Gellable treatment fluids comprising amino group gel-time modifiers and methods for use thereof.

GELIFYABLE TREATMENT FLUIDS INCLUDING

AMINO GROUP GEIATION TIME MODIFIERS AND METHODS

FOR THE SAME USE

FIELD OF THE INVENTION

The present invention relates to methods and compositions for reducing the amount of water produced from an underground formation, and, more specifically, to methods and compositions for treating at least a portion of an underground formation to reduce water permeability using a gelling treatment fluid comprising a gelation time modifier comprising at least one amino group. '.

BACKGROUND OF THE INVENTION

Often undesirably the water accompanies the production of gas and oil from a well penetrating an underground formation. Unwanted production of water from hydrocarbon-producing wells can be a significant technical problem and expense in oilfield operations. If the ratio of produced water to produced oil and gas becomes large enough, the cost of water separation and water disposal can become a barrier to continuing with, ΙΜΡΙ ^

Ζ Mexican INSTITUTE

Df THE PROPERTY fr - !? HSTRfAL production. This can lead to a well abandonment penetrating a formation. underground, even when significant amounts of hydrocarbons remain there.

In an underground formation, the high mobility of water often allows it to flow to or from the borehole of natural and man-made fractures, high permeability zones, and the like. In such cases, the less permeable zones in the formation can be bypassed. The deviation of the less permeable zones can be especially problematic when an aqueous treatment fluid is introduced into an underground formation. For example, in enhanced oil recovery techniques, an aqueous fluid can enter an underground formation during flooding operations. When the least permeable zones are present in the underground formation, lower oil and gas production may occur due to the less effective flooding operation being performed. The presence of natural and man-made fractures, zones of high permeability and the like also pose problems when liquid fluids need to be introduced into zones of low permeability for others. purposes other than flood operations. Examples may include acid stimulation treatments and cleaning fluids. IMPI ο · ΝΓπτυτη Mexican · »<λ i vrj · '^ Γ." Γ drilling wells. In such cases, aqueous fluids can preferentially enter high permeability areas and bypass low permeability areas, which are the intended goals of fluid treatments.

One way that the above issues can be addressed is through. compliance control treatments, through which high permeability zones become completely or partially blocked to fluid flow. In the event of unwanted water production, the complete blocking of water-producing permeable zones, despite high or low permeability, can stop unwanted water production. In the case of flood operations, partial blocking of high-permeability zones can allow oil production from bypassed low-permeability zones. In the case of stimulation and cleaning of nearby well boreholes, partial blocking of zones of high permeability can allow diversification of stimulation fluid (for example, an acid) or well cleaning fluid to a zone of low permeability. permeability.

Compliance control treatments may involve the introduction of gellable polymer * systems into an underground formation by means of an aqueous treatment fluid. Polymer systems

<img file="MX345855B_D0001.tif" />

JW

IMPI

INSTITUTO MEXICANO DE IA MONEDAD INDUSTRIAL gelables can form a gel through La -. ¾½iculuoy a water soluble polymer using a crosslinking agent. The gelation time and the strength of gelation of polymer gelling systems are among the factors that can determine the effectiveness of a compliance control treatment. For example, if the gelation time is too short, the introduction or placement of the gellable polymer system in an underground formation can be problematic. Conversely, if the gelation time is too long, the gellable polymer system may not form a gel in the desired portion of the underground formation, or long waiting periods may be required before operations can be carried out. additional.

A number of crosslinking agents can be used to crosslink water soluble polymers in gellable polymer systems. Chromium and other transition metal ions can be used to crosslink acrylamide-containing polymers and copolymers. Generally, gels that are formed using such cross-linking agents have proven unsuitable at high temperatures (eg, above about 80 ° C) due to uncontrolled cross-linking rates (eg, short gelation times), precipitation of crosslinking agents,

IMPI ^ s INSTITUTO MUUCAM. · ^OR HU raOHUMD iNlMlfTWlAt --- polymer degradation, and the like. Also, · chromium and certain other transition metal ions can have an undesirable environmental impact. Acrylamide-containing polymers, copolymers, and partially hydrolyzed variables thereof can also be gelled with polyalkyleneimines and polyalkylenepolyamines. In such gellable polymer systems, gelation times are often just as long. short that the crosslinking agent and the water soluble polymer are generally pumped separately - from the bottom of the well to prevent premature gelation from occurring. Gel time accelerators and retardants have also been used in the art to modify gel times in such systems.

Gellable polymer systems generally comprise a crosslinking polymer and a crosslinking agent. Typically, as the concentration of any of these components decreases in a treatment fluid, the time required to form a gel increases when measured by an increase in the viscosity of the treatment fluid at a given temperature, referred to herein as gelation time. Generally, gelation time is determined by measuring the viscosity of a treatment fluid comprising the polymer system.

MEXICAN INSTITUTE

OE INDUSTRIAL PXOPIITY gelable as a function of time. Although treatment fluids having lower concentration gellable polymer systems are desirable from a cost of goods standpoint, increased gelation times at lower concentrations may render such treatment fluids ineffective for treating an underground formation. .

The gelation time of a treatment fluid comprising a gellable polymer system is usually a function of temperature and the concentrations of soluble polymer in water and crosslinking agent thereof. Generally, at higher concentrations of these components, shorter gel times can result. On the contrary, at lower concentrations, the gelation times can be increased. In some examples, low concentration gellable polymer systems may have gelation times that increase to such an extent that they become ineffective in treating an underground formation. Furthermore, at lower concentrations, the gelation force can also be impacted to some degree. Although gelation strength is not typically a concern in most compliance control treatment fluids, due to the relatively high concentrations of water soluble polymer and the crosslinking agent that

7IMPI ^ ινγγγπγτο Mexican m the FnomoAn

INDUSTRIAL * is used, it is appropriate to mention that gelation strength can be reduced in low concentration gellable polymer systems.

In compliance control treatments using polymers and copolymers containing acrylamides and crosslinking agents such as, for example, polyethyleneimine and polyalkylenepolyamines, relatively high concentrations of both components are generally used. From a single economic standpoint, it would be desirable to reduce the amounts of either material while still maintaining acceptable gelation times and gelation forces to achieve successful compliance control. For polyethyleneimine, in particular, it would also be desirable to reduce the amounts of this highly corrosive material being used in compliance control treatment fluids to improve their environmental classification.

SUMMARY OF ΙΛ INVENTION

The present invention relates to methods and compositions for reducing the amount of water produced from an underground formation, and, more specifically, to methods and compositions for treating at least a portion of an underground formation to reduce the permeability of the

IMPI

INSTITUTO MSXICANC DE LA OMEDAD INDUSTRIAL water using a gellable treatment fluid comprising a gelation time modifier in at least one amino group.

In one embodiment, the present invention provides a method comprising: providing a gellable treatment fluid comprising: a water-based fluid, a base polymer comprising an acrylamide monomer unit, an organic cross-linking agent; and a gelation time modifier comprising at least one amino group, any salt thereof, any derivative thereof, or any combination thereof; introducing the gellable treatment fluid into at least a portion of an underground formation, and allowing the gellable treatment fluid to form a gel in the underground formation. . '

In one embodiment, the present invention provides a method comprising: providing a gellable treatment fluid comprising: a water-based fluid, a base polymer comprising an acrylamide monomer unit, an organic cross-linking agent comprising a polymer of crosslinking selected from the group consisting of polyethyleneimine, polyvinylamine, any derivative thereof, any salt thereof, and any combination thereof; and a gelation time modifier

MIXJCAM INSTITUTE

This is LA PWDFI1DAI INDUSTRI "" which comprises at least one compound selected from a group consisting of amino alcohols, oligomeric polyamines, any salts thereof, any derivatives thereof, and any combination thereof; and wherein the gelling treatment fluid has a reduced gelation time relative to a gelling treatment fluid lacking a gelation time modifier; introducing the gellable treatment fluid into at least a portion of an underground formation, and allowing the gellable treatment fluid to form a gel in the underground formation.

In one embodiment, the present invention provides a gellable treatment fluid comprising: an aqueous based fluid, a base polymer comprising an acrylamide monomer unit, an organic crosslinking agent comprising a crosslinking polymer selected from the group consisting polyethyleneimine, polyvinylamine, any derivative thereof, any salt thereof, and any combination thereof; and a gel time modifier comprising at least one amino group, any salt thereof, any derivative thereof, or any combination thereof.

