Note: Descriptions are shown in the official language in which they were submitted.
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PLUG AND ABANDONMENT SYSTEM
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority to U.S. Patent Application Serial Number
13/330,415 filed
December 19, 2011, which is incorporated herein by reference.
BACKGROUND
The present disclosure relates generally to wellbore operations and, more
particularly, to a plug and abandonment system.
Open hole plug and abandonment cement plugs require a reliable fundament to
achieve successful separation of fluids. Conventional products may only
separate the fluids and
may not be able to hold any differential pressure that can occur due to losses
and weight
changes. For horizontal wells, the adequacy of conventional products is
particularly
questionable.
Well integrity has become more and more highlighted in the industry, and a
reliable solution to overcome the above issue is needed. There is a need to
have a reliable base
for plug and abandonments in open hole and cased hole that will be able to
hold differential
pressure and avoid losses to the formation, in addition to being able to
separate fluids. And, in
cases of nearby wells, there is a need for ensuring isolation of water
breakthrough because of
nearby production.
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BRIEF DESCRIPTION OF THE DRAWING(S)
Some specific exemplary embodiments of the disclosure may be understood by
referring, in part, to the following description and the accompanying
drawings.
Figure 1 illustrates a plug and abandonment system, in accordance with certain
embodiments of the present disclosure.
Figures 2A and 2B respectively illustrate a plug of the plug and abandonment
system in inactivated and activated states, in accordance with certain
embodiments of the present
disclosure.
Figure 3 illustrates the plug and abandonment system in an activated state, in
accordance with certain embodiments of the present disclosure.
Figure 4 illustrates the plug and abandonment system at the cementing stage,
in
accordance with certain embodiments of the present disclosure.
Figures 5A and 5B illustrate one exemplary disconnect tool, in accordance with
certain embodiments 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.
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DETAILED DESCRIPTION OF THE DISCLOSURE
The present disclosure relates generally to wellbore operations and, more
particularly, to a plug and abandonment system.
Illustrative embodiments of the present disclosure are described in detail
herein.
In the interest of clarity, not all features of an actual implementation may
be 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 specific
implementation goals, 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.
Certain embodiments according to the present disclosure may provide a plug and
abandonment system that may provide for plug placement, activation, and
release. The plug and
abandonment system may allow for fluid bypass and circulation in an
inactivated state, and may
be used to create a false well bottom in an activated state. Further, the plug
and abandonment
system may aid in setting balanced and competent cement plugs during remedial
and primary
cementing operations and may allow for successful first-attempt plug setting.
Figure 1 illustrates a plug and abandonment system 100 in accordance with
certain embodiments of the present disclosure. In the non-limiting example
depicted, the plug
and abandonment system 100 includes a tubular member 105, which may include or
be coupled
to a workstring. The workstring may include a series of coupled tubular
members (not shown)
coupled in any conventional manner. By way of example without limitation,
adjacent tubular
members may be threadedly connected at corresponding end portions. A
continuous bore may
be defined by the tubular members and the tubular member 105, and may extend
for the length
of the workstring. As depicted, the plug and abandonment system 100 may be
lowered into a
borehole 120, which may be an open borehole or a cased borehole. The tubular
member 105
may be coupled to a disconnect and activation tool 110. In certain
embodiments, the tubular
member 105 may comprise a drill pipe.
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A plug 115 may be coupled to the tubular member 105 via the disconnect and
activation tool 110. The plug 115 may be lowered to any desired position
within the borehole
120, including an off-bottom position. The borehole 120 may contain fluid
disposed about the
plug and abandonment system 100. As shown in Figure 1, with the plug 115 in an
inactivated
state and not sealing the borehole 120, an annulus 121 may be defined between
the plug 115 and
a surface of the borehole 120. In that inactivated state, the plug and
abandonment system 100
may allow for fluid bypass and circulation.
The plug 115 may be formed to have any suitable dimensions in the inactivated
state to fit within various boreholes, depending on the implementation.
However, once activated,
the plug 115 may expand radially to fill the annulus 121. In particular, the
plug 115 may be
capable of being compressed longitudinally (i.e., generally along an axis of
the plug 115) to
change shape and expand radially until its outer surface substantially
sealingly contacts the
surface of the borehole 120. It should be recognized that the plug 115 may be
made of different
materials, shapes, and sizes.
Figures 2A and 2B respectively show an exemplary plug 115 of the plug and
abandonment system 100 in an inactivated state and in an activated state, in
accordance with
certain embodiments of the present disclosure. The plug 115 may include a
tubular member 106,
which may be a base pipe in certain embodiments. The plug 115 may include one
or more layers
116. For example without limitation, an inner layer 116A may surround or
partially surround the
tubular member 106. A sleeve 116B may surround or partially surround the inner
layer 116A.
