measurements and applying them requires some basic mathematical skills (roughly High School level). Most exercises involve calculation. Typical skills needed are constructing and interpreting graphs, simple manipulation of equations, curve fitting and regression. All calculations can be completed with a scientific calculator.

 

Prerequisites and linking courses

There are no specific course requirements other than outlined in ‘Who Should Attend’.