Note: Descriptions are shown in the official language in which they were submitted.
CA 02533563 2006-01-20
Casing Centralizer Coupling
BACKGROUND OF THE INVENTION
[001] Field of the Invention
[002] The present invention relates generally to well casing couplings and
well casing
centralizers . More particularly, relating to a combined well casing coupling
and
centralizer that is suitable for use in drilling with casing operations.
[003] Description of Related Art.
[004] In a standard operation of drilling and completing an oil well multiple
steps are
performed through the process. First, a bore hole of a desired diameter and
depth is
drilled into a formation using a drill bit and a drill string comprising of
coiled tubing or
multiple sections of rigid drilling pipe coupled together. Once the bore hole
has been
drilled, the drill string is removed from the bore hole and a casing string is
inserted. The
casing string includes multiple sections of pipe connected end-to-end by
threaded
couplings. Centralizing devices are attached along the length of the casing at
regular
intervals to center the casing within the bore hole so when the casing is
cemented in the
bore hole the cement is evenly distributed around the casing. Most of these
centralizers
have an outside diameter (OD) equal to or smaller than the bore hole interior
diameter
(ID). Others yet can have a greater OD and include spring loaded mechanisms
that
compress to conform to the bore hole ID.
[005] Many types of centralizers have been used in the industry and the
centralizers range from
devices that are attached to the casing by a friction system, are bolted on,
are positioned
around the casing between the casing couplings or are formed as part of a
casing
coupling.
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[006] Examples of casing centralizers can be found in U.S. patents 6,464,013;
5,575,333;
4,595,058; 3,762,472; 2,309,791 and 1,807,050.
[007] Recently, new developments have been made in the art of drilling and
completing a well
which remove the step of using a separate drill string and casing string to
complete a well.
In the drilling of shallow to medium depth formations advancements have been
made
that allow the use of the casing string as the drill string, thereby
eliminating the need of
using a separate drill string, this operation is typically termed "drilling
with casing".
[008] While the need to use a separate drill string is eliminated in drilling
with casing, the
casing must still be centralized in order to be properly cemented. The prior
art
centralizers are not capable of standing up to the force and abuse to which
they are
subjected during a drilling operation. As such, the present invention provides
a
centralizer that withstands the force and abuse during the drilling operation
while
maintaining a highly regulated specification for use, which is not attainable
by prior art
centralizers.
SUMMARY OF THE INVENTION
[009] In accordance with the present invention, a casing centralizer coupling
which meets strict
American Petroleum Institute (API) specifications and is capable of use in
drilling with
casing operations is provided.
[0010] In general, in one aspect, a casing centralizer coupling is provided.
The coupling includes
a body having a threaded first end, a threaded second end, a through bore
extending from
said first end to said second end, and an exterior surface. A plurality of
centralizing
blades projecting outwardly and extending along a length of the exterior
surface. And
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each of the plurality of centralizing blades defining an outwardly facing
surface having an
arcuately shaped transverse cross section
[0011] In general, in another aspect, a casing centralizer coupling is
provided. The coupling
includes a body having a threaded first end, a threaded second end, a through
bore
extending from said first end to said second end, and an exterior surface. A
plurality of
centralizing blades projecting outwardly and extending along a length of the
exterior
surface. Each of the plurality of centralizing blades defining an outwardly
facing surface
having an arcuately shaped transverse cross section and opposed outwardly
beveled
transverse edges and opposed outwardly beveled longitudinal edges.
[0012] In general, in another aspect, a casing centralizer coupling is
provided. The coupling
includes a body having a threaded first end, a threaded second end, a through
bore
extending from said first end to said second end, and an exterior surface. A
plurality of
centralizing blades projecting outwardly and extending along a length of the
exterior
surface. Each of the plurality of centralizing blades defining an outwardly
facing surface
having an arcuately shaped transverse cross section and opposed outwardly
beveled
transverse edges and opposed outwardly beveled longitudinal edges. And at
least a
portion of each of the plurality of centralizing blades are hard faced.
