Composition and processes for treating subterranean formations

FIELD OF THE INVENTION
The present invention relates to compositions which can be used to prepare water-soluble polymers that are useful in oil field applications and processes for producing the compositions; to water-soluble polymers which can be prepared from the compositions and nitrogen-containing olefinic compounds as well as processes for producing and using the water-soluble polymers; and to gelling compositions produced from the water-soluble polymers for applications in a subterranean formation such as, for example, altering permeability and correcting water coning problems and processes for producing and using the gelling compositions.
BACKGROUND OF THE INVENTION
It is well known to those skilled in the art that polymers and gelled or crosslinked water-soluble polymers are useful in enhanced oil recovery and other oil field operations. They have been used to alter the permeability of underground formations in order to enhance the effectiveness of water flooding operations. Generally, polymers or polymers along with a gelling agent such as an appropriate crosslinking agent in a liquid are injected into the formation. The polymers then permeate into and gel, in the cases when a polymer and a crosslinking agent are used, in the regions having the highest water permeability.
Polymers have also been used in subterranean formation treatments such as "matrix acidizing" and "fracture acidizing". Because such treatments are well known to one skilled in the art, description of which is omitted herein and can be found in U.S. Pat. No. 4,997,582, description of which is herein incorporated by reference.
Because of environmental concerns as well as cost for disposing of a produced brine which is defined as the brine co-produced with oil and gas and is generally contaminated with some oil, or gas, or both, it is desirable to utilize the produced brine as the liquid used for the polymers and appropriate crosslinking systems. Use of produced brines eliminates not only the cost associated with acquiring and pre-treating fresh water for use as the liquid but also the disposal cost for the produced brine. Most produced brines are known to be hard brines, i.e., those having a divalent cation concentration greater than 1000 ppm.
Many polymers have been developed and used in processes for the recovery of hydrocarbons. Generally a desirable property is that such polymers impart to a liquid an increased viscosity when a relatively small quantity of the polymer is added, and preferably at a minimal cost. Another desirable property is that such polymers form gels, in the presence of a suitable gelling agent such as a crosslinking agent. However, a number of such polymers are not capable of forming gels having high thermal stability, i.e., the gels formed show high syneresis after a short period, such as for example a few days, at high temperature, such as for example, 120.degree. C. in a harsh environment such as sea water.
Various polymers may be used in the process for recovery of hydrocarbons. For example, metallic ions crosslink gellable polymers through the interaction with the oxygen atoms of the polymer molecules. Therefore, the gellable polymers generally contain some carboxylate groups. Generally, the gellable polymers used such as, for example, polyacrylamide are of high molecular weight and contain high degrees of hydrolysis, i.e., contain 10-30 mole % carboxylate groups. However, these high molecular weight and/or high mole % carboxylate group-containing polymers gel almost instantly in the presence of the above-described multivalent metallic compounds. Such fast gelation rate renders the application of gelling compositions containing these polymers and multivalent metallic compounds not useful in many oil-field applications such as, for example, water shut-offs and permeability reductions.
Many processes have been developed to delay the gelation of gelling compositions by adding a gelation delaying agent to the gelling compositions. However, a gelation delaying agent is not inexpensive and a gelation delaying agent often adds appreciable costs to oil field operation. Furthermore, many gellable polymers cannot withstand a hostile environment as described above.
There is therefore an increasing demand for water-soluble polymers that can be used to prepare gels which withstand hostile environments. A hostile environment includes, but is not limited to, high temperatures, high salinity and/or high content of multivalent metal cations, commonly known as "hardness ions", as well as the high acidity, temperature and shear conditions encountered in processes such as acid fracturing.
In the art of drilling wells to tap subterranean deposits of natural resources, such as gas, geothermal steam or oil, it is well known to use a drilling fluid. In addition to having the desirably rheological properties such as viscosity and gel strength, it is very important that such drilling fluids exhibit a low rate of filtration or water loss, that is, the drilling fluid must prevent excessive amounts of fluid, or "filtrate", from flowing from the bore hole into the surrounding formation. The loss of water or other fluid from the drilling hole is prevented by the formation of a filter cake which deposits from the drilling fluid and seals the wall of the bore hole. Numerous formulations, compositions and additives to optimize the performance of drilling fluids for various applications have been developed. For instance, compositions comprising mixtures of carboxylic acid polymers and soluble metal salts with the object of increasing the "yield" (defined as the number of barrels of 15 centipoise mud which can be prepared from one ton of clay) of relatively low-grade clays have been used.
Excessive fluid loss from the drilling fluid may contaminate the producing formation, permanently displacing oil and blocking production. The adverse consequences of excessive fluid loss in the drilling of very deep wells are more severe due to the high temperatures and pressures encountered in such drilling operations. The viscosity of a fluid normally decreases with an increase in temperature, but certain polymer additive or deflocculating agents may reduce, or even reverse, this tendency. However, the polymers which are most effective in achieving this effect are the most vulnerably to breakdown through oxidation, shear and thermal effects, i.e., the duration of exposure to high temperature drilling operations. Also, many such polymers tend to precipitate and/or lose viscosity as well as effectiveness as water loss additives when exposed to dissolved electrolytes, particularly when divalent metal cations such as Ca.sup.+2 and Mg.sup.+2 are present. In drilling fluids, the resulting vulnerability to breakdown is exacerbated by the density of drilling mud, which is directly related to weighting agents required for a given formation pressure.
Breakdown of polymers causes a large increase in the fluid loss accompanied by an increase in filter cake thickness. These conditions often result in differential sticking of the drill string. It is, therefore, desirable to develop additives which enable drilling fluids to retain their proper viscosity and fluid content over a broader range of conditions.
Drilling fluids are used in the drilling of various types of wells. Workover and completion fluids, in contrast, are those fluids used in the completion and servicing of such wells. Completion fluids are those fluids used after drilling is complete and during the steps of completion, or recompletion, of the well. Completion can include cementing the casing, perforating the casing, setting the tubing and pump, etc.
Workover fluids are those fluids used during remedial work in the well. This can include removing tubing, replacing a pump, cleaning out sand or other deposits, logging, reperforating, etc. Workover also broadly includes steps used in preparing an existing well for secondary or tertiary oil recovery such as polymer additions, micellar flooding, steam injection, etc.
Both workover and completion fluids are used in part to control well pressure, to prevent the collapse of casing from overpressure, and to prevent or reduce corrosion of casing. A drilling fluid may be suitable for completion or workover applications in some cases, but not in all cases.
Although there has been considerable progress in the field of workover and completion fluids, there is significant room for further improvement. For example, wells are being completed and serviced in increasingly hostile environments involving, e.g., high temperatures and high levels of salinity and/or hardness in the formation water. Thus, new additives for workover and completion fluids which retain their properties at elevated temperatures and high concentrations of dissolved electrolytes are in demand.
Therefore, a composition which can be used to prepare a more hostile environment-withstanding polymer as well as a hostile environment-withstanding gelling composition, containing the hostile environment-withstanding polymer, that can form stable gels in a liquid such as, for example, produced brines, for near-wellbore as well as in-depth treatments, and preferably that does not require a gelation delaying agent, is highly desirable.
