OIL WELL GROUTING WITH TEMPERATURE ACTIVATED AQUEOUS SILICA GEL

FONCAGE DE PUITS DE PETROLE PAR INJECTION DE GEL DE SILICE ACTIVE A CHAUD

English Abstract

ABSTRACT

An energy level or temperature triggered aqueous
silicate mixture gelation composition and process are
provided by using certain halogenated hydrocarbons with
a solubilizing group selected from hydrogen, carbinol
sulfonate, aldehyde, ester and carboxyl.

Claims

The embodiment of the invention in which an exclusive;
property or privilege is claimed are defined as follows:-

1. An aqueous mixture having a long shelf life at an
energy level below a given level which can be gelled to a solid,
comprising water, a water soluble metal silicate and an activator
which reacts at a given energy level to gel the mixture, said
silicate having a pH in the range of about 10-13, said activator
being at least one compound of the formula:

XnR-W

werein n is an integer equal to 1-6, X is a halide
substituent on an alpha chain, a terminal carbon or
both; R is an alkyl radical an aryl radical or an
alkylaryl radical with the alkyl radicals having 1-6
carbon atoms and the aryl radicals having 6-10 carbon
atoms; and W is a carboxyl, ester, aldehyde, carbinol, hy-
drogen or sulfonyl group, acid equivalents thereof
and combinations thereof.


2. An aqueous mixture having a long shelf life at an ener-
gy level below a given level of claim 1 which can be gelled to a
solid, comprising water, a water soluble metal silicate and an
activator which reacts at a given energy level to gel the mixture,
said activator being at least one compound of the formula:
XnR-W
wherein n is an integer equal to 1-6; X is a halide
substituent on an alpha carbon, a terminal carbon or
both; R is an alkyl radical an aryl radical, or an
alkylaryl radical with the alkyl radicals having 1-6
carbon atoms and the aryl radicals having 6-10 carbon
atoms; and W is a hydrogen radical.



3. An aqueous mixture of claim 1 which can be gelled to
a solid comprising water, a water soluble metal silicate and an

19


activator which reacts at a given energy level to gel the mix-
ture, said activator being at least one compound of the formula:
XnR-W
wherein n is an integer equal to 1-6; X is a halide
substituent on an alpha carbon, a terminal carbon or
both; R is an alkyl radical, an aryl radical, or an
alkylaryl radical with the alkyl having 1-6 carbon
atoms and the aryl radical, having 6-10 carbon atoms;
and W is a carbinol group.

4. An aqueous mixture of claim l which can be gelled to a
solid, comprising water, a water soluble metal silicate and an
activator which reacts at a given energy level to gel the mixtu-
re, said activator being at least one compound of the formula:
XnR-W
wherein n is an integer equal to 1-6; X is a halide
substituent on an alpha carbon, a terminal carbon or
both, R is an alkyl radical, an aryl radical, or an
alkylaryl radical with the alkyl having 1-6 carbon
atoms and the aryl radicals having 6-10 carbon atoms;
and W is an aldehyde group.


5. An aqueous mixture of the claim 1 which can be gelled
to a solid, comprising water, a water soluble metal silicate and
an activator which reacts at a given energy level to gel the
mixture, said activator being at least one compound of the
formula:
XnR-W

wherein n is an integer equal to 1-6; X is a halide
substituent on an alpha carbon, a terminal carbon or
both, R is an alkyl radical an aryl radical, or an
alkylaryl radical with the alkyl having 1-6 carbon
atoms and the aryl radicals having 6-10 carbon atoms;




and W is a sulfonyl group.

6. An aqueous mixture of claim 1 which can be gelled to a
solid, comprising water and a water soluble metal silicate mixed
with an activator which reacts at a given energy level and gels
the mixture said activator being at least one compound of the
formula:


Image

wherein R is a hydrocarbon radical having 1-10 carbon
atoms; X is a halogen radical substituent of iodine,
bromine, fluorine, chlorine or combinations thereof;
n is an integer of 1-3; and M is a cation of hydrogen,
alkali metal, alkaline earth metal or ammonium ion.


7. An aqueous mixture of claim 1 which can be gelled to a
solid, comprising water and a water soluble alkali metal silicate
mixed with an activator which reacts at a given energy level to
lower the pH of said mixture and to gel the mixture, said activa-
tor being at least one compound of the formula:

Image

wherein R is an alkyl radical having 1-3 carbon atoms,
X is a halogen radical substituent selected from fluo-
rine, chlorine and combinations thereof; n is an
integer equal to 1-3, and M is a cation of alkali metal:
and wherein the concentration of said activator is sufficient to
react at the given energy level and lower the pH of the mixture
to a value in a range below about 10 and gel the mixture.



8. An aqueous mixture of claim 1 which can be gelled to a
solid, comprising a water soluble metal silicate in an aqueous
media mixed with an activator which at a given energy level pro-
duces reactive groups which react to lower the pH of said mixture


21


and to gel the mixture, said activator being at least one
compound of the formula:

Image

wherein R is a hydrocarbon radical having 1-3 carbon
atoms, X is a halogen radical substituent of fluorine,
chlorine or combinations thereof; n is an integer of
1-3; and M is a cation of alkali metal, alkaline earth
metal or ammonium ion.


9. A pumpable aqueous mixture of claim 1 which can be
gelled to a solid comprising a water soluble silicate of sodium,
potassium or mixtures thereof in water mixed with an activator
comprising at least one compound of the formula:

Image

wherein R is a linear alkyl radical having 1-3 carbon
atoms in the linear chain; n is an integer equal to
1-3; X is a halogen radical substituent of fluorine
chlorine or combinations thereof; and M is a cation of
sodium, potassium or mixtures thereof;
wherein said activator is present in said mixture and at a given
temperature reacts to lower the pH of said mixture and gels said
mixture.


