Note: Descriptions are shown in the official language in which they were submitted.
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Drill packer member, drill pipe, and corresponding drill pipe string
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the field of prospecting and operating oil or gas
wells in
which rotary drill strings constituted by drill pipes and possibly other
tubular
components coupled end-to-end are used depending on the drilling requirements.
More particularly, the invention concerns a profiled part, such as a drill
pipe, for rotary
drilling equipment disposed in a drill pipe section or a heavy weight drill
pipe or a drill
collar or a drill stabilizer or a cross-over sub with a different diameter or
thread type.
Such drill pipe sections associated with other components of the drill string
(drill
collars, stabilizers, etc) mean that in particular, deflected wells can be
drilled, i.e.
wells wherein the inclination with respect to the vertical or the horizontal
can be
varied during drilling. Deflected wells can currently reach depths of the
order of 2 to 8
km and horizontal distances of the order of 2 to 15 km.
In the case of deflected wells comprising practically horizontal sections, the
frictional
torques due to rotation of the drill strings in the wells can reach very high
values
during drilling. The frictional torques may mean that the equipment used or
the
drilling objectives have to be reviewed. Further, it is very often difficult
to lift the
debris produced by drilling because of sedimentation of the debris produced in
the
drilled hole, in particular in the portion of the hole which is highly
inclined with respect
to the vertical. This results in poor cleaning of the hole and an increase in
both the
coefficient of friction of the drill pipes of the drill pipe section within
the drilled hole
and the contact surfaces between the drill pipes and the walls of the hole.
2. Description of the Related Art
FR-2 760 783 proposes a profile for a drill pipe with a collar which comes
into contact
with the wall of the drilled hole and which can remain stationary in rotation
with
respect to the wall, and grooved sections which can activate circulation of
the drilling
fluid.
More recently, FR-2 824 104 concerns a profiled element for rotary drilling
equipment
comprising a zone which bears on the wall of the drilled hole, a turbulence
zone to
produce activation of the circulation of a drilling fluid in the drilled hole
around the
drilling equipment, and a deflection zone adjacent to the bearing zone and to
the
turbulence zone extending in an axial direction of the profiled element and
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comprising at least one surface which is inclined with respect to the drilling
axis,
wherein the meridian line in an axial plane moves away from the axis of the
profiled
element in the direction moving from bottom to top in the service position of
the
profiled element in the drilled hole.
That type of device has proved satisfactory until recently. However, there is
now a
need to provide drill strings which are particularly robust, multifunctional
and
designed for drilling at considerable depths and at considerable departures.
The invention aims to improve the situation.
BRIEF SUMMARY OF THE INVENTION
The drill string element for drilling a hole with circulation of a drilling
fluid around said
element and in a direction moving from the bottom of a drilled hole towards
the
surface comprises at least one zone for bearing on the wall of the hole during
drilling,
the bearing zone being provided on its external surface with at least one
bearing
section with an external diameter which is greater than the diameter of the
other
portions of the element, and two activation zones substantially adjacent to
the
bearing zone and disposed upstream and downstream of the bearing zone, said
activation zones comprising a plurality of grooves which are generally helical
in
shape about the axis of said element. The activation zones are integral with
the
bearing zone. The bearing zone comprises two guide sections in the form of a
convex rounded body of revolution, disposed upstream and downstream of the
bearing section and adjacent to the bearing section. The guide sections are
tangential to the bearing section and to the activation zones.
A drill string element for drilling a hole with circulation of a drilling
fluid around said
element and in a direction moving from the bottom of a drilled hole towards
the
surface, forms a connection between a drill string or a heavy weight drill
pipe section
and a bottom hole assembly. The element comprises a first end comprising an
external surface with a first diameter and a female thread, a second end
comprising
an external surface having a second diameter and a male thread, the first
diameter
being less than or equal to the second diameter, at least one zone bearing on
the
wall of the hole during drilling, the bearing zone being provided with at
least one
bearing section with a cylindrical external surface and with an external
diameter
which is greater than the diameter of the other portions of the element, and
two
activation zones substantially adjacent to the bearing zone and disposed
upstream
and downstream of the bearing zone. Said activation zones comprise a plurality
of
grooves which are generally helical in shape about the axis of said element.
The
bearing zone comprises two guide sections in the form of a convex rounded body
of
revolution, disposed upstream and downstream of the bearing section and
adjacent
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to the bearing section. Said guide sections are tangential to the bearing
section and
to the activation zones.
The term "drill string element" means not only components of the drill string
(drill
pipes, etc), but also the constituent portions of said components such as tool
joints,
for example, which may be attached to the ends of the drill pipes using any
means
such as by welding, for example, and which allow the drill pipes to be
connected
together by makeup.
The terms "upstream" and "downstream" as used herein refer to the direction of
circulation of drilling fluid in the annular space around the element.
Except if otherwise stated, the term "drill pipe section" means the portion of
the drill
string including both standard and heavy weight drill pipes.
