U.S. patent application number 10/242391 was filed with the patent office on 2003-01-23 for pumpable multiple phase compositions for controlled release application downhole.
Invention is credited to Bland, Ronald G., Quintero, Lirio.
Application Number | 20030017951 10/242391 |
Document ID | / |
Family ID | 22246559 |
Filed Date | 2003-01-23 |
United States Patent
Application |
20030017951 |
Kind Code |
A1 |
Bland, Ronald G. ; et
al. |
January 23, 2003 |
Pumpable multiple phase compositions for controlled release
application downhole
Abstract
Pumpable multiple phase compositions for carrying agents and
components downhole and controllably releasing them by breaking the
suspensions are described. The multiple phase composition may have
an external or third phase, which in turn has a first pumpable
emulsion internally. The first pumpable emulsion has a second phase
containing a first phase which bears the agent to be controllably
released. The entire pumpable multiple phase composition may thus
be an oil phase-in-aqueous phase-in-oil phase emulsion, or an
aqueous phase-in-oil phase-in-aqueous phase emulsion. The agent may
be released by one or more of a variety of mechanisms. For example,
a water-soluble shale stabilizer could be delivered downhole in an
aqueous phase-in-oil phase-in-aqueous phase multiple phase emulsion
by injecting the multiple phase composition into a water-based
drilling fluid, and then the suspension broken by rotary bit
nozzles under high shear stress to release the shale stabilizer at
the drilling zone. The multiple phase emulsion compositions of this
invention may also be used to deliver agents to remote locations
along a conduit.
Inventors: |
Bland, Ronald G.; (Houston,
TX) ; Quintero, Lirio; (Houston, TX) |
Correspondence
Address: |
PAUL S MADAN
MADAN, MOSSMAN & SRIRAM, PC
2603 AUGUSTA, SUITE 700
HOUSTON
TX
77057-1130
US
|
Family ID: |
22246559 |
Appl. No.: |
10/242391 |
Filed: |
September 12, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10242391 |
Sep 12, 2002 |
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09900798 |
Jul 6, 2001 |
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6464009 |
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09900798 |
Jul 6, 2001 |
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09363614 |
Jul 29, 1999 |
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6284714 |
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60094683 |
Jul 30, 1998 |
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Current U.S.
Class: |
507/200 |
Current CPC
Class: |
C09K 2208/14 20130101;
Y10S 507/902 20130101; Y10S 507/925 20130101; C09K 8/36 20130101;
C09K 8/26 20130101; Y10S 507/904 20130101 |
Class at
Publication: |
507/200 |
International
Class: |
E21B 001/00 |
Claims
We claim:
1. A pumpable multiple phase composition for carrying an agent
comprising: a first phase; a second phase; and a third phase; where
the first phase is suspended in the second phase to form a first
pumpable emulsion, and the first pumpable emulsion is dispersed in
the third phase to form the pumpable multiple phase composition,
which is selected from the group consisting of an oil
phase-in-aqueous phase-in-oil phase composition, and a aqueous
phase-in-oil phase-in-aqueous phase composition; where the agent is
present in the first phase.
2. The pumpable multiple phase composition of claim 1 in which the
agent is selected from the group consisting of a shale stabilizer,
a filtration control additive, viscosifier, suspending agent,
dispersant, thinner, an anti-balling additive, a lubricant, a
wetting agent, a seepage control additive, a lost circulation
additive, drilling enhancer, penetration rate enhancer, corrosion
inhibitors, scavengers, catalysts, acids, bases, gelling agents,
buffers, cross-linkers, and mixtures thereof.
3. The pumpable multiple phase composition of claim 2 in which the
agent is a shale stabilizer selected from the group consisting of a
polyglycol, potassium salt, an aluminum salt, a calcium salt, a
silicate salt, a chelate, an amine, an alkanolamine, an
alkanolamide, an amphoteric compound, and mixtures thereof, alone
if liquid or in solution.
4. The pumpable multiple phase composition of claim 1 further
comprising a structural stabilizer.
5. The pumpable multiple phase composition of claim 4 where the
structural stabilizer is present in the second phase.
6. The pumpable multiple phase composition of claim 4 where the
structural stabilizer is selected from the group consisting of
emulsifiers, viscosifiers, gelling agents, and mixtures
thereof.
