U.S. patent application number 10/443438 was filed with the patent office on 2004-11-25 for lubricant for use in a wellbore.
Invention is credited to Simpson, Nell A. A..
Application Number | 20040231843 10/443438 |
Document ID | / |
Family ID | 33450415 |
Filed Date | 2004-11-25 |
United States Patent
Application |
20040231843 |
Kind Code |
A1 |
Simpson, Nell A. A. |
November 25, 2004 |
Lubricant for use in a wellbore
Abstract
The present invention provides methods and apparatus for
reducing friction and preventing galling between surfaces in a
wellbore. In one aspect of the invention, a titanium carbide is
disposed between surfaces of an expansion tool and a tubular to be
expanded. The titanium carbide coating acts as a lubricant to
reduce friction and prevent galling therebetween.
Inventors: |
Simpson, Nell A. A.;
(Aberdeen, GB) |
Correspondence
Address: |
WILLIAM B. PATTERSON
MOSER, PATTERSON & SHERIDAN, L.L.P.
Suite 1500
3040 Post Oak Blvd.
Houston
TX
77056
US
|
Family ID: |
33450415 |
Appl. No.: |
10/443438 |
Filed: |
May 22, 2003 |
Current U.S.
Class: |
166/277 ;
166/384 |
Current CPC
Class: |
E21B 43/105
20130101 |
Class at
Publication: |
166/277 ;
166/384 |
International
Class: |
E21B 029/00 |
Claims
I claim:
1. A method for lubricating two contacting surfaces in a wellbore,
comprising: depositing a layer of titanium carbide on a first
surface; and causing the first surface to contact a second
surface.
2. The method of claim 1, wherein the second surface is coated with
titanium carbide.
3. A method of lubricating a surface of a downhole component,
comprising: placing a layer of titanium carbide on the surface,
whereby the surface will contact another surface in a wellbore and
create friction therebetween.
4. An expander tool for expanding a tubular, the tool comprising: a
body having a bore longitudinally formed therethrough; and one or
more roller members radially extendable from the body, wherein a
portion of the one or more roller members include a coating
comprising titanium carbide.
5. The expander tool of claim 4, wherein the one or more rollers
extend due to fluid pressure applied from the bore to a piston
surface formed on a roller housing.
6. The expander tool of claim 4, wherein an inner surface of the
tubular comprises the titanium carbide coating.
7. The expander tool of claim 6, wherein the inner surface is
expanded by the expander tool.
8. The expander tool of claim 4, wherein the titanium carbide is
deposited by sputtering.
9. A method for expanding a first tubular into a second tubular in
a wellbore, the first tubular and second tubular each having a top
portion and a bottom portion, comprising: positioning the first
tubular within the wellbore; running the second tubular to a
selected depth within the wellbore such that the top portion of the
second tubular overlaps with the bottom portion of the first
tubular, wherein an inner surface of the top portion of the second
tubular comprise a titanium carbide coating; and expanding the top
portion of the second tubular using an expander tool.
10. The method of claim 9, wherein the expander tool comprises: a
body having a bore longitudinally formed therein; and one or more
roller members radially extendable from the body.
11. The method of claim 10, wherein the one or more roller members
comprise a titanium carbide coating.
12. The method of claim 10, wherein the one or more rollers extend
due to fluid pressure applied from the bore to a piston surface
formed on a roller housing.
13. The method of claim 9, wherein the first tubular and the second
tubular each define a string of casing.
14. The method of claim 9, wherein the expander tool comprises a
cone shaped portion.
15. The method of claim 14, wherein the cone shaped portion
includes a titanium carbide coating.
16. A method for expanding a tubular in a wellbore, comprising:
positioning the tubular within the wellbore; placing an expander
tool within the tubular at a location adjacent a portion of the
tubular to be expanded, wherein at least one of the portion of the
tubular and a portion of the expander tool comprise a titanium
carbide coating disposed thereupon; and expanding the tubular using
the expander tool.
17. The method of claim 16, wherein the expander tool is a
cone-shaped member movable independently within the tubular and
having an outer diameter larger than an inside diameter of the
unexpanded tubular.