The Applicant has established that the static and dynamic loads in rotation
are
reduced, the axial weight on going in and pulling out the string from the well
are
decreased, the capacity to transmit weight to a tool is increased, the debris
pull-out
capacity is increased, the safety margin for over-tension and over-torque is
better,
the critical buckling conditions are reduced, the fatigue strength under
alternating
flexion is increased, wear and abrasion of the drill string are reduced, the
working
capacity in debris when pulling out is better, meaning that the risk of
blocking is
reduced, the mechanical integrity of the threaded connections is maintained
well, the
hydraulic pressure drops are reduced, mud and debris flow better around the
drill
pipe, wear by abrasion of the internal wall of the drilled well is reduced,
there is a
large reduction in the risks of sticking due to differential pressure,
especially when
the hydrostatic pressure of the mud is greater than the pressure prevailing in
the
material, for example rock, during drilling, the risks of the drill pipe
section jamming
during a pull-out procedure are greatly reduced, and the surface qualities of
the walls
of the drilled hole are improved.
A drill pipe may comprise at least one element as described above and a tube
welded end-to-end onto an end of said element which is free of a thread. The
tube
may be welded to the element by friction. Said element may be machined from a
short, large diameter piece while the tube may have a smaller diameter,
resulting in a
very substantial reduction in the mass of metal to be machined and of the
quantity of
machining scrap. Said short piece may be of the order of 0.3 to 1 meter long.
The drill pipe section preferably comprises a large proportion of drill pipes
as
described above, for example at least 80%, preferably more than 95%. A drill
pipe
section composed of drill pipes as described above can benefit from the
effects
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mentioned above. The drill pipe section may comprise at least two adjacent
drill
pipes.
A drill string stabilizer for drilling a hole with circulation of a drilling
fluid around said
element and in a direction going from the bottom of the drilled hole to the
surface
may comprise at least one zone for bearing on the wall of the hole during
drilling, the
bearing zone being provided with at least one bearing section with an external
diameter which is greater than the diameter of the other portions of the
stabilizer, and
two activation zones which are substantially adjacent to the bearing zone and
disposed upstream and downstream of the bearing zone, said activation zones
comprising a plurality of grooves which are generally helical in shape about
the axis
of said stabilizer. The activation zones are integral with the bearing zone.
The
bearing zone comprises at least two guide sections with a convex rounded shape
disposed upstream and downstream of the bearing section and adjacent to the
bearing section. The guide sections are tangential to the bearing section and
to the
activation zones. Circulation grooves which are generally helical in shape are
provided about the axis of said stabilizer on the external surface of the
bearing zone.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be better understood from the following detailed
description of some embodiments which are given by way of non-limiting
examples
and are illustrated in the accompanying drawings, in which:
FIG. 1 is a side view of a drill pipe (component of a drill string) comprising
a threaded
connector element at each of its two ends;
FIG. 2 is an axial sectional view of the drill pipe of FIG. 1;
FIG. 3 is a sectional view along 3-3 of FIG. 1;
FIG. 4 is a sectional view along 4-4 of FIG. 1;
FIG. 5 is a sectional view along 5-5 of FIG. 1;
FIG. 6 is a sectional view along 6-6 of FIG. 1;
FIG. 7 is a partial detailed view of FIG. 1;
FIG. 8 is a partial detailed view of FIG. 1;
FIG. 9 is a partial side view of two elements on the coupled ends of two drill
pipes;
FIG. 10 is a partial side view of two elements on the coupled ends of two
drill pipes;
FIG. 11 is a side view of a drill collar with four bearing sections;
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FIG. 12 is a side view of a heavy weight drill pipe with four bearing
sections;
FIG. 13 is a side view of a drilling stabilizer with bearing sections;
FIG. 14 is a side view of a connection piece usually termed a cross-over sub;
and
FIG. 15 shows the connected drill pipes of FIGS. 7 and 8.
5
DETAILED DESCRIPTION OF THE INVENTION
As can be seen in FIGS. 1 to 12, the profiled drill pipe 1 is generally formed
as a
body of revolution about an axis 2 which substantially constitutes the
drilling axis,
when the profiled drill pipe 1 of a drill pipe section is in the service
position inside a
drilled hole produced by a tool such as a drill bit disposed at the end of the
drill string.
The axis 2 is the axis of rotation of the drill pipe section. The profiled
drill pipe 1 has a
tubular shape; a channel 3 formed as a substantially cylindrical body of
revolution is
provided in the central portion of the profiled drill pipe 1.
The components of the drill string (in particular the drill pipes of the drill
pipe section
illustrated in FIGS. 1 to 12) are produced in a tubular shape and are
connected
together end-to-end, such that their central channels 3 are positioned in
mutual
extension and constitute a continuous central space for circulation of a
drilling fluid
from top to bottom, as indicated by the arrow 4 of FIG. 2 between the surface
from
which drilling is carried out to the bottom of the drilled hole where the
drilling tool
operates. The drilling fluid or mud then rises in the annular space defined
between
the wall of the drilled hole and the external surface of the drill pipe
section, see
arrow 5. A drill string may comprise drill pipes, heavy weight drill pipes,
drill collars,
stabilizers or connections. The drill pipes are connected end-to-end by makeup
into a
drill pipe section which constitutes a substantial or even preponderant part
of the
length of the drill string.
