U.S. patent application number 13/766506 was filed with the patent office on 2013-06-13 for magnetically controlled delivery of subterranean fluid additives for use in subterranean applications.
This patent application is currently assigned to Halliburton Energy Services, Inc.. The applicant listed for this patent is Halliburton Energy Services, Inc.. Invention is credited to Craig W. Roddy.
Application Number | 20130150267 13/766506 |
Document ID | / |
Family ID | 44735960 |
Filed Date | 2013-06-13 |
United States Patent
Application |
20130150267 |
Kind Code |
A1 |
Roddy; Craig W. |
June 13, 2013 |
MAGNETICALLY CONTROLLED DELIVERY OF SUBTERRANEAN FLUID ADDITIVES
FOR USE IN SUBTERRANEAN APPLICATIONS
Abstract
Various compositions are provided herein that include a
composition that includes a well bore treatment fluid and a
magnetically-sensitive component that includes a subterranean fluid
additive. In some instances, the magnetically-sensitive component
may be a ferrogel. In some instances, the ferrogel may include a
polymer matrix and a magnetic species.
Inventors: |
Roddy; Craig W.; (Duncan,
OK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Halliburton Energy Services, Inc.; |
Houston |
TX |
US |
|
|
Assignee: |
Halliburton Energy Services,
Inc.
Houston
TX
|
Family ID: |
44735960 |
Appl. No.: |
13/766506 |
Filed: |
February 13, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12887175 |
Sep 21, 2010 |
8424598 |
|
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13766506 |
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Current U.S.
Class: |
507/103 ;
507/203; 507/230; 523/130 |
Current CPC
Class: |
C09K 8/467 20130101;
C04B 40/0641 20130101; E21B 27/00 20130101; C04B 40/0658 20130101;
C09K 8/42 20130101 |
Class at
Publication: |
507/103 ;
507/230; 507/203; 523/130 |
International
Class: |
C09K 8/42 20060101
C09K008/42 |
Claims
1-32. (canceled)
33. A well bore composition comprising: a well bore treatment
fluid; and a magnetically-sensitive component that comprises a
subterranean fluid additive.
34. The well bore composition of claim 33 wherein the
magnetically-sensitive component includes a magnetically activated
device.
35. The well bore composition of claim 33 wherein the
magnetically-sensitive component is a ferrogel.
36. The well bore composition of claim 35 wherein the ferrogel
comprises a polymer matrix and a magnetic species.
37. The well bore composition of claim 33 wherein the subterranean
fluid additive comprises an additive selected from the group
consisting of a cement activator, a crosslinking agent, and a
curing agent.
38. The well bore composition of claim 33 wherein the well bore
treatment fluid is a cement composition.
39. The well bore composition of claim 33 wherein the well bore
treatment fluid is a pill.
40. The well bore composition of claim 33 wherein the well bore
treatment fluid further comprises a consolidating agent.
41. The well bore composition of claim 34 wherein the magnetically
activated device includes a remote control signal source capable of
generating an electromagnetic control signal.
42. The well bore composition of claim 34 wherein the magnetically
activated device is microfabricated.
43. The well bore composition of claim 34 wherein the magnetically
activated device is nanofabricated.
44. The well bore composition of claim 34 wherein the magnetically
activated device comprises at least one selected from the
following: a polymer, a ceramic, a plastic, a dielectric, metals,
and any combination thereof.
45. A well bore composition comprising: a well bore treatment
fluid; and a ferrogel that comprises a subterranean fluid
additive.
46. The well bore composition of claim 45 wherein the ferrogel
comprises a polymer selected from the group consisting of:
poly(vinyl alcohol), chitosan, gelatin, dextran, sodium
polyacrylate, an acrylate polymer, an acrylate copolymer, and any
combination thereof.
47. The well bore composition of claim 45 wherein the ferrogel
comprises a magnetic particle selected from the group consisting
of: an iron particle, a nickel particle, a cobalt particle, a
ferrous material, magnetite, maghemite, an iron oxide nanoparticle,
and any combination thereof.
48. The well bore composition of claim 45 wherein the ferrogel
comprises a magnetic particle having a size range of about 1 nm to
about 1 .mu.m.
49. The well bore composition of claim 45 wherein the well bore
treatment fluid is a cement composition.
50. The well bore composition of claim 49 wherein the ferrogel
comprises a cement activator selected from the group consisting of:
sodium hydroxide, sodium carbonate, an amine compound, calcium,
sodium, magnesium, aluminum, calcium chloride, sodium chloride,
sodium aluminate, magnesium chloride, sodium silicate, and any
combination thereof.
51. A well bore treatment fluid comprising a ferrogel that
comprises a subterranean fluid additive, a polymer matrix, and a
magnetic species.
Description
BACKGROUND
[0001] The present invention relates to subterranean treatment
operations, and more particularly, to providing controlled delivery
of subterranean fluid additives to a well bore treatment fluid
and/or a surrounding subterranean environment using intelligent
materials that respond to a magnetic stimulus to release
subterranean fluid additives downhole in a subterranean
environment.
[0002] Natural resources such as oil and gas located in a
subterranean formation can be recovered by drilling a well bore in
the subterranean formation, typically while circulating a drilling
fluid in the well bore. After the well bore is drilled, a string of
pipe, e.g., casing, can be run in the well bore. The drilling fluid
is then circulated downwardly through the interior of the pipe and
upwardly through the annulus between the exterior of the pipe and
the walls of the well bore, although other methodologies are known
in the art.