7. The pumpable multiple phase composition of claim 1 where the
third phase is selected from the group consisting of a drilling
mud, a drill-in fluid, and a completion fluid.
8. A method for releasing an agent at a remote location in a
conduit comprising: forming a first pumpable emulsion for carrying
an agent comprising suspending a first phase in a second phase
where the agent is present in the first phase; injecting the first
pumpable emulsion into a fluid, thereby dispersing the first
pumpable emulsion in the fluid to create a pumpable multiple phase
composition selected the group consisting of an oil
phase-in-aqueous phase-in-oil phase composition, and a aqueous
phase-in-oil phase-in-aqueous phase composition; transporting the
pumpable multiple phase composition in a conduit; and breaking the
pumpable multiple phase composition at a remote location different
from the injecting to release the agent.
9. The method of claim 8 further comprising adding a structural
stabilizer to at least one of the phases.
10. The method of claim 9 where adding the structural stabilizer
occurs by adding the structural stabilizer to the second phase.
11. The method of claim 8 where the breaking the pumpable multiple
emulsion is accomplished by a mechanism selected from the group
consisting of a change in temperature, a change in pressure, an
increase in shear stress, an increase in shear rate, mechanical
action, a change in electrical potential, a change in magnetic
flux, solvent thinning, presence of a chemical agent, presence of a
catalyst, and combinations thereof.
12. A method for releasing an agent downhole comprising: forming a
first pumpable emulsion for carrying an agent comprising suspending
a first phase in a second phase where the agent is present in the
first phase; injecting the first pumpable emulsion into a fluid
selected from the group consisting of drilling fluids, drill-in
fluids and completion fluids, thereby dispersing the first pumpable
emulsion in the fluid to create a pumpable multiple phase
composition selected the group consisting of an oil
phase-in-aqueous phase-in-oil phase composition, and aqueous
phase-in-oil phase-in-aqueous phase composition; and breaking the
pumpable multiple phase composition downhole to release the
agent.
13. The method of claim 12 further comprising adding a structural
stabilizer to at least one of the phases.
14. The method of claim 13 where adding the structural stabilizer
occurs by adding the structural stabilizer to the second phase.
15. The method of claim 14 where the structural stabilizer is
selected from the group consisting of emulsifiers, viscosifiers,
gelling agents, and mixtures thereof.
16. The method of claim 12 where the breaking the pumpable multiple
emulsion is accomplished by a mechanism selected from the group
consisting of a change in temperature, a change in pressure, an
increase in shear stress, an increase in shear rate, mechanical
action, a change in electrical potential, a change in magnetic
flux, solvent thinning, presence of a chemical agent, presence of a
catalyst, and combinations thereof.
17. The method of claim 12 where in breaking the pumpable multiple
phase composition, the breaking is conducted by subjecting the
pumpable multiple phase composition to increased shear stress or
shear rate.
18. The method of claim 17 where in breaking the pumpable multiple
phase composition, the breaking is conducted by subjecting the
pumpable multiple phase composition to a rotating drill bit.
19. The method of claim 12 in which in forming a first pumpable
suspension, the agent is selected from the group consisting of a
shale stabilizer, a filtration control additive, viscosifier,
suspending agent, dispersant, thinner, an anti-balling additive, a
lubricant, a wetting agent, a seepage control additive, a lost
circulation additive, drilling enhancer, penetration rate enhancer,
corrosion inhibitors, scavengers, catalysts, acids, bases, gelling
agents, buffers, cross-linkers, and mixtures thereof.
20. The method of claim 19 in which in forming a pumpable multiple
phase composition the agent is a shale stabilizer selected from the
group consisting of a polyglycol, potassium salt, an aluminum salt,
a calcium salt, a silicate salt, a chelate, an amine, an
alkanolamine, an alkanolamide, an amphoteric compound, and mixtures
thereof, alone if liquid or in solution.