SUMMARY OF THE INVENTION
An object of the invention is to provide a composition which can be used as a monomer to synthesize a hostile environment-withstanding, water-soluble polymer. Another object of the invention is to provide a process for synthesizing the composition. Yet another object of the present invention is to provide a water-soluble polymer that can be used to form a gel in a hostile environment in hydrocarbon-bearing subterranean formations. Also an object of the invention is to provide a process for altering the permeability of hydrocarbon-bearing subterranean formations using the water-soluble polymer or for other drilling applications. A further object of the invention is to provide a gelling composition which contains the water-soluble polymer and withstands a hostile environment. Still another object of the present invention is to provide a process for various drilling applications or for altering the permeability of hydrocarbon-bearing subterranean formations by using a gelling composition that contains the water-soluble polymer, withstands hostile environment, and is environmentally suitable for use in subterranean formations. Still a further object of the invention is to provide a process for various drilling applications or for altering the permeability of hydrocarbon-bearing subterranean formations with a gelling composition that does not require a gelation delaying agent. Yet still another object of the invention is to provide a process for treatment of subterranean formations employing a gelling composition that is environmentally suitable for subterranean formation operations. An advantage of the invention is that the gelling compositions of the invention generally withstand a hostile environment and the processes generally do not employ a gelation delaying agent, yet achieve the alteration of permeability of the formations or can be used in other applications. Other objects, features, and advantages will become more apparent as the invention is more fully disclosed hereinbelow.
According to a first embodiment of the present invention, a composition that can be used to prepare a water-soluble polymer which can be used in a hydrocarbon-bearing subterranean formation is provided. The composition comprises a nitrogen-containing olefinic compound.
According to a second embodiment of the present invention, a process for preparing a composition is provided that can be used to prepare a water-soluble polymer which can be used in a hydrocarbon-bearing formation wherein said composition comprises a nitrogen-containing olefinic compound.
According to a third embodiment of the present invention, a water-soluble polymer which can be used in a hydrocarbon-bearing formation is provided. The polymer comprises repeat units derived from at least one nitrogen-containing olefinic compound.
According to a fourth embodiment of the present invention, a process which can be used for treating hydrocarbon-bearing formation is provided comprises introducing into the formation a water-soluble composition wherein the water-soluble composition comprises a water-soluble polymer comprising repeat units derived from at least one nitrogen-containing olefinic compound.
According to a fifth embodiment of the present invention, a gelling composition is provided which comprises a water-soluble polymer, a crosslinking agent, and a liquid wherein the water-soluble polymer comprises repeat units derived from at least one nitrogen-containing olefinic compound.
According to a sixth embodiment of the present invention, a process is provided which comprises introducing into a subterranean formation a gelling composition comprising a water-soluble polymer, a crosslinking agent, and a liquid wherein the gelling composition forms gels when introduced into the formation and the water-soluble polymer comprises repeat units derived from at least one nitrogen-containing olefinic compound.
DETAILED DESCRIPTION OF THE INVENTION
According to the first embodiment of the present invention, a composition useful as a monomer for synthesizing a water-soluble polymer is provided. The composition comprises, or consists essentially of, or consists of a nitrogen-containing olefinic compound having the formula selected from the group consisting of sulfobetaines, vinylic amides, and combinations of any two or more thereof wherein the sulfobetaine has the formula of R.sub.1 C(R.sub.1).dbd.C(R.sub.1)--(C.dbd.O).sub.m --(Ar).sub.m --Y--N.sup.+ (R.sub.2)(R.sub.2)--Y--SO.sub.3.sup.- and the vinylic amide has the formula of ##STR1## or combinations of any two or more thereof. R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 can be the same or different and are each independently selected from the group consisting of hydrogen, alkyl radicals, aryl radicals, aralkyl radicals, alkaryl radicals, and combinations of any two or more thereof wherein each radical can contain 1 to about 30, preferably 1 to abut 20, more preferably 1 to about 15, and most preferably 1 to 10 carbon atoms and can contain functional group(s) such as ammonium, hydroxyl, sulfate, ether, carbonyl groups, amine groups, sulfhydryl groups, or combinations of any two or more thereof which can contribute to water solubility of polymers produced therefrom. Preferably R.sub.1, R.sub.3, and R.sub.4 are each hydrogen and R.sub.2, R.sub.5, R.sub.6, R.sub.7 are each independently selected from the group consisting of hydrogen, methyl, ethyl, or combinations of two or more thereof. Y is an alkylene radical, a phenylene group, an imidazolium group, a naphthylene group, a biphenylene group, or combinations of any two or more thereof. Each Y is preferably independently an alkylene radical which can have 1 to about 20, preferably 1 to about 15, and more preferably 1 to 10 carbon atoms. Most preferably, Y is a short alkylene radical having 1 to about 5 carbon atoms. Ar is an arylene radical, preferably a phenylene group, which can be substituted or unsubstituted. X is an anion selected from the group consisting of halides, sulfates, phosphates, nitrates, sulfonates, phosphonates, sulfinates, phosphinates, and combinations of any two or more thereof. Each m, m.sub.1, m.sub.2, and m.sub.3 can be the same or different and is 0 or 1.
Examples of suitable nitrogen-containing olefinic compounds of the first embodiment of the invention include, but are not limited to, N,N-dimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3 -sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3 -sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfopropyl)-N-(3 -vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N-acryloyl-N'-methyl-N'-(2-amino-2-oxoethyl) piperazinium chloride, N-acryloyl-N'-methyl-N'-(3-amino-3-oxopropyl) piperazinium chloride, N-acryloyl-N'-methyl-N'-(4-amino-4-oxobutyl) piperazinium chloride, N-acryloyl-N'-ethyl-N'-(2-amino-2-oxoethyl) piperazinium chloride, N-acryloyl-N'-ethyl-N'-(3-amino-3-oxopropyl) piperazinium chloride, N-acryloyl-N'-ethyl-N'-(4-amino-4-oxobutyl) piperazinium chloride, N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N-(2-amino-2-oxoethyl)-N'-vinylimidazolium chloride, N-(3-amino-3-oxopropyl)-N'-vinylimidazolium chloride, N-(4-amino-4-oxobutyl)-N'-vinylimidazolium chloride, and combinations of any two or more thereof.
The nitrogen-containing olefinic compounds of the first embodiment of the invention can be prepared by the process disclosed hereinbelow in the second embodiment of the invention.
In the second embodiment of the present invention, a process for preparing the nitrogen-containing olefinic compounds is provided. The nitrogen-containing olefinic compounds having the formula of R.sub.1 C(R.sub.1).dbd.C(R.sub.1)--(C.dbd.O).sub.m --(NH).sub.m --(Ar).sub.m --Y--N.sup.+ (R.sub.2)(R.sub.2)--Y--SO.sub.3.sup.- (a sulfobetaine), can be produced by contacting a vinylic tertiary amine with an alkylating agent such as, for example, an alkylsulfonic acid containing a proper leaving group such as halide, hydroxyl, tosylate, other suitable leaving groups, or combinations of any two or more thereof. These reagents can be contacted, under any suitable conditions so long as the conditions can effect the production of the nitrogen-containing olefinic compounds, in a solvent such as toluene, benzene, pentane, hexane, acetonitrile, methanol, ethanol, any other common organic solvent or combinations of any two or more solvents. Generally, a tertiary amine can be contacted with an alkylating agent at a temperature in the range of from about 10.degree. to about 120.degree. C., preferably about 20.degree. to about 90.degree. C., and most preferably 35.degree. to 65.degree. C. for about 1 to about 10 days, preferably about 1 to about 8 days, and most preferably 1 to 5 days under any suitable pressures such as, for example, about 1 atmospheric pressure. A suitable radical inhibitor such as 1,3-dinitrobenzene can be added to prevent polymerization of the nitrogen-containing olefinic compounds during the contacting. Preferably the production is carried out by using 1,3-propanesultone or 1,4-butanesultone as the alkylating reagent in toluene by heating at 45.degree.-50.degree. C. for 72 hours. The sulfobetaine generally precipitates from the solvent and can be purified by filtration, repeated washing with any common organic solvent that does not dissolve the sulfobetaine, and finally dried under reduced pressure. Preferably diethyl ether is used to wash the sulfobetaine during filtration, and the product can be dried under a pressure such as, for example, 5 cm Hg for 48 hours.