[0003] Hydraulic cement compositions are commonly employed in the
drilling, completion and repair of oil and gas wells. For example,
hydraulic cement compositions are utilized in primary cementing
operations whereby strings of pipe such as casing or liners are
cemented into well bores. In performing primary cementing, a
hydraulic cement composition is pumped into the annular space
between the walls of a well bore and the exterior surfaces of a
pipe string disposed therein. The cement composition is allowed to
set in the annular space, thus forming an annular sheath of
hardened substantially impermeable cement. This cement sheath
physically supports and positions the pipe string relative to the
walls of the well bore and bonds the exterior surfaces of the pipe
string to the walls of the well bore. The cement sheath prevents
the unwanted migration of fluids between zones or formations
penetrated by the well bore.
[0004] Hydraulic cement compositions are also commonly used to plug
lost circulation and other undesirable fluid inflow and outflow
zones in wells, to plug cracks and holes in pipe strings cemented
therein and to accomplish other required remedial well
operations.
[0005] After the cement is placed within the well bore a period of
time is needed for the cement to cure and obtain enough mechanical
strength for drilling operations to resume. This down time is often
referred to as "waiting-on-cement." If operations are resumed prior
to the cement obtaining sufficient mechanical strength, the
structural integrity of the cement can be compromised.
[0006] In carrying out primary cementing as well as remedial
cementing operations in well bores, the cement compositions are
often subjected to high temperatures, particularly when the
cementing is carried out in deep subterranean zones. These high
temperatures can shorten the thickening times of the cement
compositions, meaning the setting of the cement takes place before
the cement is adequately pumped into the annular space. Therefore,
the use of set retarding additives in the cement compositions has
been required. These additives extend the setting times of the
compositions so that adequate pumping time is provided in which to
place the cement into the desired location.
[0007] A variety of cement set retarding additives have been
developed and are utilized in oil well cementing, such as sugars or
sugar acids. Hydroxy carboxylic acids, such as tartaric acid,
gluconic acid and glucoheptonic acid are also commonly used in oil
well cementing as retarders. However, if an excess amount of
retarder is used it can over-retard the set of the cement slurry,
thereby causing it to remain fluid for an extended period of time.
This over-retardation can result in an extended waiting-on-cement
time and cause delays in subsequent drilling or completion
activities.
[0008] In a number of cementing applications, aqueous salts have
been utilized as an additive in cement compositions. Certain salts,
such as calcium salts, can act as accelerating agents, which reduce
the setting time of the cement composition in an attempt to
overcome the negative effects of set retarders. However, the
presence of a set and strength accelerating agent, such as calcium
salt, in the cement composition can increase the risk that the
cement composition may thicken or set before placement.
[0009] Given the complexity of the cement chemistry and the large
temperature and pressure gradients present in the well bore, and
the difficulty in predicting the exact downhole temperatures during
the placement and setting of the cement, it can be difficult to
control the retarding additive and accelerating agent to get the
desired setting behavior. There is a need for improved set control
methods, which bring about predictable cement composition setting
times in the subterranean environments encountered in wells. In
particular, it is desirable to develop methods for rapidly setting
cement-based systems whereby the timing of the setting is under the
control of technicians in the field without the risk of premature
setting. Therefore, a cement that can be made to set on demand
within the well bore is desirable. Such cement compositions could
be useful, for example, when lost circulation zones are encountered
in the subterranean formation. Setting a cement composition on
demand to seal off the leak to the lost circulation zone would be
desirable.
[0010] Other subterranean fluids can also benefit from the
initiation of a chemical reaction downhole on demand. For example,
it may be desirable to have a fluid that comprises a polymer
crosslink downhole to form a pill to counteract lost circulation.
The fluid could require less hydrostatic pressure for pumping, and
then crosslink downhole when and where desired to form a more
viscous fluid that may prevent fluid loss. Other downhole fluids
and chemicals may also benefit from the ability to be activated on
demand within a subterranean formation.
SUMMARY OF THE INVENTION
[0011] The present invention relates to subterranean treatment
operations, and more particularly, to providing controlled delivery
of subterranean fluid additives to a well bore treatment fluid
and/or a surrounding subterranean environment using intelligent
materials that respond to a magnetic stimulus to release
subterranean fluid additives downhole in a subterranean
environment.
[0012] In one embodiment, the present invention provides a method
of releasing a subterranean fluid additive in a subterranean
formation comprising: providing a magnetically-sensitive component
that comprises a subterranean fluid additive; providing a magnetic
source; and releasing the subterranean fluid additive in the
subterranean formation from the magnetically-sensitive component
using the magnetic source.
[0013] In one embodiment, the present invention provides a method
comprising: using a magnetic source to release a subterranean fluid
additive in a subterranean formation.
[0014] In one embodiment, the present invention provides a method
of cementing comprising: providing a cement composition that
comprises a magnetically-sensitive component; providing a magnetic
source; releasing a cement activator from the
magnetically-sensitive component using the magnetic source; and
allowing the cement composition to set.
[0015] In one embodiment, the present invention provides a well
bore composition comprising: a well bore treatment fluid; and a
magnetically-sensitive component that comprises a subterranean
fluid additive.
[0016] The features and advantages of the present invention will be
readily apparent to those skilled in the art upon a reading of the
description of the preferred embodiments that follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The following figures are included to illustrate certain
aspects of the present invention, and should not be viewed as
exclusive embodiments.
[0018] FIG. 1 illustrates an example of an embodiment of an example
of a magnetically controlled device.
[0019] FIG. 2 represents a theoretical example of the effect of
magnetic force on a ferrogel and the subterranean fluid additive
release mechanism.
[0020] FIG. 3 represents a theoretical example of a ferrogel
release of a subterranean fluid additive.