10. A pumpable aqueous mixture having a long shelf life at
an energy level below a given level and which can be gelled to a
solid at said energy level comprising a water soluble silicate of
sodium, potassium or mixtures thereof in water mixed with an
activator comprising at least one compound of the formula:


Image

wherein R is a linear alkyl radical having 1-3 carbon

22

atoms in the linear chain, n is an integer equal to
1-3; X is a halogen radical substituent of fluorine,
chlorine, or combinations thereof, and M is a cation
of sodium, potassium or mixture thereof,
wherein said silicate has a pH of about 10-13, said activator
is present in said mixture at a concentration sufficient to
produce a practical gelation rate and reacts only at a tempera-
ture above a certain level to lower the pH of said mixture and
gels said mixture.


11. A pumpable aqueous mixture of claim 10 which can be
gelled to a solid comprising water and a silicate composition
wherein said silicate composition consists essentially of a
water soluble silicate of sodium, potassium and combinations
thereof mixed with an activator comprising at least one compound
of the formula

Image

wherein R is an alkyl radical having 1-3 carbon atoms
n is an integer equal to 1-3; X is a halogen radical
substituent of fluorine, chlorine or combinations
thereof, and M is a cation of sodium, potassium or
mixtures thereof,
wherein said silicate has a pH of about 10-13, said activator is
present in said mixture in a concentration of at least about 20
milliequivalents and reacts only at a temperature greater than
a certain value to lower the pH of said mixture and gel said
mixture.


12. A pumpable aqueous mixture of claim 1 which can be gel-
led to a solid comprising water, a water soluble silicate of
sodium, potassium and combinations thereof, mixed with an acti-
vator comprising at least one compound of the formula



Image

23


wherein R is an alkyl radical having 1-3 carbon atoms,
X is a halogen radical substituent on the terminal
carbon atom of R and is fluorine, chlorine or a combi-
nation thereof; and M is a cation of sodium, potassium
or combinations thereof;
wherein said activator is present in said mixture and reacts only
at a temperature above a certain level to lower the pH of said
mixture and gel said mixture.


13. A pumpable aqueous mixture of claim 1 which can be
gelled to a solid comprising water, a water soluble silicate of
sodium, potassium and combinations thereof mixed with an activator
comprising at least one compound of the formula:


Image

wherein R is an alkyl radical having one carbon atom;
X is a halogen radical substituent and is fluorine,
chlorine or a combination thereof; and M is a cation of
sodium, potassium or combinations thereof;
wherein said activator is present in said mixture and reacts only
at a temperature greater than a certain value to gel said mixture.


14. A pumpable aqueous mixture of claim 1 which can be gelled
to a solid comprising water, a water soluble silicate of sodium,
potassium and combinations thereof mixed with an acitvator compris-
ing at least one compound of the formula:


Image

wherein M is a cation of sodium, potassium or combination
thereof; and
wherein said activator reacts only at a temperature greater than
a certain value to gel said mixture.


24

15. A pumpable aqueous mixture of claim 1 which can be
gelled to a solid comprising water, a water soluble silicate of
sodium, potassium and combinations thereof mixed with an activa-
tor comprising at least one compound of the formula:


Image

wherein M is a cation of sodium, potassium or combina-
tions thereof; and
wherein said activator reacts only at a temperature greater than
a certain value to gel said mixture.


16. A pumpable aqueous mixture of claim 1 which can be
gelled to a solid, comprising water, a water soluble silicate of
sodium, potassium and combinations thereof mixed with an activa-
tor comprising at least one compound of the formula:

Image

wherein M is a cation of sodium , potassium or combina-
tion thereof; and
wherein said activator reacts only at a temperature greater than
a certain value to gel said mixture.


17. A pumpable aqueous mixture of claim 1 which can be
gelled to a solid comprising water, a water soluble silicate of
sodium, potassium and combinations thereof mixed with an activa-
tor comprising at least one compound of the formula:


Image

wherein M is a cation of sodium, potassium or combina-
tions thereof, and
wherein said activator reacts only at a temperature greater than
a certain value to gel said mixture.




18. A pumpable aqueous mixture of claim 10, which can be
gelled to a solid comprising water, a water soluble silicate
of sodium, potassium and combinations thereof mixed with an
activator comprising at least one compound of the formula:


Image

wherein X is a halogen radical substituent of fluorine,
chlorine or a combination thereof, and M is a cation of
sodium, potassium or combinations thereof,
wherein said activator is present in said mixture in a concentra-
tion of about 0.1-10.0 grams per 100 grams of said silicate on a
dry solids basis and wherein said activator reacts only at a tem-
perature above about 60°C to gel said mixture.


19. A pumpable aqueous mixture of claim 10 which can be
gelled to a solid comprising water, a particulate filler, a
water soluble silicate of sodium, potassium and combinations
thereof mixed with an activator comprising at least one compound
of the formula:

Image

wherein X is a halogen radical substituent of fluorine,
chlorine or a combination thereof; and M is a cation of
sodium, potassium or combinations thereof;
wherein said activator is present in said mixture in a concentra-
tion of about 0.1-10 0 grams per 100 grams of said water soluble
silicate on a dry solids basis and wherein said activator reacts
only at a temperature above about 60°C to gel said mixture.



20. A process of forming an impermeable gel comprising mixing
water, a water soluble silicate and an activator to form a
mixture of claim 1 wherein said activator reacts at a given
energy level to gel said mixture and said activator comprises at
least one compound of the formula:



26

XnR-W
wherein n is an integer equal to 1-6; X is a halide
substituent on an alpha carbon, a terminal carbon or
both, R is an alkyl radical, an aryl radical or an
alkylaryl radical with the alkyl radicals having 1-6
carbon atoms and the aryl radicals having 6-10 carbon
atoms and W is carboxyl, ester, aldehyde, carbinol,
hydrogen or sulfonyl group, acid equivalents thereof
and combinations thereof;
and gelling said mixture by increasing the energy level of said
mixture to said given value.