As it rises outside the drill pipe section, the drilling fluid entrains debris
from the
geological formations traversed by the drilling tool to the surface from which
drilling is
carried out. The drill pipe section is designed to facilitate upward
circulation of drilling
fluid in the annular space between the drill pipe and the well wall. It is
desirable to
entrain the drilling debris effectively and to sweep the wall of the drilled
hole and the
bearing surfaces of the to facilitate the advance of the drill pipe section
inside the
hole.
The characteristics of a drill pipe section and more generally a component of
the drill
string contribute to the fundamental properties of quality, performance and
safety of
the general drilling process whether this is during the drilling phases proper
or during
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phases when tripping is carried out between the bottom and the surface.
Changes in
prospecting for hydrocarbons demands the creation of trajectories which are
more
and more complex and are subjected to ever more extreme geological conditions.
Currently, hydrocarbons are being prospected at depths which are routinely
over 4
km and at horizontal distances with respect to the fixed installation which
may
exceed ten kilometers.
The Applicant has determined that the mechanical and hydraulic characteristics
at
the contact points between the component of the drill string and the walls of
the
drilled hole are very important. In fact, the string rubs in rotation and in
translation
against the wall of the drilled hole. The friction causes slow but
nevertheless
significant wear of the components of the string and relatively rapid wear of
the walls
of the drilled hole, resulting in an increase in the diameter of the drilled
hole and an
increase in the volume of debris which may prove to be considerable for very
long
holes. Further, blocking due to an increase in the mass of debris between the
drilled
hole and the string has to be avoided.
The Applicant has developed a novel universal profile which can very
substantially
reduce the axial coefficients of friction from the bottom to the surface and
from the
surface to the bottom, and of rotation while allowing dynamic cleaning of the
entire
hole during drilling and destruction of accumulations of debris which may be
produced during drill pipe section pull-out trips. The profile can drastically
reduce
wear by abrasion of the string and in particular the drill pipe section and
reduce wear
of the walls of the drilled hole by abrasion. The profile can also prevent
contact
between the zones of maximum stress in the made up connections. The profile
means that the service life of equipment can be increased, and its mechanical
strength during drilling and tripping stages is maintained.
The profiled drill pipe 1 may be produced from high strength steel in a
monoblock
form, or it may be produced in sections and then welded together. More
particularly,
the profiled drill pipe 1 may comprise two profiled end sections 6 and7 which
are
relatively short forming tool joints for connecting drill pipes and a central
tubular
section 8 with a length which may exceed ten meters when welded together. The
central section 8 may have an external diameter which is smaller than the end
sections. Fabrication of the long central section 8 from the short end
sections 6, 7 can significantly reduce the amount of waste, in particular
machining
chips or turnings. In this manner, a considerably higher material yield is
obtained.
The central section 8 may be in the form of a tube with a substantially
constant bore
and with a substantially constant external diameter (nominal diameter of the
drill pipe
section), possibly with an excess thickness at the ends near the sections 6
and 7 to
facilitate connection of said sections 6 and 7 by welding.
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In general, the description below is given from the free end of the section 6
to the
free end of the section 7. The section 6(female tool joint) comprises a female
connection portion 9 with an external annular cylindrical surface comprising a
bore
provided with a female thread 9 a for connection to a male thread of another
drill
pipe 1. The female thread 9 a may be tapered, for example in accordance with
API
specification 7, or in accordance with one of the Applicant's patents, for
example U.S.
Pat. Nos. 7,210,710, 6,513,840. The connection portion 9 constitutes the free
end of
the end section 6 of the drill pipe 1.
The end section 6 then comprises, on an external surface, an activation zone
10 a
sectional view of which is shown in FIG. 3. The activation zone 10 comprises
an
external surface which is tangential to the external cylindrical surface of
the
connection portion 9, but may have a very slight annular recess with respect
to the
external diameter of the connection portion 9, then an increasing external
diameter.
The activation zone 10 comprises a plurality of grooves 11 formed as a helix
and
having a general shape (including an inclination) which encourages mud to rise
in the
direction of rotation of the drill pipe section, said direction of rotation
being shown
in FIGS. 1 and 3 to 6 by the arrow 91. The grooves 11 extend axially from the
external cylindrical surface of the connection portion 9 to near the end of
the
activation zone 10. The angle of inclination of the helix of the grooves 11
with respect
to the axis 2 may be in the range 7 to 45 degrees.
The bottom of the grooves 11 comprises a portion 11 a with a decreasing
diameter
with respect to the connection portion 9, an annular bottom 11 b of short
length and
an inclined portion 11 c on the side opposite to the connection portion 9 then
rejoins
the external diameter of the activation zone 11. The annular recess in the
external
surface of the activation zone 10 is located substantially at the inclined
portion 11 a of the groove 11. As can be seen in FIG. 3, the grooves 11 have a
unsymmetrical profile in the form of a scoop with an obtuse angle with respect
to the
external cylindrical surface of the activation zone 10 on one side and an
acute angle
on the opposite side. The acute angle may be provided on the back side or
trailing
side of the grooves in the direction of rotation of the drill pipe section
(arrow 91). It
will be recalled that a drill pipe section is always driven in rotation in the
same
direction in order to prevent the threaded joints from unscrewing. The obtuse
angle
provided on the front side or leading side of the grooves is designed to
facilitate entry
of fluid into the grooves 11. The grooves 11 provide a debris scooping
function due to
their unsymmetrical profile.