21. A method for drilling a well for the recovery of hydrocarbons
comprising: drilling a hole with a rotary drill bit; forming a
first pumpable emulsion for carrying an agent comprising suspending
a first phase in a second phase where the agent is present in the
first phase; injecting the first pumpable emulsion into a fluid
selected from the group consisting of drilling fluids, drill-in
fluids and completion fluids, thereby dispersing the first pumpable
emulsion in the fluid to create a pumpable multiple phase
composition selected the group consisting of: an oil
phase-in-aqueous phase-in-oil phase composition, and a aqueous
phase-in-oil phase-in-aqueous phase composition; and breaking the
pumpable multiple phase composition downhole to release the
agent.
22. The method of claim 21 further comprising adding a structural
stabilizer to at least one of the phases.
23. The method of claim 21 where the breaking the pumpable multiple
emulsion is accomplished by a mechanism selected from the group
consisting of a change in temperature, a change in pressure, an
increase in shear stress, an increase in shear rate, mechanical
action, a change in electrical potential, a change in magnetic
flux, solvent thinning, presence of a chemical agent, presence of a
catalyst, and combinations thereof.
24. The method of claim 21 in which in forming a first pumpable
suspension, the agent is selected from the group consisting of a
shale stabilizer, a filtration control additive, viscosifier,
suspending agent, dispersant, thinner, an anti-balling additive, a
lubricant, a wetting agent, a seepage control additive, a lost
circulation additive, drilling enhancer, penetration rate enhancer,
corrosion inhibitors, scavengers, catalysts, acids, bases, gelling
agents, buffers, cross-linkers, and mixtures thereof.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to methods and compositions
for the controlled release of agents and components downhole in an
oil recovery operation, and more particularly relates, in one
embodiment, to emulsions for the controlled release of agents and
components downhole.
BACKGROUND OF THE INVENTION
[0002] Drilling fluids used in the drilling of subterranean oil and
gas wells as well as other drilling fluid applications and drilling
procedures are known. In rotary drilling there are a variety of
functions and characteristics that are expected of drilling fluids,
also known as drilling muds, or simply "muds". The drilling fluid
is expected to carry cuttings up from beneath the bit, transport
them up the annulus, and allow their separation at the surface
while at the same time the rotary bit is cooled and cleaned. A
drilling mud is also intended to reduce friction between the drill
string and the sides of the hole while maintaining the stability of
uncased sections of the borehole. The drilling fluid is formulated
to prevent unwanted influxes of formation fluids from permeable
rocks penetrated and also often to form a thin, low permeability
filter cake which temporarily seals pores, other openings and
formations penetrated by the bit. The drilling fluid may also be
used to collect and interpret information available from drill
cuttings, cores and electrical logs. It will be appreciated that
within the scope of the claimed invention herein, the term
"drilling fluid" also encompasses "drill-in fluids".
[0003] Drilling fluids are typically classified according to their
base material. In water-based muds, solid particles are suspended
in water or brine. Oil can be emulsified in the water. Nonetheless,
the water is the continuous phase. Oil-based muds are the opposite.
Solid particles are suspended in oil and water or brine is
emulsified in the oil and therefore the oil is the continuous
phase. Oil-based muds which are water-in-oil emulsions are also
called invert emulsions.
[0004] It is apparent to those selecting or using a drilling fluid
for oil and/or gas exploration that an essential component of a
selected fluid is that it be properly balanced to achieve the
necessary characteristics for the specific end application. Because
the drilling fluids are called upon to do a number of tasks
simultaneously, this desirable balance is not always easy to
achieve.
[0005] It would be desirable if compositions and methods could be
devised to aid and improve the ability of drilling fluids to
accomplish these tasks by delivering agents and components
downhole, which could be released controllably to accomplish one or
more jobs.
SUMMARY OF THE INVENTION
[0006] Accordingly, it is an object of the present invention to
provide a method and composition for delivering an agent downhole
in a hydrocarbon recovery operation, particularly during a drilling
and/or completion operation.
[0007] It is another object of the present invention to provide a
method and composition for delivering an agent downhole where the
agent is released at a controlled time and place.
[0008] In carrying out these and other objects of the invention,
there is provided, in one form, a pumpable multiple phase
composition, also called a multiple phase emulsion drilling or
completion fluid, for carrying an agent having a first phase, a
second phase, and a third phase. The first phase is suspended in
the second phase to form a first pumpable emulsion, and next the
first pumpable emulsion is dispersed in the third phase to form the
final pumpable multiple phase composition. The pumpable multiple
phase composition may be an oil phase-in-aqueous phase-in-oil phase
emulsion, or an aqueous phase-in-oil phase-in-aqueous phase
emulsion. The agent is present in the first phase.