Examples of suitable tertiary amines include, but are not limited to, N,N-dimethyl-N-(4-vinylbenzyl) amine, N,N-dimethyl-N-(4-vinylbenzyl) amine, N,N-diethyl-N-(4-vinylbenzyl) amine, N,N-diethyl-N-(4-vinylbenzyl) amine, N,N-dimethyl-N-(3-vinylbenzyl) amine, N,N-dimethyl-N-(3-vinylbenzyl) amine, N,N-diethyl-N-(3-vinylbenzyl) amine and N,N-diethyl-N-(3-vinylbenzyl) amine, and combinations of any two or more thereof.
Examples of suitable alkylating reagents include, but are not limited to, 3-chloro-propane-1-sulfonic acid, 4-chloro-butane-1-sulfonic acid, 3-hydroxy-propane-1-sulfonic acid, 4-hydroxy-butane-1-sulfonic acid, the corresponding esters of the hydroxy-alkane-1-sulfonic acids such as 1,3-propanesultone and 1,4-butanesultone, and combinations of any two or more thereof.
The nitrogen-containing olefinic compounds with the amide functional group of the first embodiment of the invention have general formulae of ##STR2## and combinations of any two or more thereof. These compounds can be produced by alkylation of a vinyl-substituted amine with an alkylating agent such as, for example, an alkyl amide containing a proper leaving group such as halide, hydroxyl, tosylate, other suitable leaving groups, or combinations of any two or more thereof. These reagents can be contacted, under any conditions so long as the conditions can effect the production of the nitrogen-containing olefinic compounds in a solvent such as toluene, benzene, pentane, hexane, acetonitrile, methanol, ethanol, any other common organic solvents, or combinations of any two or more thereof. Generally, a vinyl-substituted amine and an alkylating agent can be contacted under a condition including a temperature in the range of from about 10.degree. to about 150.degree. C., preferably about 20.degree. to about 120.degree. C., and most preferably 30.degree. to 100.degree. C. for about 1 to about 15 days, preferably 1 to 8 days under any suitable pressure such as, for example, about 1 atmospheric pressure. A suitable radical inhibitor such as, for example, 1,3-dinitrobenzene can be added to prevent polymerization of the nitrogen-containing olefinic compounds during the contacting. Preferably the production is carried out by using a 2-chloro-acetamide as the alkylating agent in acetonitrile by heating at 45.degree.-80.degree. C. for 50-150 hours. The nitrogen-containing olefinic compounds generally precipitate from the solvent and can be purified by filtration, repeated washing with any common organic solvent that does not dissolve the nitrogen-containing olefinic compounds, and finally dried under reduced pressure. Preferably diethyl ether is used to wash the nitrogen-containing olefinic compounds during filtration, and the nitrogen-containing olefinic compounds generally can be dried under a suitable pressure such as, for example, 5 cm Hg for 48 hours.
Examples of suitable vinyl-substituted amines include, but are not limited to, N,N-dimethyl-N-(4-vinylbenzyl) amine, N,N-dimethyl-N-(4-vinylbenzyl) amine, N,N-diethyl-N-(4-vinylbenzyl) amine, N,N-diethyl-N-(4-vinylbenzyl) amine, N,N-dimethyl-N-(3-vinylbenzyl) amine, N,N-dimethyl-N-(3-vinylbenzyl) amine, N,N-diethyl-N-(3-vinylbenzyl) amine, N,N-diethyl-N-(3-vinylbenzyl) amine, N-acryloyl-N'-methyl piperazine, N-acryloyl-N'-ethyl piperazine, N-acryloyl-N'-propyl piperazine, N-vinyl imidazole, and combinations of any two or more thereof.
Examples of suitable alkylating agents include, but are not limited to, 2-chloro-acetamide, 2-bromo-acetamide, 3-chloro-propanamide and 3-bromo-propanamide, and combinations of any two or more thereof.
In the second embodiment of the invention, the molar ratio of the alkylating agent to the amine can be any ratio so long the ratio can effect the production of the nitrogen-containing olefinic compounds. Generally, the molar ratio can be in the range of from about 1:0.01 to about 0.01:1, preferably about 1:0.05 to about 0.05:1, and most preferably 1:0.1 to 0.1:1. The molar ratio of the radical inhibitor to the amine can be in the range of from about 0.1:1 to about 1,000:1. The molar ratio of the solvent to the amine can be any ratio that is effective in the production of a nitrogen-containing olefinic compound and can be in the range of from about 0.1:1 to about 1,000:1.
According to the third embodiment of the present invention, a water-soluble polymer is provided which can withstand a hostile environment and can be used for treating a hydrocarbon-bearing subterranean formation. The water-soluble polymer comprises, or consists essentially of, or consists of, repeat units derived from at least one nitrogen-containing olefinic compound. The term "polymer" as used herein denotes a molecule having at least about 10 repeat units and can be homopolymer, copolymer, terpolymer, tetrapolymer, or combination of any two or more thereof.
Any nitrogen-containing olefinic compounds having a polymerizable ethylenic linkage and being capable of producing a polymer which withstands hostile environment can be used for preparing the water-soluble polymer of the third embodiment of the present invention. Though it is not necessary, it is preferred that the ethylenic linkage be at the terminal end of the nitrogen-containing olefin molecule and that at least one nitrogen be a tertiary amine. The presently preferred repeat units include, but are not limited to ##STR3## and combinations of any two or more thereof. R.sub.1 and R.sub.2 can be the same or different and are each independently selected from the group consisting of hydrogen, alkyl radicals, aryl radicals, aralkyl radicals, alkaryl radicals, and combinations of any two or more thereof wherein each radical can contain 1 to about 30, preferably 1 to abut 20, more preferably 1 to about 15, and most preferably 1 to 10 carbon atoms and can contain functionalities such as, for example, hydroxyl, sulfate, carbonyl, amine, sulfhydryl, or combinations of any two or more thereof. Preferably R.sub.1 is hydrogen, R.sub.2 is hydrogen, methyl, ethyl, or combinations of any two or more thereof. M is a morpholine group which can be substituted or unsubstituted. Y is an alkylene radical, a phenyl group, an imidazolium group, a naphthyl group, a biphenyl group, or combinations of any two or more thereof which can have 1 to about 20, preferably 1 to about 15, and most preferably 1 to 10 carbon atoms. Most preferably, Y is a short alkylene radical having 1 to about 5 carbon atoms. Ar is an arylene radical, preferably phenyl, which can be substituted or unsubstituted. X is an anion selected from the group consisting of halides, sulfate, phosphate, nitrate, sulfonates, phosphonates, sulfinates, phosphinates, and combinations of any two or more thereof. Each m can be the same or different and is independently 0 or 1.