The features and advantages of the present invention will be readily apparent to one skilled in the art.

<img file="MX345855B_D0002.tif" />

IMPI

MUUCANO INSTITUTE

DE LA INDUSTRIAL FROPIEDaD on a reading of the description of the preferred modalities that follow.

BRIEF DESCRIPTION OF THE FIGURES

The following figures are included to illustrate certain aspects of the present invention, and should not be viewed as exclusive embodiments. The subject matter described is capable of considerable modification, alteration, and equivalents in form and function, as will be apparent to one skilled in the art and the benefit of this description.

FIGURE 1 shows an illustrative graph of viscosity as a function of time at 71.1 ° C (160 ° F) for various gellable treatment fluids comprising a base polymer of t-butylacrylate / acrylamide, polyethyleneimine, and optionally, a time modifier. of gelation of amino alcohol.

FIGURE 2 shows an illustrative graph of viscosity as a function of time at 160 ° F (71.1 ° C) for various gellable treatment fluids comprising a base polymer of t-butylacrylate / acrylamide, polyethyleneimine, and optionally, a time modifier. diethylenetriamine gelation.

IMPI ^

1 IHSTTrUT · MUUCANO ^χ- * - «; ía i&gt; RomDAt&gt;

INDUSTRIAL X »»

FIGURE 3 shows an illustrative graph of viscosity as a function of time at 160 ° F (71.1 ° C) for various gellable treatment fluids comprising a t-butylacrylate / acrylamide base polymer, polyethyleneimine, and optionally, a time modifier. triethylenetetramine gelation. ·

FIGURE 4 shows an illustrative graph of viscosity as a function of time at 71.1 ° C (160 ° F) for various gellable treatment fluids comprising a base polymer of t-butylacrylate / acrylamide, polyethyleneimine, and optionally, a time modifier. of gelation of amino alcohol. '

FIGURE 5 shows an illustrative graph of viscosity as a function of time at 160 ° F (71.1 ° C) for various gellable treatment fluids comprising a t-butylacrylate / acrylamide base polymer, polyethyleneimine, and optionally, a time modifier. of gelation of amino alcohol.

FIGURE 6 shows an illustrative graph of viscosity as a function of time at 121.1 ° C (250 ° F) for various gellable treatment fluids comprising a base polymer of t-butylacrylate / acrylamide, polyethyleneimine, and optionally, a time modifier. of gelation of amino alcohol. .

<img file="MX345855B_D0003.tif" />

FIGURE 7 shows an illustrative graph of viscosity as a function of time at 160 ° F (71.1 ° C) for various gellable treatment fluids comprising a base polymer of t-butylacrylate / acrylamide, polyethyleneimine, 5-tetramethylammonium chloride and optionally, ethanolamine.

FIGURE 8 shows an illustrative graph of viscosity as a function of time at 71.1 ° C (160 ° F) for various gelatable treatment fluids comprising a partially hydrolyzed polyacrylamide, polyethyleneimine, and various gelation modifiers in KC1 to 2 base fluid. %.

FIGURE 9 shows an illustrative graph of viscosity as a function of time at 160 ° F (71.1 ° C) for various gelatable treatment fluids, comprising a partially hydrolyzed polyacrylamide, polyethyleneimine, and various gelation modifiers in KC1 base fluid at 7%.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to methods and compositions for reducing the amount of water produced from an underground formation, and, more specifically, to methods and compositions for treating at least a portion of an underground formation to reduce it. water permeability using a gellable treatment fluid that

<img file="MX345855B_D0004.tif" />

IMPI

MEXICAN INSTITUTE

DE LA NkOmOAO INDUSTRIAL comprises a gelation time modifier on at least one amino group.

There are many advantages of the present invention. For example, the present invention provides compositions and treatment fluids for use thereof in which the gellable polymer systems are present in concentrations lower than those conventionally used in the art, while still providing gelation times that are of an effective duration for the placement and ideal performance within the well to be performed. As defined herein, a treatment fluid is a fluid that is placed in an underground formation to perform a desired function. Treatment fluids can be used in a variety of underground operations, including, but not limited to, op drilling operations, production treatments, stimulation treatments, remedial treatments, fluid diversion treatments, fracturing operations, secondary EOR operations. or tertiary, and the like. As used herein, the terms "treat" and "treat" refer to any underground operation that uses a fluid in conjunction with performing a desired function and / or achieving a desired purpose. The terms treatment and treat as used in this document do not imply any particular action.

<img file="MX345855B_D0005.tif" />

IMPI intotuto mucamo Dt LA PROriSDAO INDumUM for the fluid or any particular component thereof unless otherwise specified. Treatment fluids can include, for example, drilling fluids, fracturing fluids, acidifying fluids, conformation treatment fluids, damage control fluids, remediation fluids, scale inhibition and removal fluids, chemical fluids, and the like. .

According to the present embodiments, it has surprisingly been discovered that the inclusion of the present gel time modifiers can reduce the gel times in a treatment fluid comprising a gellable polymer system. In the case of a low concentration gellable polymer system, additives can reduce gelation time to a level that is more akin to treating an underground formation. That is, the additives can serve as gel time promoters in such embodiments. However, in some alternative embodiments, the additives can increase the gelation time at higher additive concentrations. That is, additives can serve as retardants in these modes. In such embodiments, additives can increase the gel time of a treatment fluid whose gel time is otherwise too short to be useful for a desired application. Therefore,

<img file="MX345855B_D0006.tif" />

IMPI

INSTITUTO MCXICANO M LA PROPIIDAB INDUSTRIAL present additives can be added to a treatment fluid comprising a system of gelable polymers in amounts sufficient to increase or decrease the gelation time to a desired degree.

More specifically, it has surprisingly been discovered that treatment fluids comprise an acrylamide monomer unit (eg, polyacrylamide, acrylamide copolymers, and partially hydrolyzed versions thereof) and an organic crosslinking agent (eg, polyethyleneimine and polyalkyleneamines. ), They can have reduced gel times when large amounts of gel time modifier that comprise at least one amino group can modify gel times according to the present embodiments include, for example, amino alcohols and oligomeric polyamines (for example, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine). Although polyamine compounds that have much higher molecular weights (e.g. polyethyleneimine and polyalkyleneamines) can induce crosslinking of acrylamide polymers, it has been found in control experiments that amino alcohols and small molecule oligomeric polyamines do not appear crosslinking effectively (or even initiating medial crosslinking) only with acrylamide polymers. Therefore, the

<img file="MX345855B_D0007.tif" />

IMPI

INSTITUTO MEXICANO Ot LA FROFIÍOaD impihctuiai fact that amino alcohols and oligomeric polyamines can facilitate crosslinking is particularly surprising. Furthermore, the fact that oligomeric amino alcohols and polyamines become gelation time retardants at higher concentrations is also surprising, since gel time promotion would ordinarily be expected to increase continuously with increasing concentration.

Other additives may also be used in combination with gel time modifiers comprising at least one amino group, as discussed below, to further modify gel times. For example, in one embodiment, quaternary ammonium salts can be used to further modify gel times.

Concerns have been raised regarding the environmental impact of treatment fluids used for various underground operations. Since the treatment fluids of the present invention may comprise a lower concentration of at least one of the components of the gellable polymer system compared to conventional treatment fluids having comparable gel times, the present treatment fluids can be particularly advantageous from an environmental point of view. Particularly, in some modalities, the fluids of

<img file="MX345855B_D0008.tif" />

IMPIi iNjTtrtrro mujquo

INDUJTHI * L present treatments may comprise a lower concentration of crosslinking agent and / or base polymer than would otherwise be required to achieve a given gelation time. In more specific embodiments, the use of a gel time modifier comprising at least one amino group in the present treatment fluids can allow lower concentrations of polyethyleneimine, which is highly corrosive, to be used in the treatment fluid.