[0009] Additionally, there is provided in one form, a method for
releasing an agent downhole beginning by forming a first pumpable
emulsion for carrying an agent. The first pumpable emulsion has a
first phase containing the agent, and a second phase. The first
phase is suspended in the second phase to form a first pumpable
emulsion. The first pumpable emulsion may be an oil
phase-in-aqueous phase emulsion, or an aqueous phase-in-oil phase
emulsion, where the agent is present in the first phase or is the
first phase. Next, the first pumpable emulsion is injected into a
fluid which may be either a drilling fluid or a completion fluid,
such that the external phase of the drilling or completion fluid is
immiscible with the second phase of the first pumpable emulsion
thereby forming a pumpable multiple phase composition (multiple
emulsion). Finally, the pumpable multiple phase composition is
broken downhole to release the agent. The pumpable multiple phase
composition may be broken by shear, for example, by pumping through
drill bit nozzles.
DETAILED DESCRIPTION OF THE INVENTION
[0010] Pumpable multiple phase compositions (emulsions) are
anticipated as being useful to organize a liquid phase to isolate
one miscible phase from another. An oil-in-water emulsion could be
used in an invert emulsion, hydrocarbon-based or ester-based or
other water immiscible, non-aqueous-based system (forming an
oil-in-water-in-oil system), while a water-in-oil emulsion could be
used in an aqueous system (forming a water-in-oil-in-water system).
In short, the multiple emulsion compositions of this invention and
methods for their use may be applied to any two immiscible phases
that form stable emulsions. The phases need not be "oil" and
"water", although such phases are likely to be the most common
implementation. One non-limiting example is the combination of a
water soluble, relatively high molecular weight glycol that forms
an emulsion with brine.
[0011] One important application of this kind of organization would
be the controlled release of the internal phase contents, such as
an agent within the innermost (first) phase. A non-limiting example
of such an application would be the emulsion of, for instance, a
polyglycol, potassium salt, aluminum salt, calcium salt, a silicate
salt, chelate or other shale stabilizer, or an aqueous solution
thereof, as a first, internal phase in a hydrocarbon or hydrophobic
carrier (second phase) optionally containing an emulsifier and/or
stabilizer, and then adding the emulsion to a water-based drilling
fluid. The polyglycol, potassium salt, aluminum salt, etc. or other
shale stabilizer, alone if liquid, or in solution, e.g., is
isolated from the water in the external phase of a water-based
drilling fluid. Dilution is prevented, suppressed, or delayed until
the emulsion is broken intentionally. A likely area for breakage of
the emulsion is the high shear environment of and below the
drilling bit, where the shale stabilizer is released to the
borehole and cuttings in concentrated form on a localized basis.
While the invention does not contemplate, as a preferred
embodiment, making the multiple emulsion so stable that it is not
broken in a drilling fluid or completion fluid application, such
stable multiple emulsions are anticipated and may find utility.
[0012] Of course, emulsifiers, viscosifiers, or other structural
stabilizers may also be added to increase the mechanical stability
of the first pumpable emulsion in some cases to delay release of
the contents (agent).
[0013] In more detail, the agent to be delivered as the contents of
the internal phase or the first phase, may be any conventional
agent, including, but not necessarily limited to, a shale
stabilizer, as noted above, a filtration control additive,
viscosifier, suspending agent, dispersant, thinner, an anti-balling
additive, a lubricant (particularly in the oil-in-water-in-oil
multiple phase compositions), a wetting agent, a seepage control
additive, a lost circulation additive, drilling enhancer,
penetration rate enhancer, corrosion inhibitor, acid, base, buffer,
scavenger, gelling agent, cross-linker, catalyst, and the like, and
mixtures thereof. Specific useful shale stabilizers include, but
are not necessarily limited to, polyglycols, potassium salts,
aluminum salts, calcium salts, silicate salts, chelates, amines,
alkanolamines, alkanolamides, amphoteric compounds, alone if liquid
or in aqueous solutions, and mixtures thereof. Some other specific
agents include, but are not limited to amines (failing quartz bonds
in certain sands, corrosion inhibitors in clay based systems, shale
stabilizers) and metal halides, e.g. aluminum and thorium halides.