The water-soluble polymer of the third embodiment of the present invention can be a homopolymer, copolymer, terpolymer or tetrapolymer. However, if the nitrogen-containing olefinic repeat units contain an amide group, it is preferred that the water-soluble polymer be derived from repeat units comprising at least one of the nitrogen-containing olefinic compounds described above and at least one olefinic comonomer selected from the group consisting of R.sub.1 --C(R.sub.1).dbd.C(R.sub.1)--W, R.sub.1 --C(R.sub.1).dbd.C(R.sub.1)--(C.dbd.O).sub.m --Z, R.sub.1 --C(R.sub.1).dbd.C(R.sub.1)--Y--W, R.sub.1 --C(R.sub.1).dbd.C(R.sub.1)--(C.dbd.O).sub.m --N(R.sub.2)--Y--R.sub.2, R.sub.1 --C(R.sub.1).dbd.C(R.sub.1)--(C.dbd.O).sub.m --G--Y--Z, R.sub.1 C(R.sub.1).dbd.C(R.sub.1)--(C.dbd.O).sub.m --G--Y--W, R.sub.1 --C(R.sub.1).dbd.C(R.sub.1)--(C.dbd.O).sub.m --Y--Z, and combinations of any two or more thereof wherein Z has a formula selected from the group consisting of N(R.sub.2)(R.sub.2), N.sup.+ (R.sub.2)(R.sub.2)(R.sub.2)X.sup.-, and combinations of any two or more thereof wherein X is an anion selected from the group consisting of halides, sulfate, phosphate, nitrate, sulfonates, phosphonates, sulfinates, phosphinates, and combinations of any two or more thereof. M, Y, R.sub.1, and R.sub.2 are the same as those disclosed above. The letter m is 0 or 1. G is N(R.sub.1) or O. W is an acid moiety selected from the group consisting of phosphinic acid, phosphonic acid, sulfinic acid, sulfonic acid, sulfuric acid, sulfurous acid, carboxylic acid, phosphoric acid, ammonium salts or alkali metal salts of these acids, and combinations of any two or more thereof.
Examples of suitable nitrogen-containing olefinic compounds of the third embodiment of the invention include, but are not limited to, N-acryloyl morpholine, N-acryloyl-N'-methyl piperazine, N-acryloyl-N'-ethyl piperazine, N-acryloyl-N'-propyl piperazine, N-acryloyl-N'-(3-sulfopropyl)-N'-methyl piperazinium inner salt, N-acryloyl-N'-(3-sulfopropyl)-N'-ethyl piperazinium inner salt, N-acryloyl-N'-(4-sulfopropyl)-N'-methyl piperazinium inner salt, N-acryloyl-N'-(4-sulfopropyl)-N'-ethyl piperazinium inner salt, N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-methyl piperazinium chloride, N-acryloyl-N'-(3-amino-3-oxopropyl)-N'-methyl piperazinium chloride, N-acryloyl-N'-(4-amino-4-oxobutyl)-N'-methyl piperazinium chloride, N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-ethyl piperazinium chloride, N-acryloyl-N'-(3-amino-3-oxopropyl)-N'-ethyl piperazinium chloride, N-acryloyl-N'-(4-amino-4-oxobutyl)-N'-ethyl piperazinium chloride, N,N-dimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-N-(4-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-N-(3-vinylbenzyl) ammonium inner salt, N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(2-amino-2-oxoethyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzvl) ammonium chloride, N,N-diethyl-N-(3-amino-3-oxopropyl)-N-(4-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(2-amino-2-oxoethyl)-N-(3-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(2-amino-2-oxoethyl)-N-(3-vinylbenzyl) ammonium chloride, N,N-dimethyl-N-(3-amino-3-oxopropyl)-N-(3-vinylbenzyl) ammonium chloride, N,N-diethyl-N-(3-amino-3-oxopropyl)-N-(3-vinylbenzyl) ammonium chloride, N-(2-amino-2-oxoethyl)-N'-vinyl imidazolium chloride, N-(3-amino-3-oxopropyl)-N'-vinyl imidazolium chloride, N-(4-amino-4-oxobutyl)-N'-vinyl imidazolium chloride, N,N-dimethyl-N-(3-sulfopropyl)-3-(acryloyl amino)-1-propanammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-3-(acryloyl amino)-1-propanammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-3-(acryloyl amino)-1-propanammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-3-(acryloyl amino)-1-propanammonium inner salt, N,N-dimethyl-N-(3-sulfopropyl)-2-(acryloyl amino)-1-ethanammonium inner salt, N,N-diethyl-N-(3-sulfopropyl)-2-(acryloyl amino)-1-ethanammonium inner salt, N,N-dimethyl-N-(4-sulfobutyl)-2-(acryloyl amino)-1-ethanammonium inner salt, N,N-diethyl-N-(4-sulfobutyl)-2-(acryloyl amino)-1-ethanammonium inner salt, and combinations of any two or more thereof.
Examples of suitable olefinic comonomers include, but are not limited to, acrylamide, styrene sulfonic acid, salt of styrene sulfonic acid, N-methylacrylamide, N,N-dimethylacrylamide, acrylic acid, salt of acrylic acid, N-vinylpyrrolidone, methyl acrylate, methacrylate, vinylic sulfonic acid, salt of vinylic sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, salt 2-acrylamido-2-methylpropanesulfonic acid, and combinations of any two or more thereof. The salt can be an ammonium salt, an alkali metal salt, or combinations of any two or more thereof.
Some of the olefinic comonomers can be purchased commercially. The others can be synthesized by the process disclosed in the second embodiment of the present invention or in the Examples section.
For example, the olefinic comonomers having the formula of R.sub.1 --(R.sub.1).dbd.C(R.sub.1)--(C.dbd.O).sub.m --M in which M is the same as disclosed above can be prepared from R.sub.1 --C(R.sub.1).dbd.C(R.sub.1)--(C.dbd.O).sub.m --X where X is the same as that disclosed above, such as acryloyl chloride, and morpholine or from R.sub.1 --C(R.sub.1).dbd.C(R.sub.1)--(C.dbd.O).sub.m --OH, such as acrylic acid, and morpholine. The molar ratio of morpholine to the other reactant can be in the range of from about 2:1 to about 1:2. Generally the reaction can be carried out in an organic solvent such as chloroform or any solvents illustrated above, at a temperature in the range of from about -50.degree. C. to about 20.degree. C., for about 1 to about 10 hours. The reactants are commercially available. See Examples section below for details.
The water-soluble polymers of the third embodiment of the present invention can be prepared by mixing the monomer(s) (i.e., the nitrogen-containing olefinic compounds and the olefmic comonomers), in desired molar ratios if copolymers, terpolymers, or tetrapolymers are desired, in an appropriate liquid medium and then initiating the free-radical polymerization in solution, suspension, or emulsion environment. Generally, any molar ratios can be employed depending on the final polymer desired. The liquid can be an aqueous solution, non-aqueous solution, or mixtures thereof.