In some applications, depending on the underground formation, inorganic salts (eg, alkali metal salts or alkaline earth metal salts), such as sodium chloride or potassium chloride can be included in the treatment fluid. Generally, an increase in the salt concentration can increase the gelation time. Increased gelation time can be particularly problematic at low temperatures, where gelation times are inherently longer due to slower chemical reaction rates at low temperatures. The increased gelation times in treatment fluids comprising a salt can be advantageously compensated for by, in some embodiments, the use of gelation time accelerators. At high temperatures, the gelation times are shorter. By selecting an appropriate concentration of a modifier

IMPI ^ η or INSTITUTE ΜίΧΚΛΜΟ

1Ο ΟΕ LAΙΈΟΜΕΟΑΓ Ό ·

INDUSTRIAL gelation, the use of treatment fluids at higher C '' temperatures may become possible. Specifically, in some embodiments, gelation time modifiers can increase gelation time so that a proper gelation rate can be performed under high temperatures.

Although the present invention primarily describes treatment fluids that can be used in compliance control operations, it should be understood that the treatment fluids of the present invention can be used in any of the drilling stages, the production stage, the stimulation, enhanced oil recovery (EOR) operations, or the remedial stage of an underground operation. Any of these operations can benefit from the reduced amount of water produced, for example from underground formation or from decreased formation water permeability.

The treatment fluids of the present invention generally comprise an aqueous base fluid as the continuous phase. Aqueous phase base fluids can include, for example, fresh water, acidified water, salt water, sea water, brine, or an aqueous salt solution. In some embodiments, the treatment fluids can also comprise small amounts of hydrocarbons so that they can be introduced from any source. In one embodiment, the

<img file="MX345855B_D0009.tif" />

IMPI fNsrrruTO muican &lt;&gt; Dt THE PROPERTY

INDUSTRIAL hydrocarbons in the introduction of small amounts of treatment fluids present can ¹ &lt;.

take place concurrently with the components of the gellable polymer system, as some of these components can be obtained commercially in a hydrocarbon-based fluid. Small amounts of hydrocarbons, when present, are not believed to significantly impact the performance of treatment fluids in a gel build.

In various embodiments, the treatment fluids of the present invention may include a water-based fluid as the continuous phase. In some embodiments, the water-based fluid can be a water-based solution. Such aqueous based solutions can have a salt concentration with a range between about 0.1% and about 10% by weight. The salt concentration may range from about 1% to about 10% by weight in some embodiments or from about 2% to about 5% by weight in other embodiments. In certain embodiments, some or all of the salt can be replaced by another material. For example, in some of the present embodiments, the gelation time modifier comprising at least one amino group can replace at least a portion of the salt in the water-based fluid. That's it, sayings

<img file="MX345855B_D0010.tif" />

IMPI

INSTITUTO MÉXtCAfK) M LA HtOMÍDAC treatment fluids may have a lower concentration than a similar treatment fluid that lacks a gelation time modifier. In other embodiments, the gel time modifier can be used in a base fluid that is comparable in composition to a similar treatment fluid lacking a gel time modifier. That is, in these modalities, the. gelation time modifier does not replace the salt in the base fluid. The salt of the aqueous salt solution is generally an alkali metal salt or an alkaline earth metal salt. Of these, sodium chloride and potassium chloride are now preferred. Other alkali metal or alkaline earth metal salts such as, for example, soluble nitrates, acetates, and formates can also be used to form the aqueous salt solution.

In some embodiments, the gellable treatment fluids of the present invention may comprise a water-based fluid, a base polymer comprising an acrylamide monomer unit, an organic cross-linking agent, and a gelation time modifier comprising at least an amino group. .

In some embodiments, gellable treatment fluids may have a reduced gelation time relative to that of a similar treatment fluid lacking

<img file="MX345855B_D0011.tif" />

IMPI INSTITUTO MEXICANO • Ot THE «INDUSTRIAL OHYNESS of a gelation time modifier.

In alternative * I II embodiments, the gellable treatment fluids may have an increased gelation time relative to that of a similar treatment fluid lacking a gelation time modifier. As used herein, the term "similar treatment fluid" refers to a second treatment fluid that has substantially the same composition as that of the first treatment fluid, with exceptions for: 1) the second treatment fluid that has a concentration different from at least one component, and 2) the second treatment fluid lacking the gelation time modifier comprising a quaternary ammonium salt. Inert components that do not substantially affect gelation time may also be present in a similar treatment fluid.

In some embodiments, the base polymers can be water soluble. In some embodiments, the base polymers of the present treatment fluids may comprise an acrylamide monomer unit. Such base polymers can include, for example, polyacrylamide, acrylamide copolymers, and partially hydrolyzed versions thereof. In alternative embodiments, base polymers comprising a methacrylamide monomer unit can be used. Examples of base polymers of ₂₂ IMPI ^

4 Mexican wfrrwro

I heard the name IND— INDUSTIUAL met (acrylamides) are described in US Patent 6,176,315,. .. ........

which is incorporated herein by reference in its entirety. Such base polymers can include, for example, water soluble methacrylamide and polymethacrylamide copolymers, and partially hydrolyzed variants thereof.

Optionally, acrylamide and methacrylamide monomers can be used in combination with one another. In some embodiments, the base polymer can be a partially hydrolyzed polyacrylamide. Such a base polymer is available from Halliburton Energy Services of Duncan, Oklahoma under the trade name FDP-835 ™, which has a molecular weight of about 640,000. In some embodiments, the base polymer can be a copolymer of acrylamide and an acrylate. In more specific embodiments, the base polymer can be a copolymer of acrylamide and t-butyl acrylate. Such a base polymer is available from Halliburton Energy Services of Duncan, Oklahoma under the trade name HZ-10 ™, which has a molecular weight of about 107,000. In still other embodiments, the base polymer can be a copolymer of acrylamide and / or methacrylamide and monomers such as, for example, ethylene, propylene, styrene, maleic anhydride, and the like. Said polymers can also be partially hydrolyzed. Still in . other alternative embodiments, an acrylate ester monomer unit can replace

<img file="MX345855B_D0012.tif" />

<img file="MX345855B_D0013.tif" />

acrylamide or methacrylamide or used in combination with acrylamide or methacrylamide.

A portion of a base polymer comprising an acrylamide monomer unit is shown in Formula (1) below, where wavy lines represent binding to other monomer units.

<img file="MX345855B_D0014.tif" />

Formula 1)

In some embodiments, the base polymer may comprise an acrylate ester monomer unit. A portion of a base polymer comprising an acrylate ester monomer unit is shown in Formula (2) below, where the curved lines represent attachment to other monomer units and R is an alkyl or aryl group, for example.

<img file="MX345855B_D0015.tif" />

IMPI

MEXICAN INSTITUTE OF INDUSTRIAL PROPERTY

<img file="MX345855B_D0016.tif" />

Formula (2)

In some embodiments, the base polymers comprising acrylamide or acrylate ester monomer units can be at least partially hydrolyzed. As used herein, the term "at least partially hydrolyzed" refers to base polymers that have at least a portion of side chain amide or ester groups hydrolyzed to form side chain acid groups. That is, base polymers that are partially hydrolyzed that have at least some acrylic acid monomer units. In various embodiments, the degree of hydrolysis can range from about 0.1% to about 30% of the acrylamide / acrylate monomer units. A partial structure of a base polymer comprising acrylic acid monomer units is shown in formula (3) below, where the wavy lines represent a bond to other monomer units (e.g. other monomer units).

IMPI

INSTITUTO MEXICANO oe LA JROMtOAO INDUSTRIAL acrylic acid monomer and / or other acrylate or acrylamide ester monomer units).

<img file="MX345855B_D0017.tif" />

Formula (3). Depending on the pH of the treatment fluid, base polymers that are at least partially hydrolyzed may have their acid side chains protonated (ie, acidic) or deprotonated (ie, anionic form). In various embodiments, the base polymers of the present invention may have a molecular weight in the range of 100,000 to about 20,000,000.

Among other factors, the performance of the above base polymers can be impacted by the temperature at which they were allowed to gel. That is, the gelation times of the base polymers can vary depending on the temperature of the underground formation at which they are introduced. For example, a base polymer that produces an acceptable gelation time at low temperatures may gel unacceptably at a rapid rate at higher temperatures. In contrast, a base polymer that gels at an acceptable rate at a higher temperature may not gel at an acceptable rate, if at all, at lower temperatures. For conformation control treatments using the 5 specific base polymers set out above in combination with polyethyleneimine as an organic crosslinking agent, a t-butyl acrylate / acrylamide copolymer is generally used when the temperature of the underground formation is around 71.1 ° C (160 ° F) or higher, While a partially hydrolyzed polyacrylamide is generally used when the underground temperature has a temperature range between about 15.6 ° C (60 ° F) and about 71.1 ° C · (160 ° F). It should be noted that the preferred temperature ranges are for gellable treatment fluids lacking a gelation time modifier comprising at least one amino group or any other gelation time modifier. The use of a gelation time modifier as in the present embodiments can allow an expanded effective operating temperature with a range of base polymer. Accordingly, the present treatment fluids can be used effectively at lower temperatures than those conventionally used in the art,

IMPI ^ η π MEXICAN MSTITOTO. ^ζ 'Of ΙΑ CURRENCY Ο ··.