DETAILED DESCRIPTION
[0021] The present invention relates to subterranean treatment
operations, and more particularly, to providing controlled delivery
of subterranean fluid additives to a well bore treatment fluid
and/or a surrounding subterranean environment using intelligent
materials that respond to a magnetic stimulus to release
subterranean fluid additives downhole in a subterranean
environment.
[0022] Of the many advantages of the present invention, only a few
of which are discussed or alluded to herein, the present invention
provides for the use of novel intelligent materials for the
magnetically controlled release of subterranean fluid additives to
a well treatment fluid located downhole in a subterranean
formation. The intelligent release materials of the present
invention respond to the use of magnetic forces from a magnetic
source to effect the release of subterranean fluid additives. The
term "magnetic source" as used herein refers to a material or
object that produces a magnetic force. This magnetic force is
invisible, but is responsible for the most notable property of a
magnet: a force that pulls on other ferromagnetic materials like
iron and attracts or repels other magnets. Magnetic stimulation for
release of the subterranean fluid additive is desirable because
magnetic stimulation is an action-at-a-distance force (i.e., a
non-contact force). The novel intelligent materials adaptively
change their physical profiles due to the application of an
external magnetic force, resulting in release of the contained
subterranean fluid additives. This release may be advantageously
employed in downhole applications to affect an immediate change in
a fluid, for example, a cement composition, a gelled fluid, or a
consolidating agent.
[0023] For instance, if the subterranean fluid additive is a cement
activator, upon release, the activator can interact with a cement
slurry in the downhole environment to provide setting of the cement
slurry on demand in a desired location within a well bore or a
subterranean formation. This may be useful to activate hydration of
a cement composition downhole. In certain embodiments of the
present invention, the release of the magnetically-sensitive
component can result in a "flash-set" of at least a portion of the
cement composition. As referred to herein, the teen "flash-set"
will be understood to mean the irreversible setting of at least a
portion of the cement composition within a time in the range of
from about 1 minute to about 5 minutes after contacting the cement
composition with an activator that is released from the
magnetically-sensitive component.
[0024] Similarly, if the subterranean fluid additive is a
crosslinking agent, the crosslinking agent can interact with
polymers in a well bore treatment fluid that comprises
crosslinkable polymer located downhole so as to crosslink those
polymers to create a viscous pill or plug that can prevent fluid
leak-off into the surrounding formation. This may be desirable, for
example, to facilitate the formation of a gelled pill to prevent
fluid loss into an area in a subterranean formation where a thief
zone or a lost circulation zone is present. In counteracting
lost-circulation problems, a lost-circulation pill prepared in
accordance with the present invention may be designed to plug the
perforations or formation interval losing the fluid. The viscous
pill also may be useful to perform a sweep around the well bore to
pick up debris or well bore fill.
[0025] An additional application is where the subterranean fluid
additive is a curing agent for a consolidating agent polymer
located downhole. Such applications may be useful for activating
consolidating agents such as curable resins and tackifiers that may
be used downhole to combat particulate migration. The curing agent
may interact with the consolidating agent polymer so as to activate
the polymer to enable it to consolidate particulates downhole to
prevent their migration to the well bore. Curing or activating the
consolidating agent polymers on-demand with a curing agent of the
present invention may prevent premature curing of the polymer,
which is undesirable.
[0026] Other subterranean applications for which it may be
desirable to contain subterranean fluid additives until a desired
reaction time may also benefit from the intelligent materials and
methods of the present invention.
[0027] The term "well bore treatment fluid" as used herein refers
to a fluid that is present in a subterranean formation. The
subterranean formation may comprise a well bore penetrating that
subterranean formation. The term "in a subterranean formation" and
its derivatives as used herein does not imply any particular
location in the formation other than being subsurface.
[0028] In some embodiments, the magnetically-sensitive component is
a mechanically activated device, a ferrogel, or combination thereof
that contains a subterranean fluid additive for release. Each of
these will be discussed below.
[0029] Suitable mechanically activated devices are those that are
activated by a magnetic force to cause a mechanical release of a
subterranean fluid additive therefrom. An example of a mechanically
activated device is a remotely controlled device that is activated
by a magnetic force generated from a magnetic source so as to
release a contained or enclosed subterranean fluid additive
downhole. By repeating the on-off operation of the magnetic force,
a controllable release of the subterranean fluid additive from the
mechanically activated device can be programmably designed. In an
embodiment, a system includes a remotely, magnetically controlled
device and an associated controller.
[0030] FIG. 1 illustrates an embodiment of an example of a
magnetically activated device. This is merely an example, and
should not be read to incorporate all embodiments of suitable
magnetically activated devices. Shown in FIG. 1 is a body structure
102 adapted for positioning in a subterranean formation, a reaction
region 104 located in the body structure, the reaction region
incorporating a first subterranean fluid additive 106 (shown after
release), and a remotely magnetically activatable control element
108 operably connected to the body structure and responsive to a
magnetic force to release at least a portion of the subterranean
fluid additive 106 from the device. Optionally, an internal space
110 may be located within the device. An embodiment may include a
remote control signal source capable of generating an
electromagnetic control signal sufficient to activate the remotely
activatable control element to release a portion of the
subterranean fluid additive 106. In some embodiments, the reaction
region 104 may be in fluid communication with the surrounding
environment, via an inlet 112 and/or an outlet 114, as shown in
FIG. 1.
[0031] As used herein, the term "remote" refers to the transmission
of information (e.g., data or control signals) or power signals or
other interactions between the remote controller or the reaction
system without a connecting element such as a wire or cable linking
the remote controller and the reaction system, and does not imply a
particular spatial relationship between the remote controller and
the reaction device, which may, in various embodiments, be
separated by relatively large distances (e.g., greater than about a
meter) or relatively small distances (e.g., less than about a
meter). In addition, remote control of the magnetically-sensitive
component may be accomplished through the use of a wireless network
system, for example, as that taught in U.S. Pat. No. 6,985,750, the
entirety of which is hereby incorporated by reference.