Well known compounds commonly employed to initiate free radical polymerization reactions include hydrogen peroxide, azo compounds such as, for example, 2,2'-azobis(2-(2-imidazolin-2-yl)propane) dihydrochloride, alkali metal persulfates such as K.sub.2 S.sub.2 O.sub.8, alkali metal perborates, alkali metal perphosphates, and alkali metal percarbonates. Well known organic peroxide compounds commonly employed to initiate free radical polymerization reactions include lauryl peroxide, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, t-butylperoxyprivilate, t-butylperoctoate, p-methane hydroperoxide, and benzoylperoxide. The compound t-butylhyponitrite is a well known alkyl hyponitrite commonly employed to initiate free radical polymerization reactions. Furthermore, ultraviolet light and gamma irradiation are commonly employed to initiate free radical polymerization reactions. In addition, such other method of polymerization as would have occurred to one skilled in the art may be employed, and the present invention is not limited to the particular method of preparing the polymer set out herein. Because the polymerization techniques are well known to one skilled in the art, the description of which is omitted herein for the interest of brevity.
If copolymers, terpolymers, or tetrapolymers are desired, the molar ratio of the nitrogen-containing olefinic monomer to the olefinic comonomer can be any ratio so long as the ratio can produce a polymer that can withstand hostile environment. Generally, the molar ratio can be in the range of from about 0.01:1 to about 100:1, preferably about 0.05:1 to about 50:1, and most preferably 0.1:1 to 30:1. If a combination of the nitrogen-containing olefinic monomers, or the olefinic comonomers, or both are employed, the molar ratios can be any ratio so long as the molar ratio of total nitrogen-containing olefinic monomers to the olefinic comonomers is within the range disclosed above.
According to the fourth embodiment of the present invention, a process which can be used in hydrocarbon-bearing subterranean formations such as water-flooding is provided. The process comprises, or consisting essentially of, or consisting of, introducing a water-soluble composition into a subterranean formation. The water-soluble composition comprises, consists essentially of, or consists of a water-soluble polymer. The scope of the water-soluble polymer is the same as that disclosed in the first embodiment of the present invention, description of which is omitted herein for the interest of brevity.
The term "process" used herein and hereinafter in conjunction with a subterranean formation generally denotes, unless otherwise indicated, a use in drilling fluids, workover fluids, completion fluids, permeability corrections, water or gas coning prevention, fluid loss prevention, matrix acidizing, fracture acidizing, and combinations of any two or more thereof.
The water-soluble composition used in the fourth embodiment of the invention can also comprise a liquid. The term "liquid" used in the present invention denotes water, a solution, a suspension, or combinations thereof wherein the suspension contains dissolved, partially dissolved, or undissolved substances such as salts. The presently preferred liquid is an aqueous liquid such as, for example, sea water or a produced brine which is defined above.
Examples of salts include metal salts. Generally, the total salts content can vary widely from, for instance, 1 to as high as 30 weight percent (%). The typical salts content can be in the range of from, for instance, about 2 to about 25 weight %.
The introduction of the water-soluble composition into a subterranean formation can be carried out by any methods known to one skilled in the art. Generally the water-soluble polymer can be dissolved, or substantially dissolved, in a liquid so that the water-soluble composition is present in the liquid in an amount, or concentration, sufficient to alter the permeability of a subterranean formation. The amount, or concentration, can be in the range of from about 50 to about 100,000, preferably about 100 to about 50,000, most preferably 200 to 10,000 mg of the water-soluble composition per liter of the liquid.
The water-soluble composition in a liquid medium can then be introduced, by any means known to one skilled in the art such as pumping, into a subterranean formation so that it can diffuse into the more water-swept portions of the formation. The nature of the formation is not critical to carrying out the process of the present invention. The formation can have a temperature in the range of from about 70.degree. F. to about 400.degree. F., preferably 75.degree. F. to 350.degree. F.
According to the fifth embodiment of the present invention, a gelling composition which can be used in oil field applications is provided. The gelling composition comprises, consists essentially of, or consists of a water-soluble composition, a crosslinking agent, and a liquid. The scope of the water-soluble composition is the same as that disclosed in the third embodiment of the present invention. The liquid component is the same as that disclosed in the fourth embodiment of the present invention.
Any crosslinking agents can be used. For example, a multivalent metallic compound that are capable of crosslinking the gellable carboxylate-containing polymer in the hydrocarbon-bearing formations can be used in the process of the present invention. Examples of suitable multivalent metal compounds include, but are not limited to, Al.sup.+3, Cr.sup.+3, Fe.sup.+3, Zr.sup.30 4, Ti.sup.+4, and combinations of any two or more thereof.
The presently preferred multivalent metal compound is a metal compound selected from the group consisting of a complexed zirconium compound, a complexed titanium compound, and combinations of any two or more thereof. Examples of the preferred multivalent metallic compounds include, but are not limited to, zirconium citrate, zirconium complex of hydroxyethyl glycine, ammonium zirconium fluoride, zirconium 2-ethylhexanoate, zirconium acetate, zirconium neodecanoate, zirconium acetylacetonate, tetrakis(triethanolamine)zirconate, zirconium carbonate, ammonium zirconium carbonate, zirconyl ammonium carbonate, zirconium lactate, titanium acetylacetonate, titanium ethylacetoacetate, titanium citrate, titanium triethanolamine, ammonium titanium lactate, aluminum citrate, chromium citrate, chromium acetate, chromium propionate, chromium malonate, and combinations thereof. The presently most preferred crosslinking agent is zirconium lactate, zirconium citrate, tetrakis(triethanolamine)zirconate, or zirconium complex of hydroxyethyl glycine, or combinations thereof. These compounds are commercially available.
According to the fifth embodiment of the present invention, a metallic compound used as a crosslinking agent can also contain a complexing ligand if necessary to further delay the rate of gelation. Preferably, however, the crosslinking agent does not contain such complexing agent. The complexing ligand useful for the present invention to retard the rate of gelation is generally a carboxylic acid containing one or more hydroxyl groups and salts thereof. The complexing ligand can also be an amine that has more than one functional group and contains one or more hydroxyl groups and that can chelate the zirconium or titanium moiety of the zirconium or titanium compounds described above. Examples of suitable complexing ligands include, but are not limited to, hydroxyethyl glycine, lactic acid, ammonium lactate, sodium lactate, potassium lactate, citric acid, ammonium, potassium or sodium citrate, isocitric acid, ammonium, potassium or sodium isocitrate, malic acid, ammonium, potassium or sodium malate, tartaric acid, ammonium, potassium or sodium tartrate, triethanolamine, malonic acid, ammonium, potassium or sodium malonate, and mixtures thereof. The presently preferred complexing ligands are citric acid, lactic acid, tartaric acid and salts thereof, triethanolamine, and hydroxyethyl glycine because of their ready availability and low cost.
A crosslinking agent can also contain two components. The first crosslinking component useful as crosslinking agent is generally water-dispersible or soluble and can be phenol, substituted phenols, aspirin, .rho.-aminobenzoic acid, resorcinol, catechol, hydroquinone, furfuryl alcohol, R'ArO (C.dbd.O).sub.m R', HOAr(C.dbd.O).sub.m OR', HOArOH, R'OArOH, R'OArOR', or combinations of any two or more thereof where Ar is an arylene group which can be non-substituted or substituted; each R' can be the same or different and is each independently selected from the group consisting of hydrogen, carboxylic group, a C.sub.1 -C.sub.6 alkyl, a phenyl group or combinations of any two or more thereof, and m is 0 or 1. The term "water dispersible" used herein is to describe a component that is truly water soluble or is dispersible in water to form a stable suspension. Examples of suitable first crosslinking components include, but are not limited to, phenol, hydroquinone, resorcinol, catechol, .rho.-aminosalicylic acid, furfuryl alcohol, phenyl acetate, phenyl propionate, phenyl butyrate, salicylic acid, phenyl salicylate, aspirin, .rho.-hydroxybenzoic acid, methyl .rho.-hydroxybenzoate, methyl .omicron.-hydroxybenzoate, ethyl .rho.-hydroxybenzoate, .omicron.-hydroxybenzoic acid, hexyl .rho.-hydroxybenzoate, and combinations of any two or more thereof. Presently preferred water dispersible first crosslinking components are phenol, phenyl acetate, phenyl salicylate, methyl .rho.-hydroxybenzoate, resorcinol, catechol, hydroquinone, and combinations of any two or more thereof.