(NOU * T »IAl particularly those fluids comprising a t-butyl acrylate / acrylamidal copolymer.

In some embodiments, the base polymers of the present invention are not hydrophobically modified. As used herein, the term "hydrophobically unmodified" refers to a base polymer that does not comprise a hydrophobic modification therein. As used herein, a hydrophobic modification of a base polymer will be considered to be a hydrophobic group having more than 4 carbon atoms. More particularly, in some embodiments, the base polymers of the present invention are devoid of monomer units having a quaternized hydrogen atom and a hydrophobic modification therein.

Particularly suitable organic crosslinking agents that can be used with the base polymers above are the crosslinking polymers themselves. In some embodiments, crosslinking polymers include, for example, polyalkyleneimines and polyalkylenepolyamines, any derivatives thereof, any salt thereof, and any combination thereof. In more specific embodiments, suitable crosslinking polymers include, for example, polyethyleneimine, polyvinylamine (polyethylenepolyamine),. any derivative thereof,₂₈ IMPIAS ° INSTITUTO MEXICANO '&amp;? * ·

Dt THE fWOMMiAO OjMe. INDUSTRIAL any salt thereof, and any combination thereof. In alternative embodiments, suitable crosslinking polymers can include polypropyleneimine, polypropylenepolyamine, polyallylimine, any derivative thereof, any salt thereof, and any combination thereof. In still other alternative embodiments, the organic crosslinking agent can be chitosan, polymyxins, polylysine, any derivative thereof, any salt thereof, and any combination thereof. '

In some embodiments, suitable gel time modifiers comprising at least one amino group can be amino alcohols, oligomeric polyamines, any salt thereof, any derivative thereof, or any combination thereof. In general it is contemplated that any amino compound having at least some miscibility with water may be suitable for use in the present embodiments. It is also contemplated that any derivatives of oligomeric amino alcohols or polyamines comprising derived amino nitrogen atoms may undergo reactions under in-well conditions to release the amino groups in non-derivatized form. That is, precursors to said oligomeric amino alcohols and polyamines are also contemplated by the present embodiments. For example,

<img file="MX345855B_D0018.tif" />

IMPI INSTITUTE MWCAM M LA momOAL INOUTHUAI contemplates that amino compounds comprising an acylated amino group can be subjected to. Hydrolysis lowered conditions within the well to release amino groups, which then function as gel time modifiers.

Illustrative amino alcohol gel time modifiers can include, for example, ethanolamine, diethanolamine, triethanolamine, propanolamine, triisopropanolamine, any salt thereof, any derivative thereof, any combination thereof, and the like. When present in a salt form, the free amino alcohol can be regenerated either by pH adjustment before pumping into the well in some embodiments or under suitable in-well conditions in other embodiments. .

The oligomeric polyamines suitable for use in the present embodiments generally have a molecular weight of less than about 400. That is, the oligomeric polyamines suitable for use in the present embodiments are non-polymeric amino compounds. Illustrative examples of suitable oligomeric polyamines can include, for example, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, any salt thereof, any derivatives thereof, any combination thereof. When present in a salt form, the free oligomeric polyamine can be regenerated either by pH adjustment prior to pumping into the well in some embodiments or under suitable in-well conditions in other embodiments. In alternative embodiments, non-oligomeric amines such as, for example, propylamine, butylamine, diethylamine, diisopropylamine, ethyldiisopropylamine, triethylamine, pyridine, and the like can be used.

In general, the 'gel times of the treatment fluids present' are a function of the amount of gel time modifier used. Generally, higher concentrations of the gel time modifier comprising at least one amino group can lead to shorter gel times. However, above a threshold concentration of gelation time modifier, longer gelation times can result. Therefore, according to some embodiments of the present invention, a gelation time modifier comprising at least one amino group can be added to a treatment fluid comprising a system of gellable polymers of a given composition to increase or decrease gelation time.

Without being bound by theory, it is believed that the mechanism by which the amino-containing gelation time modifier functions as a gelation time accelerator or a

<img file="MX345855B_D0019.tif" />

IMPI gelation time retarder can be explained below. Crosslinking agents such as, for example, polyethyleneimine and polyalkylene polyamines can exist in partially protonated forms in aqueous fluids. The degree of protonation can depend on the pH of the fluid, the type of amino group (eg, primary, secondary or tertiary, arite or aliphatic amino groups) and the structure of the polymer. It is believed that a crosslinking agent comprising protonated amino groups does not function as a crosslinking center due to the unavailability of the isolated electron pairs on the nitrogen atom. Furthermore it is believed that amino-containing gelation time modifiers can deprotonate protonated amino nitrogen atoms in the crosslinking agent, thus making them available for crosslinking reactions and reduction of gelation time. At higher concentrations of gelation time modifier, it is believed that there may be an excess of amino groups from the gelation time modifier, even after deprotonating the amino nitrogen atoms in the crosslinking agent. It is believed that excess amino groups can react with water to generate hydroxide ions according to Equation (1), where R is an alkyl or aryl group.

R-NH2 + Η2Ο

<img file="MX345855B_D0020.tif" />

R-NH₃⁺ + OH (1)

It is believed that the hydroxide ion generated can hydrolyze the amide functional groups in the crosslinking agent to generate carboxylate ions according to equation (2).

. OH ”+ RC (O) NH₂ -► RC (O) O ”+ NH₃ (2)

It is generally the case that increased hydrolysis levels in polyacrylamide polymers can increase the gelation times of treatment fluid formed therefrom.

Generally, the base polymer, the organic crosslinking agent, and the gel time modifier are used together in concentrations that are appropriate to achieve a desired gel time for a given application. Given the benefit of the present disclosure, one skilled in the art will be able to determine appropriate concentrations of the base polymer, the organic crosslinking agent, and the gelation time modifier through routine experimentation. In some embodiments, the gellable treatment fluids of the present invention may have reduced gel times relative to a similar gellable treatment fluid lacking a gel time modifier. .

IMPIttg

In some embodiments, the concentration of the gel time modifier can be less than about 5% by weight. In other embodiments, the concentration of the gel time modifier can be less than about 2% by weight. In still other embodiments, the concentration of the gel time modifier can be less than about 1% by weight. In some embodiments, the concentration of the gelation time modifier may range from about 0.1% to about

1% by weight. In some embodiments, the gel time modification can be in a range of 0.2% to about 0.8% by weight. In still other embodiments, the concentration of the gel time modifier may range from about 1% to about 2% by weight.

Generally, the concentration of the base polymer can be about 10% or less by weight in a treatment fluid lacking a gelation time modifier comprising at least one amino group. Likewise, the concentration of the organic crosslinking agent can typically be about 5% or less by weight in a treatment fluid lacking a gelation time modifier comprising at least one amino group. In treatment fluids of the present invention, concentrations of the

IMPI

INSTITUTO MEXICANO DE LA NtOMÍDAD INDUSTRIAL base polymer and organic crosslinking agent can generally be set at the above or lower values. In some embodiments, the inclusion of a gelation time modifier that comprises at least one amino group can allow the concentration of at least one of the base polymer or organic crosslinking agent to be reduced by at least about 20% relative to a similar treatment fluid that lacks a gelation time modifier, while maintaining a gelation time that is suitable for use in an underground formation. In other embodiments the inclusion of a gelation time modifier that comprises at least one amino group can allow the concentration of at least one of the base polymer or organic crosslinking agent to be reduced by at least 40% relative to a treatment fluid. similar that lacks a gelation time modifier. In still other embodiments the inclusion of a gelation time modifier comprising at least one amino group may allow the concentration of at least one of the base polymer or organic crosslinking agent to be reduced by at least about 60% relative to similar treatment fluid lacking a gelation time modifier. In some embodiments, at lower concentrations of the base polymer and / or the organic crosslinking agent, the

<img file="MX345855B_D0021.tif" />

IMPI

INSTTjyro MEXICANO 0Ϊ LA MKWIBDAO INBUSTXIXL gelation may be substantially that of the higher concentration similar treatment fluid lacking gelation time modifier. In other embodiments, the gelation time may be an intermediate between that of a similar treatment fluid of higher concentration that lacks a gelation time modifier and a similar treatment fluid of lower concentration that lacks a time modifier. gelation. Thus, it is not a necessary condition that the treatment fluids of the present invention have a gelation time that is substantially the same as that of the higher concentration treatment fluid. According to the present embodiments, the present treatment fluids have a gelation time that is altered from that of a similar treatment fluid lacking a gelation time modifier. Modification of the gelation time can make the treatment fluids of the present invention suitable for use in a given underground application.

