Page 24 - Air and Gas Drilling Manual

Chapter
One

Introduction

This engineering practice book has been prepared for engineers, earth scientists,
and technicians who work in modern rotary drilling operations. The book derives
and illustrates engineering calculation techniques associated with air and gas drilling
technology. Since this book has been written for a variety of professionals and
potential applications, the authors have attempted to minimize the use of field
equations. Also the technical terminology used in the book should be easily
understood by all those who study this technology. In nearly all parts of the book,
equations are presented that can be used with any set of consistent units. Although
most of the example calculations use English units, a reader can easily convert to the
Systeme Internationale d’Units (SI units) using the tables in Appendix A.
Air and gas drilling technology is the utilization of compressed air or other
gases as a rotary drilling circulating fluid to carry the rock cuttings to the surface that
are generated at the bottom of the well by the advance of the drill bit. The
compressed air or other gas (e.g., nitrogen or natural gas) can be used by itself, or
can be injected into the well with incompressible fluids such as fresh water,
formation water, or formation oil. There are three distinct operational applications
for this technology: air or gas drilling operations (using only the compressed air or
other gas as the circulating fluid), aerated drilling operations (using compressed air
or other gas mixed with an incompressible fluid), and stable foam drilling operations
(using the compressed air or other gas with an incompressible fluid to create a
continuous foam circulating fluid).

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