The term "acids" in this context includes organic acids and
inorganic acids. Such acids can be used to treat cement
contamination. If appropriate or desirable, the agent may be in
aqueous or hydrocarbon solution.
[0014] This first or internal phase should match that of the
ultimate fluid in which the first pumpable emulsion is to be
injected or added. That is, if the first pumpable emulsion is to be
injected into an aqueous fluid, the first, internal phase should be
aqueous; if the fluid is hydrophobic, the first, internal phase
should be hydrophobic.
[0015] Of course, the second phase, which together with the first
or internal phase forms the first pumpable emulsion, should be of
the opposite type. It may be necessary or desirable to add
emulsifiers, viscosifiers, stabilizers, and mixtures thereof as
structural stabilizers to increase the mechanical stability of this
first emulsion to aid in delaying release or breaking. In the
context of this invention, emulsifiers should be understood to
include, but are not limited to, surfactants and the like, and
viscosifiers are understood to include, but are not limited to,
gelling agents and the like. The emulsifiers and viscosifiers may
be in liquid or solid (e.g. powder) form. Suitable emulsifiers
include, but are not necessarily limited to, sorbitan fatty acid
esters including sorbitan monooleate and sorbitan trioleate,
glycerol fatty acid esters including mono- and/or dioleates,
polyglycerol fatty acid esters, polyglycols, alkanolamines and
alkanolamides such as ethoxylated amines, ethoxylated amides,
ethoxylated alkanolamides, including non-ethoxylated ethanolamides
and diethanolamides, and the like. Viscosifiers and gelling agents
include, but are not necessarily limited to, polymers of ethylene,
propylene, butylene, butadiene, styrene, vinyltoluene and various
copolymers and terpolymers thereof, organophilic clays, aluminum
soaps and alkoxides and other aluminum salts, alkaline earth soaps,
lithium soaps, fumed silica and alumina and the like and mixtures
thereof. Other suitable stabilizers include, but are not
necessarily limited to, cholesterol and long chain oil soluble waxy
alcohols, and the like. These structural stabilizers would usually
be added directly to the second phase although they may be added to
the third phase, if that is more convenient. In one non-limiting
embodiment of the invention, the proportion of structural
stabilizer based on the second phase ranges from about 0.1 to about
90 vol. %, preferably from about 1 to about 50 vol. %.
[0016] However, the pumpable multiple phase compositions of the
invention (emulsions) are designed to be broken in a preferred
embodiment. Indeed, they are desirably and rather controllably
broken within a certain area of the borehole at a designated and
relatively controlled time.
[0017] The preparation of the first pumpable emulsion would
typically involve the mixing of the first phase with the second
phase, where any emulsifier or structural stabilizer is preferably
present in the second phase. The speed of stirring or mixing of the
two phases would depend upon the size of the emulsified internal
phase droplets desired, and the particular system used. It is
expected that the size of the first phase droplets would range from
about 0.01 to about 1000 microns or less, preferably from about 1
to about 100 microns or less, as non-limiting examples. In one
embodiment of the invention, the first phase droplets would be as
large as is practical. The proportion of first, internal phase to
the overall first pumpable composition may range from about 90 to
about 5 vol. % or less, preferably from about 60 to about 40 vol. %
or less, and most preferably, 50 vol. % or less, as non-limiting
examples. A lower threshold of 5 vol. % may be appropriate in some
embodiments of the invention.
[0018] The formation of the first pumpable emulsion could be
accomplished within an injection pump itself. This technique would
be similar to in-line mixing the first, internal phase "on the fly"
with the second phase forming the first emulsion before it exits
into the third phase finally forming the multiple emulsion in the
mud system.
[0019] The first pumpable emulsion is then, in turn, suspended in
the drilling and/or completion fluid which is the third phase. This
third phase is generally to be miscible with the first phase and
may contain an emulsifier to help disperse the first pumpable
emulsion into suitable sized droplets. Conventional drilling and/or
completion fluids may be used as the third phase. If the third
phase is oil-based or a hydrocarbon, in a preferred embodiment, the
hydrocarbon is a synthetic material, and, for instance, may
include, but is not necessarily limited to, esters, iso-olefins,
alpha-olefins, polyolefins, poly-alpha-olefins, paraffins,
Fischer-Tropsch reaction products, and the like. The oil phase may
be a mixture or blend of petroleum distillates and synthetic
hydrocarbons. Suitable petroleum distillates include, but are not
limited to, diesel oil, kerosene, mineral oils, food grade mineral
oils, paraffinic oils, cycloparaffinic oils, aromatic oils, or
n-paraffins, isoparaffins and similar hydrocarbons. Crude oil could
be used in some cases. In the case where the second phase is an
oil-based phase, it is anticipated that any of these hydrocarbons
may be used.
[0020] In the case where the multiple phase composition is
water-in-oil-in-water multiple emulsion, the aqueous phase may be
brine. Careful adjustment of the internal phase salinity of brine
multiple emulsions may be required (osmotic pressure gradient
adjustment). Too much salt or too low an activity in a first
aqueous phase may make the droplets unstable. However, this
mechanism may be intentionally used to cause failure or rupture of
the first pumpable emulsion droplets or capsules downhole. For
example, the droplets could be designed to grow on the journey
downhole and break at or near the desired zone.
[0021] It is expected that the size of the droplets of the first
pumpable emulsion (first phase in second phase) in the third phase
would range from about 10,000 to about 1 micron or less, preferably
from about 5 to about 1,000 microns or less, as non-limiting
examples. In one embodiment of the invention, the pumpable emulsion
droplets would be as large as possible. The larger the first phase
droplets in the first emulsion droplets, all things being equal,
the easier it would be to break the multiple phase composition to
release the agent from the first emulsion.
[0022] The proportion of the first pumpable emulsion to drilling
and/or completion fluid (third phase) may range from about 0.5 to
about 90 vol. %, alternatively from about 0.5 to about 40 vol. %,
preferably from about 1 to about 10 vol. %, in another embodiment
from about 1 to about 5 vol. %, and most preferably from about 2 to
about 6 vol. %, as non-limiting examples, to make the overall
pumpable multiple phase composition.
[0023] Conventional drilling and/or completion fluid additives may,
of course, be employed, including, but not necessarily limited to,
wetting agents, viscosifiers, suspending agents, weighting agents,
shale stabilizers, filtration control additives, anti-balling
additives, lubricants, seepage control additives, lost circulation
additives, corrosion inhibitors, alkalinity control additives,
thinners, dispersants, and the like. Indeed, the agents to be
delivered by the multiple emulsion compositions and methods herein
may also be present in the third phase.
[0024] The method of this invention may find particular usefulness
in increasing the local concentration of an agent downhole after
rupture of the first pumpable emulsion droplets while keeping the
overall concentration of the agent in the drilling mud (including
the entire multiple phase composition) low. For example,
styrene-butadiene rubber (SBR), useful as a viscosifier and/or
filtration control additive, could be the agent in the first phase
of the first pumpable emulsion and be in relatively low
concentrations overall. However, once the first pumpable emulsion
droplets are broken or failed, the local concentration of SBR at
the droplet failure zone would be relatively increased.
[0025] Using the pumpable emulsion composition of the invention is
straightforward and requires no special equipment. The first
pumpable emulsion is injected into a fluid that is pumped downhole.
The fluid may be a drilling fluid, drill-in fluid, a completion
fluid, or the like. In a preferred embodiment of the invention, the
fluid is a drilling fluid or drill-in fluid. A number of mechanisms
could be used to break the pumpable multiple phase composition at a
particular time, including, but not limited to, input of energy,
including but not limited to, an increase in temperature, increase
in pressure, increase in shear stress or shear rate, mechanical
action (such as a rotating drill bit or drill string), change in
pH, change in electrical potential, solvent thinning, presence of a
chemical agent, presence of a catalyst, change in magnetic flux,
and the like. A non-limiting, but preferred method is breaking the
multiple phase composition by subjecting it to a high shear
environment, in particular the fluid stream exiting a nozzle
impinging on the borehole such as below a bit or opposite a reamer
or hole opener. In a preferred method of the invention, the
multiple phase emulsion is broken within a required period of time,
and within a required physical volume. In one embodiment, if the
agent being delivered was a shale stabilizer, the shale stabilizer
could be delivered. essentially instantaneously to the borehole and
cuttings in a concentrated form on a localized basis.
[0026] It will also be understood that more than one agent may be
delivered downhole, and that the two or more agents may interact or
react with each other to provide a beneficial effect. For example,
crosslinkers could be transported in first water-in-oil emulsion in
the same aqueous third phase as a second water-in-oil emulsion
containing the agent to be cross-linked. Alternatively, two
separate internal phases which react on contact could be delivered
in the same first emulsion added to the third phase such as an
aqueous cross-linker and aqueous polymer solution could both be
transported in the same first emulsion and added to a water-based
mud. Indeed, one reactant could be present in the third phase and
another reactant could be present in the first phase and the
reaction could occur when the boundary of the second phase (first
pumpable emulsion) is broken.
[0027] The agent may also be a polymer serving any of the stated
functions, or a monomer to be polymerized or in the course of being
polymerized to such a polymer.
[0028] Further, the multiple phase compositions of this invention
are not limited to utility in downhole applications, but could be
used to deliver and transport agents along a pipeline or other
conduit, such as agents to prevent blockages (e.g. asphaltenes,
hydrates, etc.) in a subsea pipeline or the like, or other agents.
Any of the agents previously mentioned may be used in this way, and
suitable agents may additionally include, but are not limited to,
hydrate inhibitors, asphaltene inhibitors, scale inhibitors,
etc.
[0029] The invention will be illustrated further with respect to
the following Examples which are not intended to limit the
invention but rather simply to additionally illuminate it.
EXAMPLES 1-7
[0030] The following ISOTEQ solutions were mixed:
[0031] 80/20 I/SMO--2 g sorbitan monooleate (SMO) was mixed with 8
g ISOTEQ.RTM. isomerized olefin marketed by Baker Hughes INTEQ.
[0032] 80/20 I/PGO--2 g Limulse polyglyercol oleate (PGO) was mixed
with 8 g ISOTEQ.
[0033] 80/20I/295/S--2 g Alkamide DIN-295/S (Rhone Poulenc's
linoleamide DEA) was mixed with 8 g ISOTEQ
[0034] All of the above were clear solutions.
[0035] The following mixtures of AQUACOL.TM. polyglycol solution
marketed by Baker Hughes INTEQ were prepared:
1 50% Aq 5 g AQUACOL with 5 g D.I. water 30% Aq 3 g AQUACOL with 7
g D.I. water 20% Aq 2 g AQUACOL with 8 g D.I. water
[0036] The AQUACOL solutions were then emulsified into the
indicated ISOTEQ solution at 50/50 wt/wt.
[0037] For the 80/20 I/295/S solutions, the following were
obtained:
[0038] Ex. 1 using 50% Aq: The emulsion was unstable, i.e. it
separated instantly.
[0039] Ex. 2 using 30% Aq: The emulsion was unstable, i.e. it
separated almost immediately.
[0040] Ex. 3 using 20% Aq: The emulsion was relatively stable, i.e.
it formed an emulsion which seemed stable at least short term.
[0041] The 20% AQUACOL aqueous solutions were then emulsified into
the ISOTEQ solutions at 50/50 wt/wt using a high speed mixer
(TISSUE-TEARER by BIOSPEC Products, Inc.). Then 0.5 g of this
emulsion was mixed into 9.5 g of D.I. water to form multiple
emulsions. 80/20 I/SMO (Ex. 4), 80/20 I/PGO (Ex. 5) and 80/20
I/295/S (Ex. 6) all seemed to work fairly well forming multiple
emulsions viewed in a microscope.
[0042] The 20% AQUACOL aqueous solutions were again emulsified into
the ISOTEQ solutions at 50/50 weight/weight using the TISSUE-TEARER
as above and 0.5 g of the resulting emulsions were mixed with 9.5 g
of 12% KCl to form multiple emulsions, but only the composition
with 80/20 I/PGO actually formed a multiple emulsion (Ex. 7), the
80/20 I/SMO and 80/20 I/295/S seemed to form only simple oil in
water emulsions.
[0043] After 12 days, the multiple emulsions from 50/50 (wt/wt) 20%
Aq in ISOTEQ solutions were examined, with the following
observations:
[0044] Ex. 5: 80/20 I/PGO in D.I. water--Still had ISOTEQ phase
droplets with outside diameters of 2.3 .mu. to 97 .mu., but no
internal aqueous phase droplets.
[0045] Ex. 7: 80/20 I/PGO in 12% KCl--Still had ISOTEQ phase
droplets with outside diameters 37 .mu., but no internal aqueous
phase droplets.
[0046] Ex. 6: 80/20 1/295/S in D.I. water--Still had external phase
droplets with outside diameters 83 .mu. diameter, and contained
internal aqueous phase droplets.
[0047] Ex. 4: 80/20 I/SMO in D.I. water--similar observations to
those of Example 7.
[0048] Only 80/20I/295/S of Example 6 actually retained multiple
emulsion character with both internal aqueous phase droplets
contained within external ISOTEQ phase droplets.
[0049] The Examples also show:
[0050] the importance of matching the emulsifier to the salinity of
the (in this case) external phase;
[0051] the effect of different emulsifiers on multiple emulsion
stability;
[0052] how internal phase composition can affect emulsion
stability; and
[0053] how salinity can regulate multiple emulsion stability.
EXAMPLE 8
[0054] It is expected that the invention would be implemented as
follows. A 20 vol. % polyglycol solution in tap water would be
prepared using a polyglycol known for its shale stabilizing
properties, such as AQUACOL.RTM. polyglycol solution marketed by
Baker Hughes INTEQ. This solution would be Phase 1. A second phase,
Phase 2, would be prepared by adding 20 vol. % of a mixture of
glycerol monooleate and glycerol dioleate (equal parts) to 80 vol.
% of a C.sub.14-C.sub.18 isomerized olefin such as ISOTEQ.RTM.
olefin marketed by Baker Hughes INTEQ. Phase 1 would be gently
mixed into Phase 2 at a 50/50 vol/vol ratio to form a crude,
pumpable, emulsion. This emulsion would be added to a water-based
drilling fluid (Phase 3) at a concentration of 5 vol. % forming a
multiple emulsion drilling fluid. The multiple emulsion drilling
fluid would be formed "on the fly" while drilling a water sensitive
shale prone to balling bits and stabilizers by addition of the
original, pumpable emulsion to the suction pit of the water-based
drilling fluid prior to pumping the fluid downhole. The
concentrated AQUACOL in the Phase 1 droplets would be isolated from
the miscible Phase 3 by the hydrophobic Phase 2 film and would be
transported to the bottom of the hole during pumping. The multiple
emulsion droplets would be designed to survive the high shear
environment of the drill pipe, but not the extreme high shear
environment below the bit nozzles. The extreme high shear
environment at the borehole wall surface under the bit nozzles as
the nozzles blast fluid at the borehole surface would induce
rupture of the hydrophobic film separating Phase 1 and Phase 3 to
expose the borehole to Phase 1. The localized concentration of the
AQUACOL shale stabilizer near the exposed borehole wall would be
greater than the gross concentration of the AQUACOL
(20%.times.50%.times.5%=0.5%) which would increase the efficiency
of the AQUACOL over that achievable by simply adding the AQUACOL to
the drilling fluid at a uniform 0.5 vol. %.
[0055] In the foregoing specification, the invention has been
described with reference to specific embodiments thereof, and has
been suggested as effective in providing pumpable, multiple phase
compositions which can effectively carry agents and components
downhole for controlled release in space and time. However, it will
be evident that various modifications and changes can be made
thereto without departing from the broader spirit or scope of the
invention as set forth in the appended claims. Accordingly, the
specification is to be regarded in an illustrative rather than a
restrictive sense. For example, specific combinations of phases,
agents, structural stabilizers, etc. and proportions thereof
falling within the claimed parameters, but not specifically
identified or tried in a particular composition to improve the
delivery of agents and components herein, are anticipated to be
within the scope of this invention.
* * * * *