In some embodiments, the base polymer and organic crosslinking agent may be present in a ratio of up to about 50: 1 base polymer: organic crosslinking agent. In other embodiments, the ratio of a base polymer: organic crosslinking agent can be

<img file="MX345855B_D0022.tif" />

IMPI

INSTITUTO MUUCan · Dt LA nOflEOA »INDUSTWfAt at most around 20: 1. In still other embodiments, the ratio of base polymer: organic crosslinking agent can be a maximum of 10: 1. In some embodiments, the ratio of the base polymer: organic crosslinking agent can be at least about 5: 1. As will be apparent to one skilled in the art, when the amount of the base polymer is reduced in the present treatment fluids with the amount of organic crosslinking agent remaining the same as that of the similar treatment fluid lacking a time modifier of gelation, the ratio of these two components will be lower than that of the higher concentration similar treatment fluid lacking the gelation time modifier. Similarly, when the amount of organic crosslinking agent is reduced in the treatment fluids present with the amount of base polymer remaining the same as in the similar treatment fluid lacking the gelation time modifier, the ratio of the two components will be higher. When the amount of both the base polymer and the organic crosslinking agent is lowered, the ratio of these two components can be lower, higher or the same, depending on how much quality of each component is lowered relative to the other.

Λ

<img file="MX345855B_D0023.tif" />

IMPI

INSTITUTO MEXICANO ocunontOAD INDUSTRIAL

In some embodiments, the present treatment fluids may further comprise at least one additional gelation time modifier in addition to the gelation time modifier comprising at least one amino group.

Such gel time modifiers can be gel time accelerators in some modalities or gel time retardants in other modalities, depending on whether one wants to increase or decrease gel time in a particular treatment fluid. Illustrative gel time modifiers can include, for example, pH modifying agents such as, for example, inorganic acids, organic acids, organic salts, and inorganic salts. Examples of such gelation time modifiers are set forth in US patents 7,331, 390, 7,325, 613, 7,322,414, and 7,287,5.87, and co-pending US patent applications 12 / 716,951. 12 / 716,979 and 12 / 717,004, all filed on March 3, 2010. Specific illustrative examples of pH modifying agents can include, for example, alkali metal carbonates, bicarbonates, acetates, formates, and hydroxides; organic acids (eg phenols or acetic acid); mineral acids (eg hydrochloric acid); and Lewis acids (eg boric acid). Illustrative gel time retardants that

IMPIAS

A Ββηιυιυ muican J mu nontnu) iweomuL can be used in the present embodiments include, for example, transition metal salts that can coordinate the organic crosslinking agent and acid anhydrides that can at least partially acylate amino groups in the organic crosslinking agent. A suitable coordinate crosslinking agent is described in commonly owned US Patent 6,196,317, which is incorporated herein by reference in its entirety. The use of acid anhydrides as a gel time retardant is described in commonly owned US Patent 7,091,160, which is incorporated herein by reference in its entirety. When using a gelation time retardant, the coordination bond strength or level of acylation can help control gelation time. .

In some embodiments, the at least one additional gel time modifier may be other compounds than those described above that have been used in a conventional manner in the art. For example, in some embodiments, the at least one additional gelation time modifier can be a quaternary ammonium salt. The use of quaternary ammonium salts as gelation time modifiers is described in U.S. Patent Application (Attorney Docket Number

2011-IP-041816U1

Gelifiable that titled Fluids

IMPI muhcan institute »Of the industrial rwmtDAD

<img file="MX345855B_D0024.tif" />

Treatment include Time Modifiers

Quaternary Ammonium Salts Gelation and Methods for

Use thereof filed June 29, 2011), 5 filed concurrently herewith, which is incorporated herein by reference in its entirety. In some embodiments, the use of a quaternary ammonium salt in combination with a gelation time modifier comprising at least one amino group 10 can result in further decreases in the gelation time of a gellable polymer system.

Suitable quaternary ammonium salts that can be used in the present treatment fluids are generally tetraalkylammonium salts. Illustrative tetraalkylammonium salts. They may include, without limitation, tetramethylammonium halides, tetraethylammonium halides, tetrapropylammonium halides, tetrabutylammonium halides, and the like. The alkyl groups in quaternary ammonium salts can be either straight chain or branched. In some embodiments, the treatment fluids of the present invention may comprise tetramethylammonium chloride as the quaternary ammonium salt. Longer chain quaternary ammonium salts (eg OC4) can be cationic surfactants.

<img file="MX345855B_D0025.tif" />

IMPI

INSTTTUT · MEXICAN

M LA PROHEDAT INOUSTW1AI.

However, without being bound by theory or mechanism of action, it is believed that quaternary ammonium salts are not functioning in a surfactant function in the present embodiments. Although it is believed that quaternary ammonium salts having some carbon chain length can be used in the present embodiments, it is preferred that the quaternary ammonium salts comprise alkyl groups in which none of the alkyl groups is larger than the alkyl groups. C₄. However, in alternative embodiments, quaternary ammonium salts having at least one alkyl group which is longer than an alkyl group can be used.

C₄. It should be noted that it is particularly surprising that quaternary ammonium salts can serve to reduce gelation times in present treatment fluids, since inorganic ammonium salts have been found in the art to increase gelation times in fluids. similar treatment.

In some embodiments, the treatment fluids of the present invention may further comprise at least one surfactant. Such surfactants include cationic surfactants, anionic surfactants, zwitterionic surfactants, and nonionic surfactants, numerous examples of all of which are known to one skilled in the art. When present, a surfactant can be used in

<img file="MX345855B_D0026.tif" />

IMPI ΙΗΓΓΓΠ.ΓΓΟ MiJUCXHC DE LA PMWIMMC treatment fluids present in a concentration of between about 0.1% and about 2.0% by weight or between about 0.5% and about 1.0% by weight in various modalities.

Illustrative examples of surfactants include, without limitation, ethoxylated nonyl phenol phosphate esters, alkyl phosphonates, linear alcohols, nonylphenol compounds, alkoxylated fatty acids, alkylphenol alkoxylates, ethoxylated amides, ethoxylated alkyl amines, betaines, ester sulfonates of methyl (for example, as described in U.S. Patent Application

United 7,159,659; 7,299.87-4; and 7,303,019 commonly owned and United States Patent Application Publication 11 / 058,611, filed February 2, 2005 (now available as United States Patent Application Publication 2006/0183646) , the entire disclosures of which are incorporated herein by reference), hydrolyzed keratin (eg, as described in U.S. Patent No. 6,547,871, 20 common property, the full description of which is incorporated herein by reference), sulfosuccinates ,. taurates, amine oxides, alkoxylated fatty acids, alkoxylated alcohols (e.g. lauryl alcohol ethoxylate, ethoxylated nonyl phenol), ethoxylated fatty amines, alkyl

<img file="MX345855B_D0027.tif" />

ethoxylated amines (eg ethoxydc-cocoalkylamine), modified betaines, alkylamidobetaines (eg cocoamidopropyl betaine) and quaternary ammonium compounds (eg trimethylzeboammonium chloride, trimethylcocoammonium chloride). Suitable surfactants can be used in liquid or powder form.