Once the plug 115 has been activated, the sleeve 116B may facilitate the
maintenance of the one
or more layers 116 in the compressed condition. An outer layer 116C may
surround or partially
surround the sleeve 116B. The inner layer 116A and outer layer 116C may
include an elastomer
material in certain embodiments. The sleeve 116B may include steel in certain
embodiments. In
other various embodiments, one or more of the inner layer 116A, sleeve 116B,
and outer layer
116C may include any other suitable material that allows for a shape change of
the plug 115 as
disclosed herein. And in alternative embodiments, alternatives to the sleeve
116B (e.g., a
squirrel cage-like structure, or any other suitable structure) may be used to
facilitate the shape
change of the plug 115.
The plug 115 may include a ring 119A disposed about the tubular member 106.
A base 119B may be disposed generally opposite to the ring 119A, relative to
the one or more
layers 116, at a distal portion of the plug 115. The ring 119A may slidingly
engage the tubular
member 106 so that, with a suitable force applied to the ring 119A, the ring
119A may slide
along the tubular member 106 and compress the one or more layers 116 against
the base 119B so
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that the one or more layers 116 expand radially, as illustrated in Figure 2B.
The ring 119A and
the base 119B may include any suitable material and may have any suitable form
that facilitates
compression of the one or more layers 116 when a suitable force is applied to
the ring 119A.
Figure 3 illustrates the plug and abandonment system 100 in the activated
state, in
accordance with certain embodiments of the present disclosure. As depicted,
the shape change
of the plug 115 accordingly may provide a hydraulic seal against the inner
diameter of the
borehole 120. In this manner, the plug 115 may be set on-demand.
The plug 115 may be fabricated in any suitable mariner so that it can be
coupled
to the disconnect and activation tool 110. The disconnect and activation tool
110 may include an
activation feature 111. The activation feature 111 may include any suitable
means for conveying
a suitable force to compress the plug 115. In certain embodiments, the
activation feature 111
may allow for a pressure inside the tubular 105 to be transferred, directly or
indirectly, to
compress the plug 115. In certain embodiments, the pressure may be
transferred, directly or
indirectly, to the ring 119A of the plug 115 in the non-limiting example
illustrated in Figures 2A
and 2B. In certain embodiments, the activation feature 111 may include an
activation ball or dart
that may be dropped within the tubular member 105 to the activation tool 110.
As such, the
activation feature 111 may be a surface-released, ball-operated or dart-
operated, activation tool.
When the activation ball or dart lands in the disconnect and activation tool
110, a pressure inside
the tubular 105 may be transferred, directly or indirectly, to the compress
plug 115.
With the plug 115 in the activated state as depicted in Figure 3, the plug 115
may
be disconnected from the tubular member 105. Figure 4 illustrates the plug and
abandonment
system 100 at a cementing stage with the plug 115 disconnected from the
tubular member 105, in
accordance with certain embodiments of the present disclosure. With the plug
115 in the
activated state, the tubular member 105 may be pulled a suitable distance away
from the plug
115. Cement 130 may be conveyed via the tubular member 105 to a portion of the
wellbore
above the plug 115 after the separation of the tubular member 105 from the
plug 115 has
occurred. Centralizers (not shown) may be necessary to help hold the tubular
member 105
tubing in place at this stage.
In various embodiments, the disconnect and activation tool 110 may be one of
many types; the particular type may depend on well path, temperature, size,
price, etc. Any
suitable drop-off tool may be used. The disconnect and activation tool 110 may
be a
mechanically operated release device made of steel or composite, for example.
By way of non-
limiting example, the disconnect and activation tool 110 may be ball-operated
or dart-operated.
A ball or a dart may be dropped into the work string and displaced to the
disconnect and
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activation tool 110. With suitable pressure applied from the behind to
displace the ball or dart,
the disconnect and activation tool 110 may be activated to disconnect the plug
from the tubular
105. In certain embodiments, the disconnect and activation tool 110 may be
connected to the
plug 115 with a mechanical locking mechanism. In various embodiments, the
disconnect and
activation tool 110 may be adapted to either be retrieved to the surface with
the tubular member
105 or to remain with the plug 115 downhole. Certain non-limiting details of
exemplary tool
structure and operation are provided in U.S. Patent No. 6,772,835, which is
hereby incorporated
by reference in its entirety for all purposes.
