IMPROVED LINER HANGER SYSTEM
BACKGROUND
The present disclosure relates generally to equipment utilized and operations performed in
conjunction with a subterranean well and, more particularly, to an improved liner hanger system.
When performing subterranean operations, a wellbore is typically drilled and completed to
facilitate removal of desired materials (e.g., hydrocarbons) from a subterranean formation. Often,
once a wellbore is drilled, a casing may be inserted into the wellbore. Cement may then be used
to install the casing in the wellbore and prevent migration of fluids in the annulus between the
casing and the wellbore wall. In certain implementations, the casing may be made of heavy steel.
Once an upper portion of the wellbore has been drilled and cased, it may be desirable to
continue drilling and to line a lower portion of the wellbore with a liner lowered through the
upper cased portion thereof. Liner hangers are typically used to mechanically support an upper
end of the liner from the lower end of a previously installed casing. Additionally, liner hangers
may be used to seal the liner to the casing.
Traditional liner hangers utilized slips for mechanically supporting the liner from the
casing and packers to seal the different components. Expandable liner hangers ("ELH(s)") such
as VERSAFLEX™, available from Halliburton Energy Services, have been recently developed
and provide an improvement over traditional liner hangers. Specifically, ELHs utilize
elastomeric rings (e.g., rings made of rubber) carried on a section of expandable tubing to
provide both mechanical support and a fluid seal. Accordingly, once an ELH is placed at a
desired position downhole within a casing, an expansion cone may be forced through the ELH.
The expansion cone expands the elastomeric rings of the ELH, bringing them into contact with
the casing to provide both mechanical support and a fluid seal between the casing and a liner.
It is often desirable to use an ELH in a larger size casing (e.g., casing having a diameter of
between approximately 5.5" and approximately 22") and/or a high pressure high temperature
("HPHT") environment downhole. However, the properties of elastomeric rings of an ELH are
often susceptible to changes in pressure and temperature. Accordingly, the high pressures and
high temperatures of HPHT environments can adversely impact the ELH's ability to provide
mechanical support and/or seal the liner to the casing. These adverse impacts become even more
pronounced in instances when the liner is installed in a large casing.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete understanding of the present embodiments and advantages thereof may
be acquired by referring to the following description taken in conjunction with the accompanying
drawings, in which like reference numbers indicate like features.
Figure 1 is a cross-sectional view of a liner hanger system in accordance with the prior art.
Figure 2 is a cross-sectional view of a liner hanger system in accordance with an
illustrative embodiment of the present disclosure.
Figure 3 is a cross-sectional view of spikes of a liner hanger in accordance with another
illustrative embodiment of the present disclosure.
While embodiments of this disclosure have been depicted and described and are defined by
reference to exemplary embodiments of the disclosure, such references do not imply a limitation
on the disclosure, and no such limitation is to be inferred. The subject matter disclosed is
capable of considerable modification, alteration, and equivalents in form and function, as will
occur to those skilled in the pertinent art and having the benefit of this disclosure. The depicted
and described embodiments of this disclosure are examples only, and not exhaustive of the scope
of the disclosure.
DETAILED DESCRIPTION
The present disclosure relates generally to equipment utilized and operations performed in
conjunction with a subterranean well and, more particularly, to an improved liner hanger system.
Illustrative embodiments of the present disclosure are described in detail below. In the
interest of clarity, not all features of an actual implementation are described in this specification.
It will of course be appreciated that in the development of any such actual embodiment,
numerous implementation-specific decisions must be made to achieve the developers' specific
goals, such as compliance with system-related and business-related constraints, which will vary
from one implementation to another. Moreover, it will be appreciated that such a development
effort might be complex and time-consuming, but would nevertheless be a routine undertaking
for those of ordinary skill in the art having the benefit of the present disclosure.
To facilitate a better understanding of the present disclosure, the following examples of
certain embodiments are given. In no way should the following examples be read to limit, or
define, the scope of the disclosure. Embodiments of the present disclosure may be applicable to
horizontal, vertical, deviated, or otherwise nonlinear wellbores in any type of subterranean
formation. Embodiments may be applicable to injection wells as well as production wells,
including hydrocarbon wells. Devices and methods in accordance with certain embodiments
may be used in one or more of wireline, measurement-while-drilling (MWD) and logging-whiledrilling
(LWD) operations. Certain embodiments according to the present disclosure may
provide for a single trip liner setting and drilling assembly.