21. A process of forming an impermeable gel comprising mix-
ing water, a water soluble silicate and an activator to form a
mixture of claim 1 wherein said mixture and said activator
comprises at least one compound of the formula:
XnR-W
wherein n is an integer equal to 1-6; X is a halide
substituent on an alpha carbon, a terminal carbon or
both; R is an alkyl radical, an aryl radical or an
alkylaryl radical with the alkyl radicals having 1-6
carbon atoms and the aryl radicals having 6-10 carbon
atoms; and W is a hydrogen radical;
and gelling said mixture by increasing the energy level of said
mixture to said given value.


22. A process of forming an impermeable gel comprising mix-
ing water, a water soluble silicate and an activator to form a
mixture of claim 1 wherein said mixture and said activator com-
prises at least one compound of the formula:

XnR-W
wherein n is an integer equal to 1-6; X is a halide
substituent on an alpha carbon, a terminal carbon or

27


both; R is an alkyl radical, an aryl radical or an
alkylaryl radical with the alkyl radicals having 1-6
carbon atoms and the aryl radicals having 6-10 carbon
atoms and W is a carbinol group;
and gelling said mixture by increasing the energy level of
said mixture to said given value.

23. A process of forming an impermeable gel comprising
mixing water, a water soluble silicate and an activator to
form a mixture of claim 1 wherein said mixture and said activator
comprises at least one compound of the formula:

XnR-W
wherein n is an integer equal to 1-6; X is a halide
substituent on an alpha carbon, a terminal carbon or
both, R is an alkyl radical, an aryl radical or an
alkylaryl radical with the alkyl radicals having 1-6
carbon atoms and the aryl radicals having 6-10 carbon
atoms; and W is an aldehyde group;
and gelling said mixture by increasing the energy level of said
mixture to said given value.

24. A process of forming an impermeable gel comprising
mixing water, a water soluble silicate and an activator to form
a mixture of claim 1 wherein said mixture and said activator
comprises at least one compound of the formula:

XnR-W
wherein n is an integer equal to 1-6; X is a halide
substituent on an alpha carbon, a terminal carbon or
both: R is an alkyl radical, an aryl radical or an
alkylaryl radical with the alkyl radicals having 1-6
carbon atoms and the aryl radicals having 6-10 carbon
atoms, and W is a sulfonyl group;


28

and gelling said muxture by increasing the energy level of said
mixture to said given value.


25. A process of claim 20 for forming an impermeable gel
comprising mixing water, a water soluble silicate and an activa-
tor comprising at least one compound of the formula:

Image

wherein R is an alkyl radical having 1-3 carbon atoms;
X is a halogen radical substituent on the terminal
carbon atom of R of fluorine, chlorine or combinations
thereof, n is an integer equal to 1-3 and M is a cation
of alkali metals, alkaline earth metals, ammonium or
combinations thereof, and
wherein said activator reacts at an energy value greater than
a given value to gel said mixture; and gelling said mixture by
increasing said energy level of said mixture to said given value.


26. A process of claim 20 for forming an impermeable gel
comprising mixing water, a water soluble silicate of sodium,
potassium and a combination thereof in an aqueous media and
an activator comprising at least one compound of the formula:


Image
wherein X is a halogen radical substituent of fluorine,
chlorine or combinations thereof; n is an integer equal
to 1-3; and M is a cation of sodium, potassium or com-
binations thereof; and
wherein said activator reacts only at an energy level greater
than a certain value to gel said mixture; applying said mixture
to a substrate and gelling said mixture by increasing said
energy value to said certain value.


29

27. A process of claim 20 for forming an impermeable gel
comprising mixing water, a water soluble silicate of sodium,
potassium or a combination thereof and an activator comprising
at least one compound of the formula:


Image

wherein X is a halogen radical substituent of fluorine,
chlorine or a combination thereof; M is a cation of so-
dium, potassium or a combination thereof, and
wherein said activator reacts only at an energy level greater
than a certain value to gel said mixture, applying said mixture
to a porous substrate and gelling said mixture by increasing
said energy level of said mixture and thereby forming a zone imp
permeable to fluid flow in said porous substrate.


28. A process for forming an impermeable gel comprising
mixing water, a water soluble silicate of sodium, potassium
or a combination thereof and an activator wherein said activator
reacts at a given energy level to gel said mixture and said
activator comprising at least one compound of the formula:


Image

wherein X is a halogen radical substituent of fluorine,
chlorine or a combination thereof; M is a cation of
sodium, potassium or a combination thereof:
wherein said silicate has a pH of about 10-13,said activator
reacts only at a temperature greater than about 60°C to gel said
mixture and wherein said activator is present in said mixture
in a concentration of about 0.1 10.0 grams per 100 grams of said
water soluble silicate on a dry solids basis; applying said
mixture to a porous substrate and gelling said mixture by increas-
ing the temperature of said mixture to a value of at least 60°C
to gel said mixture and forming a zone impermeable to fluid flow.




29. A process of claim 28 for forming an impermeable gel
comprising mixing water, a water soluble silicate of sodium,
potassium or a combination thereof and an activator consisting
essentially of at least one compound of the formula:


Image

wherein X is a halogen radical substituent of fluorine,
chlorine, or a combination thereof; M is a cation of
sodium, potassium or a combination thereof;
wherein said activator reacts only at a temperature greater
than about 60°C to gel said mixture, and wherein said activator
is present in said mixture in a concentration of about 0.1-10.0
grams per 100 grams of said water soluble silicate on a dry
solids basis, injecting said mixture into a porous structure
and gelling said mixture by increasing the temperature of said
mixture to a value of at least 60°C to gel said mixture and form
a zone impermeable to fluid flow.