Any water-dispersible or soluble aldehyde, its derivative, or compound that can be converted into aldehyde can be utilized as the second crosslinking component in crosslinking agent. Examples of suitable second crosslinking components include, but are not limited to aliphatic monoaldehydes, aromatic monoaldehydes, aliphatic dialdehydes, aromatic dialdehydes and their precursors. Preferred aldehydes and their precursors can be selected from the group consisting of formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, decanal, glutaraldehyde, terephthaldehyde, hexamethylenetetramine, and combinations of any two or more thereof.
The weight ratio of the water-dispersible first crosslinking component to the second crosslinking component can be any ratio so long as the ratio can effect the gelation of the gelling composition. Generally, such ratio can be in the range of from about 0.01:1 to about 100:1, preferably about 0.1:1 to about 10:1, and most preferably 0.5:1 to 2:1.
Any suitable procedures for preparing the gelling composition can be used. Some of the polymers can require particular mixing conditions, such as slow addition of finely powdered polymer into a vortex of stirred brine, alcohol prewetting, protection from air (oxygen), preparation of stock solutions from fresh rather than salt water, as is known for such polymers.
The concentration or amount of the water-soluble polymer in the gelling composition can range widely and be as suitable and convenient for the various polymers, and for the degree of gelation needed for particular reservoirs. Generally, the concentration of the water-soluble polymer in a liquid is made up to a convenient strength of about 100 to 100,000 mg/l (ppm), preferably about 200 to 70,000 ppm and most preferably 500 to 50,000 ppm.
The concentration of crosslinking agent used in the present invention depends largely on the concentrations of polymer in the composition. Lower concentrations of polymer, e.g., require lower concentrations of the crosslinking agent. Further, it has been found that for a given concentration of polymer, increasing the concentration of crosslinking agent generally substantially increases the rate of gelation. The concentration of crosslinking agent in the injected slug varies generally over the broad range of about 1 mg/l (ppm) to about 10,000 ppm, preferably over the range of about 1 ppm to about 7,500 ppm, and most preferably 1 ppm to 2,500 ppm. The liquid generally makes up the rest of the gelling composition.
The concentration of the complexing ligand, if present, in the gelling composition also depends on the concentrations of the water-soluble polymer in the composition and on the desired rate of gelation. Generally, the lower the concentration of the complexing ligand is, the faster the gelation rate is.
According to the sixth embodiment of the present invention, a process which can be used to alter the permeability of a subterranean formation is provided. The process comprises or consists essentially of, or consists of introducing a gelling composition into a subterranean formation. The scope of the gelling composition is the same as that disclosed in the fifth embodiment of the invention.
The use of gelled polymers to alter the water permeability of underground formations is well known to those skilled in the art. Generally, an aqueous solution containing the polymer and a crosslinker is pumped into the formation so that the solution can enter into the more water swept portions of the formation and alter water permeability by gelling therein.
According to the process of the sixth embodiment of the present invention, an aqueous gelling composition comprising a crosslinking agent and a gellable polymer is injected into an injection or production well. The definition and scope of the crosslinking agent and gellable polymer are the same as those described above. The amount of the aqueous gelling composition introduced or injected can vary widely depending on the treatment volume injected. The amount of the gellable polymer injected is also dependent on the gel strength desired, same as that described for the crosslinking agent.
According to the sixth embodiment of the invention, the gelling can be prepared on the surface followed by introducing the prepared composition into a subterranean formation. Alternatively, individual components of the gelling composition described above can also be simultaneously or sequentially introduced into a subterranean formation.
The nature of the underground formation treated is not critical to the practice of the present invention. The described gelling composition can be introduced or injected into a formation having a temperature range of from about 70.degree. F. to about 350.degree. F. Any means known to one skilled in the art such as, for example, a pump means can be used for introducing or injecting the gelling composition and polymer solution.

Examples provided hereinbelow are intended to assist one skilled in the art to further understand the invention and should not be considered limitative.
EXAMPLE I
This example illustrates the preparation of nitrogen-containing olefinic monomers. ##STR4##
N-acryloyl morpholine was prepared from morpholine and acryloyl chloride. Morpholine (0.35 mole; 30.0 g), 0.42 mole (42.5 g) of triethylamine and 0.1 g of 1,3-dinitrobenzene were dissolved in 350 ml of chloroform and cooled to ca. -15.degree. C. Acryloyl chloride (0.42 mole; 37.8 g) was then added from a dropping funnel in such a way that the temperature in the reaction flask did not exceed 0.degree. C. The reaction mixture was then allowed to reach room temperature (about 25.degree. C.). After 2 hours at room temperature the solution was poured into an excess of diethyl ether (500 ml), and the precipitated material was filtered from the ether. The organic phase was concentrated on a rotavapour. Hydroquinone (0.1 g) was added to the crude product in order to prevent polymerization and then distilled under reduced pressure. The product was immediately placed in the refrigerator. B.p. 74.degree. C./0.01 mbar. The yield was 64%. ##STR5##
N-acryloyl-N'-methyl piperazine was prepared by adding 0.44 mole (39.8 g) of acryloyl chloride to a solution of 0.40 mole (40.0 g) N-methyl piperazine and 0.1 g hydroquinone in 200 ml of acetonitrile. The addition was carried out in such a way that the temperature in the reaction flask did not exceed 5.degree. C. The reaction mixture was allowed to reach room temperature. A 10M aqueous NaOH-solution (17.6 g NaOH in 44 ml distilled water, 0.44 mole) was then added and the precipitated material was filtered. The two phases were separated and the organic layer was dried with CaCl.sub.2. Distillation under reduced pressure gave the product as a clear liquid. B.p. 90.degree.-95.degree. C./0.5 mbar. The yield was 72%. ##STR6##
N-acryloyl-N'-(3-sulfopropyl)-N'-methyl piperazinium inner salt was prepared from 0.26 mole (40.1 g) of N-acryloyl-N'-methyl piperazine and 0.29 mole (34.9 g) of 1,3-propanesultone. The reagents were mixed together with 0.1 g of 1,3-dinitrobenzene in 260 ml of acetonitrile. The reaction mixture was heated to 90.degree. C. for 21/2 hours. The precipitated material was then filtered and washed three times with diethyl ether (100 ml) each. The white powder was dried under reduced pressure (12 mm Hg) for 18 hours. The yield was 68%. ##STR7##