The terms "couple" or "couples" as used herein are intended to mean either an indirect or a
direct connection. Thus, if a first device couples to a second device, that connection may be
through a direct connection, or through an indirect electrical or mechanical connection via other
devices and connections. The term "wellbore" as used herein refers to any hole drilled into a
formation for the purpose of exploration or extraction of natural resources such as, for example,
hydrocarbons. The term "uphole" as used herein means along the drillstring or the hole from the
distal end towards the surface, and "downhole" as used herein means along the drillstring or the
hole from the surface towards the distal end.
It will be understood that the term "oil well drilling equipment" or "oil well drilling
system" is not intended to limit the use of the equipment and processes described with those
terms to drilling an oil well. The terms also encompass drilling natural gas wells or hydrocarbon
wells in general. Further, such wells can be used for production, monitoring, or injection in
relation to the recovery of hydrocarbons or other materials from the subsurface. This could also
include geothermal wells intended to provide a source of heat energy instead of hydrocarbons.
Embodiments may be applicable to injection wells as well as production wells, including
hydrocarbon wells.
Figure 1 depicts an ELH in accordance with the prior art. As shown in Figure 1, a wellbore
10 may be drilled through earth formation 12. A casing 14 may then be placed in an upper
portion 16 of the well 10 and held in place by cement 18 which is injected between the casing 14
and the upper portion 16 of well 10.
Below casing 14, a lower portion 20 of the wellbore 10 may be drilled through casing 14,
The lower portion 20 may have a smaller diameter than the upper portion 16. A length of liner 22
is shown positioned within the lower portion 20. The liner 22 may be used to line or case the
lower portion 20 and/or to drill the lower portion 20. If desired, cement may be placed between
the liner 22 and lower portion 20 of wellbore 10. The liner 22 may be installed in the wellbore 10
by means of a work string 24. The work string 24 may include a releasable collet, not shown, by
which it can support and rotate the liner 22 as it is placed in the wellbore 10.
Attached to the upper end of, or formed as an integral part of, liner 22 is a liner hanger 26
which may include a number of annular seals 28. While three seals 28 are depicted for
illustrative purposes, any number of seals 28 may be used. A polished bore receptacle, or tie
back receptacle, 30 may be coupled to the upper end of the liner hanger 26. In one embodiment,
the polished bore receptacle 30 may be coupled to the liner hanger 26 by a threaded joint 32, but
in other embodiments a different coupling mechanism may be employed. The inner bore of the
polished bore receptacle 30 may be smooth and machined to close tolerance to permit work
strings, production tubing, etc. to be connected to the liner 22 in a fluid-tight and pressure-tight
manner. For instance, a work string may be connected by means of the polished bore receptacle
30 and used to pump fracturing fluid at high pressure down to the lower portion 20 of the
wellbore 10 without exposing the casing 1 to the fracturing pressure.
It is desirable that the outer diameter of liner 22 be as large as possible while being able to
lower the liner 22 through the casing 14. It is also desirable that the outer diameter of the
polished bore receptacle 30 and the liner hanger 26 be about the same as the diameter of liner 22.
In the run in condition, the outer diameter of liner hanger 26 is defined by the outer diameter of
the annular seals 28. In the run in condition, a body or mandrel 34 of liner hanger 26 has an outer
diameter reduced by about the thickness of the seals 28 so that the outer diameter of the seals is
about the same as the outer diameter of liner 22 and tie back receptacle 30.