By way of example without limitation, Figures 5A and 5B illustrate one
disconnect and activation tool 110, in accordance with certain embodiments of
the present
disclosure. Figure 5A shows the disconnect and activation tool 110 in the
connected state; and
Figure 5B shows the disconnect and activation tool 110 in the disconnected
state. The
disconnect and activation tool 110 comprises an upper body member 124 that may
be coupled to
the tubular member 105 and a lower body member 126 that may be coupled to the
plug 115. The
two body members are quick-releasably coupled together, and the upper member
124 defines a
seat for receiving a flow prevention tool. The flow prevention tool may be a
releasing dart or a
ball. The flow prevention tool may be a ball valve as disclosed in U.S. Patent
No. 7,472,752,
which is hereby incorporated by reference in its entirety for all purposes.
The seat has a greater
diameter than the ball valve so as to allow the latter ball valve to pass
through the disconnect
110.
In certain embodiments, the plug 115 may include a swellable material. The
swellable material may be able to close gaps that tend to form. For example,
gaps may form
over time due to formation changes that can occur due to faulting, depletion
shrinkage, or
stresses. In certain embodiments, the swellable material may expand to
increase the sealing
contact between the plug 115 and the borehole 120. In general, the plug 115
generally should
remain dormant until the activation agent is introduced to the swellable
material. The term
"swellable" is used herein to indicate an increase in volume of a material.
Typically, this
increase in volume is due to incorporation of molecular components of a fluid
into the swellable
material itself, but other swelling mechanisms or techniques may be used, if
desired. The
swellable material may swell when contacted by an activating agent, such as an
inorganic or
organic fluid. In one embodiment, a swellable material may be a material that
swells upon
contact with and/or absorption of a hydrocarbon, such as oil. In another
embodiment, a
swellable material may be a material that swells upon contact with and/or
absorption of an
aqueous fluid.
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Suitable swellable materials include, but are not limited, to those disclosed
in U.S.
Patent Nos. 3,385,367; 7,059,415; and 7,143,832; the entire disClosures of
which are
incorporated by reference. Some exemplary swellable materials may include, but
are not limited
to, elastic polymers, such as EPDM rubber, styrene butadiene, natural rubber,
ethylene propylene
monomer rubber, ethylene-propylene-copolymer rubber, ethylene propylene diene
monomer
rubber, ethylene-propylene-diene terpolymer rubber, ethylene vinyl acetate
rubber, hydrogenized
acrylonitrile butadiene rubber, acrylonitrile butadiene rubber, isoprene
rubber, butyl rubber,
halogenated butyl rubber, brominated butyl rubber, chlorinated butyl rubber,
chlorinated
polyethylene, chloroprene rubber and polynorbornene. In one embodiment, the
rubber of the
swellable material may also have other materials dissolved in or in mechanical
mixture
therewith, such as fibers of cellulose. Additional options may be rubber in
mechanical mixture
with polyvinyl chloride, methyl methacrylate, acrylonitrile, ethylacetate or
other polymers that
expand in contact with oil. Other swellable materials that behave in a similar
fashion with
respect to hydrocarbon fluids or aqueous fluids also may be suitable. Those of
ordinary skill in
the art, with the benefit of this disclosure, will be able to select an
appropriate swellable material
for use in the present invention based on a variety of factors, including the
desired swelling
characteristics of the swellable material and the environmental conditions in
which it is to be
deployed.
Delay systems may be used to delay the swelling activation in certain
embodiments. For example, swellable material elements may be encapsulated so
that they
generally do not swell until after a delay period after exposure to
hydrocarbon and/or water. The
hydrocarbon is absorbed into the swellable material such that the volume of
the swellable
material increases creating an expansion of the swellable material.
Accordingly, certain embodiments according to the present disclosure may
enable
the placement of a competent plug downhole. Thus, certain embodiments may
ensure well
integrity and may provide reliable plug and abandonment in open hole and cased
hole
implementations. Certain embodiments may provide zonal isolation on demand,
being able to
hold differential pressure and avoid losses to the formation. Certain
embodiments may ensure
isolation of water breakthrough because of production from nearby wells.
Certain embodiments
also may have the swellable feature of closing gaps that may tend to form over
time due to
formation changes. Certain embodiments may avoid the problems of conventional
plugging
approaches that are vulnerable to contamination and disturbance during initial
setting. With
certain embodiments, there is no need for a separate physical barrier between
a cement plug and
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the fluid below the plug, as is needed in conventional operations to prevent
the introduction of
cement slurry into in the fluid.
Even though 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.
Accordingly, 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 "e or an, as used in the claims, are each
defined herein to
mean one or more than one of the element that the article introduces.
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