N-acryloyl-N'-methyl piperazine (0.13 mole; 20.0 g) was dissolved in 260 ml of dry acetonitrile (distilled over P.sub.2 O.sub.5) together with 0.1 g 1,3-dinitrobenzene. Then 0.16 mole (14.6 g) 2-chloro acetamide was added to the N-acryloyl-N'-methyl piperazine, and the mixture was heated to ca. 80.degree. C. for 123 hours. A white, precipitated powder was filtered and washed three times with diethyl ether (150 ml). The product was dried under reduced pressure (12 mm Hg) for 12 hours. The yield was 75%. ##STR8##
N,N-dimethyl-N-(4-vinylbenzyl) amine (93.0 mmole; 15 g), 111.6 mmole (13.6 g) of 1,3-propanesultone and 0.1 g of 1,3-dinitrobenzene were mixed together and dissolved in 180 ml of toluene. The mixture was heated at 45.degree.-50.degree. C. for 72 hours. A white, precipitated material was filtered, washed three times with diethyl ether (100 ml). and finally dried under reduced pressure (11 mm Hg) for 15 hours. The yield was 87%. ##STR9##
N,N-dimethyl-N-(4-vinylbenzyl) amine (62.0 mmole; 10.0 g), 68.0 mmole (6.4 g) of 2-chloro acetamide and 0.1 g of 1,3-dinitrobenzene were dissolved in 125 ml of acetonitrile and heated at ca. 45.degree. C. for 48 hours. The precipitated material was filtered and washed three times with diethyl ether (100 ml). A white powder was dried under reduced pressure (12 mm Hg) for 16 hours. The yield was 88%. ##STR10##
1-Vinyl imidazole (0.17 mole; 15.8 g) , 0.20 mole (19.1 g) of 2-chloro acetamide and 0.1 g of 1,3-dinitrobenzene were mixed together, dissolved in 340 ml of acetonitrile and heated at 70.degree.-75.degree. C. for three nights (about 64 hours). The precipitated material was then filtered and washed three times with acetonitrile (150 ml). The product was dried under reduced pressure (12 mm Hg) for 15 hours. The product was a white powder, and the yield was 65%. ##STR11##
Acryloylchloride (0.70 mole; 63.8 g) and 0.1 g of hydroquinone were dissolved in 350 ml of acetonitrile and cooled to -15.degree. C. Then 0.59 mole (60.0 g) of 3-dimethylamino-1-propylamine was added from a dropping funnel in such a way that the temperature in the reaction flask did not exceed 5.degree. C. The reaction mixture was allowed to reach room temperature. A 10M aqueous NaOH-solution (28.0 g NaOH in 70 ml distilled water, 0.70 mole) was added and the precipitated material was filtered. The filtrate was concentrated on a rotavapour and then distilled under reduced pressure. B.p.122.degree. C./0.1 mbar. The yield was 55%.
Eighty-three mmole (13.0 g) of this product was reacted further with 99.6 mmole (12.2 g) of 1,3-propanesultone in 83 ml of toluene. In the mean time, 0.1 g 1,3-dinitrobenzene was added to prevent polymerization. The reaction mixture was heated at ca. 55.degree. C. for 3 hours. A white, precipitated powder was filtered and washed three times with diethyl ether (200 ml). Finally the product was dried under reduced pressure (12 mm Hg) for 17 hours. The yield was 80%.
EXAMPLE II
This example illustrates the production of polymers of the present invention.
Polymerizations were carried out in distilled water or synthetic sea water. For synthetic sea water, one liter distilled water contained 23.83 g NaCl, 0.21 g NaHCO.sub.3, 10.77 g MgCl.sub.2.6H.sub.2 O, 1.65 g CaCl.sub.2.2H.sub.2 O, and 42.9 g anhydrous Na.sub.2 SO.sub.4. The monomer solution was 35 weight % and the initiator concentration was 0.3 mole % with respect to total concentration of monomers. The azo-type initiator VA-044 (2,2'-azobis(N,N'-dimethyleneisobutyramidine) dihydrochloride) was used to start the polymerizations. The polymerizations were carried out at room temperature. In a typical synthesis, specified quantities of the monomers were dissolved in distilled water or synthetic sea water and the mixture was purged with nitrogen for 50 minutes. Initiator was then added. The polymers were precipitated in methanol or acetone, redissolved in distilled water or synthetic sea water and finally lyophilized. The term "parts" used hereinafter in defining a polymer denotes mole %. The products were white, amorphous powders.
Copolymer Am/AMP
Eighty parts of acrylamide and 20 parts of N-acryloyl-N'-methyl piperazine (AMP) were polymerized in distilled water for 4 hours with use of 0.3 mole % VA-044 as a initiator. The polymer was precipitated in acetone. The yield was 34%.
Copolymer Am/NAM
Eighty parts of acrylamide and 20 parts of N-acryloyl morpholine (NAM) were dissolved in distilled water and the polymerization was carried out with use of 0.3 mol % VA-044 as initiator. The polymerization was stopped after 6 hours. The polymer was precipitated in acetone. The yield was 69%.
Terpolymer Am/NAM/AMP
The polymer was prepared from 70 parts of acrylamide, 15 parts of N-acryloyl morpholine (NAM) and 15 parts of N-acryloyl-N'-methyl piperazine (AMP) with use of 0.3 mole % VA-044 as initiator. Distilled water was used as solvent. After 5 hours the polymer was precipitated in acetone. The yield as 41%.
Copolymer Am/AMPPS
Eighty parts of acrylamide and 20 parts of N-acryloyl-N'-(3-sulfopropyl)-N'-methyl piperazinium inner salt (AMPPS) were polymerized in synthetic sea water for 2 hours with use of 0.3 mole % VA-044 as initiator. The polymer was precipitated in methanol. The yield was 62%.
Copolymer Am/DMAMSPS
A polymer was prepared from 80 parts of acrylamide and 20 parts of N,N-dimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt (DMAMSPS) dissolved in synthetic sea water. 0.3 mole % VA-044 was used as initiator. After 4 hours the polymer was precipitated in methanol. The yield was 48%.
Copolymer Am/APDAPS
Eighty parts of acrylamide and 20 parts of N,N-dimethyl-N-(3-sulfopropyl)-3-(acryloylamino)-1-propanammonium inner salt (APDAPS) were polymerized in synthetic sea water for 5 hours with use of 0.3 mole % VA-044 as initiator. The polymer was precipitated in methanol. The yield was 81%.
Terpolymer Am/AMP/DMAMSPS
Sixty parts of acrylamide, 20 parts of N-acryloyl-N'-methyl piperazine (AMP) and 20 parts of N,N-dimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl) ammonium inner salt (DMAMSPS) were dissolved in synthetic sea water and the polymerization was carried out with use of 0.3 mole % VA-044 as initiator.
The polymerization was stopped after 31/2 hours by precipitation of the polymer in methanol. The yield was 23%.
Terpolymer Am/AMP/APDAPS
Seventy parts of acrylamide, 25 parts of N-acryloyl-N'-methyl piperazine (AMP) and 5 parts of N,N-dimethyl-N-(3-sulfopropyl)-3-(acryloylamino)-1-propanammonium inner salt (APDAPS) were polymerized in synthetic sea water with use of 0.3 mole % VA-044 as initiator. The polymerization was stopped after 3 hours by precipitation of the polymer in methanol. The yield was 59%.
Terpolymer Am/AMP/AMPPS
Seventy parts of acrylamide, 15 parts of N-acryloyl-N'-methyl piperazine (AMP) and 15 parts of N-acryloyl-N'-(3-sulfopropyl)-N'-methyl piperazinium inner salt (AMPPS) were dissolved in synthetic sea water and polymerized for 23 hours. VA-044 was used as initiator. The polymer was precipitated in methanol. The yield was 34%.