30. A process of claim 20 for forming an impermeable gel
comprising mixing water, a water soluble silicate of sodium,
potassium or a combination thereof and an activator comprising
at least one compound of the formula:


Image

wherein X is a halogen radical substituent of fluorine,
chlorine or a combination thereof; M is a cation of
sodium, potassium or a combination thereof;
wherein said activator reacts only at a temperature greater
than about 60°C to gel said mixture; applying said mixture to
a porous, permeable formation, increasing the temperature of
said mixture thereby gelling said mixture and forming a zone
impermeable to fluid flow through said gelled mixture.


31

31. A process of claim 20 for forming an impermeable gel
comprising mixing water, a water soluble silicate of sodium,
potassium or a combination thereof and an activator comprising
at least one compound of the formula:


Image

wherein X is a halogen radical substituent of fluorine,
chlorine or a combination thereof; M is a cation of
sodium, potassium or a combination thereof,
wherein said activator reacts only at a temperature greater
than about 60 C to gel said mixture, applying said mixture to
a porous, permeable formation, increasing the temperature of
said mixture to gel said mixture and maintaining said mixture
in a quiescent state of flow immediately prior to gel formation
thereby forming a high strength gel and a zone impermeable to
fluid flow through said gel.


32. A process of claim 20 for forming an impermeable gel
comprising mixing water, a water soluble silicate of sodium,
potassium or a combination thereof and an activator comprising
at least one compound of the formula:

Image

wherein X is a halogen radical substituent of fluorine,
chlorine or a combination thereof; M is a cation of
sodium, potassium or a combination thereof.
wherein said activator reacts only at a temperature greater than
about 60 C to gel said mixture, injecting said mixture into a
subterranean permeable, porous formation; increasing the tempera-
ture of said mixture to gel said mixture and thereby form a zone
impermeable to fluid flow through said gel.


32


33. A process of claim 20 for forming an impermeable gel
comprising mixing water, a water soluble silicate of sodium,
potassium or a combination thereof and an activator comprising
at least one compound of the formula:


Image

wherein X is a halogen radical substituent of fluorine,
chlorine, or a combination thereof; M is a cation of
sodium, potassium or a combination thereof;
wherein said activator reacts only at a temperature greater
than about 60°C to gel said mixture, injecting said mixture
through a conduit into an annular space around said conduit;
increasing the temperature of said mixture to gel said mixture
and thereby form a zone impermeable to fluid flow through said
gel.


34. A process of claim 20 for forming an impermeable gel
comprising mixing water, a water soluble silicate of sodium,
potassium or a combination thereof and an activator comprising
at least one compound of the formula:


Image

wherein X is a halogen radical substituent of fluorine,
chlorine or a combination thereof; M is a cation of
sodium, potassium or a combination thereof;
wherein said activator reacts only at a temperature greater than
about 60°C to gel said mixture; injecting said mixture through
a conduit into a porous permeable subterranean formation,

increasing the temperature of said mixture by allowing heat trans-
fer from said formation into said mixture to gel said mixture
thereby forming a zone impermeable to fluid flow through said
gel.


33


35. A process of claim 20 for forming an impermeable gel
comprising mixing water, a water soluble silicate of and
an activator comprising at least one compound of the formula:

Image

wherein X is a halogen radical of fluorine, chlorine
and combinations thereof; and M is a cation of sodium,
potassium or a combination thereof; and
wherein said activator reacts only at a temperature greater than
a certain reaction temperature to gel said mixture; injecting a
cooling liquid into a porous, permeable formation normally at
a temperature greater than said certain reaction temperature;
injecting said silicate mixture into said formation; increasing
the temperature of said silicate mixture to gel said silicate
mixture by allowing heat transfer from said formation to said
silicate mixture; and thereby forming a zone impermeable to
fluid flow through said gel.


36. In an aqueous silicate mixture comprising water and
a water soluble silicate which can be gelled to form an impermea-
ble solid gel, the improvement wherein said mixture also comprises
an activator comprising at least one compound of the formula:


Image

wherein X is a halogen substituent of fluorine, chlorine
or a combination thereof; M is a cation of alkali metals,
alkaline earth metals, ammonium or a combination thereof:
wherein said silicate has a pH of about 10-13,said activator
reacts only at a temperature greater than about 60°C to gel said
mixture to produce a silicate composition which can be gelled
by increasing the temperature to an impermeable gel.

34


37. In a process for producing an impermeable silicate gel
by gelling a mixture comprising water and a water soluble silica-
te which can be gelled to form an impermeable solid gel, the im-
provement of including in said mixture an activator which reacts
only at a temperature greater than about 60°C to gel said mixture,
said silicate having a pH of about 10-13,said activator compris-
ing at leat one compound of the formula:


Image

wherein X is a halogen radical substituent of fluorine,
chlorine, or a combination thereof; and M is a cation
of alkali metals, alkaline earth metals, ammonium or
combinations thereof.

Description

lL~7093~;
This invention deals with the gelation of aqueous
silicate solutions and specifically with a class of compounds
which react at energy levels above a given value to cause or
complete gelation of the aqueous silicate mixture. These
compounds are activators and in view of this di~closure can
be selected to cau~e gelation of aqueous silicate producing
novel silicate compositions and processes.
Aqueous silicate solutions have been known and used
for many application~. A specific process covered herein is
commonly referred to as grouting, sealing or formation
consolidation. Conventional soluble silicates, processes and
the details thereof are described in U.S. patents 3,202,214,
3,375,872 and 3,376,926. A typical soluble silicate is
described in SODIUM SILICATE HANDBOOK published in 1970 by
the Diamond Shamrock Corporation. These references can be
used in view of this disclosure to produce obvious variations
of the invention described herein.
Previously known aqueous silicate mixtures or
solutions began gelation when the activator was added to the
silicate mixture so that use or placement of the silicate had
to be completed within a relatively shor~ p2riod of time
before the silicate formed a gel or polymer structureO
Unexpected conditions or details frequently resulted in
failure in the silicate application.