More particularly, the activation zone 10 may be provided with grooves 11 in a
number in the range seven to ten, for example nine. The axial length of the
portion 11a may be in the range 10 to 70 mm, preferably in the range 35 to 45
mm,
for example 39 mm. The axial length of the central portion 11 b may be in the
range 5
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to 40 mm, preferably in the range 10 to 15 mm, for example 11 mm. The angle al
of
the first portion 1 1 a with respect to the axis may be in the range 100 to 30
,
preferably in the range 15 to 25 , for example 20 . The angle 131 of the
portion 11c may be in the range 30 to 60 , preferably in the range 40 to 50
, for
example 45 . The fillet radii between said portions may be in the range 3 to
10 mm.
The depth of the grooves 11 may be in the range 5 to 20 mm, preferably in the
range
to 15 mm. The acute angle on the trailing edge of the groove 11, complementary
to Vi, may be in the range 50 to 80 , preferably in the range 60 to 70 , for
example
65 . The distance dl between two grooves 11 on the exterior of the activation
10 portion 10 may be in the range 20 to 40 mm, for example in the range 25
to 30 mm.
The activation zone 10 provides a mud and debris recirculation effect during
drilling
(rotational drop-in of drill pipe section) and scrapes or back reams the walls
of the
hole when the drill pipe section is pulled out.
Next, the drill pipe 1 comprises a bearing zone 12 on its external surface,
moving
away from the connection portion 9. The bearing zone 12 comprises a guide
portion 13, a central bearing portion 14 and a guide portion 15. In the
direction of
flow 5of drilling mud outside the drill pipe 1, the guide section 13 is
downstream and
the guide section 15 is upstream. The bearing zone 12 may have an axial length
of
the order of 50 to 110 mm, preferably of the order of 70 to 80 mm. The central
bearing portion 14 is in the shape of a cylindrical body of revolution with an
external
diameter which is greater than the external diameter of the other portions of
the drill
pipe 1.
The external shape of the guide sections 13 and 15 is as a rounded body of
revolution, for example toroidal, ogival or ellipsoidal. The guide
portions 13 and 15 are externally tangential to the central bearing portion
12. The
guide portion 13 is externally tangential to the external surface of the
activation
zone 10. The guide portion 15 is externally tangential to the activation
zone 16 described below. The length of the bearing section 14 may be of the
order of
half the length of the bearing zone 12. The guide portions 13 and 15 may each
have
a length of the order of a quarter of the length of the bearing zone 12. In
the case of a
toroidal shape, the guide portions 13 and 15 may have a radius of curvature of
the
order of 50 to 100 mm, preferably in the range 70 to 80 mm. The bearing zone
12, in
particular the bearing section 14, may be produced in the form of a coating or
facing
formed from a material which is harder than the remainder of the drill pipe 1.
The
hard material may be composed of chromium or tungsten carbide. The hard
material
may have a thickness in the range 1 to 10 mm, for example 2 to 4 mm. Said hard
material is in the form of a hard coating which may be supplied by a welding
or
thermal projection operation (for example in a flame or a plasma). The bearing
zone 12 is provided to withstand axial and rotational friction against the
wall of the
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drilled hole. The bearing zone 12, in particular the profile of the guide
portions, allows
the fluid to generate a fluid bearing effect.
The activation zone 16 disposed upstream of the bearing zone 12 in the
direction of
flow of the drilling mud outside the drill pipe 1 has an external diameter
which
generally increases in the direction of flow of the drilling mud in the
direction of arrow
5. The external shape may, for example, be as a convex ovoid. The activation
zone 16 connects tangentially to one side of the guide portion 15 of the
bearing
zone 12 and may connect on the other side to a tapered surface to vertically
support
the drill pipe 1 before connecting it to another drill pipe 1 (elevator
taper). The
activation zone 16 comprises a plurality of grooves 17 with a shape generally
similar
to that of the grooves 11 and with different dimensions. The grooves 17 may be
in
the range four to eight in number, for example six. The activation zone 16
ensures
that mud and debris are scooped up to recirculate mud during drilling
(dropping drill
string). To increase the axial speed of the mud between the upstream
activation
zone 16 and the downstream activation zone 10 and thus the mud recirculation
effect, the inclination to the axis of the helix of grooves 11 located
downstream of the
grooves 17 may be smaller than that of the grooves 17.
A groove 17 comprises a downstream portion 17a close to the guide portion 15,
a
central portion 17b with a cylindrical bottom and an upstream portion 17c with
a
diameter that decreases in the direction of the arrow 5. The downstream
portion
17a may have an angle 132 with respect to the axis 2 which is in the range 30
to 60 ,
preferably in the range 40 to 50 , for example 45 . The upstream portion 17c
may
have an angle a2 with respect to the axis 2 which is in the range 10 to 30 ,
preferably in the range 15 to 25 , for example 20 . The axial length of the
central
portion 17b may be in the range 20 to 60 mm, more preferably in the range 30
to 40
mm, for example 36 mm. The axial length of the upstream portion 17 c may be in
the
range 10 to 50 mm, preferably in the range 20 to 30 mm, for example 24 mm. The
central portion 17b may have a diameter which is lower than the diameter of
the
central portion 11 b of the grooves 11 of the activation zone 10. The grooves
17 may
have a depth which is greater than the depth of the grooves 11, preferably
more than
two times greater. The depth of the grooves 17 may be in the range 20 to 30
mm,
preferably in the range 25 to 28 mm. Preferably, the thickness of the material
between the cylindrical bottom 17b of the grooves and the bore 3 is greater
than that
of the connection zone 18 described below. As an example, the groove bottom
diameter may be greater than or equal to the external diameter of the
connection
zone 18.