[0032] According to various embodiments, a mechanically activated
device is placed in an environment in order to initiate a chemical
reaction in that environment. Exemplary environments include a
subterranean formation, for example, to activate a cement
composition, crosslink a polymer, or cure a consolidating
agent.
[0033] Suitable mechanically activated devices may be placed
downhole, for example, in a fluid or via a wireline or other
suitable carrier. The structure of the device may be adapted for a
specific environment. The size, shape, and materials of the
structure influence suitability for a particular environment. For
use in a subterranean environment, the device may be designed to
withstand environmental conditions such as temperature, pressure,
chemical exposure, erosion, abrasion, and other mechanical
stresses. Moreover, the device may include features that allow it
to be placed or positioned in a desired location in the
subterranean formation, or targeted to a desired location in the
subterranean formation. Such features may include size and shape
features, tethers, or gripping structures to prevent movement of
the device in the environment (in the case that the device is
placed in the desired location) or targeting features (surface
chemistry, shape, etc.) that may direct the device toward or cause
it to be localized in a desired location in the subterranean
formation.
[0034] Small devices may be constructed using methods known to
those having ordinary skill in the art of microfabrication or
nanofabrication. In applications where size is not a constraint, a
wide variety of fabrication methods may be employed.
[0035] In some embodiments, a mechanically activated device may be
formed entirely of a magnetically or an electrically responsive
material or structure. In other embodiments, a mechanically
activated device may include multiple magnetically responsive
components (e.g., ferrous particles). For example, the mechanically
activated devices may comprise ferrous materials, magnetite
(Fe.sub.3O.sub.4), maghemite (Fe.sub.2O.sub.3), iron oxide
nanoparticles, and combinations thereof, so as to respond to a
magnetic force.
[0036] In selected embodiments, a magnetic field, an electric
field, or electromagnetic control signal may be used to activate
the mechanically activated device. The response of the mechanically
activated device may include, but is not limited to, one or more
of: heating, cooling, vibrating, expanding, stretching, unfolding,
contracting, deforming, softening, or folding. The mechanically
activated device may include various materials, such as polymers,
ceramics, plastics, dielectrics or metals, or combinations thereof.
The mechanically activated device may include a shape memory
material such as a shape memory polymer or a shape memory metal, or
a composite structure such as a bimetallic structure. The
mechanically activated device may include a magnetically or
electrically active material. Examples of magnetically active
materials include permanently magnetizable materials, ferromagnetic
materials such as iron, nickel, cobalt, and alloys thereof,
ferrimagnetic materials such as magnetite, ferrous materials,
ferric materials, diamagnetic materials such as quartz,
paramagnetic materials such as silicate or sulfide, and
antiferromagnetic materials such as canted antiferromagnetic
materials which behave similarly to ferromagnetic materials;
examples of electrically active materials include ferroelectrics,
piezoelectrics and dielectrics. In some embodiments, the remotely
activatable control element may include a ferrogel.
[0037] Suitable examples of mechanically activated devices that
might be adapted for use in subterranean applications for the
release of subterranean fluid additives are described herein in
U.S. Patent Application Publication No. 2007/0106331, the entirety
of which is hereby incorporated by reference.
[0038] In some embodiments, the magnetically-sensitive component is
a magnetically controlled ferrogel comprising a subterranean fluid
additive, whereby an external magnetic field can be used to control
the release of the subterranean fluid additive from the ferrogel to
the surrounding environment, for example, a well treatment fluid
for initiating a desired result. The term "ferrogel" as used herein
refers to a magnetically-sensitive polymer gel. The
three-dimensional network structure of a ferrogel is believed to be
formed from hydrogen-bond-bridges or polymer microcrystals within
the gel structure. Magnetically-sensitive hydrogels can undergo
quick, relatively controllable changes in shape when subjected to
magnetic force because of the presence of the magnetic particles
within the gel particles. When subjected to a magnetic force, the
magnetic particles align so as to change the shape and/or internal
molecular configuration of the ferrogel, releasing at least some of
the subterranean fluid additive from the ferrogel into the desired
well treatment fluid or area of a subterranean formation. In an
embodiment, a ferrogel that may be used comprises a subterranean
fluid additive, a polymer matrix, and magnetic particles.
[0039] While not wishing to be limited by any particular theory as
to how the ferrogels function to release the subterranean fluid
additive, FIG. 2 shows a possible release mechanism of the
subterranean fluid additive from the ferrogel when subjected to
magnetic force. As shown in 202, when there is no magnetic force,
the magnetic particles are randomly oriented within the polymer
matrix, and the diffusion mechanism is based on the diffusion of
the subterranean fluid additive through the polymer matrix. This
diffusion may be related to the dissolution of the polymer matrix
under downhole conditions, and the inherent diffusion rate of the
subterranean fluid additive within the polymer matrix. When a
magnetic applied, the magnetic moments of the magnetic particles
align, generally along the magnetic fields, and are thought to
produce a bulk magnetic moment. This is thought to induce the
Fe.sub.3O.sub.4 particles within the ferrogel to aggregate together
instantly, leading to a rapid decrease in the porosity of the
ferrogel leading to a "closed configuration" as shown in 204. This
closed configuration may reduce the inherent diffusion rate of the
subterranean fluid additive from the ferrogel by confining the
subterranean fluid additive within the network of the ferrogel. The
closed configuration may also exhibit a decreased swelling ratio.