-- 2 --

93~

This invention provides a broad class of activators
and several subclasses which can be mixed with the aqueous sili-
cate mixture as part or all of the required activator; yet, the
mixture containing the activator will not gel until the energy
level, such as temperature, of the mixture is raised to a given
level. This now makes it possible to apply or place the silicate
mixture for the purpose desired with less risk of premature
gelation~ Typically, the complete aqueous silicate mixtu~e
including activator can be stored for a time before it is used
without premature gelation.
In accordance with the invention there is provided an
aqueous mixture having a long shelf life at an energy level
below a given level which can be gelled to a solid, comprising
water, a water solubLe metal silicate and an activator which
reacts at a given energy level to gel the mixture, said silicate
having a pH in the range of about 10-13, said activator being at
least one compound of the formula:
XnR~W
wherein n is an integer equal to 1-6; X is a halide substituent on
an alpha chain, a terminal carbon or both, R is an alkyl radical
an aryl radical or an alkylaryl radical with the alkyl radicals
having 1-6 carbon atoms and the aryl radicals having 6-10 carbon
atoms, and W is a carboxyl, ester, aldehyde, carbinol, hydrogen
or sulfonyl group, acid equivalents thereo~ and combinations
thereof.
The energy level of the aqueous silicate mixture can
be raised by conventional methods in view of this disclosure
when gelation is desired. In a preferred grouting process the
aqueous silicate is mixed with activator~ applied to the porous
substrate which is to be grouted; then the silicate is heated cause
ing the activator to react and gel the silicate. Such a substrate
could be heated by appropriate conventional methods such as radiant

3~ ~

r ~ al7~3~

light, heat or an electromagnetic field. For substra-tes with high
metallic concentrations inductive heating could be used. Appli-
cation of heat by conduction is a preferred method.
In another process, aqueous silicate mixed with activa-
tor can be applied to or injected into a formation at a tempera~
ture higher than the activation level of the selected activatorO
In this case, the formation heat causes the temperature of the
silicate mixture to rise to the level necessar~ for the
activator to react




i -3a~ :

~)7~393~;
and gel the silicate. If the formation temperature is
~ell above the activator reaction temperature, it may be
desirable to cool the ~ormation prior to application
or injection of the silicate mixture to delay gelation
or insure against premature gelation. Conventional
gelation agents can be used with the energy triggered
activator as long as the acid or acid equivalent con-
centration is below about 20 milliequivalents per about
16 milliliters of concentrated aqueous silicate.
The energy triggered activators of this invention
are compounds of the formula:
X R W
wherein n is an integer equal to 1-6; X is a halide
substituent on an alpha carbon, a terminal carbon or
both; R is an alkyl radical, an aryl radical or an
alkylaryl radical with the alkyl radicals having 1-6
carbon atoms and the aryl radicals having 6-10 carbon
atoms; and W is a group selected from carboxyl, ester,
aldehyde, carbinol, hydrogen, sulfonyl (e.g. sulfonate)
and combinations and equivalents thereof.
These activators can be considered bifunctional
compounds. It is thought that the number, location
and t~rpe of halide substituents permit disassociation
of the compound and determine the temperature or energy
leval at which this reaction occurs in the aqueous
mixture. The W group is considered a solubili~ing
group. The R or hydrocarbon group ties these group~
together and also helps determine the energy level at
which the reaction begins. The disassociation may


4~


1~7(g936
begin when the activ~tor is mixed with the aqueous
silicate; howevar, at temperatures below the given
reaction temperature of the activator the reaction rate
is negligible and counter reactions such as settling of
precipitate giving the mixture a long shelf life. The
gelation reaction of this mixture can be triggered by
elevating the energy level to the necessary value
producing gelation in a practical time.
It is thought that the activators disassociate at
a given energy level to produce acid groups or acid
equivalent groups. These acid functional groups are
defined as Lewis acids herein and serve to cause gelation
or polymerization of the aqueous silicate. This can also
be considered an adjustment of the the rnixture pH to a
value within the range of about 1-10.5 which results in
the gelation phenomenon. It is known that groups such as
hydrogen ions, acid halides, halide radicals and carbon
dioxide rapidly cause gelation of aqueous silicate.
Preferred energy triggered activators of this invention
produce a high concentration of these gelation groups. ~;
For example, sodium trichloroacetate ~NaTCA) from the
preferred class of halogenated alkyl acid salts is thought
to begin disassociation by splitting off a carbonyl group
and ultimately producing the equivalent of two moles
of hydrochloric acid and two moles of carbon dioxide per
mole of acid or acetate. This compound requires only
about 1.5-2 grams of sodium trichloroacetate per 100
milliliters of aqueous silicate containing about one
volume of concentra~ed aqueous silicate per six volumes


-5

. ~

~al7~ 3 E;

of aqueous silicate mixture for a practical gelation
time of about 24 hours. This mixture is activated at a
temperature of about 100-140C or temperatures above
about 65C. At temperatures below about 60C most acti-
vators produce aqueous silicate-activator mixtures with
good shelf life and little risk of premature gelation.
A pre~erred group of activators are the halogenated
alkyl carboyxlic acids and the water soluble salts and
equivalents thereof. The salts are preferred because a
highly acidic group would tend to affect gelation upon
mixing rather than upon disassociation at a minimum
energy level. The salts of alkali metals, alkaline earth
metals and ammonia are preferred for solubility in an
aqueous system. The preferred alkali metals are sodium,
potassium and combinations thereof. The preferred alka-
line earth metals are calcium, magnesium and combinations
thereof. The equivalents include esters especially
those in which the ester linkage would tend to hydrolyze
or disassociate at a temperature near the disassociation
temperature of the halogena~ed alkyl group. Likewise, in
view of this disclosure, similar suitable groups which
correspond to the carboxyl group can be considered as a
progressive or corresponding order. These groups must
be considered with the halogenated hydrocarbon portion
of the activator since it is beIieved that the triggering
effect is caused by a certain balanced molecular stability.
The group should also be considered for its ability to
produce the desired acidic groups upon disassociation
without high acidity below the activation tempera~ure.



-6-

107~3~ :

Groups and illustrative compounds are listed as follows:
sulfonyl, trifluoromethylsulfonic acid or the alkali ~ `
metal salt (e.g., sodium or potassium) thereof; aldehyde,
chloral; carbinol, ~,2,2-trichloroethanol; esters, methyl
trichloro acetate and 2,2,2-trichloroethyl acetate; and
hydrogen, chloroform. Suitable carbinols include 2,2,2-
trichloro-l-ethanol; 1,1,1-trichloro-2-propanol; 111,1,3-
tetrachloro-2-propanol; 1,1,1-trichloro-2-butanol and
1,1,1-txichloro-2-methyl-2-propanol. Suitable aldehydes ~-
include trichloroacetaldehyde; alpha,alpha,beta-trichloro-
propionaldehyde; alpha,alpha,beta-trichloro-n-butyraldehyde;
alpha,alpha,gamma-trichloro-n-butyraldehyde; choral
hydrate and chloral diethylacetal. Suitable esters
include methyl trichloroacetate, trichloromethyl trichloro-
acetate, beta-hydroxyethyl trichloroacetate, ethyl trichloro-
acetate, beta-methoxyethyl trichloroacetate, n-propyl
trichloroacetate, isopropyl trichloroacetate, n-butyl ,
trichloroacetate, isobutyl trichloroacetate, tert-butyl-
trichloroacetate, sec-butyltrichloroacetate, n-amyl-
trichloroacetate, iso-amyltrichloroacetate, and tert-amyl-
trichloroacetate. Suitable compounds with hydrogen in
the place of carboxyl include chloroform, iodoform,
bromoform, fluoroform, chlorodifluoromethane, and di-
chlorofluoromethane.
The last class of compounds includes halogenated
hydrocarbons especially the chlorinated and fluorinated
alkyls~ Although the water solubility of these compounds
may re~uire that the activator be dispersed in the aqueous
silicate mixture, the chlorinated and ~luorinated hydro- ;



-7

)936

carbons hclving 1-6 carbon atoms in the alkyl radicals
are preferred for hiyh temperatures. Such fluorocarbons
are described in ADV~NCES IN FLUORINE CHEMISTRY, by
Barbour et al and by Hamilton, published in 1963 by
Butterworth, Inc., Washington, D.C. See especially
Volume 3. Preferred fluorocarbons include dichloro-
difluoromethane and trichlorofluoromethane Preferred
chlorohydrocarbons include carbon tetrachloride.
The activator can be selected in view of this
disclcsure to produce silicate gelation at the energy
level or temperature desired. For one preferred class
of activators, the halogenated alkyl carboxylic acid
salts, the activation temperature increases as the
degree of halogenation increases and/or as the degree
of fluorination increases. The chlorine, fluorine and
combinations thereof are preferred for the halogen sub-
stituents for good predictability of activation
temperature. For example, with sodium salt of tri-
halogenated acetate, the trichloro salt has an activation
temperature of about 200F; the dichloromonofluoro salt
has an activation of about 275F; the monochlorodifluoro
salt has an activation temperature of about 325F; and the
trifluoro salt has an activation temperature of about
400F. Thus, by selecting the solubilizing group (i.e.,
-W), the size and configuration of the hydrocarbon group R,
the degree and location of halogenation and the particular
halogen substituents on the activator can be selected to
give the desired solubility, acidity and activation
temperature. For most applications, the high solubility


~C~7~3~

of activators ~rith short hydrocarbon groups and hydro-
philic solubilizing groups (i~e. -W) are preferred. Migh
solubllity reduces the tendency of activator to separate
from -the aqueous silicate theraby producing more uniform
gelation and reducing the risk of premature gelation or
localized gelation.
For the hydrocarbon group (i.e. R) short chain
alkyl or difunctional aryl, preferably phenyl, groups
are preferred. The alkyl radicals can have straight or
branched chains. rrhe alkyl can also be unsaturated or
the alkylene radical. The preferred alkylene is vinyl. ~
Preferrably the alkyl and alkylene radicals have 1-6 ''
carbon atoms and for high solubility 1-3 carbon atoms.
For aryl or alkylaryl R groups, the aryl radical should
have 6-10 carbon atoms and preferably 6 carbon atoms in
each aryl radical. Substituents other than halogens
and those listed hexein can be presented as long as they
aid or do not interfere substantially with disassociation
of the activator or gelation of the silicate. With long
chains, the halogen substituents should be on both the "
alpha carbon adjacent the solubilizing group and on the
terminal carbon opposite the solubilizing group. It is
thought that the activation energy level is determined
by balance of the electron affinity of the solubilizing
group and the halogen substituents along the hydrocarbon , ,
chain, or in other woras that the unsaturated linkages, '~
the halogen substituents and the, solubilizing group
have what will be termed a balanced electron affinity
which'makes the activator stable up to a given energy




.

11)7(~336
level, at which the activator, more or lesq, completely
disa~sociates with a high concentration of acid groups to
cause relatively rapid and uniform gelation.
Acti~ator concentration also affect~ the gelation
time. For a preferred aqueou~ silicate mixture containing
about one volume of concentrated aqueous ~ilicate in six
volumes o-f aqueous mixture, the acid or acid mole equivalents
(MEQ) concentration is about 20 MEQ for a practical gelation
time of about 24 hours or less. For preferred activators
this concentration is about 0.5-5 grams per 100 milliliters
of silicate mixture or 0.1-10 grams, preferably 0.2-5 grams
of activator per 100 grams of water soluble silicate solids
in the mixture. This acid or acid equivalent is defined
herein as a Lewis acid which i5 described in the ENCYCLOPEDIA
OF CHEMICAL TECHNOLOGY, by Kirk-Othmer, published in 1963,
by John Wiley and Son~, New York. Acids are discussed at
about pages 213~222. These acid equivalents will al~o be
referred to herein as proton or hydro~en ion concentration.
For a preferred type of composition herein, conventional
acid gelation a~ents can be included at a concentration less
than that requixed to give a significant or practical gela-
tion rate. Activator can then be used w~ich would increase
the gelation rate to a practical value at the activation
energy level. However, for maximum shelf life of the aqueous
silicate mixture, it is preferred to use only the energy
triggered activator of this invention. The shelf life of these




-- 10 --

ILO'70936

preferred compositions can be in ~xcess of six mGnths.
Silicates which can be used for the cornpositions
and processes of this invention are the water soluble
silicates which for silicate polymer chains or gel upon
acidiEication. The preferred silicates are those of
the alkali metals, especially sodium, potassium and
combinations thereof. These silicates are commercially
available as dry powders or concentrated aqueous solu~
tions having about 38-55 parts solids per hundred parts
of solution and a pH of about 10-13. With highly con-
centrated silicate mixtures, contamination by salts,
acids, etc. must be carefully avoided and the solution
should be carefully and uniformly mixed with activator
and any optional particulate filler such as silica
flour. For most applications, the activator is prefer-
ably added to and mixed with the silicate solution as a
solution or an aqueous dispersion. The silicate is
also typically diluted to reduce the viscosity for easier
application and pumping.
In certain applications it may be necessary to follow
special mixing procedures to avoid the likelihood of
local dehydration of the sodium silicate when the activator
is combined therewith. To this end, it is proposed that, -
where the activator to be used is relatively readily
soluble in water~ it i~ diluted to some extent prior to
adding it to the sodium silicate solution. It is preferred
that the dilution be accomplished by using one of the two
volumes of water ordinarily used to dilute the com-
mercially availabLe concentrated sodium silica~e solution.

~L~7~936

Sodium silicate is not a true solution but it is
capable of sealing yeological formations. It has been
used at high temperatures with limited success. Some of
these prior art methods of sealing or plugging with sodium
silicate are disclosed in U.S. Patents Nos. 2,236,147;
2,198,120 and 2,330,145.
Sodium silicate is a complicated system of various
molecular weight silica polymers in an alkaline solution.
Aside from requiring a certain minimum amount of alkalinity,
sodium silicate has no definite chemical combining numbers.
When sodium silicate is acidified to a pH less than about
10 or ll, the sodium silicate is converted partially to
silicic acid. Silicic acid exists at these alkaline
pH's as it is such a weak acid. Instead of precipi-
tating and making silica, Si~2, the silicic acid
remains hydrated and forms a three dimensional network
in trapping the solvent water. This network is a gel
since both phases are continuous.
A slight lowering of the pH brings about radical
changes in gel time. Consequently, gel timas are diffi-
cult to control, and lumping from local acid concentrations
during large scale mixing frequently occurs.
One particular advantage of the invention resides
in the fact that each of these activators provide some
delay in the gelling reaction and in the feature which
permits the activator to be seIected to provide the
delay which is necessary or desirable for best results in
accordance with the conditions which prevail in the
particular operation involved.



-12-

~7~)~3\3~;

For example, where a grouting fluid is pr~pared,
the need for a slow or delayed acting activator may not
be as great as whe.re the invention is used in preparing
a treating fluid which is to be used in performing a well
operation at a considerable depth below the surface of ~:
; the ground. Also, there will be instances where the :
prevailing temperature and other conditions will make
one activator more suitable for use than another.
While the rate o gelation will depend upon various
factors, including the prevailing temperature and pres-
sure conditions, it is emphasized that each of the acti--
vators herein. disclosed acts indirectly in that the
sodium silicate solution is gelled by first producing
acid or hydrogen ions which result in lowering the pH
of the solution. The delay may range from only a few
seconds up to several hours. However, if the solution .:
were contacted with an acid directly, gelation would
ordinarily be substantially instantaneous. In fact, one ; :
: difficulty which has been encountered in attempting to
effect gelation in this manner has been that of being
unable to mix relatively large quantities of the solution
and acid due to gelation occurring so quickly that all
the ingredients cannot be stirred together.
In carrying out a grouting operation, such as in
treating earth strata located near the surface of the
i ground or near the opening of a mine shaft, it may be
necessary to first drill a relatively short or shallow
bore hole into the strata and then inject the grouting
fluid ~hrough the bore hole into the section or zone to
.~
13-

~7~3~

be treated. Satisfactory results may be obtained in
these and other operations using activators which
give at most only a few minutes delay, since the time
required for the mixing and placement of the gel-forming
composition may be relatively short.
In carrying out a well treating operation, on the
other hand, it will ordinarily be necessary or desirable
to employ an activator which gives a sufficiently
long delay to allow for the time required in pumping
the gel-forming composition into the well, as well as
in preparing the composition and in applying pressure
to inject it into the treated zone or formation after ~-
reaching the desired depth in the well.
Where the delay obtainable using a particular acti-
vator is not considered sufficient to allow ample time
for pumping the gel-forming composition into a well, it
may be necessary or desirable to cool the formation or
use high temperature activators as the major or only
activator. The sodium silicate solution and activator
ca~ be pumped into the well following a cooling fluid,
e.g., gas or liquid. For example, the activator and
sodium silicate solution may be introduced into the well
as a continuous fluid stream behind a quantity of water
used as a cooling or spacer fluid in the stream ahead
of the ingredients of the gel-forming composition. Where
this procedure is followed, the delay obtainable due to ;
the slow or delayed action of the activator after con-
tacting the sodium silicate solution in the well with
the adjacent high temperature strata may nonetheless
-14-

93~

afford particular advan-tages. For example, the delay
enables the ingredients of the treating fluid to pene-
trate more deeply and uniformly into the permeable zone
or formation prior to the viscosity of the combined
inyredients becoming so great as to hinder or prevent
further penetration.

FXAMPLES
Samples of aqueous alkali metal silicate mixture
are prepared by mixing one volume of concentrated
aqueous sodium silicate with two volumes of water. The
concentrated aqueous sodium silicate is described as
Grade 40 in the SODIUM SILICATE HANDBOOK and contains
about 38 parts solids per 100 parts concentrate with
a ratio of 3.22 moles of SiO2 per mole of Na20 and a
pI~ of about 13.
An activator solution is prepared by mixing a
halogenated alkyl carboxylic acid preferably in the
salt form with water. Sodium trichloroacetate (i.e.
NaTCA) is mixed with water at a concentration of 2 grams
of salt per 50 milliliters of solution.
Fifty milliliters of sodium silicate mixture are
mixed with 50 milliliters of activator to produce a
100 milliliter sample. To this sample, 171 grams o~
silica 10ur filler can be added to increase the response
of solution viscosity to gel formation.
Several 100 milliliter samples with silica flour
filler are prepared and placed in a constant temperature
bath which is at about 94C. The samples are stirred
in the bath. The time for initial gel forma-tion and



--15--

~7~ 36

final gel quality are observed and notecl. The initial
gel time is observed as the time at which the viscosity
of the mixture increases to the point where it reduces
the mixture's tendency to flow from the sample con-
tainer. This can also be observed as a change of the
mixture from clear to cloudy or translucent. The final
gel time is observed as the time when the mixture
completely ceases to flow or there is a rapid and large
increase in in viscosity. Samples are also prepared
and tested using different concentrations of activators
and different bath temperatures. The variation of gel
time with activator concentration is shown in Tables I
and II. Table I also shows the effect of mixture tempera-
ture on gel time and quality. Tables III and IV show the
effect of using 2 and 1.5 grams respectively of ~aTCA
activator per 100 milliliter of silicate mixture and
various bath temperatures on gel time and quality. Table
V also shows the effect of various NaT~A activatox
concentrations and bath temperatures where samples were
heated in the bath under autogenous pressure.
~ rom the data in the Tables it can be seen -that a
practical gel time is af~ected by activator concentration
and the activation temperature. Tables II through IV show
that for NaTCA activator temperatures below about 60C,
silicate-activator mixtures have a good shelf life or an

: -,
adequate storage and handling period without risk o~
premature gelation.




-16-




,~

~76)~33~
, .

TABLE I ~;
: Gelation o~ Aqueous Sodium Silicate at 200F
_ _ Activator _ _ :
Gm NaTCA Gel
Sample per 100 ml Time Gel .
No. Solution ~EQ-H~ Min. Quali-ty
1 2 38.9 38:00 Firrn Gel
2 2 38.9 33:00 Firm Gel
3 1.5 29.1 44:00 Firm Gel
4 1.5 29.1 44O00 Firm Gel
1.25 24.3 51:00 Good Gel
6 1.25 24.3 55:00 Good Gel ~:
7 1.2 23.3 50:00 Good Gel
8 1.2 23.3 53:00 Good Gel
9 1.15 22.3 61:00 Fair Gel
1.15 22.3 67:00 Fair Gel
11 1.1 21.4 71:00 Soft Gel ~-
12 1.1 21.4 75:00 Soft Gel
13 1 19.45 74.00 Soft Gel

T~BLE II ; .
:
Gelation of Aqueous Sodium Silicate
NaTCA Gel
Sample (gms/100 ml Temp. Time Gel
No. Solution)(F) (Min.) Quality
1 2.0 200 40 Firm gel
2 1.5 200 46 Firm gel
3 2~0 180 127 Firm gel
4 2.0 lR0 125 Firm gel
1.5 180 187 Fair gel
6 1.5 180 188 Fair gel
7 2.0 165 350 Firm gel
8 2.0 165 350 Firm gel
9 1.5 165 523 Fair gel
1.5 165 515 Fair gel
11 2.0 150 708 Fair gel
12 2.0 150 710 Fair gel
13 1.5 150 1408 Fair gel
14 1.5 150 1411 Fair gel
2.0 140 2181 Weak gel
16 2.0 140 2172 Weak gel
17 1.5 140 3877 Weak gel
18 1.5 1~0 3816 Weak geI

-17--

~07t~3~

TABLE III
Gelation of Aqueous Sodium Silicate with 2 Grams NaTCA
Cloud Gel
Temperature Time Time Gel
(F) (min.) (min.) Quality
..
140 1790 2160 Firm gel (510wly)
150 -- 1470 Firm gel
165 435 460 Firm gel
180 110 125 Firm gel
200 -- 53 Firm gel


; TABLE~ IV
Gelation o~ Aqueous Sodium Silicate with 1.5 Grams NaTCA
: Cloud Gel
Temperature Time Time Gel
(F~ (min.) (min.) Quality
,
140 3000 3840 Fair gel (settling)
150 1095 1250 Firm gel
165 145 180 Firm gel
; 180 -- -- Firm gel
200 -- 33 Firm gel


TABLE V_
Gelation of Aqueous Sodium Silicate - : :
NaTCA : ~ :
grams/100 ml Gel Time, Minutes
Total Solution 165F 180F 200F :
1.5 650 178 51 ~ :.
: 1.5 540 175 54 ~. .
1.5 519 1~7 46
2.0 416 136 44
: 2.0 355 140 42
2.0 350 126 40



-18-