[0013] In general, in another aspect, a combined casing coupling and casing
centralizer is
provided. The combined casing coupling and casing centralizer includes a body
having a
threaded first end, a threaded second end, a through bore extending from said
first end to
said second end, and an exterior surface. A plurality of centralizing blades
projecting
outwardly and extending along a length of the exterior surface. Each of said
plurality of
centralizing blades defining an outwardly facing surface having an arcuately
shaped
transverse cross section, opposed outwardly beveled transverse edges, opposed
outwardly
beveled longitudinal edges, and wherein at least the outwardly facing surface
is hard
faced.
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[0014] There has thus been outlined, rather broadly, the more important
features of the invention
in order that the detailed description thereof that follows may be better
understood and in
order that the present contribution to the art may be better appreciated.
[0015] Numerous objects, features and advantages of the present invention will
be readily apparent
to those of ordinary skill in the art upon a reading of the following detailed
description of
presently preferred, but nonetheless illustrative, embodiments of the present
invention when
taken in conjunction with the accompanying drawings. The invention is capable
of other
embodiments and of being practiced and carried out in various ways. Also, it
is to be
understood that the phraseology and terminology employed herein are for the
purpose of
descriptions and should not be regarded as limiting.
[0016] As such, those skilled in the art will appreciate that the conception,
upon which this
disclosure is based, may readily be utilized as a basis for the designing of
other structures,
methods and systems for carrying out the several purposes of the present
invention. It is
important, therefore, that the claims be regarded as including such equivalent
constructions insofar as they do not depart from the spirit and scope of the
present
invention.
[0017] For a better understanding of the invention, its operating advantages
and the specific
objects attained by its uses, reference should be had to the accompanying
drawings and
descriptive matter in which there is illustrated preferred embodiments of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The invention will be better understood and objects other than those
set forth above will
become apparent when consideration is given to the following detailed
description
thereof. Such description makes reference to the annexed drawings wherein:
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[0019] Figure 1 is a schematic diagram of the casing centralizer coupling
positioned within a
well bore;
[0020] Figure 2 is a perspective view of the casing centralizer coupling
having straight
centralizing blades positioned radially around an exterior surface of the
coupling;
[0021] Figure 3 is an end view of the casing centralizer coupling;
[0022] Figure 4 is a sectional view of the casing centralizer coupling take
along line 4-4 in
Figure 3;
[0023] Figure 5 is a sectional view of the casing centralizer coupling taken
along line 5-5 in
Figure 4; and
[0024] Figure 6 is an alternate embodiment of the casing centralizer coupling
having swept
shaped centralizing blades.
[0025] The same reference numerals refer to the same parts throughout the
various figures.
DETAILED DESCRIPTION OF THE INVENTION
[0026] Referring now to the drawings, and particularly to Figures 1-5, a
preferred embodiment of
the casing centralizer coupling of the present invention is shown and
generally designated
by the reference numeral 10. The casing centralizer coupling 10 is of a design
and
construction such that the coupling can withstand the abuse of drilling
rotation, thereby
making the coupling of the present invention desirable and usable for the
coupling of casing
for using in drill while casing operations. Prior art centralizers are not
designed nor are they
robust enough to withstand forces subjected upon the centralizer during
drilling rotation.
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100271 Now with reference to Figure 1, a new and improved casing centralizer
coupling 10 of the
present invention for coupling sections of casing together in drilling while
casing
operations will be described. More particularly, the casing centralizer 10 is
shown in use
within a bore hole 100 coupling two sections of casing 102 and 104 together
and
centralizing the casing within the bore hole.
[0028] With reference to Figures 2 and 3, the casing centralizer coupling 10
includes a body 12
having opposed threaded ends 14 and 16 and a through-bore 18 extending through
the
body between ends 14 and 16. While the body 12 is shown with female threaded
ends 14
and 16, the body can include male threaded ends or a male threaded end and a
female
threaded end depending upon the casing in which the casing centralizer
coupling is to be
used. Additionally, the threaded ends can include torque shoulders 15 that are
commonly
used in threaded casing couplings to resist high tightening torque which can
result in
damage to the threaded coupling.
[0029] The casing centralizer coupling 10 includes a plurality of centralizing
blades 20 arranged
radially around and project outwardly from an exterior surface 22 of the body
12. Each
centralizing blade 20 extends along a length of the exterior surface 22 in a
general
longitudinal direction. Each centralizing blade 20 includes outwardly beveled
transverse
edges 24 and 26, outwardly beveled longitudinal edges 28 and 30, and an
outwardly
facing surface 32 having an arcuately shaped transverse cross section. The
outwardly
facing surface 32 can be hard faced.