When the magnetic force is removed, as shown in 206, the closed
pores reopen allowing the subterranean fluid additive to move to
the surfaces of the ferrogel, resulting in a burst release of the
subterranean fluid additive. After the burst release, it is
believed that the diffusion rate of the subterranean fluid additive
from the ferrogel may be reduced to a normal diffusion profile. By
repeating the on-off operation of the magnetic field, a
controllable release of the subterranean fluid additive from the
ferrogel can be programmably designed. The time spent switching
between the on and off position of the magnetic force can control
the release profile of the subterranean fluid additive.
[0040] FIG. 3 illustrates another hypothetical release mechanism
for the ferrogels. In FIG. 3, a schematic drawing of a ferrogel
structure shows iron oxide particles 302, a polymer matrix 304, and
subterranean fluid additive molecules 306. When a high frequency
magnetic field is applied, the iron oxide particles 302 provide
heat energy 308 to release the structures and twist and shake the
polymer matrix to effectively accelerate release of the
subterranean fluid additive 306. The bursting release of the
subterranean fluid additive from the ferrogel is indicative of a
mixture of mechanical actions imposed by the ferrogels, which may
include, but are not limited to, (1) an "open" configuration of the
network structure, and (2) an elastic deformation (i.e.,
contractile deformation) of the ferrogels, while being subject
instantly to the high frequency magnetic field stimulus. Under high
frequency magnetic force, the nanomagnets are activated kinetically
and possibly thermally (for larger nanoparticles), and they
transform the structural or molecular configurations of the
ferrogels upon microstructural deformation (shrinking) of the
polymer matrix.
[0041] Suitable polymers for use in the polymer matrixes of the
ferrogels include, but are not limited to, poly(vinyl alcohol)
("PVA"), chitosan, gelatin, dextran, sodium polyacrylate, and
acrylate polymers, and copolymers with an abundance of hydrophilic
groups. PVA may be especially suitable because it displays
amphoteric characteristics and can be applied in aqueous
environments as well as in organic solvents for the encapsulation
of subterranean fluid additives. Moreover, PVA may act as a sort of
dispersing agent within the ferrogels to more uniformly disperse
the magnetic particles therein.
[0042] Suitable magnetic particles include, but are not limited to,
particles that may be incorporated within a ferrogel so as to allow
the ferrogel to respond to a magnetic force so as to release a
subterranean fluid additive from the ferrogel to a desired well
bore treatment fluid or subterranean environment. Such particles
commonly consist of magnetic elements such as iron, nickel and
cobalt and their chemical compounds. Specific examples include, but
are not limited to, ferrous materials, magnetite (Fe.sub.3O.sub.4),
maghemite (Fe.sub.2O.sub.3), iron oxide nanoparticles, and
combinations thereof. In an embodiment, the particles are sized to
be present in an adequate concentration within the ferrogel to
allow the ferrogel to respond to the magnetic force while also
allowing for a sufficient concentration of the subterranean fluid
additive to be present therein.
[0043] In some embodiments, the magnetic particles are nano-sized
or micro-sized. If nanoparticles are used, suitable sizes for the
magnetic particles may be, for example, (1) larger diameter
(150-500 nm), (2) medium diameter (40-60 nm), or smaller diameter
(5-10 nm). However, it is understood that the magnetic particles
may comprise any suitable size or range of sizes within the range
of from about 1 nm to about 1 .mu.m. In some embodiments, the
magnetic particles may be larger than about 1 .mu.m. The magnetic
particles may be fabricated from an in situ coprecipitation
process. The size of the magnetic particles may affect the quantity
and release profile of the subterranean fluid additive.
[0044] To determine the concentration of the subterranean fluid
additive in a ferrogel for use in the methods of the present
invention, a controlled release model may be developed. A release
model may be realized with a predetermined release amount of the
subterranean fluid additive, either as a membrane or a bulk
structural configuration, via internally or externally magnetically
triggered operations. In general, enough subterranean fluid
additive should be used to provide the necessary action downhole
relative to the treatment fluid. Considerations include, but are
not limited to, the inherent diffusion rate as well as the burst
release concentration and any subsequent diffusion of the
subterranean fluid additive. Particle size and microstructural
variations in the ferrogels may affect their release profile.
[0045] The magnetic-sensitive behaviors in the ferrogels may be
further expressed by the difference in the permeated subterranean
fluid additive amount between the magnetic force in an "off" mode
and in an "on" mode. The magnetic force can be alternately switched
on and off cyclically during a single operation to achieve a
desired release rate and profile. The time period between the on
and off modes may be referred to as a switching duration. The
length of the switching duration may affect the release of the
subterranean fluid additive from the ferrogels. Cyclic release
rates may allow the subterranean fluid additive to reach a
kinetically favorable distribution in the ferrogel for a subsequent
burst release.
[0046] Some ferrogels that can be adapted for use in subterranean
applications for the release of subterranean fluid additives are
described herein in U.S. Patent Application Publication Nos.
2009/0258073 and 2007/0106331, the entirety of each is hereby
incorporated by reference. Other references that describe ferrogels
include the following: Hu, et al., "Controlled Pulsatile Drug
Release from a Ferrogel by a High-Frequency Magnetic Field,"
Macromolecules 2007, 40, 6786-6788; Filipcsei, et al., "Magnetic
Field-Responsive Smart Polymer Composites," Adv. Polymer Sci.