The grooves 17 illustrated in section in FIG. 4 have an leading edge in the
direction
of rotation of the drill pipe section with an obtuse angle with respect to the
external
surface of revolution of the activation zone 16 and an acute angle on the
trailing side,
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which is complementary to y2, for example in the range 500 to 80 , preferably
in the
range 60 to 70 , for example 65 . The distance d2 between two grooves 17 may
be
in the range 10 to 50 mm, preferably in the range 20 to 40 mm, for example 30
mm in
the zone where said distance is a minimum.
5 Beyond the activation zone 16, the end section 6 may comprise a tapered
elevator
zone 92 (intended to support the drill pipe when it is lifted and maintained
by the
elevator of the drilling rig before it is connected to another drill pipe)
which is
tangential to the external surface of the activation zone 16, then a
connection
zone 18 with a cylindrical external surface up to its end which is welded to
the central
10 section 8.
The shape of the upstream end section 7 (male tool joint) is, very generally,
symmetrical to that of the end section 6. The end section 7 comprises on its
external
surface in the direction of the arrow 4a connection zone 19, an activation
zone 20provided with grooves 21, a bearing zone 22 comprising a downstream
guide
portion 23, a central bearing portion 24 and an upstream guide portion 25, an
activation zone 26 provided with grooves 27 and a male connection zone 28.
More precisely, the connection zone 19 is shaped as an external cylindrical
body of
revolution fixed on one side by welding to the central section 8 and on the
opposite
side tangentially to the activation zone 20. The activation zone 20 is
provided with
grooves 21 which are four to eight in number, for example six. The grooves 21
may
have geometrical characteristics viewed in section illustrated in FIG. 5 which
are
close to the geometrical characteristics of the grooves 17, but are, however,
slightly
shallower in depth. The activation zone 20 provides a recirculation effect for
mud and
debris during drilling (drop-in of the drill pipe section) and scrapes or back
reams the
hole on lifting the drill pipe section.
Viewed in axial section, see FIGS. 2 and 8, the grooves 21 comprise two
principal
portions instead of three for grooves 11 and 17. The grooves 21 comprise a
downstream portion 21 a located in the extension of the external surface of
the
connection zone 19 in order to maintain a thickness of the wall of the drill
pipe at the
portions 21 a of the grooves 21 which is at least equal to that of the wall of
the
connection zone 19. In other words, in the downstream zone 21 a, the bottom of
the
grooves 21 is substantially flat. Beyond the downstream portion 21 a, the
grooves 21 comprise an upstream portion 21b which is inclined in order to join
the
external diameter of the activation zone 20. The upstream portion 21 b may
have an
angle of inclination 03 with respect to the axis 2 which is in the range 30
to 60 ,
preferably in the range 40 to 50 , for example 45 . The external surface of
the
activation zone 20 has a generally domed shape, for example ogival, between
the
connection zone 19 and the bearing zone 22. The axial length of the downstream
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portion 21a may be in the range 50 to 100 mm, preferably in the range 60 to 80
mm,
more preferably again less than the mean diameter of the guide sections. The
distance d3 between the grooves 21 may be equal to the distance d2.
The bearing zone 22 may have geometrical, physical and/or chemical
characteristics
which are similar to those of the bearing zone 12. The downstream guide
section 23 is tangential to the external surface of the activation zone 20 and
to the
external surface of the bearing portion 22. The upstream guide section 25 is
tangential to the external surface of the activation zone 26 and to the
external surface
of the bearing portion 22.
The activation zone 26 comprises a plurality of grooves 27, for example five
to ten in
number, for example seven. The external surface of the activation zone 26
comprises
a portion with an increasing diameter in the direction of the arrow 5 then a
portion
with a decreasing diameter connecting to the external diameter of the
connection
portion 28. The bottom of the grooves 27 comprises a downstream portion 27a
with
an increasing diameter in the direction of the arrow 5, a central cylindrical
bottom
portion 27 b and an upstream portion 27c with a decreasing diameter in the
direction
of the arrow 5. The downstream portion 27a may have an angle 134 with respect
to the
axis 2 in the range 30 to 60 , preferably in the range 40 to 50 , for
example 45 .
The upstream portion 27c may have an angle a4 with respect to the axis 2 in
the
range 10 to 300, preferably in the range 150 to 25 , for example 20 . The
diameter of
the central portion 27b may be in the range from the diameter of the central
portion 11 b of the grooves 11 to the diameter of the central portion 17b of
the
grooves 17. The axial length of the central portion 27b may be in the range 10
to 50
mm, preferably in the range 20 to 30 mm. The axial length of the upstream
portion 27c may be in the range 20 to 80 mm, preferably in the range 40 to 60
mm,
for example 53 mm. The activation zone 26 scoops up and recirculates mud and
debris during drilling (drop-in of drill pipe section). To increase the axial
speed of the
mud between the upstream 26 and the downstream activation zone 20 and thus the
rise of debris, the inclination to the axis of the helix of the grooves 21
located
downstream of the grooves 27 may be less than that of the grooves 27.