Furthermore, the optionally present treatment fluids may comprise any number of additional additives commonly used in treatment fluids including, for example, anti-oxidants, polymer degradation prevention additives, relative permeability modifiers, scale inhibitors, corrosion inhibitors. , foaming agents, anti-foaming agents, emulsifying agents, demulsifying agents, iron control agents, proppalants or other particulate materials, particle diverters, salts, acids, fluid loss control additives, gas, catalysts, clay control agents, dispersants, flocculants, scavengers (e.g. H2S scavengers, CO2 scavengers or O2 scavengers), lubricants, viscosity reducers, friction reducers, bridging agents, viscosifiers, bulking agents, solubilizers, pH control agents (e.g. buffers), hydrate inhibitors, agents

<img file="MX345855B_D0028.tif" />

consolidation, bactericidal, and the like

IMPI uermrro Mexican M tA NtOHMAD INO'J5T »IAl

Combinations of these additives can also be used.

In some embodiments, the gellable treatment fluids described herein can be used to treat at least a portion of an underground formation. In some embodiments, such treatments may involve reducing an amount of water produced from the portion of the underground formation. In some modalities, such treatments can result in partial or complete permeability reduction of the subsurface formation to water. .

In some embodiments, the methods of the present invention may comprise providing a gellable treatment fluid which comprises a water-based fluid, a base polymer comprising an acrylamide monomer unit, an organic cross-linking agent, a time modifier of gelation comprising at least one amino group, any salt thereof, any derivative thereof, or any termination thereof: introducing the gellable treatment fluid into at least a portion of an underground formation, and allowing the gellable treatment fluid to form a gel in the underground formation.

In some embodiments, the methods of the present invention may comprise providing an aqueous gellable treatment fluid, an acrylamide base polymer, an agent comprising a polyethyleneimine polymer, polyvinylamine,

IMPI

4 MEXICAN INfflTUTO

DE LA FROREDAD INDUSTRIAL comprises a base fluid

<img file="MX345855B_D0029.tif" />

comprises a crosslinking organic crosslinking monomer unit selected from any derivative thereof, any salt thereof, and any combination thereof, and a gelation time modifier comprising at least one compound selected from amino alcohols, polyamines oligomeric, any salt thereof, any derivative thereof, and any combination thereof; introducing the gellable treatment fluid into at least a portion of an underground formation; and allowing the gellable treatment fluid to form a gel in the underground formation. In these modalities, the fluid of. Gellable treatment can have a reduced gel time relative to a similar gellable treatment fluid lacking a gel time modifier.

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 redefine, the scope of the invention.

<img file="MX345855B_D0030.tif" />

EXAMPLES

IMPI

ΙΝΠΤΠΠΌ MMICAM '

W THE HYDRIFICATION INDUSTRY!

EXAMPLE 1: Gel times at 71.1 ° C (160 ° F) in gelable treatment fluids comprising a base polymer of t-butylacrylate / acrylamide, polyethyleneimine, and a gelation time modifier containing an amino group (Reduction of amounts crosslinking polymer): Control gelable treatment fluids were prepared in the following compositions: (1) 350 1 / M1 (gal / Mgal) HZ10 and 60 1 / M1 (gal / Mgal) HZ-20 in 2% aqueous KC1 base fluid, and (2) 350 1 / M1 (gal / Mgal) HZ -10 and 30 1 / M1 (gal / Mgal) HZ-20 in 2% aqueous KC1 base fluid. The inventive treatment fluids were prepared in the following compositions: (3) 350 1 / M1 (gal / Mgal) HZ-10, 30 1 / M1 (gal / Mgal) HZ-20, and 0.36% by weight ethanolamine in 2% aqueous KC1 base fluid, (4) 350 1 / M1 (gal / Mgal) HZ-10, 30 1 / M1 (gal / Mgal) HZ-20, and 0.75% by weight ethanolamine in 2% aqueous KC1 base fluid, (5) 350 1 / M1 (gal / Mgal) HZ10, 30 1 / M1 (gal / Mgal) HZ-20, and 0.8% by weight diethanolamine in 2% aqueous KC1 base fluid, (6) 350 1 / M1 (gal / Mgal) HZ-10, 30 1 / M1 (gal / Mgal) HZ-20, and 0.36% by weight of diethylene triamine in 2% aqueous KC1 base fluid, (7) 350 1 / M1 (gal / Mgal) HZ-10, 30 1 / M1 (gal / Mgal) HZ-20, and 0.75% by weight of diethylene triamine in 2% aqueous KC1 base fluid, (8) 350 1 / M1 (gal / Mgal) HZ-10, 30 1 / M1 (gal / Mgal) HZ46 IMPI ^

INSTITUTO MEXICANO o * la raomnAD Ο ^ · ^ ε

INDUSTRIAL —-- 20, and 1.5% by weight diethylenetriamine in 2% aqueous KC1 base fluid, (9) 350 1 / M1 (gal / Mgal) HZ-10, 30 1 / M1 (gal / Mgal) HZ-20 , and 0.36% by weight triethylenetriamine in 2% aqueous KC1 base fluid, (10) 350 1 / M1 (gal / Mgal) HZ-10, 30 1 / M1 (gal / Mgal) HZ-20, and 0.75% in triethylenetriamine weight in 2% aqueous KC1 base fluid, (11) 350 1 / M1 (gal / Mgal) HZ-10, 30 1 / M1 (gal / Mgal) HZ-20, and

1.5% by weight triethylenetriamine in 2% aqueous KC1 base fluid. HZ-10 is a t-butylacrylate / acrylamide copolymer that is available from Halliburton Energy Services of Duncan, Oklahoma. HZ-20 is a polyethyleneimine polymer that is available from Halliburton Energy Services of Duncan, Oklahoma. .

The viscosities of the treatment fluids above were measured as a function of time to determine their gelation times. Viscosity measurements were made at 71.1 ° C (160 ° F). FIGURE 1 shows a chart of viscosity as a function of time at 71.1 ° C (160 ° F) for various gelatable treatment fluids comprising a t-butylacrylate / acrylamide base polymer, polyethyleneimine, and optionally a time modifier of gelation of amino alcohol. As shown in FIGURE 1, the control treatment fluid (1) had a gelation time of approximately 350 minutes. When the concentration of

7 · INffflVIO ^ iCAA. &lt;«

DE LA H.OU'-IA kja »· INDUSTRY! - polyethyleneimine was halved in the control treatment fluid (2), the gelation time was increased to about 750 minutes. In contrast, when 0.36 wt% ethanolamine was included in the inventive treatment fluid (3), the gel time decreased to around 600 minutes. A further decrease in gelation time of about 500 minutes was observed in the inventive treatment (4) when the ethanolamine concentration was doubled to 0.75% by weight. A similar gelation time was observed in the inventive treatment fluid (5), which comprised 0.8% weight diethanolamine. Although the gel times of the inventive treatment fluids did not reach those of the original control treatment fluid (1), the gel times were still significantly reduced compared to those seen for the control treatment fluid (2). In the case of the inventive treatment fluids (3) - (5), the gelation times were comparable to those obtained when about 45-50 1 / M1 (gal / Mgal) of polyethyleneimine were used in the treatment fluid without the amino alcohol gelation time modifier being present.

Similar results were observed when the amino alcohol gel time modifier was replaced with an oligomeric polyamine gel time modifier.

IMPI &lt;NSTTTUTO MfcXICAAK&gt;

D € JA «e« SOAC&gt; O, ¿gW ^ gp

FIGURE 2 shows an illustrative scheme of viscosity as a function of time at 160 ° F (71.1 ° C) for various gellable treatment fluids comprising a t-butylacrylate / acrylamide base polymer, polyethyleneimine, and optionally a gel time modifier. diethylenetriamine. FIGURE 3 shows an illustrative scheme of viscosity as a function of time at 160 ° F (71.1 ° C) for various gellable treatment fluids comprising a t-butylacrylate / acrylamide base polymer, polyethyleneimine, and optionally a triethylenetriamine gelation time modifier. . As shown in FIGURE 2, the addition of 0.36 wt% diethylenetriamine in the inventive treatment fluid (6) decreased the gelation time to approximately 550 minutes, compared to approximately 750 minutes in the control treatment fluid (2). . A further increase in the concentration of diethylenetriamine to 1.5% wt in the inventive treatment fluid (8) decreased the gelation time to around 500 minutes. Similarly, as shown in FIGURE 3, the addition of triethylenetetramine at 0.36% weight in the inventive treatment fluid (9) decreased the gelation time to approximately 500 minutes, compared to approximately 750 minutes in the treatment fluid of control (2). A further increase in the concentration of triethylenetetramine to 1.5% weight in the treatment fluid

<img file="MX345855B_D0031.tif" />

inventive

IMPI rwtrrruTo mukano ot la raonwAi! INDUSTRY l (11) decreased the gelation time to approximately 47 minutes. As shown in FIGURES 2 and 3, the two oligomeric polyamines produced gel time results comparable to one another at a similar concentration. Furthermore, when compared to FIGURE 1, the gelation times produced by the amino alcohols and oligomeric polyamines were comparable to one another at a similar concentration. In summary, the preceding example shows that the amount of crosslinking polymer can be decreased through the use of a gelation time modifier comprising at least one amino group.