18. The method of claim 16, wherein the expander tool includes at
least one radially extendable member that is extendable with the
application of fluid pressure to a backside thereof.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to lubrication of components
for use in a wellbore. Particularly, the invention relates to
reducing friction encountered during operation of a downhole tool
in a wellbore. More particularly, the invention relates to the
lubrication of wellbore components with a carbide material having a
spherical grain structure. More particularly still, the invention
relates to lubricating an expander tool with titanium carbide.
[0003] 2. Description of the Related Art
[0004] Galling of wellbore components due to friction has always
been a problem in wellbore operations. Galling is surface damage to
mating, moving, metal parts due to friction between the parts. In a
wellbore, galling can take place between moving parts of a single
component, like slips and cones of a packer or between a component
and some other surface in the wellbore that is necessarily
contacted as a component operates. Soft metals are more susceptible
to galling than hard metals, and similar metal surfaces are more
prone to galling than dissimilar metal surfaces.
[0005] Galling may occur when expanding tubulars in a wellbore.
Expansion technology enables a tubular to be expanded and its
diameter to be increased in a wellbore. Using this method, a liner,
for example, can be hung off of an existing string of casing
without the use of a conventional slip assembly. Tubulars can be
expanded with a swedge or tapered cone that is physically pushed
through the inside of the tubular with enough force that the inside
diameter of the tubular is increased to at least the outside
diameter of the cone. More recently, expander tools are fluid
powered and are run into a wellbore on a working string. The
hydraulic expander tools include radially extendable rollers which
are urged outward radially from the body of the expander tool and
into contact with a tubular therearound. As sufficient fluid
pressure is generated upon a piston surface behind these rollers,
the tubular is expanded past its point of plastic deformation. By
rotating the expander tool in the wellbore and moving it axially, a
tubular can be expanded along a predetermined length in a
wellbore.
[0006] FIG. 1 is an exploded view of an exemplary expander tool 100
for expanding a tubular (shown as 200 in FIG. 2). A tubular is
expanded by an expander tool 100 acting outwardly against the
inside surface of the tubular. The expander tool 100 has a body 102
which is hollow and generally tubular with connectors 104 and 106
for connection to other components (not shown) of a downhole
assembly. The connectors 104 and 106 are of a reduced diameter
compared to the outside diameter of the longitudinally central body
part of the tool 100. The central body part 102 of the expander
tool 100 shown in FIG. 1 has three recesses 114, each holding a
respective roller 116. Each of the recesses 114 has parallel sides
and extends radially from a radially perforated tubular core (not
shown) of the tool 100. Each of the mutually identical rollers 116
is somewhat cylindrical and barreled. Each of the rollers 116 is
mounted by means of an axle 118 at each end of the respective
roller 116 and the axles are mounted in slidable pistons 120. The
rollers 116 are arranged for rotation about a respective rotational
axis that is parallel to the longitudinal axis of the tool 100 and
radially offset therefrom at 120-degree mutual circumferential
separations around the central body 102. The axles 118 are formed
as integral end members of the rollers 116, with the pistons 120
being radially slidable, one piston 120 being slidably sealed
within each radially extended recess 114. The inner end of each
piston 120 is exposed to the pressure of fluid within the hollow
core of the tool 100 by way of the radial perforations in the
tubular core. In this manner, pressurized fluid provided from the
surface of the well, via a working string 310, can actuate the
pistons 120 and cause them to extend outward whereby the rollers
116 contact the inner surface of a tubular to be expanded.
[0007] In one example of utilizing an expander tool, a new section
of liner is run into the wellbore using a run-in string. As the
assembly reaches that depth in the wellbore where the liner is to
be hung, the new liner is cemented in place. Before the cement
sets, an expander tool is actuated and the liner is expanded into
contact with the existing casing therearound. By rotating the
expander tool in place, the new lower string of casing can be fixed
onto the previous upper string of casing, and the annular area
between the two tubulars is sealed.
[0008] Galling takes place during expansion due to friction between
the outside surface of an outwardly extended roller and an inside
surface of the tubular being expanded. Friction between the
surfaces increases the amount of torque needed at the surface of
the well to rotate the expansion tool in the wellbore and complete
the expansion process. Increased friction causes galling of the
contacting surfaces leading to even greater friction and less
efficiency of the expansion tool.