Viewed in cross section, see FIG. 6, the grooves 27 have an leading edge in
the
direction of rotation of the drill pipe section with an obtuse angle with
respect to the
external circumference of the activation zone 26 and an acute angle on the
trailing
edge side which is complementary to y4, for example with an angle in the range
50
to 80 with respect to the external circumference, preferably in the range 60
to 70 ,
for example 65 . The depth of the grooves 27 may be in the range 15 to 30 mm,
preferably in the range 20 to 25 mm. The distance d4 between the grooves may
be in
the range 10 to 40 mm, preferably in the range 20 to 35 mm, for example 25 mm.
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The connection zone 28 upstream of the activation zone 26 has the external
shape of
a cylindrical body of revolution. The connection zone 28 also comprises a male
thread 28 a provided to cooperate with a corresponding female thread.
In the embodiment shown, the profiled element 1 comprises two bearing
zones 12 and 22 separated from each other and each surrounded by two
activation
zones, respectively 10 and 16, and 26. The distance between the bearing
zones 12 and 22 may be relatively large, for example of the order of 5 to 15 m
depending on the length of the profiled element 1. It is advantageous to
fabricate the
profiled drill pipe 1 in distinct sections 6, 7 and 8. The central section 8,
which is in
the form of a body of revolution with a maximum diameter which is
substantially
smaller than the maximum diameter of the end sections 6 and 7 (tool joints),
may be
fabricated from a tubular blank with a substantially smaller external
diameter, for
example of the order of 15% to 30% of the external diameter of the end
sections 6 and 7. Thus, the quantity of material to be machined is reduced
considerably compared with a drill pipe 1 produced from a monoblock blank. The
sections 6, 7 and 8 are welded together, for example by friction, before or
after
machining the grooves of the activation zones and before or after formation of
the
hard reinforcement of the bearing zones 12 and 22.
A drill string may be composed of drill pipes 1 to which other elements such
as cross-
over subs, or heavy weight drill pipes, drill collars or stabilizers may or
may not be
added. It is particularly advantageous to compose a string and more
particularly a
drill pipe section from a high proportion of drill pipes 1 ensuring excellent
drilling
characteristics, especially as regards linear advance speed, a low entrainment
torque
and little abrasion of the drilled hole. The activation zones 10, 16, 20 and
26 cause
the drilling mud and the debris located outside the drill pipe 1 to move with
a scraping
or back-reaming effect, especially in the case of substantially horizontally
deflected
wells in which the drilling debris tends to become sedimented in the lower
portion of
the drilled hole. The activation zones can pick up this sediment and tend to
lift it in
the direction of the arrow 5because of their helical inclination and the
direction of
rotation of the drill string. In general, the bearing zone 12, 22 is produced
from a
material which is harder than that of the remainder of the drill pipe 1 and
over a radial
thickness such that the external diameter of the bearing section reduced by
double
the radial thickness is greater than the external diameter of a threaded
portion of the
element.
At least one guide section may have a toroidal shape, preferably with a mean
radius
of more than 20 mm, preferably more than 60 mm, in order to form a fluid
bearing.
At least one activation zone may have an external diameter which increases
towards
the bearing zone.
CA 02712670 2015-07-17
13
At least one guide section may have an ogival or ellipsoidal shape.
The length of the bearing section may be in the range 20 to 50 mm, preferably
in the
range 30 to 40 mm.
The length of the bearing zone may be in the range 50 to 100 mm, preferably in
the
range 70 to 80 mm, more preferably less than the mean radius of the guide
sections.
FIG. 15 shows an assembly of two drill pipes 1 via their threads 9a and 28a.
The
bearing zone 12 and the activation zones 10, 16 of one of the drill pipes are
relatively
close to the bearing zone 22 and the activation zones 20 and 26 of the other
drill pipe
(distance of the order of less than 0.50 m). Because of the direction of
circulation 5 of
mud and debris outside the drill pipe section, the mud and debris initially
encounter
the activation zone 16, then the bearing zone 12 then the activation zone 10,
then
after a few tens of cm the activation zone 26, then the bearing zone 22 and
finally the
activation zone 20.
Because of the proximity of these zones, it may be advantageous to try and
increase
the axial speed of the mud and debris along these various zones. To this end,
it is
possible to select an angle of inclination of the grooves such that this angle
reduces
regularly from the most upstream grooves 17 to the most downstream grooves 21.
In
other words, the angle of inclination of the grooves 21 may be selected so as
to be
lower than that of the grooves 27, the angle of inclination of the grooves 27
may be
selected so as to be lower than that of the grooves 11 and the angle of
inclination of
the grooves 11 may be selected so as to be lower than that of the grooves 17.
A drill pipe 41 may comprise an end section 7 (male tool joint) comprising an
activation zone 20 downstream of a downstream bearing zone 22, an activation
zone 26 upstream of an upstream bearing zone 42 and an activation zone 46
between said downstream and upstream bearing zones, see FIG. 10. The
pipe 41 offers increased activation of mud and excellent slipping over the
walls of the
well.