In this embodiment, first and second expansion cones 36 and 38 may be carried on the
work string 24 just above the reduced diameter body 34 of the liner hanger 26. Fluid pressure
applied between the work string 24 and the liner hanger 26 may be used to drive the cones 36, 38
downward through the liner hanger 26 to expand the body 34 to an outer diameter at which the
seals 28 are forced into sealing and supporting contact with the casing 14. The first expansion
cone 36 may be a solid, or fixed diameter, cone having a fixed outer diameter smaller than the
inner diameter 33 of the threaded joint 32. In the run in condition, second expansion cone 38
may have an outer diameter greater than first cone 36 and also greater than the inner diameter 33
of the threaded joint 32. In an embodiment, the second expansion cone 38 may be collapsible,
that is, may be reduced in diameter smaller than the inner diameter 33 of the threaded joint 32
when it needs to be withdrawn from the liner hanger 26. In some contexts, the second expansion
cone 38 may be referred to as a collapsible expansion cone. After the liner hanger 26 is
expanded, expansion cones 36, 38 may be withdrawn from the liner hanger 26, through the
polished bore receptacle 30 and out of the wellbore 10 with the work string 24.
Typical seals 28 are made of elastomeric elements (e.g., rubber) which as discussed above
may be susceptible to degradation as a result of exposure to the high temperatures and high
pressures downhole. In accordance with an embodiment of the present disclosure, the seals 28
may be replaced with one or more metallic spikes. Figure 2 depicts a cross-sectional view of a
system, including an improved liner hanger 26' where spikes 202 in accordance with an
illustrative embodiment of the present disclosure have replaced the seals 28. The spikes 202 may
be metal spikes. The metal spikes may be made of any suitable steel grade, Aluminum, any other
ductile material, and a combination thereof. In certain implementations, the spikes may be made
from a combination of one or more of the recited materials. In certain embodiments, the spikes
202 may be made from AISI4140 steel or AISI4340 steel. In certain implementations, each spike
202 may be a circular ring that extends along an outer perimeter of the liner hanger 26' at a
desired axial location. However, the present disclosure is not limited to this particular
configuration of spikes 202. For instance, in certain embodiments, the spikes 202 may extend
along an axial direction of the liner hanger 26'. Moreover, in certain implementations, the
different spikes 202 may have different surface geometries without departing from the scope of
the present disclosure. Specifically, a first spike may extend along an outer perimeter of the liner
hanger 26' at a first axial position along the liner hanger 26' and a second spike may extend
along an outer perimeter of the liner hanger 26' at a second axial position along the liner hanger
26'.
The spikes 202 may be formed using any suitable methods known to those of ordinary skill
in the art. For instance, in certain implementations, the spikes 202 may be formed by machining
the hanger body 26'. However, the present disclosure it not limited to machined spikes. In fact,
any suitable methods known to one of ordinary skill in the art may be used to form the spikes
202. For instance, in certain implementations, the spikes 202 may be formed as a separate
structure that can be coupled to the liner hanger 26' using any suitable coupling mechanisms
known to one of ordinary skill in the art. Moreover, any number of spikes 202 may be formed
along the axial direction of the liner hanger 26'. The number of spikes 202 formed along the
axial direction of the liner hanger 26' may depend upon a number of factors such as, for
example, the anchor load that is desired to be reached.
Accordingly, each of the spikes 202 provide a metal-to-metal seal between the liner hanger
26' and the casing 14. In certain implementations, the spikes 202 may have a flat top portion
204. The use of spikes 202 with a flat top portion 204 as opposed to pointed spikes or threads is
beneficial because flat spikes 202 are less sensitive to casing variations and have a higher load
capacity than pointed spikes. The spikes 202 may be symmetrically aligned such that an angle Q
is the same on both sides of each spike 202 as shown in Figure 2. However, in certain
implementations, the angle Qmay be different on the opposing sides of the spike 202 without
departing from the scope of the present disclosure. The angle Qis referred to herein as the "spike
angle." In one embodiment, the spike angle (Q) is selected such that after expansion, the spikes
202 remain substantially normal to the liner hanger 26' body. For instance, in certain
implementations, the spike angle (Q) may be selected to be in a range of from approximately 30°
to approximately 70°.