EXAMPLE 2: Gel times at 71.1 ° C (160 ° F) in gellable treatment fluids comprising a base polymer of t-butylacrylate / acrylamide, polyethyleneimine, and an amino alcohol gelation time modifier (Reduction of amounts of base polymer): Control gelable treatment fluids were prepared in the following compositions: (12) 350 1 / M1 (gal / Mgal) HZ-10, 30 1 / M1 (gal / Mgal) HZ-20, in 2% aqueous KC1 base fluid (same as control treatment fluid (2 )), and (13) 175 1 / M1 (gal / Mgal) HZ-10 and 30 1 / MI (gal / Mgal) HZ-20, in 2% aqueous KC1 base fluid. The inventive treatment fluids were prepared in the following compositions: (14) 175 1 / M1 (gal / Mgal) HZ-10, 30 1 / M1

<img file="MX345855B_D0032.tif" />

IMPI (NSTM / TO MEXICANO • eiAMOFtCDAD (NtMfSTAíAC (gal / Mgal) HZ-20, and 0.36% by weight ethalonamine in 2% aqueous KC1 base fluid, and (15) 175 1 / M1 (gal / Mgal) HZ- 10,

1 / M1 (gal / Mgal) HZ-20, and 0.5% by volume triethanolamine in 2% aqueous KC1 base fluid.

The viscosities of the treatment fluids above were measured as a function of time to determine their gelation times. Viscosity measurements were made at 71.1 ° C (160 ° F). FIGURE 4 shows a chart of viscosity as a function of time at 160 ° F (71.1 ° C) for various gellable treatment fluids comprising a t-butylacrylate / acrylamide base polymer, polyethyleneimine, and, optionally, a time modifier of gelation of amino alcohol. As shown in FIGURE 4, the control treatment fluid (12) had a gelation time of approximately 750 minutes. When the base polymer concentration was reduced by half in the control treatment fluid (13), the gelation time increased to approximately 1200 minutes. The addition of 0.36 wt% ethanolamine in the inventive treatment fluid (14) produced a gelation time of approximately 950 minutes. The addition of triethanolamine at 0.5% vol. in the inventive treatment fluid (15) it produced a gelation time of approximately 1100 minutes. Although the gelation times of the inventive treatment fluids did not reach

<img file="MX345855B_D0033.tif" />

IMPI

IMSTTTVT · MEXICANO oeu nomoAD tWMNTUtAl those of the original c.ontrnl treatment fluid Í121 the gelation times were still significantly reduced compared to those seen for the control treatment fluid (13). In the case of inventive treatment fluids (14) and (15), the gelation times were comparable to those obtained when about 215-275 1 / M1 (gal / Mgal) of base polymer was used in the treatment fluid without the amino alcohol gelation time modifier being present. In summary, the preceding example shows that the amount of base polymer can be decreased through the use of an amino alcohol gel time modifier.

EXAMPLE 3: Gel times at 71.1 ° C (160 ° F) in gellable treatment fluids comprising a base polymer of t-butylacrylate / acrylamide, polyethyleneimine, and an amino alcohol gelation time modifier (Reduction of amounts of base polymer and crosslinking polymer): A control gelable treatment fluid was prepared in the following composition: (16) 175 1 / M1 (gal / Mgal) HZ-10 and 30 1 / M1 (gal / Mgal) HZ-20, in 2% aqueous KC1 base fluid (same as control treatment fluid (13 The inventive treatment fluids were prepared in the following compositions: (17)

175 1 / M1 (gal / Mgal) HZ-10, 30 1 / M1 (gal / Mgal) HZ-20, and ₅₂ IMPI

OF THE FS0WEOA »

0.36 wt% ethalonamine in 2% aqueous KC1 base fluid, (18) 175 1 / M1 (gal / Mgal) HZ-10, 30 1 / M1 (gal / Mgal) HZ-20, and 0.75 wt% ethalonamine in base fluid of 2% aqueous KC1, and (19) 175 1 / M1 (gal / Mgal) HZ-10, 30 1 / M1 (gal / Mgal) HZ-20, and 1.55% by weight ethalonamine in base fluid of 2% aqueous KC1.

The viscosities of the above treatment fluids were measured as a function of time to determine their gelation times. Viscosity measurements were made at 71.1 ° C (160 ° F). FIGURE 5 shows an illustrative scheme of viscosity as a function of time at 160 ° F (71.1 ° C) for various gellable treatment fluids comprising a base polymer t-butylacrylate / acrylamide, polyethyleneimine, and optionally, a time modifier of gelation of amino alcohol. As shown in FIGURE 5, the control treatment fluid (16) had a gelation time of approximately 1300 minutes. When 0.36-0.75% wt of ethanolamine was added in the inventive treatment fluids (17) and (18), the gelation time decreased to approximately 1000 minutes. In contrast, when 1.5 wt% ethanolamine was used in the inventive treatment fluid (19), the gelation time actually increased to about 1400 minutes. Thus, in a treatment fluid comprising reduced concentrations of both

<img file="MX345855B_D0034.tif" />

<img file="MX345855B_D0035.tif" />

IMPIí

INSTTTVTO MiXICAN ”OF“ OMiDA. ”· INDUrnUAl base polymer as well as the crosslinking polymer, excessively high concentrations of ethanolamine in fact served as a gelation time retardant rather than a gelation time promoter. However, at lower concentrations of ethanolamine, the lower concentrations of the base polymer and the cross-linking polymer can be used to obtain a gelation time comparable to that which can be obtained using higher concentrations of these components.

EXAMPLE 4: Gel times at 121.1 ° C (250 ° F) in freezing treatment fluids comprising a base polymer of t-butylacrylate / acrylamide, polyethyleneimine, and an amino alcohol gelation time modifier.

Control gelatable treatment fluids were prepared in the following compositions: (20) 250 1 / M1 (gal / Mgal) HZ-10 and 20 1 / M1 (gal / Mgal) HZ-20 in 2 aqueous KC1 base fluid %, and (21) 167 1 / M1 (gal / Mgal) HZ-10 and 20 1 / M1 (gal / Mgal) HZ-20 in 2% aqueous KC1 base fluid. An inventive treatment fluid was prepared in the following composition: (22) 167 1 / M1 (gal / Mgal) HZ-10, 20

1 / M1 (gal / Mgal) HZ-20, and 1% by volume of ethanolamine in 2% aqueous KC1 base fluid.

The viscosities of the above treatment fluids were measured as a function of time to determine their

<img file="MX345855B_D0036.tif" />

IMPI

Ηβππ / ΤΟ MKIUCazo gelation times. Viscosity measurements were made in

121.1 ° C (250 ° F). FIGURE 6 shows an illustrative scheme of viscosity as a function of time at 121.1 ° C (250 ° F) for various gellable treatment fluids comprising a base polymer of t-butylacrylate / acrylamide, polyethyleneimine, and optionally, a time modifier. of gelation of amino alcohol. As shown in FIGURE 6, the control treatment fluid (20) had a gelation time of approximately 80 minutes. Decreasing the base polymer concentration in the control treatment fluid (21) lengthened the gelation time to more than 200 minutes. It is also notable that the gelation force, as measured by the magnitude of the observed viscosity, was considerably lower in the treatment control fluid (21). The inclusion of ethanolamine in the inactive treatment fluid (22) lowered the gelation time to approximately 120 minutes. Furthermore, the gelation force of the inventive treatment fluid (22) was considerably greater than that of the control treatment fluid (21). In summary, the amino alcohol gel time modifier again produced a reduced gel time relative to the control treatment fluid lacking the gel time modifier.