(2007) 206: 137-189; and Lui, et al., "Magnetic-Sensitive Behavior
of Intelligent Ferrogels for Controlled Release of Drug," Langmuir
(2006), 22, 5974-5978, the entirety of each is hereby incorporated
by reference. Suitable subterranean fluid additives for use in the
present invention include, but are not limited to, additives that
are useful in downhole operations for causing a rapid reaction in
the context of a treatment fluid. Examples include, but are not
limited to, cement activators, crosslinking agents, and curing
agents for curable consolidating agents. The term "subterranean
fluid additive" as used herein refers to a subterranean fluid
additive that has utility in subterranean applications.
[0047] Examples of suitable cement activators include, but are not
limited to, sodium hydroxide, sodium carbonate, an amine compound,
calcium, sodium, magnesium, aluminum, calcium chloride, sodium
chloride, sodium aluminate, magnesium chloride, sodium silicate, or
any combination thereof. An example of a suitable calcium salt is
calcium chloride. Examples of suitable sodium salts are sodium
chloride, sodium aluminate, and sodium silicate. An example of a
suitable magnesium salt is magnesium chloride. Other activators may
include seawater and those known in the art. The choice of a proper
cement activator will be made in consideration for the chemical
composition of the cement composition being set.
[0048] In certain embodiments of the present invention wherein the
cement composition is intended to flash-set, activators that may be
particularly suitable may include, inter alia, sodium hydroxide,
sodium carbonate, potassium carbonate, bicarbonate salts of sodium
or potassium, sodium silicate salts, sodium aluminate salts,
ferrous and ferric salts (e.g., ferric chloride and ferric
sulfate), polyacrylic acid salts, and the like. In certain
embodiments of the present invention, activators such as calcium
nitrate, calcium acetate, calcium chloride, and calcium nitrite may
be used to cause the cement composition to flash-set, though the
concentration of these activators that may be required in order to
cause such flash-setting may be greater than the concentration
required for the other activators described herein, and their
equivalents. One of ordinary skill in the art, with the benefit of
this disclosure, will be able to identify an activator
concentration sufficient to cause flash-setting of a cement
composition.
[0049] The amount of activator generally required is an amount that
is sufficient to cause the cement composition to set within a time
in the range of from about 1 minute to about 2 hours after
contacting the activator. In certain embodiments wherein the
activator is sodium chloride, the desired effective concentration
may be in the range of from about 3% to about 15% by weight of the
water in the cement composition. In certain embodiments wherein the
activator is calcium chloride, the desired effective concentration
may be in the range of from about 0.5% to about 5% by weight of the
water in the cement composition.
[0050] Although the compositions and methods of the present
invention may be useful in conjunction with any cement composition
that is used in a subterranean application, examples of cement
compositions that may be used in conjunction with the present
invention include hydraulic cement compositions. These are
typically used in the form of an aqueous slurry of hydraulic cement
with a concentration of retarder mixed in the aqueous slurry to
control or delay the cement setting time so that it exceeds the
pumping time with an adequate safety margin. Sufficient water is
added to the slurry to make the composition pumpable. Such
hydraulic cements, include, but are not limited to, Portland
cements, pozzolana cements, gypsum cements, high-alumina-content
cements, slag cements, silica cements, and combinations thereof. In
certain embodiments, the hydraulic cement may comprise a Portland
cement. The Portland cements that may be suited for use in
exemplary embodiments of the present invention are classified as
Class A, C, H and G cements according to American Petroleum
Institute, Recommended Practice for Testing Well Cements, API
Specification 10B-2 (ISO 10426-2), First edition, July 2005.
[0051] Other additives suitable for use in subterranean cementing
operations also may be added to embodiments of the cement
compositions, in accordance with embodiments of the present
invention. Examples of such additives include, but are not limited
to, strength-retrogression additives, set accelerators, set
retarders, weighting agents, lightweight additives, gas-generating
additives, mechanical property enhancing additives,
lost-circulation materials, filtration-control additives, a fluid
loss control additive, dispersants, defoaming agents, foaming
agents, thixotropic additives, and combinations thereof. By way of
example, the cement composition may be a foamed cement composition
further comprising a foaming agent and a gas. Specific examples of
these, and other, additives include crystalline silica, amorphous
silica, fumed silica, salts, fibers, hydratable clays, calcined
shale, vitrified shale, microspheres, fly ash, slag, diatomaceous
earth, metakaolin, rice husk ash, natural pozzolan, pumicite,
perolite, zeolite, cement kiln dust, lime, elastomers, resins,
latex, combinations thereof, and the like. A person having ordinary
skill in the art, with the benefit of this disclosure, will readily
be able to determine the type and amount of additive useful for a
particular application and desired result.
[0052] Another subterranean fluid additive that may be useful in
the present invention is a crosslinking agent that when released,
crosslinks a gelled fluid downhole so as to increase its viscosity
to form a pill. This "pill" can be useful to control fluid loss or
prevent further leak-off into a particular area in a formation. The
pill may have a traditional pill form, or it may form a type of
plug. These gelled fluids may be aqueous-based fluids that comprise
a gelling agent, which may be crosslinked. These gelling agents may
be biopolymers or synthetic polymers. Common biopolymer gelling
agents include, e.g., galactomannan gums, cellulosic polymers, and
other polysaccharides. Because of their cost and effectiveness,
biopolymers are most commonly used. However, in high temperature
applications, these gelling agents can degrade, which can cause the
viscosified treatment fluid to prematurely lose viscosity. Various
synthetic polymer gelling agents have been developed for use in
viscosified treatment fluids. The choice of a particular
crosslinking agent to include will depend on the gelling agent
polymer present in the gelled fluid downhole. Suitable crosslinking
agents may include boron-based crosslinking agents, zirconium-based
crosslinking agents and titanium-based crosslinking agents.
Hafnium-based crosslinking agents also may be suitable.
