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PREFACE

Drilling circulation systems in the oil and gas industry have advanced
significantly in the last decade. The major changes resulted from the merging
of air and gas drilling and underbalanced drilling with traditional liquid
drilling systems. During the several years of teaching drilling engineering
courses in both academia and industry, the authors realized the need for a
book that covers modern drilling practices. The books that are currently
available fail to provide adequate information about how engineering princi-
ples are applied to solving problems that are frequently encountered in
drilling circulation systems. This fact motivated the authors to write this book.
This book is written primarily for well drilling engineers and college
students of both senior and graduate levels. It is not the authors’ intention
to simply duplicate general information that can be found in other books.
This book gathers the authors’ experiences gained through years of teach-
ing courses on drilling hydraulics, air and gas drilling, and underbalanced
drilling engineering in the oil and gas industry and in universities. The
mission of this book is to provide drilling engineers with handy guide-
lines for designing, analyzing, and operating drilling circulation systems.
This book covers the full scope of drilling circulation systems. Follow-
ing the sequence of technology development, it contains ten chapters
presented in three parts.
Part I contains four chapters that cover liquid drilling fundamentals as the
first course for entry-level drilling engineers and undergraduate students.
Chapter 1 presents an introduction to the equipment used in mud drilling
systems. Chapter 2 documents mud hydraulics fundamentals that are essential
for selecting and optimizing mud pumps and mud hydraulics programs.
Chapter 3 covers in detail the procedure for selecting mud pumps. Chapter 4
presents techniques used to optimize mud hydraulics programs.
Part II includes three chapters that present the principles and rules of
designing and operating gas drilling systems. Chapter 5 introduces the
equipment used in gas drilling systems. Chapter 6 covers in detail the
procedure for selecting gas compressors. Chapter 7 provides guidelines for
operating gas drilling systems.
Part III consists of three chapters that cover underbalanced drilling
systems. Chapter 8 presents an introduction to the equipment used in
underbalanced drilling systems. Chapter 9 describes the procedure for

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