[0030] As can be seen in Figure 3, each centralizing blade 20 includes a
transverse profile that
results in the blade having a reduced contact with the well bore. The reduced
contact
with the well bore is such that during rotation of the casing centralizer
coupling 10 along
with the casing string 106 the centralizing blades 20 rotate across and
against the bore
hole with a bruising (glancing impact) not in a digging or direct impact as
would occur
with a profile including sharp edges. The resulting effect is lower torque
requirements for
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rotation of the casing string during drilling and a high wear resistance of
the casing
centralizer coupling.
[0031] Additionally, the outwardly beveled transverse edges 24 and 26 clearly
shown in Figure 4
provides smooth entrance of each centralizing blade 20 as the blade moves into
the bore
hole. The smooth entrance of each centralizing blade 20 also reduces
rotational torque
requirements of the casing string and prevents the centralizing blades 20 from
digging
into the bore hole and provides increased wear resistance of the casing
centralizer
coupling 10.
[0032] Each centralizing blade 20 having the unique transverse and
longitudinal profiles can
either be formed integrally with the body 12 for example through integral
machining or
casting. Preferably, the blades 20 are of a multi-component construction
formed onto the
body 12 using a specialized process.
[0033] With reference to Figures 4 and 5, the multi-component construction of
a centralizing
blade 20 is shown. In this construction, the centralizing blade includes a
central core
member 40, first and second fillet members 42 and 44 defining the outwardly
beveled
transverse edges 24 and 26 respectively, third and fourth fillet members 46
and 48
defining the outwardly beveled longitudinal edges 28 and 30 respectively, and
a surface
member 50 defining the outwardly facing surface 32.
[0034] The multi-component centralizing blade is created by a specialized
process which results
in a casing centralizing collar that meets current American Petroleum
Institute (API)
Grade specifications. The specialized process includes welding the core member
40 to
the exterior surface 22 of the body 12 using a welder, such as a pulse arc
GMAW robot
welder, thereby making the core member integral with the body. The first,
second, third
and fourth fillet members 42, 44, 46, 48 are formed by the welder in the
process of
welding the core member 40 to the body 12. The use of a pulse arc GMAW robot
welder
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eliminates the requirement of preheating the body 12 to reduce deformation
caused by
heat generated by a standard MIG welder.
[0035] The process further includes a step of forming the surface member 50
onto the core
member 40 as illustrated. The surface member 50 is formed of a hard face
material which
is deposited upon the core member 40 using a robot plasma system. The core
member 40
acts as a heat sink during this process and absorbs and dissipates a
sufficient amount of
heat generated during the deposition of the hard face material so that the
body 12 is not
dimensional distorted. Hard facing is defined as the application of a hard
material on the
surface of a softer material or substrate. The hard face material of the
surface member 50
is of a tungsten hard facing material comprising tungsten in a matrix, such as
a chromium
nickel (CrNi) matrix. Most preferably, of a tungsten carbide hard facing
material
comprising tungsten carbide in a matrix, such as chromium nickel (CrNi).
[0036] In a test sample, the core member 40 was a flat bar having a dimension
of 0.25 inches x
0.75 inches and the body was a standard API L casing coupling. However, other
casing
couplings having API 513, 5CT and 5C2 specification can also be utilized. It
is
contemplated that other API standard couplings could reasonably be used.
Further, any
casing coupling having specifications defined by another system which meet or
exceed
the API standards could also be used.
[0037] The test sample demonstrated a Vickers hardness, tensile strength and
bend test results of
the HAZ and other critical areas of the casing centralizer coupling meeting
API N-80
specifications.
[0038] In a further step, the casing centralizer coupler 10 can be H2S
environment certified by
post weld heat treating the core member 40 prior to depositing the hard facing
material of
the surface member onto the core member 40.
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[0039] With reference to Figure 6, the casing centralizer coupling 10 is shown
having at least
one swept centralizing blade 20.
[0040] A number of embodiments of the present invention have been described.
Nevertheless, it
will be understood that various modifications may be made without departing
from the
spirit and scope of the invention. Accordingly, other embodiments are within
the scope of
the following claims.
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