„IMPI ^

5 meúhqmo o »LA / MMBtM» LV-S • &lt;wnai «vw * A, -

EXAMPLE 5: The gelation times at 71.1 ° C (160 ° F) in gelable treatment fluids comprising a base polymer of t-butylacrylate / acrylamide, polyethyleneimine, an amino alcohol gel time modifier and a gelation of quaternary ammonium salt. Control gelable treatment fluids were prepared in. the following compositions: (23) 350 1 / M1 (gal / Mgal) HZ-10 and 30 1 / M1 (gal / Mgal) HZ-20 in 2% aqueous KC1 base fluid (the same as the (2)), and (24) 175 1 / M1 (gal / Mgal) HZ10 and 30 1 / M1 (gal / Mgal) HZ-20 in 2% aqueous KC1 base fluid (same as control fluid treatment (13)). The inventive treatment fluids were prepared in the following compositions: (25). 175 1 / M1 (gal / Mgal) HZ15 10 and 30 1 / M1 (gal / Mgal) HZ-20 in 2% aqueous tetramethylammonium chloride, and (26) 175 1 / M1 (gal / Mgal) HZ-10 and 30 1 / M1 (gal / Mgal) HZ-20 in 2% aqueous tetramethylammonium chloride also comprising 0.5% ethanolamine by weight. The source of the tetramethylammonium chloride was FIXED CLAY II, which is available from Halliburton Energy Services of Duncan, Oklahoma. It should be noted in the inventive treatment fluids (25) and (26), that tetramethylammonium chloride replaced KC1 as the salt in the base fluid.

IMPIí

INSTTTWTO MÍJICANC Dt LA PWOP1E · *!

iwDumi * '

<img file="MX345855B_D0037.tif" />

The viscosities of the above treatment fluids were measured as a function of time to determine their gelation times. Viscosity measurements were made at

71.1 ° C (160 ° F). FIGURE 7 shows an illustrative scheme of viscosity as a function of time at 160 ° F (71.1 ° C) for various gellable treatment fluids comprising a base polymer of t-butylacrylate / acrylamide, polyethyleneimine, tetramethylammonium chloride and optionally, ethanolamine. . As shown in FIGURE 7, the control treatment fluid (23) had a gelation time of approximately 750 minutes. When the base polymer concentration was halved in the control treatment fluid (24), the gelation time increased to approximately 1300 minutes. In contrast, when the control treatment 2% aqueous KC1 base fluid (24) was replaced with 2% tetramethylammonium chloride, the gelation time decreased to about 900 minutes in the inventive treatment fluid (25). A further decrease in the gelation time was carried out in the inventive treatment fluid (26) under the incorporation of 0.5% weight ethanolamine in the base fluid. In the case of the inventive treatment (26), the gelation time was approximately 750 minutes, which is comparable to that of the original control treatment fluid (23). However, the inventive treatment. (26)

<img file="MX345855B_D0038.tif" />

IMPI

INSTITUTE M4 \ CAN &lt;i »IA WWIO * · ΙΝΓΜΛΤΤΙΑ!

it reached this gelation time with only half the original amount of the base polymer.

EXAMPLE 6: Gel times at 71.1 ° C (160 ° F) in gellable treatment fluids comprising a partially hydrolyzed polyacrylamide base polymer, and various gel time modifiers. A gelatable treatment fluid was prepared in the following composition: (27) 175 1 / M1 (gal / Mgal) FDP-835 ™ and 30 L / Ml (gal / Mgal) HZ-20 ™ in 2 aqueous KC1 base fluid % aqueous. The fluids of. Inventive treatment were prepared in the following compositions: (28) 175 1 / M1 (gal / Mgal) FDP835 ™, 30 L / Ml (gal / Mgal) HZ-20 ™ and 0.38% by volume of ethanolamine in aqueous KC1 base fluid 2% aqueous; (29)

175 1 / M1 (gal / Mgal) FDP-835 ™, 30 L / Ml (gal / Mgal) HZ-20 ™ and

0.5% by volume triethylenetetramine in 2% aqueous KC1 base fluid; and (30) 175 1 / M1 (gal / Mgal) FDP-835 ™, 30 L / Ml (gal / Mgal) HZ-20 ™ and 0.70% by volume of triethylenetetramine in 2% aqueous KC1 base fluid.

A gellable control fluid was prepared in the following composition: (31) 175 1 / M1 (gal / Mgal) FDP-835 ™, and 30 L / Ml (gal / Mgal) HZ-20 ™ in alkaline aqueous KC1 base fluid 7%. The inventive treatment fluids were prepared in the following compositions: (32) 175 1 / M1 (gal / Mgal) FDP835 ™, 30 L / Ml (gal / Mgal) HZ-20 ™ and 0.38% by volume of

<img file="MX345855B_D0039.tif" />

IMPI IWfflVTO MEXICANO OS LA MOMWAC! NOUST »I ​​* &lt;

ethanolamine in 7% aqueous KC1 base fluid (33) 175 1 / M1 (gal / Mgal) FDP-835 ™, 30 L / Ml (gal / Mgal) HZ-20 ™ and 0.5% by volume triethylenetetramine in base fluid of aqueous KC1 to

7%; and (34) 175 1 / M1 (gal / Mgal) FDP-835 ™, 30 L / Ml (gal / Mgal)

HZ-20 ™ and 0.70% by volume of triethylenetetramine in 7% aqueous KC1 base fluid. FDP-835 ™ is a partially hydrolyzed polyacrylamide having a molecular weight of about 640,000 that is available from Halliburton Energy Services of Duncan, Oklahoma. The source of chloride, 10 tetramethylammonium was FIXED CLAY 11 ™.

The viscosities of the above treatment fluids were measured as a function of time to determine their gelation times. Viscosity measurements were made at 71.1 ° C (160 ° F). FIGURE 8 shows an illustrative scheme of viscosity as a function of time at 71.1 ° C (160 ° F) for various gelable treatment fluids comprising a partially hydrolyzed polyacrylamide, polyethyleneimine, and various gelation modifiers in aqueous KC1 base fluid. at 2%. FIGURE 9 shows an illustrative chart of viscosity at 160 ° F (71.1 ° C) as a function of time for various gelatable treatment fluids comprising a partially hydrolyzed polyacrylamide, polyethyleneimine, and various gel modifiers in 7% base fluid. . The results showed that in 2% base fluid, the

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Gel time modifiers increased the times of. gelation, while at 7% KC1 the same concentrations of the gelation time modifiers shortened the gelation times. It should be noted that gelation times can generally increase significantly at high salt concentrations, mainly due to the anionic character of partially hydrolyzed polyamide. The foregoing results are believed to demonstrate that the gel times of treatment fluids can be advantageously modified using gel time modifiers in combination with appropriate inorganic salt concentrations.

Therefore, the present invention is well suited to achieve the aforementioned purposes and advantages as well as those that are inert herein. The particular embodiments described above are illustrative only, as the present invention may be modified and practiced in different but equivalent ways apparent to one skilled in the art having the benefit of the teachings herein. Furthermore, no limitation is intended on the details of construction or design shown in this document, other than those described in the claims below. Therefore it is evident that the particular illustrative modalities described above may

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IMPI “« τπυτο μιχκλνο iNDurnuAi be altered, combined or modified and all such variants are considered within the scope of the spirit of the present invention. While the 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 of the numbers and ranges described above may vary by some amount. Whenever a numerical range is described with a lower bound and an upper bound, any number and any included range that is within the range specifically described. In particular, each range of values ​​(of the form, from about to about, or, equivalently, from about a to b, or, equivalently, from about ab) described in this document should be understood to establish each number and range that encompasses within the wide range of values. Also, the terms in the claims have their meaning, ordinary, plain that unless clearly and explicitly defined otherwise defined by the patent owner. Furthermore, the indefinite articles one or one, as used in the claims, are defined herein to mean one or more than one of the elements it introduces. If there is any conflict in the uses

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C1 OtSnTUVO MEXICANO οε the youth Ow »eróumiAt of a word or term is this specification and one or more patents or other documents that may be incorporated in this document for reference, definitions that are consistent with this specification should be adopted.

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IMPI

INSTITUTO MUUCANU DE LA MOÍ'IEDAI INDUSTRIA!

NOVELTY OF ΙΑ INVENTION

Having described the present invention,

.....-------- “Γ is considered a novelty, and therefore the content of the following is claimed as property: