Q921 de1 lec 7 v1

Drilling Engineering 1 Course (1st Ed.)

1. The Rotary System
A. Introduction
B. Kelly, Kelly Valves, and Kelly Saver Sub
C. Rotary Table and Components

2. Well Control System
3. Well Monitoring System

1. Drillstring Tubulars
A. Drill Pipes
a.

properties of drill pipes

B. Drill Pipe Elevator
C. Drill Collars & Heavy Wall Drill Pipes
D. Special Tools

Drillstring purpose & constitutes
The purpose of the drillstring is
to transmit mechanical power (torque and rotation),
hydraulic power (pressure and flow rate), and
weight to the bit.

The drillstring is composed mainly
of the following elements:
Drill pipes,
Heavy wall drill pipes,
Drill collars,
Several special elements and tools.

Fall 13 H. AlamiNia


5

schematic of a typical rotary drillstring

Fall 13 H. AlamiNia


6

Drill Pipe
Below the kelly assembly
(upper kelly valve + kelly +lower kelly valve + kelly saver
sub) is a length of drill pipes (DP).
Drill Pipe is a primary and important drillstring member.
Since the drill pipes are generally compose
the upper and longest portion of the drillstring,
they must be light and strong.

The drill pipe body is a seamless pipe
with outside diameter (OD) varying from 2 3/8in to 6 5/8in.

The outside diameter and the wall thickness t
determine the linear weight of the drill pipe.
The inside diameter (ID) is equal to OD minus 2t.
Fall 13 H. AlamiNia


8

Drill pipe material
Drill pipes are made of
high grade steel

(there are also drill pipes made of
aluminum, carbon fiber, etc).

API has standardized four steel grades:
E–75, X–95, G–105, and S–135.
The figures represent
the minimum yield strength Ys
(in ksi) of the the steel.

Fall 13 H. AlamiNia


9

Drill pipe specification and
following basic parameters
Drill pipes are specified with the following basic parameters:
1. Length range:
 Range I: 18ft to 22ft,
 Range II: 27ft to 30ft (most common),
 Range III: 38ft to 45 ft,

2. Nominal linear weight:
 in general 2 or 3 linear weight or wall thickness for each standard
OD

3. Wall upset:
 EU (external upset), IU (internal upset),
and IEU (internal & external upset).
 The wall upset is a length of extra thickness at both ends of the drill
pipe body to provide a smooth transition between the pipe body
and the tool joint, in order to reduce the stress concentration,
Fall 13 H. AlamiNia


10

Drill pipe specification and
following basic parameters (Cont.)
4. Tool joint OD, ID, and tong length,
5. Steel grade:
(D-55), E-75, X-95, G-105, S-135,

6. Connection size and type:
from 2 3/8in to 5 1/2in, type
IF (internal flush),
EF (external flush),
FH (full hole),
XH (extra hole),
SH (slim hole),
DS (double streamline), and NC (numbered connection),

The API RP-7G contains the specification of all API
standard drill pipes approved for oil and gas drilling use.
Fall 13 H. AlamiNia


11

The tool joints
The tool joints
are heavy coupling elements having coarse,
tapered threads and sealing shoulders designed
to sustain the weight and
to transmit torque along the drillstring.

The threads of the tool joints are specially designed
to offer strength (axial and torsional), easy handling,
fast connections (number of turns to make the
connection), and leak-proof sealing (metal to metal).

Tool joints might be
welded or screwed to the ends of the drill pipe body.
Fall 13 H. AlamiNia


12

Typical tool joint designs
(A)
Internal upset DP
with full–hole
shrink–grip TJ,
(B)
External upset DP
with internal–
flush shrink–grip
TJ,
(C) External upset
DP with flash–
weld unitized TJ,
(D) External–
internal upset DP
with Hydrill™–
pressure welded
TJ.
Fall 13 H. AlamiNia


13

common properties of drill pipes
Two other common properties of drill pipes are
capacity and displacement.
Pipe Capacity:
The capacity Ap of a drill pipe is a measure of
its internal area, expressed as volume/length,
usually gal/ft or bbl/ft.
Sometimes the capacity is expressed as the reversal of the area,
usually in ft/bbl. The reader should be attended to the units.

If Di is the inside diameter (ID) of a drill pipe in inches,
then

Fall 13 H. AlamiNia


15

common properties of drill pipes
(Cont.)
Pipe Displacement:
The displacement As of the drill pipe is the measure of its
cross-section area, expressed as volume/length, normally
bbl/ft.
If Do is the outside diameter (OD) of a drill pipe in inches,

Annulus Capacity:
The annulus capacity Aa is not a property of the pipe because
it depends on the diameter of the hole opposite to the pipe.

DW is the diameter of the well, & the annulus capacity Aa in bbl/ft
Fall 13 H. AlamiNia


16

Drill pipe nominal weight
The capacity and displacement formulas above
do not take into account the tool joints,
and manufacturer tables must be consulted
when more accurate values are required.

In particular, the nominal weight that specify a
given drill pipe represents
neither the pipe body linear weight,
nor the average linear weight
(body plus tool joint divided by its length).
It is just a nominal value.

Fall 13 H. AlamiNia


17

adjusted linear weight of the drill
pipe
a typical 5in DP with 19.5 lb/ft has an internal
diameter of 4.276in.
The density of steel is 489.5 lb/ft3.

Therefore, one foot of pipe body weights
Considering a 30 ft long DP (Range II), the tool
joints (pin and box) comprise about 2 1/2 ft of its
length.
Outside and inside diameters of the tool joints are 6in
and 3 1/2 in respectively.
Fall 13 H. AlamiNia


18

adjusted linear weight of the drill
pipe (Cont.)
Therefore, the linear weight of the tool joint is

The weight of the drill pipe (body plus TJ) is
Consequently,
the adjusted linear weight of the drill pipe is

Fall 13 H. AlamiNia


19

DP Classification according to wearing
Drill pipes are subjected to wear during operation.
In particular,
reduction of tool joints OD and wall thickness
reduce tensile and torsion capacity of the element.

Used drill pipes are classified as
Premium or Class I
if the minimum wall thickness is at least 80%
of the wall thickness of a new pipe, and
A new pipe that for the first time is connected to a drillstring is
immediately re–classified to premium DP.

Class II when at least 70%.

Fall 13 H. AlamiNia


20

New Drill Pipe Dimensional Data
The table
presents
dimensional
data for new
drill pipes.

Fall 13 H. AlamiNia


21

drill pipe elevator
Drill pipes are handled during tripping using a drill
pipe elevator.
(The swivel and kelly are set aside in the rat hole.)
It is connected by two links to the hook body.

A hinge and latch allows opening and closing the
bi–parted collar around the drill pipe.
The elevator is operated
by the roughnecks at the rotary table level, and
by the derrick man at the monkey board.

Fall 13 H. AlamiNia


24

A DP elevator and the links to the
hook body

Fall 13 H. AlamiNia


25

Drill pipes
Drill pipes extend
across almost the whole length of the drillstring and,
although relatively light, they contribute with a significant
part of the drillstring weight (50% or more).

However, drill pipes are, in general,
used only under tension.
They should not be subjected to compression
due to its low resistance to buckling.
Therefore, they cannot be used to apply weight on the bit.
• In horizontal wells, drill pipes can be put under compression
if located in a suitably curved section of the hole; in addition,
compression service drill pipes
(CSDP, S-135 grade DP with 2 or 3 wear knots) are specially designed
to work under compression to drill short radius horizontal wells.
Fall 13 H. AlamiNia


26

Drill collars role and specifications
Since drill pipes
cannot be used to apply weight on bit,
this role is played be the drill collars
(and also by heavy weight drill pipes as shown next).

Drill collars (DC)
are thick walled steel pipes
located normally right above the bit, and
purpose is to provide weight (axial force) to the bit.
are manufactured with carbon steel (AISI 4115), or
some non-magnetic alloy (stainless steel, monel metal).

Fall 13 H. AlamiNia


28

A spiraled and a slick drill collars
The outside of drill collars may
be slick (small diameters) or
spiral grooved (any size.).
The purpose of the groves is to
reduce or avoid the risk of
differential sticking opposite to
permeable formations.
The depth of the grooves is made
larger than the average thickness
of a flocculated mud.
Average length of drill collars is
34 ft, but re–threading normally
makes them shorter.
Fall 13 H. AlamiNia


29

Drill collars elevators
The elevators for drill collars are very similar to the
elevators for drill pipes.
They differ in the shape of the internal hole that clamps
on the pipe.
Most drill collars are recessed so as to be handled with
the elevator.
If the drill collar is not recessed (sometimes even if it is!),
a special sub called lift sub is used.
Lift subs have the shape of the upper end of a drill pipe, and
connects to the top of sections of drill collars during trips.
• Then the drill pipe elevator can be used to lift or lower the
drillstring.

Fall 13 H. AlamiNia


30

heavy wall drill pipes (HWDP)
In addition to drill pipes and drill collars, there are
special pipes called heavy wall drill pipes (HWDP).
They are intermediary pipes between drill pipes and drill
collars,
being strong enough to be put under compression
(they contribute to the available weight
to apply to the bit), and
they are flexible enough to be used in directional drilling (less
torque and drag than drill collars.)

The use of HWDP also
allow a gradual transition
between the flexible drill pipes and the stiff drill collars
(less stress concentration, and
therefore, less mechanical fatigue on the threads.)
Fall 13 H. AlamiNia


31

Heavy wall drill pipes
HWDPs look very similar to regular drill pipes,
being of the same length of Range II DP (27 to 30 ft),
but with longer tool joints (to permit re–threading).

HWDPs have a central external upset.
it provides an additional third point of contact,
increasing the overall stiffness and protecting the pipe
sections from excessive wearing in high inclination wells
(normally the tool joints and central upset have a band
of hard material to prevent/reduce wear).

Fall 13 H. AlamiNia


32

Drillstring equipment
Several drilling equipment are used in the
drillstring.
The most important are:
stabilizers,
provide localized additional support points
(localized larger diameter)
in one or more positions along the drillstring.

reamers,
hole–openers.

Fall 13 H. AlamiNia


34

Advantages of drillstring
For vertical wells, the stabilizer prevents low
frequency vibration in the drillstring during
rotation.
The advantages are:
reduce wear (of both drillstring and casing),
reduce mechanical fatigue,
reduce mechanical instability of formation (caving),
reduce tortuous hole.

Stabilizers are essential equipment for directional
drilling.
Fall 13 H. AlamiNia


35

Stabilizer special characteristics and
types
angle drop–off,
Suitable choice of
angle hold.
number and position of
stabilizers in the
Stabilizer may be of the
drillstring lend to the
following types:
bottom hole assembly
integral blade,
(BHA, the lower part of
the drillstring composed
of drill collars, stabilizers
and HWDP)

special characteristics in
terms of inclination
control:

interchangeable blade,
non–rotating blades,
replaceable blades,
clamp–on
near-bit,

angle build–up,
Fall 13 H. AlamiNia


36

The diameter of stabilizers
The diameter of stabilizers can be in gauge or under
gauge.
More recently, remote adjustable blade stabilizers
were introduced.
Changing suitably the diameter of the stabilizers provide
a level of control in the directional behavior of BHAs.

Fall 13 H. AlamiNia


37

Some Stabilizers
(a)
integral,

(b)
interchangea
ble,

(c)
non–
rotating,

(d)
replaceable
Fall 13 H. AlamiNia


38

Reamers
The purpose of the reamer is to keep
the diameter of the open hole in
gauge, that is, with the expected
original diameter of the bit.
Two reasons may cause
a decrease in the original diameter:
 formation swelling (hydrated shales,
moving salt),
 bit diameter reduction (hard and
abrasive formations).

The reamer also functions as a
stabilizer since the rollers touch the
borehole wall.
Different types of rollers can be
selected to suit the formations being
reamed.
A roller reamer
Fall 13 H. AlamiNia


39

The hole–opener
 The hole–opener is a tool designed to
enlarge the diameter of a previously (or
simultaneously drilled smaller borehole.
Three situations (at least) are possible:

 to drill the borehole section with a smaller bit,
and later to enlarge to the final diameter (a
special tool called bull nose is connected in the
place of the bit, to guide the hole opener along
the pre-drilled hole),
 to drill the borehole section with a smaller bit
and simultaneously enlarge to the final
diameter,
 to enlarge a section below a casing with a
diameter larger than the internal diameter of
the casing.
 In this case, a special hole opener (also caller
underreamer) with hinged arms actuated
hydraulically is used (the drilling fluid pressure
actuates in rams that open the arms forcing the
cutters against the borehole wall).

A fixed hole–opener
Fall 13 H. AlamiNia


40

1. Jorge H.B. Sampaio Jr. “Drilling Engineering
Fundamentals.” Master of Petroleum
Engineering. Curtin University of Technology,
2007. Chapter 3

Q921 de1 lec 7 v1

More Related Content

What's hot (19)

Viewers also liked (20)

Similar to Q921 de1 lec 7 v1 (20)

More from AFATous (20)

Recently uploaded (20)

Q921 de1 lec 7 v1