[0009] In order to reduce friction and prevent galling in a
wellbore, lubricants have been used on threads and on surfaces
between moving parts, like the rollers of expander tools and
tubulars to be expanded. Lubricants have included grease and oil.
Sometimes, soft metals such as copper, lead, zinc, or tin are added
to the material making up contacting surfaces. The reasons for
adding the soft metals are two fold. First, the soft metals provide
a barrier that prevents galling and second, they deform under
pressure and act as a lubricant. While these solutions reduce
friction and the likelihood of galling, they are not completely
effective.
[0010] There is a need, therefore, for a method and apparatus to
reduce the friction encountered during the operation of a downhole
tool that operates by contacting other surfaces. There is a further
need for a method and apparatus for preventing galling created by
friction between a downhole tool and other surfaces.
SUMMARY OF THE INVENTION
[0011] The present invention provides methods and apparatus for
reducing friction and preventing galling between surfaces in a
wellbore. Preferably, one or both of the contact surfaces are
coated with a material having a spherical structure. In one aspect
of the invention, a titanium carbide coating is placed between the
roller of an expander tool and the surface of the tubular to be
expanded in order to reduce friction and prevent galling.
[0012] In another aspect, the present invention provides a method
for expanding a tubular in a wellbore. Initially, a tubular is
disposed in the wellbore. The tubular is then expanded using an
expander tool. The expander tool or the expanded area of the
tubular include a coating of titanium carbide to prevent galling of
the components. Furthermore, the coating reduces the friction
forces between the tool and the tubular, thereby increasing
efficiency.
[0013] In another aspect still, the present invention provides a
method for lubricating two contacting surfaces in a wellbore. The
method includes depositing a layer of titanium carbide on a first
surface and causing the first surface to contact a second
surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] So that the manner in which the above recited features of
the present invention are attained and can be understood in detail,
a more particular description of the invention, briefly summarized
above, may be had by reference to the embodiments thereof which are
illustrated in the appended drawings.
[0015] It is to be noted, however, that the appended drawings
illustrate only typical embodiments of this invention and are
therefore not to be considered limiting of its scope, for the
invention may admit to other equally effective embodiments.
[0016] FIG. 1 is an exploded view of an exemplary expander
tool.
[0017] FIG. 2 is a partial section view of a tubular in a wellbore
showing an expander tool attached to a working string also disposed
within the tubular.
[0018] FIG. 3 is a partial section view of the partially expanded
tubular of FIG. 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0019] The aspects of the present invention are related to a
downhole tool with a coating of carbide material having a spherical
structure to reduce friction and prevent galling between two
contacting surfaces.
[0020] In one aspect, titanium carbide ("TiC") is coated on the
exterior surfaces of an expander tool. The physical properties of
titanium carbide make it one of the hardest and most durable
materials. Additionally, titanium carbide has a generally spherical
grain structure when viewed under a microscope. It must be noted
that the term "spherical" encompasses a structure that is
"multi-faceted". These properties make titanium carbide a prime
candidate for use as a lubricant to reduce friction.
[0021] Titanium carbide may be coated on a surface using any
suitable method known to a person of ordinary skill in the art. For
example, the titanium carbide coating may be deposited by physical
vapor deposition, or sputtering. Using sputtering, the titanium
carbide may be arranged as a target within a vacuum chamber in
spaced relation to a surface to be coated. The surface may be
positioned proximate a grounded electrode, and the target
positioned proximate a conductive electrode. The chamber is
back-filled with a gas at low pressure and a source of potential is
applied to the electrodes. The potential source serves both to
produce a plasma of the gas between the spaced electrodes and to
attract the gas ions to the target. The potential causes the gas
ions to bombard the target and break or knock off titanium carbide
atoms or molecules from the target. These atoms or molecules settle
on the surface and form a layer of titanium carbide. In another
embodiment, the titanium carbide coating may be applied using a
chemical vapor deposition process. It is understood that other
deposition methods known to a person of ordinary skill in the art
may also be used without deviating from aspects of the present
invention.
