Introductory Well Testing

While there are many excellent and important books on the subject of well testing, few provide an introduction to the topic at the very basic level. The objective is to provide an easy to read introduction to classical well test theory. No previous knowledge in well testing is required. The reader is expected to understand basic concepts of flow in porous media. Well test interpretation depends on mathematical models. Some calculus skill is required. Hopefully, this book will give the reader a useful introduction to a fascinating subject and stimulate further studies.

Well testing is important in many disciplines: petroleum engineering, groundwater hydrology, geology and waste water disposal. The theory is the same, but different nomenclature and units are used. The present book use consistent units and petroleum engineering nomenclature. A consistent unit system leads to dimensionless constants in all equations. Equations in a consistent unit system are dimensional transparent but inconvenient numerically. Hence a myriad of practical unit systems have evolved. Many authors present equations first in consistent units and then convert them to the practical unit system of their choice. Conversion factors are easily available in the literature.

1. Preface
2. Introduction
3. Productivity of Wells
   1. Introductory remarks
   2. Flow equations for boundary dominated flow
   3. Productivity index, PI
   4. Time dependency of the pseudo-steady solution
   5. Flow efficiency
4. Skin Factor
   1. Introductory remarks
   2. Steady state flow
   3. Skin factor
   4. Pseudo-steady flow
5. Hawkins’ Formula for Skin
   1. Introductory remarks
   2. Hawkins’ model
6. Equivalent Wellbore Radius
   1. Introductory remarks
   2. The equivalent wellbore radius
7. Drawdown Test
   1. Introductory remarks
   2. Drawdown test
   3. Determination of permeability
   4. Determination of skin factor
8. Reservoir Limit Test
   1. Introductory remarks
   2. Reservoir limit test
   3. Determination of pore volume, circular drainage area
9. Interference Test – Type Curve Matching
   1. Introductory remarks
   2. Interference test
   3. The line source solution
   4. Type curve matching
10. Pressure Buildup Test
    1. Introductory remarks
    2. Pressure buildup test
    3. Infinite-acting reservoir
    4. Determination of permeability
    5. Determination of the initial reservoir pressure
    6. Determination of the skin factor
    7. Bounded reservoir
    8. Determination of the average pressure
    9. Average reservoir pressure
    10. Horner time
11. Pressure Derivative
    1. Introductory remarks
    2. Drawdown
    3. Buildup
    4. Derivation algorithm
12. Wellbore Storage
    1. Introductory remarks
    2. Drawdown
    3. Buildup
13. Principle of Superposition
    1. Introductory remarks
    2. Several wells in an infinite reservoir
    3. Method of images
    4. Superposition in time
14. Appendix A: Core Analysis
    1. Introduction
    2. Well testing
    3. Average porosity obtained by core analysis
    4. Average permeability obtained by core analysis
    5. Arithmetic average
    6. Harmonic average
    7. Probability distribution function
    8. Geometric average
    9. Powerlaw average
    10. Commingled reservoir
15. Appendix B: A Note on Unit Systems
    1. Introductory remarks
    2. Consistent SI Units
    3. American Field Units
    4. Conclusion