Moreover, as shown in Figure 2, the dimension d denotes the width of the flat portion 204
of the spike 202 and is referred to herein as the spike width (d) . The spike width (d) may be
selected as desired such that the liner hanger 26' can expand without significant increase in
expansion pressure while maintaining optimum contact area between the spikes 202 and the
casing 14. Specifically, as the spikes 202 are expanded, the flat portion 204 of the spike
interfaces with the inner surface of the casing 14 and will eventually couple the liner hanger 26'
to the casing 14. The spikes 202 may be extended using one or more expansion cones in a
manner similar to that disclosed in conjunction with expanding the seals 28 of Figure 1. As
shown in Figure 2, the spacing between the spikes 202 along the length of the liner hanger 26' is
denoted as "L". The distance between the spikes (L) may be configured such that the
deformation zones in the casing 14 induced by the spikes 202 are isolated. The distance (L) may
be selected to maximize the hanging capacity per spike. The term "hanging capacity" as used
herein refers to the maximum downward load (anchor load) a hanger can carry without inducing
an appreciable relative motion between the hanger 26' and the casing 14 after the hanger is set in
the casing. Accordingly, in certain implementations, it may not be desirable for the distance
between the spikes (L) to fall below a certain threshold value. For instance, in certain
implementations, it may not be desirable for the distance between the spikes (L) to be less than
three times the thickness of the casing 14. Accordingly, the distance (L) between the spikes 202
has an optimum value which is dependent upon a number of factors including, but not limited to,
the outer diameter of the hanger (hanger OD), the hanger wall thickness, the inner diameter of
the casing (casing ID) and the casing wall thickness. Moreover, the available length of the liner
hanger 26' may limit the number of spikes 202 that may be placed thereon. Beyond this optimum
value an increase in the distance (L) will no longer improve the hanging capacity per spike.
The height (H) of the spikes 202 (and their resulting outer diameter (OD)) may be
configured to have dimensions similar to the seals 28. Specifically, in certain implementations,
the height (H) of the spike (also referred to herein as "spike height") must be selected so that it is
between an upper and a lower boundary. The upper spike height boundary may be selected as a
function of the amount of flow area that is desired around the liner hanger 26' and the amount of
possible rubber compression between the liner hanger 26' and the casing 14. In contrast, the
lower spike height boundary may be selected as a function of the amount of rubber compression
desired between the liner hanger 26' and the casing 14. Moreover, if the spike height is too large,
it may destroy downhole equipment as it expands and if the spike height is too low, it wouldn't
be able to support a liner as required. Configuration of the height (H) may cause a significant
deformation of the spikes 202 and an appreciable localized plastic deformation of the casing.
Once the spikes 202 of the liner hanger 26' are expanded, the spikes 202 and the inner diameter
of the casing 14 form multiple metal-to-metal seals. The liner hanger 26' is coupled to the liner
22. Accordingly, the spikes 202 of the liner hanger 26' provide mechanical support for the liner
22.
Figure 3 depicts a partial cross-sectional view of a liner hanger 26" having spikes 302 in
accordance with another implementation of the present disclosure. The spikes 302 may be
configured in the same manner discussed above in conjunction with Figure 2. The spikes 302
may be metal spikes. In certain implementations, each spike 302 may be a circular ring that
extends along an outer perimeter of the liner hanger 26". The spikes 302 may be formed using
any suitable methods known to those of ordinary skill in the art. For instance, in certain
implementations, the spikes 302 may be formed by machining the hanger body 26". Moreover,
any number of spikes 302 may be formed along the axial direction of the liner hanger 26". The
number of spikes 302 formed along the axial direction of the liner hanger 26" may depend upon
a number of factors such as, for example, the anchor load that is desired to be reached.
Accordingly, each of the spikes 302 may provide a metal-to-metal seal between the liner hanger
26" and the casing 14.
In accordance with this implementation, a sealing element may be positioned at a desired
location and utilized in conjunction with the spikes 302. For instance, in certain
implementations, a sealing element 304 may be placed at an axial position on the liner hanger
26" above and/or below the spikes 302. The axial section of the liner hanger that contains the
spikes 302 may be referred to herein as the "spiked portion." In the illustrative embodiment of
Figure 3, a first sealing element 304A and a second sealing element 304B are positioned at distal
ends of the spiked portion. The placement of a sealing element at one or both of the distal ends
of the spiked portion of the liner hanger 26" may provide redundancy and pressure integrity for
the system. This redundancy may be particularly beneficial in instances when one or more of the
leading spikes 302 are damaged when the liner hanger 26" is being directed downhole.