[0022] FIG. 2 is a partial section view of a tubular 200 in a
wellbore 300. The tubular 200 is disposed coaxially within the
casing 400. An expander tool 100 is attached to a working string
310 and visible within the tubular 200. Preferably, the tubular 200
is run into the wellbore 300 with the expander tool 100 disposed
therein. The working string 310 extends below the expander tool 100
to facilitate cementing of the tubular 200 in the wellbore 300
prior to expansion of the tubular 200 into the casing 400. A remote
connection (not shown) between the working, or run-in, string 310
and the tubular 200 temporarily connects the tubular 200 to the
run-in string 310 and supports the weight of the tubular 200. For
example, the temporary connection may be a collett (not shown), and
the tubular 200 may be a string of casing.
[0023] FIG. 2 depicts the expander tool 100 with the rollers 116
retracted, so that the expander tool 100 may be easily moved within
the tubular 200 and placed in the desired location for expansion of
the tubular 200. Hydraulic fluid (not shown) is pumped from the
surface to the expander tool 100 through the working string 310.
When the expander tool 100 has been located at the desired depth,
hydraulic pressure is used to actuate the pistons (not shown) and
to extend the rollers 116 so that they may contact the inner
surface of the tubular 200, thereby expanding the tubular 200.
[0024] In one embodiment, the contact surfaces of the rollers 116
of the expander tool 100 may be coated with titanium carbide 150.
FIG. 3 is a partial section view of the tubular 200 partially
expanded by the expander tool 100. At a given pressure, the pistons
(not shown) in the expander tool 100 are actuated and the rollers
116 are extended until they contact the inside surface of the
tubular 200. The rollers 116 of the expander tool 100 are further
extended until the rollers 116 plastically deform the tubular 200
into a state of permanent expansion. The working string 310 and the
expander tool 100 are rotated during the expansion process, and the
tubular 200 is expanded until the tubular's outer surface contacts
the inner surface of the casing 400. The working string 310 and
expander tool 100 are then translated within the tubular 200 until
the desired length of the tubular 200 has been expanded.
[0025] It is believed that the titanium carbide coating 150
provides a lubricant like effect between the rollers 116 and the
tubular 200. As the expander tool 100 is rotated against the
tubular 200, the spherical grain structure of the titanium carbide
150 facilitates the relative movement between the contact surfaces.
Consequently, less torque is needed to overcome the friction
between the rollers 116 and the tubular 200. It is further believed
that the titanium carbide coating 150, because it reduces friction,
may also prevent galling of surfaces. The result is a more
efficient expansion of the tubular 200. It must be noted that the
either the rollers 116 or the tubular 200, or both may be coated
with the titanium carbide 150. Moreover, the titanium carbide
coating 150 may be applied to other downhole tools to reduce
friction. Additionally, the components of the expander tool 100,
such as the rotors, bearings, and the shaft, may also be coated
with titanium carbide 150 to reduce friction.
[0026] In another aspect, the titanium carbide coating may be used
with a swedge shaped mandrel or a cone to increase the diameter of
a tubular without the use of an expander tool having extendable
rollers. In one example, a cone-shaped member is run into a
wellbore and into contact with the upper end of a tubular to be
expanded. In another example, the cone can be run into the wellbore
on a lower end of a tubular run in string. The cone is designed
with an outer diameter greater than the inner diameter of the
unexpanded tubular. The outer surface of the cone may be coated
with titanium carbide to reduce friction and prevent galling as the
cone is urged into the tubular. Alternatively, an inner surface of
the tubular in contact with the cone may be coated with titanium
carbide, or both contacting surfaces may be coated with the
same.
[0027] With the coating in place, it is believed that the amount of
friction generated during the process of passing the cone into the
tubular will be significantly reduced. Additionally, any galling
between the surface of the cone and the inner surface of the
tubular will be minimized. The reduction in surface damage to the
tubular wall can be important if the surface characteristics of the
tubular after expansion are critical. In one example, a tubular is
enlarged in situ in order to form a polish bore receptacle ("PBR")
therein. The use of a coating of titanium carbide according to the
present invention will help ensure that the PBR has surface
characteristics according to specification.
[0028] While the foregoing is directed to the preferred embodiment
of the present invention, other and further embodiments of the
invention may be devised without departing from the basic scope
thereof, and the scope thereof is determined by the claims that
follow.
* * * * *