Zirconium-based commercially available crosslinking agents suitable
for use in this invention include those available under the trade
names "CL-23" and "CL-24," which are both available from
Halliburton in Duncan, Okla.
[0053] In certain embodiments, the crosslinking agent may be
included in a magnetically-sensitive component in an amount in the
range of from about 0.02% to about 1.2% by volume of the aqueous
base fluid, more preferably in the amount of about 0.5%.
[0054] Another subterranean fluid additive that may be suitable for
use in the present invention is a curing agent (also known as a
polymerization initiator) for a consolidating agent downhole to
control, for example, particulate migration downhole. Sand
consolidation is a near well bore treatment of a well to be tested
or placed in production. Surrounding a well bore in many instances
are incompetent highly porous and fragmentable sand or particulate
formations. Under production conditions, the particulate is often
displaced from its aggregated structure and carried along by a
fluid flowing to a producing well. If the particulate flow is
allowed to proceed unchecked the producing well bore soon becomes
full of sand, thereby clogging oil production. Furthermore,
particulate arriving at the surface of the well can cause wear to
the production hardware.
[0055] Suitable consolidating agents comprise curable resins;
tackifying agents; or a getable liquid compositions. Examples of
curable resins that can be used in the present invention include,
but are not limited to, organic resins such as polyepoxide resins
(e.g., bisphenol A-epichlorihydrin resins), polyester resins,
urea-aldehyde resins, furan resins, urethane resins, and mixtures
thereof. Some suitable resins, such as epoxy resins, may be cured
with an internal catalyst or activator so that when pumped down
hole, they may be cured using only time and temperature. Other
suitable resins, such as furan resins generally require a
time-delayed catalyst or an external catalyst to help activate the
polymerization of the resins if the cure temperature is low (i.e.,
less than 250.degree. F.), but will cure under the effect of time
and temperature if the formation temperature is above about
250.degree. F., preferably above about 300.degree. F.
[0056] Generally, a curing agent used is included in an amount in
the range of from about 5% to about 75% by weight of the curable
resin. In some embodiments of the present invention, the resin
curing agent used is included in the curable resin composition in
an amount in the range of from about 20% to about 75% by weight of
the curable resin.
[0057] The magnetic force used to activate the release mechanism of
the magnetically-sensitive components described herein may be
generated from any suitable magnetic source.
[0058] In some embodiments, the magnetic force is generated from an
electromagnetic, for example, an electromagnet that is placed on a
wireline and run downhole through casing. The electromagnet may
also be pulled up through the casing. The magnetic force may also
be generated from a more permanent magnet located on the casing or
a portion of the cement shoe. In such embodiments, it may be
possible to pump a cement composition past the downhole magnetic
source near the casing or shoe so that the cement is then
activated. The activated cement composition can then be pumped
further to its desired location and allowed to set. In such
embodiments, the additional pumping time after activation is taken
into account so that the cement composition does not prematurely
set before desired placement. In other embodiments, the magnetic
source may be located at the well site above-ground. In such
instances, the activated species may be activated on-the-fly and
pumped downhole.
[0059] In some embodiments, the magnetic force may be generated by
applying a current to an electromagnetic coil. In other
embodiments, the magnetic force may be applied by a magnetic
circuit.
[0060] Other examples of tools that contain magnetic sources that
may be used to activate the release mechanism of the
magnetically-sensitive components include, but are not limited to,
MRI tools, solenoid actuators, and magnetic couplings. Examples of
such downhole tools may include, but are not limited to,
subterranean logging devices, flow meters, formation evaluation
tools, directional drilling equipment, directional or other survey
instruments, coils, gyroscopic apparatus, MRI tools,
photo-multipliers, casing or tubing collar locators, information
gathering and/or transmitting devices and various electrical
tools.
[0061] In some embodiments, the source of the magnetic force may be
located within a plug that is pumped down a casing, for example, a
cementing plug. In this example, as the cementing plug proceeds
downhole, the magnetic force activates the cement slurry by
releasing a cement activator from a magnetically-sensitive
component located downhole.
[0062] In some embodiments, the present invention provides a method
comprising: using a magnetic force to release a subterranean fluid
additive downhole.
[0063] In some embodiments, the present invention provides a method
of releasing a subterranean fluid additive in a subterranean
formation comprising: providing a magnetic source and a
magnetically-sensitive component that comprises a subterranean
fluid additive; and releasing the subterranean fluid additive in
the subterranean formation from the magnetically-sensitive
component using a magnetic force generated from the magnetic
source.
[0064] In some embodiments, the present invention provides a method
comprising: placing a magnetic source in a well bore penetrating a
subterranean formation; and releasing a subterranean fluid additive
in the subterranean formation from a magnetically-sensitive
component using a magnetic force generated from the magnetic
source.
[0065] In some embodiments, the present invention provides a method
comprising: placing a ferrogel in a subterranean formation.
[0066] In some embodiments, the present invention provides a method
comprising: placing a remotely, magnetically controlled device and
an associated controller in a subterranean formation.
[0067] In some embodiments, the present invention provides well
bore treatment fluids that include a ferrogel comprising a well
bore subterranean fluid additive, a polymer matrix, and a magnetic
species.
[0068] In some embodiments, the present invention provides well
bore treatment fluids that include a magnetically-sensitive
component comprising a subterranean fluid additive.
[0069] In some embodiments, the present invention provides a method
of cementing in a subterranean formation: introducing a cement
composition into the subterranean formation, wherein the cement
composition comprises cement, a retarder, and water; providing a
magnetic source and a magnetically-sensitive component that
comprises a subterranean fluid additive; introducing the
magnetically-sensitive component into the subterranean formation;
releasing the subterranean fluid additive from the
magnetically-sensitive component using a magnetic force generated
from the magnetic source, wherein the subterranean fluid additive
activates hydration of the cement; and allowing the cement
composition to set in the subterranean formation. In some
embodiments, the cement composition is placed in an annulus between
casing and the subterranean formation, and is allowed to set
therein.