A drill pipe 31 may comprise a section 6 (female tool joint) comprising an
activation
zone 16 upstream of an upstream bearing zone 12 and an activation
zone 11 between a downstream bearing zone 32 and said upstream bearing
zone 12, see FIG. 9. The section 31 thus comprises two bearing zones and two
activation zones.
In the embodiment shown in FIG. 11, the profiled element 1 is a drill collar.
The
profiled element 1 comprises four bearing zones 12, 22, 52 and 62, each
surrounded
by activation zones 10 and 16, 20 and 26, 50 and 56 and 60 and 66.
CA 02712670 2015-07-17
14
In the embodiment of FIG. 12, the profiled element 1 is a heavy weight drill
pipe. The
profiled element 1 comprises four bearing zones 12, 22, 52 and 62, each
surrounded
by activation zones 10 and 16, 20 and 26, 50 and 56 and 60 and 66.
In the embodiment of FIG. 13, there is provided a stabilizer 70, for example
disposed
beneath the lower end of a drill pipe section. The stabilizer 70 comprises a
male
thread at one end and a female thread at another end.
The stabilizer 70 comprises on its external surface a bearing zone 12
comprising two
bearing sections, downstream 14 and upstream 74, and two activation
zones 10 and 16 downstream and upstream of the bearing zone 12. The bearing
zone 12comprises two guide sections 13, 15 respectively between the activation
zone 10 and the downstream bearing section 14 and between the activation
zone 16 and the upstream bearing section 74. The bearing zone 12 comprises a
linking section73 between the downstream bearing section 14 and the upstream
bearing section 74. The linking section may have an external diameter which is
smaller than the external diameter of the bearing sections 14 and 74. The
external
diameter of the activation zone 10 may be different from the external diameter
of the
activation zone 16.
The stabilizer 70 comprises a first tubular portion between the male thread
and the
bearing zone 12 and a second tubular portion between the female thread and the
bearing zone 12. The external diameter of each tubular portion is less than
the
maximum diameter of the bearing zone 12, preferably 65% less than the maximum
diameter of the bearing zone 12. The external diameter of the first tubular
portion
may be greater than or equal to the external diameter of the second tubular
portion.
The length of the first tubular portion may be in the range 254 to 1219 mm.
Flutes 71 which are generally helical in shape may be provided at least in the
bearing
zone 12 to constitute blades 75 of the stabilizer between the flutes 71. The
flutes 71 extend at least from the downstream bearing section 14 to the
upstream
bearing section 74. The flutes 71 may be two to six in number, for example
three.
The flutes 71 have an angle of inclination with respect to the axis 2 in the
range 150
to 350 The angle of inclination may be in the range between the angle of
inclination of
the grooves 11 of the activation zone 10 and the angle of inclination of the
grooves 17 of the activation zone 16. The flutes 71 may extend from the
activation
zone 10 to the activation zone 16. The flutes 71 may open at their ends into
at least a
portion of the grooves 11 and 17, for example three of the six. The flutes 71
serve to
circulate drilling mud; the external diameter of the stabilizer may be close
to that of
the drilled hole and at least some of the blades 75 come to bear against the
internal
surface of the hole.
CA 02712670 2015-07-17
In the embodiment of FIG. 14, a connection piece or cross-over sub 80 is free
of
flutes 71. The cross-over sub 80 may have a bearing zone 41 similar to that
shown
in FIG. 10, a male thread at one end and a female thread at another end, a
first
tubular portion between the male thread and the bearing zone 41 and a second
5 tubular portion between the female thread and the bearing zone 41. The
external
diameter of each tubular portion is less than the maximum diameter of the
bearing
zone 12which may itself be much smaller than the diameter of the drilled hole.
The
inertia of the first and second tubular portions may be close to the inertia
of the ends
of the components adjacent to them. Thus, if the component adjacent to the
first
10 portion is a drill collar, the inertia of the first portion may be close
to that of the drill
collar. If the component adjacent to the second portion is a heavy weight
drill pipe,
the inertia of the second portion may be close to that of the heavy weight
drill pipe.
Each stabilizer 70 or cross-over sub 80 may act as a connector between a
bottom
hole assembly (or BHA) and a drill pipe section which may have heavy weight
drill
15 pipes at its lower end. In one embodiment, a stabilizer 70 or cross-over
sub 80 is
disposed between a heavy weight drill pipe (or standard drill pipe if a heavy
weight
drill pipe is not used) which forms part of a drill pipe section and a drill
collar or
another component forming part of the bottom hole assembly. More particularly,
the
external diameter of the upper tubular portion of the drill collar may be
different from
the external diameter of the first tubular portion of the stabilizer 70 or the
cross-over
sub 80. The external diameter of the lower tubular portion of the heavy weight
drill
pipe may be different from the external diameter of the second tubular portion
of the
stabilizer 70 or the cross-over sub 80. It should be noted that the
stabilizers are
ordinarily disposed within the bottom hole assembly (for example towards the
lower
and upper ends). The positioning of a stabilizer 70 or a cross-over sub 80
between
the drill pipe section and the bottom hole assembly offers particular
advantages
during backreaming operations for lifting the drill string. In a standard
configuration
(without a component of type 70, 80 between the bottom hole assembly and the
drill
pipe section), an accumulation of debris or a "dune" tends to be formed just
above
the bottom hole assembly under backreaming drill string lifting conditions.
The
inventors have noted the particularly beneficial influence on the evacuation
of debris
by disposing at least one component 70, 80 between the bottom hole assembly
and
the drill pipe section. Further, a cross-over sub 80 may allow a transition to
be made
between the high inertia of a drill collar of the bottom hole assembly and the
lower
inertia of a heavy weight drill pipe or a standard drill pipe section.
More generally, grooves 11, 17, 21, 27 may comprise a bottom portion which is
inclined in a plane intersecting the axis close to the adjacent bearing zone,
the
inclination of this plane with respect to the axis being in the range 30 to
60 ,
preferably in the range 40 to 50 .
CA 02712670 2015-07-17
16
At least a portion of grooves 11, 17, 21, 27 may comprise a central portion
the
bottom of which is in a plane substantially parallel to the axis.
A drill pipe may comprise a substantially tubular portion between an
activation zone
upstream of a first bearing zone and an activation zone downstream of a second
bearing zone.
The grooves of the activation zone upstream of the second bearing zone may
comprise an inclined portion distant from the adjacent bearing zone the bottom
of
which is inclined in a plane intersecting the axis. The inclination of this
plane with
respect to the axis may be in the range 100 to 30 , preferably in the range
150 to 25 .
The grooves of the activation zone upstream of the second bearing zone may
comprise a portion distant from the bearing zone the bottom of which is
inclined in a
plane intersecting the axis and with a length in the range 20 to 80 mm,
preferably in
the range 40 to 60 mm, and a central portion the bottom of which is in a plane
substantially parallel to the axis, with a length in the range 10 to 50 mm,
preferably in
the range 20 to 30 mm.
The grooves of the activation zone downstream of the second bearing zone may
comprise a portion the bottom of which is in a plane substantially parallel to
the axis,
with a length in the range 50 to 120 mm, preferably in the range 70 to 80 mm.
The grooves of the activation zone downstream of the second bearing zone may
comprise a portion the bottom of which is in a plane substantially parallel to
the axis
and tangential to an external surface of a substantially tubular surface.
The grooves of the activation zone upstream of the first bearing zone may
comprise
a portion distant from the adjacent bearing zone the bottom of which is
inclined in a
plane intersecting the axis. The inclination with respect to the axis may be
in the
range 10 to 30 , preferably in the range 15 to 25 .
The grooves of the activation zone upstream of the first bearing zone may
comprise
a portion distant from the adjacent bearing zone the bottom of which is
inclined in a
plane intersecting the axis and with a length in the range 10 to 60 mm,
preferably in
the range 20 to 30 mm, and a central substantially axial portion with a length
in the
range 10 to 80 mm, preferably in the range 30 to 40 mm.
The grooves of the activation zone downstream of the first bearing zone may
comprise a portion distant from the adjacent bearing zone the bottom of which
is
inclined in a plane intersecting the axis, the inclination with respect to the
axis being
in the range 10 to 30 , preferably in the range 15 to 25 .
CA 02712670 2015-07-17
17
The grooves of the activation zone downstream of the first bearing zone may
comprise a portion distant from the adjacent bearing zone the bottom of which
is
inclined in a plane intersecting the axis and with a length in the range 10 to
70 mm,
preferably in the range 35 to 45 mm, and a central substantially axial portion
with a
length in the range 5 to 40 mm, preferably in the range 10 to 15 mm.
The product of the depth of a groove and the number of grooves of an
activation
zone may be in the range 80 to 200 mm, preferably in the range 100 to 160 mm.
The grooves of the activation zones may, with the external surface of the
activation
zone, form an acute angle with one edge and an obtuse angle with the opposite
edge
in the circumferential direction and with respect to the external
circumference of the
activation zone. The acute angle may have a value in the range 60 to 70 .
The distance between two grooves of an activation zone may be in the range 10
to
50 mm, preferably in the range 20 to 35 mm.
The depth of a groove of an activation zone may be in the range 10 to 40 mm,
preferably in the range 11 to 28 mm.
The grooves have the general shape of a helix with an angle with respect to
the axis
which decreases from upstream to downstream of a bearing zone.
A section as described above may be provided with a threaded connection at one
of
its ends and be free of a thread at the other end. Thus, a drill pipe section
may
comprise at least one section of this type (constituted, for example, from a
tool joint)
and a tube one end face of which is welded to the end which is free of a
thread on
said section (butt welding). The drill pipe section may comprise two sections
connected via a tube welded by its end faces to the end which is free of a
thread on
each section. A drill pipe section comprising at least 80% drill pipes
according to the
invention, or even 100%, may be formed.
We have here a drill pipe section element which can considerably improve
drilling
performance, especially an increase in the rate of advance of the order of 10%
to
30%, a reduction in the frictional torque of the order of 10% to 60%, a
reduction in the
axial friction of the order of 10% to 50%, an increase in the service life of
the drill pipe
section of the order of 10% to 30% and an increase in the total length of the
drilled
hole of the order of 1 to 2 km.