The sealing element 304 may be made of any suitable material, including, but not limited
to, rubber, extremely ductile metals (e.g., AISI type 316L stainless steel), other polymeric
materials, or any other pliable material known to those of ordinary skill in the art. With the liner
hanger spikes 302 in an expanded position, the sealing element 304 reinforces the seal between
the liner 22 and the casing 14. The implementation of Figure 3 may be particularly beneficial in
instances when installed in a large size casing or a galled casing inner diameter having a
pronounced inner diameter weld seam.
Although one sealing element 304 is shown in Figure 3, as would be appreciated by those
of ordinary skill in the art having the benefit of the present disclosure, two or more sealing
elements 304 may be used between the spikes 302 without departing from the scope of the
present disclosure. Moreover, the sealing element 304 may be positioned at any desired location
along the liner hanger 26". For instance, one sealing element 304 may be positioned at an axial
position on the liner hanger 26" uphole relative to the spiked portion and/or one sealing element
304 may be positioned at an axial position on the liner hanger 26" downhole relative to the
spiked portion. In certain implementations, the sealing element 304 may be positioned such that
there are equal number of spikes 302 provided uphole and downhole relative to the sealing
element 304.
The metallic spikes 202, 302 of the improved liner hanger system (26' or 26") are much
less susceptible to degradation than the traditional elastomeric seals 28 when exposed to high
temperatures and/or pressures downhole. Moreover, the flat portion of the spikes 202, 302
minimizes the sensitivity of the liner hanger (26' or 26") to variations for a given weight casing.
Accordingly, the improved liner hanger (26' or 26") provides several advantages. Not only does
it provide an improved anchor load carrying capacity, it reduces the costs associated with
performing operations using a liner hanger. Specifically, the use of metallic spikes instead of
elastomeric seals 28 reduces the need for replacement of elastomeric elements 28 necessitated by
performance of subterranean operations in HTHP environments downhole.
Moreover, the improved liner hanger (26' or 26") reduces the possibility of extruding long
elastomers beyond the standard retainer spikes during expansion of the ELH. Specifically, as the
liner hanger 26" expands, the spikes 302 and the sealing element 304 are also moved until they
touch an Inner Diameter "ID" of the casing 14. As the expansion of the liner hanger 26"
continues, the sealing element 304 is compressed along an axis of the liner hanger 26" and
stretched along the perimeter of the liner hanger 26" due to pressure applied to it by the liner
hanger 26", the inner wall of the casing 14 and the spikes 302 located at its two opposing lateral
ends. Consequently, as the sealing element 304 is compressed, it will eventually spill over the
spikes 302 located at its lateral ends. However, as the spikes 302 are also pushed out by the liner
hanger 26", they cut off the spilled portion of the sealing element 304 and the new compressed
volume of the sealing element is trapped between the liner hanger 26" and the casing 14.
Moreover, the use of expandable spikes (202, 302) in the liner hanger (26' or 26") is
advantageous over using traditional mechanical mechanisms such as, for example, a gauge
hanger. Specifically, in certain implementations, the expandable spikes provide a simple, singlepart
mechanism that forms a reliable and robust seal between the casing and the liner and
supports the liner. Moreover, the use of spikes (202, 302) provides a robust seal in applications
where the inner diameter of the casing 14 is imperfect.
Accordingly, once a wellbore is drilled in a subterranean operation, it may be cased using
methods and systems known to those of ordinary skill in the art. For instance, a casing may be
lowered into the wellbore and cemented in place. A liner coupled to a liner hanger in accordance
with an implementation of the present disclosure may then be lowered downhole through a
casing. Once the liner reaches a desired position downhole, the metal spikes extending along the
perimeter of the liner hanger expand. Once the metal hangers are expanded, the flat portion of
the spikes forms a metal-to-metal seal with an inner surface of the casing. This metal-to-metal
seal couples the liner to the casing.
Although the figures depict embodiments of the present disclosure in a particular
orientation, it should be understood by those skilled in the art that embodiments of the present
disclosure are well suited for use in a variety of orientations. Further, it should be understood by
those skilled in the art that the use of directional terms such as above, below, upper, lower,
upward, downward and the like are used in relation to the illustrative embodiments as they are
depicted in the figures, the upward direction being toward the top of the corresponding figure
and the downward direction being toward the bottom of the corresponding figure.