[0070] In some embodiments, the present invention provides a method
of forming a crosslinked pill in a subterranean formation:
introducing a fluid comprising a crosslinkable polymer into the
subterranean formation; providing a magnetic source and a
magnetically-sensitive component that comprises a subterranean
fluid additive; introducing the magnetically-sensitive component
into the subterranean formation; releasing the subterranean fluid
additive from the magnetically-sensitive component using a magnetic
force generated from the magnetic source, wherein the subterranean
fluid additive activates crosslinking of the polymer; and allowing
a crosslinked pill to form.
[0071] In some embodiments, the present invention provides a method
of consolidating particulates in a subterranean formation:
introducing a fluid comprising a curable consolidating agent into
the subterranean formation; providing a magnetic source and a
magnetically-sensitive component that comprises a subterranean
fluid additive that comprises a curing agent; introducing the
magnetically-sensitive component into the subterranean formation;
releasing the subterranean fluid additive from the
magnetically-sensitive component using a magnetic force generated
from the magnetic source; and allowing the consolidating agent to
cure.
[0072] In some embodiments, the present invention provides a method
of calculating the diffusion of a subterranean fluid additive from
a ferrogel using a diffusion coefficient corresponding to the
diffusion and release rate of the subterranean fluid additive from
the ferrogel into a fluid located in a subterranean formation.
[0073] To facilitate a better understanding of the present
invention, the following examples of preferred embodiments are
given. In no way should the following examples be read to limit, or
to define, the scope of the invention.
EXAMPLES
[0074] A suitable ferrogel for use in the present invention may be
prepared according to the following prophetic method involving a
freezing-thawing technique.
[0075] First, 5 wt % PVA with a molecular weight of about 72,000,
and a degree of hydrolyzation of about 97.5% to about 99.5% is
dissolved in 10 ml of dimethyl sulfoxide ("DMSO") at 80.degree. C.
under stirring for 6 hours and then mixed with 17 wt % of magnetic
particles at 60.degree. C. under ultrasonication for 6 h to ensure
that the magnetic particles are well dispersed. The resulting
solution is then poured into a plastic dish and frozen at
-20.degree. C. for 16 h. Subsequently, the gels are then thawed at
25.degree. C. for 5 h. This cyclic process including freezing and
thawing is repeated 5 times. The resulting ferrogels are then
washed to removed DMSO. This is done by washing the ferrogels 5
times and then immersing them in water for 24 h. The ferrogels can
be stored at 4.degree. C. until they are used or tested.
[0076] The diffusion coefficients for the ferrogels may be measured
using this prophetic procedure. The diffusion coefficients can be
measured using a switching magnetic force (400 Oe) in a diffusion
diaphragm cell (a side-by-side cell). The solution in the donor
side is a 80 ml of an isotonic phosphate buffer ("PBS") (pH of 7.4)
containing 200 ppm of the subterranean fluid additive. The receptor
compartment, separated by the ferrogel, is tilled with 80 ml of PBS
solution. The concentration of each compound in the receptor
compartment can be determined to by .lamda.=361 nm using a UV
spectrophotometer. The diffusion coefficient can be calculated
according to the following equation for the diaphragm cell:
In(C.sub.d0/(C.sub.d-C.sub.r))=2PAt/.delta. V Equation 1
Where C.sub.d0 is the initial concentration of the permeant in the
donor compartment; C.sub.d and C.sub.r are indicative of the
concentrations in the donor side and the receptor side,
respectively; P is the permeability coefficient (cm2/min); A is the
effective area of the ferrogel; .delta. is the thickness of the
ferrogel; V are respectively the volumes of solution in the donor
and receptor compartment (both are 80 ml above). By plotting
ln(C.sub.d0/(C.sub.d-C.sub.r)) versus time (t), the permeability
coefficient (P) can be calculated from the slope of the line by
Equation 1. Data points may be averaged to form the plot.
[0077] A prophetic cementing example of the present invention
includes providing a cementing composition that comprises a cement,
water, a ferrogel including a cement activator, and optionally a
set retarder; and pumping the cement composition into the annulus
of a well bore located between the casing and the surrounding
subterranean formation. Thereafter, at a desired time, a magnetic
force is used to activate the ferrogel, enabling a release of the
activator to the cement composition so that the cement composition
is activated to set in a desired portion of the annulus.
[0078] Therefore, the present invention 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 invention 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, combined,
or modified and all such variations are considered within the scope
and spirit of the present invention. While compositions and methods
are described in terms of "comprising," "containing," or
"including" various components or steps, the compositions and
methods can also "consist essentially of" or "consist of" the
various components and steps. All numbers and ranges disclosed
above may vary by some amount. Whenever a numerical range with a
lower limit and an upper limit is disclosed, any number and any
included range falling within the range is specifically disclosed.
In particular, every range of values (of the form, "from about a to
about b," or, equivalently, "from approximately a to b," or,
equivalently, "from approximately a-b") disclosed herein is to be
understood to set forth every number and range encompassed within
the broader range of values. Also, the terms in the claims have
their plain, ordinary meaning unless otherwise explicitly and
clearly defined by the patentee. Moreover, 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 it introduces. If there is any
conflict in the usages of a word or term in this specification and
one or more patent or other documents that may be incorporated
herein by reference, the definitions that are consistent with this
specification should be adopted.
* * * * *