Drilling Assembly Handbook 2001

DRILLING ASSEMBLY
HANDBOOK
© 1977, 1982, 1987, 1988, 1990, 1992, 1997,
1998, 2000 and 2001 Smith International, Inc.
All rights reserved.
P.O. Box 60068 · Houston, Texas 77205-0068
U.S. and Canada: 800-US SMITH · Tel: [phone]
Fax: [phone] · www.smith.com
Requests for permission to reproduce or translate all or any part of
the material published herein should be addressed to the Marketing
Services Manager, Smith International, P.O. Box 60068, Houston,
Texas 77205-0068.
The following are marks of Smith International, Inc.:
Drilco, Grant, Ezy-Change, RWP, Shock Sub, Hevi-Wate,
Ezy-Torq and Drilcolog.

TABLE OF CONTENTS
Bottom-Hole Assemblies .............................. 1
Differential Pressure Sticking ........................ 27
Bit Stabilization ........................................... 31
Drill Collar ................................................... 37
Hevi-WateTDrill Pipe ................................... 105
Tool Joints ................................................... 117
Kellys .......................................................... 135
Inspection .................................................... 143
Rotating Drilling Heads ................................ 159
Additional Information ................................. 173
Index ........................................................... 179
ii iii
PREFACE
This handbook has been altered you should
engineers to help rig personnel do a
better job.
It summarizes proven drilling techniques
and technical data that, hopefully, will
enable you to drill a usable hole at the
lowest possible cost. Carry it in your hip
pocket for easy reference.
If there are any questions about the
Drilling Handbook, just call your nearest
Smith representative or talk with our
service people when they visit your rig.
The Field Operations, Sales,
Business Development and
Engineering Departments.

HOW TO USE THIS HANDBOOK
The Drilling Assembly Handbook is broken down
into eleven (11) major sections, as described in
the table of contents.
A detailed index is provided starting on page 179.
The topics in the index will give the page numbers
of information relating to specific drilling problems
which you might face on the rig floor.
If you have any suggestions on how we can
make this handbook work better for you, please
send them to us or tell your Smith representative.
Refer suggestions to:
Reader Service Dept.
Smith International
P.O. Box 60068
Houston, Texas 77205-0068
iv
BOTTOM-HOLE
ASSEMBLIES
1
SECTION ONE

Bottom-Hole Assemblies
BOTTOM-HOLE ASSEMBLIES
Introductory Comments on Bottom-Hole Assemblies
The title of this publication is “Drilling Assembly
Handbook” and most of the pages are devoted to
the entire drilling assembly, from the swivel to the
bit. We have included useful information about
the rotary shouldered connections (pins and
boxes) that are used on every drill stem member.
In this section, however, we are primarily
interested in the bottom-hole assembly — the
tools between the bit and the drill pipe. Over the
years, the bottom-hole assembly has grown from
one or two simple drill collars to quite a complex
array of tools, stacking up above the bit about
500 to 1,000 ft (150 to 300 m).
Our job in this rig floor pocketbook is to sim-
plify the complexities of all these tools. We’ll
explain the purposes of each one and how to select
and assemble them for maximum effectiveness
and minimum trouble.
Today the bottom-hole assembly serves several
useful purposes, in addition to the simple need to
effectively load the bit with drill collar weight.
Correctly designed, they can:
· Prevent doglegs and key seats.
· Produce a smooth bore and full size hole.
· Improve bit performance.
· Minimize drilling problems.
· Minimize harmful vibrations.
· Minimize differential pressure sticking.
· Reduce production problems.
In the following pages we explain how these
desirable objectives can be attained.
1

Bottom-Hole Assemblies
Figure No. 2
In a straight hole drilling contract, many of the
possible troubles can be prevented by obtaining
satisfactory contract terms on deviation and dog-
legs. It is extremely important, when negotiating
the contract itself, that the operator be aware of the
advantages in giving the broadest possible limits
for deviation. By relaxing deviation clauses to rea-
sonable limits, it is possible to drill a so-called
straight hole at high rates of penetration and avoid
the costly operations of plugging back and straight-
ening the hole. In addition to the operator’s devia-
tion limits, it may be possible to work with him to
select a location so that the well may be allowed to
drift into the target area. If it is desired to reach a
certain point on the structure, and it is known that
the well will drift in a certain direction up-structure,
it is desirable to move the location down-dip so,
when drilling normally, the bottom of the well will
drift into the target area.
From the contractor’s standpoint, valuable time
can be spent in planning the drill stem and the bit
program along with the hydraulics.
Drift planning will include obtaining the largest
drill collars that may be safely run in a given hole
size and planning for optimum bit weights to get
the best rate of penetration. If it is anticipated that
there will be a problem maintaining the deviation
within the contract limits, there are more extreme
methods available which will assure a more nearly
vertical hole and still allow relatively high rates
of penetration.
3
Bottom-Hole Assemblies
STRAIGHT HOLE DRILLING
A better title would probably be “Controlled
Deviation Drilling” because it has been learned
through the years that a perfectly straight hole is
virtually impossible to drill. No one knows the
exact cause of holes going crooked but some logi-
cal theories have been presented. It has been con-
firmed that the drilling bit will try to climb uphill
or updip in laminar formations with dips up to
40° (see Figure No. 1).
Figure No. 1
Another factor to consider is the bending char-
acteristic of the drill stem. With no weight on the
bit, the only force acting on the bit is the result of
the weight of the portion of the string between the
bit and the tangency point. This force tends to
bring the hole toward vertical. When weight is
applied, there is another force on the bit which
tends to direct the hole away from vertical. The
resultant of these two forces may be in such a
direction as to increase angle, to decrease angle
or to maintain constant angle. This was stated by
Arthur Lubinski (research engineer for Amoco) at
the spring meeting of the Mid-Continent District,
Division of Production, in Tulsa, March 1953, and
was based upon the assumption that the drill stem
lies on the low side of an inclined hole (see Figure
No. 2).
In general, it is easier to drill a hole in soft forma-
tions than in hard formations. In particular, the effect
of the drill stem bending may be much less when
drilling soft formations, while the hard formations
require high bit weights.
2