Therefore, the present disclosure is well adapted to attain the ends and advantages
mentioned as well as those that are inherent therein. The particular embodiments disclosed
above are illustrative only, as the present disclosure may be modified and practiced in different
but equivalent manners apparent to those skilled in the art having the benefit of the teachings
herein. Furthermore, no limitations are intended to the details of construction or design herein
shown, other than as described in the claims below. It is therefore evident that the particular
illustrative embodiments disclosed above may be altered or modified and all such variations are
considered within the scope and spirit of the present disclosure. Also, the terms in the claims
have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the
patentee. The indefinite articles "a" or "an," as used in the claims, are defined herein to mean
one or more than one of the element that the particular article introduces; and subsequent use of the definite article "the" is not intended to negate that meaning.

WHAT IS CLAIMED IS:
1. A system for performing subterranean operations comprising:
a liner hanger positioned within a casing,
wherein the liner hanger comprises a spiked portion having one or more
spikes, wherein the spikes comprise a flat portion,
wherein at least one of the one or more spikes is expandable, and
wherein the flat portion of each of the one or more spikes interfaces with
the casing when the spike is in the expanded position; and
a liner coupled to the liner hanger.
2. The system of claim 1, wherein the one or more spikes extend along an outer
perimeter of the liner hanger.
3. The system of claim 1, wherein the one or more spikes are made from a material
selected from a group consisting of Aluminum, steel, and a combination thereof.
4. The system of claim 1, wherein expanding the one or more spikes couples the
liner hanger to the casing.
5. The system of claim 1, wherein a spike height of the one or more spikes is
selected from a value between an upper spike height boundary and a lower spike height
boundary.
6. The system of claim 1, further comprising a sealing element, wherein the sealing
element is positioned at a distal end of the spiked portion.
7. The system of claim 6, wherein the sealing element is selected from a group
consisting of rubber, polymeric materials and ductile metals.
8. The system of claim 1, wherein the one or more spikes comprise a first spike
positioned at a first axial location along the liner hanger and a second spike positioned at
a second axial location along the liner hanger.
9. A method for coupling a liner to a casing of a cased wellbore in a subterranean
formation comprising:
coupling a liner hanger to the liner,
wherein the liner hanger comprises a spiked portion having a first metal
spike;
lowering the liner and the liner hanger downhole through the casing; and
expanding the first spike,
wherein expanding the first spike couples the liner hanger to the casing.
10. The method of claim 9, wherein a spike height of the first spike is selected from a
value between an upper spike height boundary and a lower spike height boundary.
11. The method of claim 9, further comprising a sealing element, wherein the sealing
element is positioned at a distal end of the spiked portion.
12. The method of claim 9, wherein the spiked portion further comprises a second
metal spike, wherein the first metal spike is positioned at a first axial location along the
liner hanger and the second metal spike is positioned at a second axial location along the
liner hanger.
13. The method of claim 9, wherein the first metal spike is formed by machining.
14. The method of claim 9, wherein the first metal spike is made from a material
selected from a group consisting of Aluminum, steel, and a combination thereof.
15. A system for supporting a liner in a casing comprising:
a liner hanger coupled to the liner;
a first metal spike and a second metal spike formed on a spiked portion of the
liner hanger,
wherein the first metal spike and the second metal spike extend along an
outer perimeter of the liner hanger,
wherein the first metal spike is positioned at a first axial location along the
liner hanger and the second metal spike is positioned at a second axial
location along the liner hanger, and
wherein expanding at least one of the first metal spike and the second
metal spike couples the liner to the casing.
16. The system of claim 15, wherein a spike height of the first metal spike and the
second metal spike is selected from a value between an upper spike height boundary and
a lower spike height boundary.
17. The system of claim 15, further comprising a sealing element, wherein the sealing
element is positioned at a distal end of the spiked portion.
18. The system of claim 17, wherein the sealing element is selected from a group
consisting of rubber, polymeric materials and ductile metals.
19. The system of claim 15, wherein at least one of the first metal spike and the
second metal spike is formed by machining.
20. The system of claim 15, wherein at least one of the first metal spike and the
second metal spike is made of a material selected from a group consisting of Aluminum,
steel, and a combination thereof.