Copolymer AOMPC/AMPS
Fifty parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 50 parts N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-methyl piperazinium chloride (AOMPC) and 50 parts NaOH were dissolved in NaCl-solution and polymerized for 6 hours with use of 0.3 mole % VA-033 as initiator. The polymer was precipitated in methanol. The yield was 54%.
Terpolymer AOVC/AMP/AMPS
A polymer was prepared from 15 parts of N-(2-amino-2-oxoethyl)-N'-vinyl imidazolium chloride (AOVC), 70 parts of N-acryloyl-N'-methyl piperazine (AMP), 15 parts of 2-acrylamido-2-methylpropane-sulfonic acid (AMPS) and 15 parts of NaOH in synthetic sea water. Three tenths mole % VA-044 was used as initiator and the polymerization was stopped after 5 hours by precipitation of the polymer in methanol. The yield was 38%.
AOMPC Homopolymer
N-acryloyl-N'-(2-amino-2-oxoethyl)-N'-methyl piperazinium chloride (AOMPC) (20.19 mmol) was dissolved in synthetic sea water and 0.3 mole % VA-044 was added. The polymerization was stopped after 6 hours by precipitation of the polymer in acetone. The yield was 57%.
Terpolymer Am/AMP/AMPS
Seventy parts of acrylamide, 15 parts of N-acryloyl-N'-methyl piperazine (AMP) and 15 parts of 2-acrylamido-2-methyl-propanesulfonic acid (AMPS) were dissolved in distilled water and polymerized for 3 hours. Three tenths mole % VA-044 was used as initiator. The polymer was precipitated in acetone. The yield was 47%.
EXAMPLE III
This example illustrates the preparation of gelling compositions from the polymers disclosed above and the stability of gels formed from the gelling compositions.
Preparation of Gelling Compositions
Stock solutions of a polymer contained 4 weight % of the polymer in synthetic sea water. The polymer solution was allowed to stand at least three nights (about 64 hours) with magnetic stirring before use.
Stock solutions of phenol, formaldehyde and HMTA each containing 10,000 mg/l (ppm) were used.
For each test 4.0 g of gelling composition were made by adding polymer, phenol and formaldehyde/HMTA solution and diluting with synthetic sea water to the correct concentration. The same ppm concentration of both phenol and formaldehyde/HMTA was used. Magnetic stirring was used to mix the gelling compositions. After mixing the pH of the gelling compositions were registered using pH indicator strips. The pH of the was not adjusted in any way. The gelling compositions were thereafter transferred to glass vials, and the solutions were flushed with argon gas for 5 minutes before the vials were closed. The glass vials were weighed before and after adding gelling compositions.
For aging at 120.degree. C., the glass vials were placed in stainless steel containers filled with water. After aging at 120.degree. C., the stainless steel containers were cooled down to room temperature, the gel strength of the samples were characterized visually as weak, strong or rigid. The syneresis of the gels were measured as (weight of gel after exposure) / (initial weight of gel forming solution).
For gels in ampules, the syneresis was measured by measuring the gel height and the length of the liquid layer after ageing.
Measurement of Inherent Viscosity
Polymer solution (0.1 weight %) in synthetic sea water was made for viscosity measurements. The polymer solution was allowed to stand for 3 days with magnetic stirring. Before viscosity measurement the polymer solution was filtered through a 5 .mu.m Millipore filter. The relative viscosity of the 0.1 weight % polymer solution (relative to synthetic sea water) was measured with an Ubbelhode viscosimeter with an inner capillary diameter of 0.69 mm. At least 3 parallel measurements were performed for each solution. The temperature of the polymer solution under the viscosity measurement was 25.0.degree..+-.0.05.degree. C. ##EQU1##
The results are shown in the following Tables I-XXI. These tables show that gels formed from the polymers of the present invention were resistant to high temperature and high salinity environment. Little or no syneresis was observed after prolonged aging at high temperature and high salinity environment.
TABLE 1__________________________________________________________________________ Polymer Phenol/ Gel height (G) Inherent conc. HMTA.sup.d and Liquid height (L) after agingRun Am/AMP.sup.a Viscosity (ppm) in (ppm of at 120.degree. C. in SNSW forNo. Feed Ratio.sup.b dl/g SNSW.sup.c each) 30 days 55 days 70 days__________________________________________________________________________181 80/20 5.4 6200 2500 G = 25 mm G = 25 mm G = 25JSI L - 5 mm L = 5 mm L = 5 mmII 23 Rigid Rigid Rigid181 80/20 5.4 10400 2500 G = 30 mm G = 25 mm G = 25 mmJSI L = 0 mm L = 5 mm L = 5 mmII 23 Rigid Rigid Rigid181 80/20 5.4 20000 2500 G = 26 mm G - 24 mm G = 24 mmJSI L = 0 mm L = 1 mm L = 2 mmII 23 Rigid Rigid Rigid__________________________________________________________________________ .sup.a Am = acrylamide, AMP = Nacryloyl-Nmethyl piperazine .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d HMTA = hexamethylenetetramine
TABLE II______________________________________ Polymer Phenol/ Inherent conc. HMTA.sup.d Weight % gel.sup.eRun Am/AMP.sup.a Viscosity (ppm) in (ppm of Gel CharacterNo. Feed Ratio.sup.b dl/g SNSW.sup.c each) 5 months______________________________________181 80/20 5.4 6200 2500 80HSI RigidII 23181 80/20 5.4 10400 2500 80JSI RigidII 23181 80/20 5.4 20000 2500 90JSI RigidII 23______________________________________ .sup.a Am = acrylamide, AMP = Nacryloyl-Nmethyl piperazine .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d HMTA = hexamethylenetetramine .sup.e Weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
TABLE III______________________________________ Polymer Phenol/ Am/AMP.sup.a Inherent conc. HCHO.sup.d Weight % gel.sup.eRun Feed Viscosity (ppm) in (ppm of Gel CharacterNo. Ratio.sup.b dl/g SNSW.sup.c each) 5 days 30 days______________________________________154 70/30 5.1 20000 2500 100TOB StrongVII 43168 70/30 3.8 10000 500 55JSI WeakI 76168 70/30 3.8 20000 2500 100JSI RigidI 76155 60/40 4.3 20000 2500 100TOB StrongVII 52155 60/40 4.3 5000 1000 82TOB RigidVII 52155 60/40 4.3 10000 1000 100TOB StrongVII 52155 60/40 4.3 10000 2000 100TOB RigidVII 52156 50:50 3.4 20000 2500 100TOB WeakVII 49156 50/50 3.5 5000 1000 83TOB StrongVII 49156 50/50 3.5 10000 1000 89TOB StrongVII 49156 50/50 3.5 10000 2500 100TOB RigidVII 49______________________________________ .sup.a Am = acrylamide, AMP = Nacryloyl-Nmethyl piperazine .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d HCHO = formaldehyde .sup.e Weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
TABLE IV______________________________________ Polymer Phe- Inherent conc. nol.sup.d / Weight % gel.sup.fRun Am/AMP.sup.a Viscosity (ppm) in HMTA.sup.c Gel CharacterNo. Feed Ratio.sup.b dl/g SNSW.sup.c (ppm) 30 days______________________________________154 70/30 5.1 10000 2000 96TOB StrongVII 43154 70/30 5.1 20000 2000 100TOB StrongVII 43168 70:30 3.8 5000 1000 61JSI StrongI 76168 70:30 3.8 10000 500 73JSI WeakI 76168 70:30 3.8 10000 1000 80JSI WeakI 76155 60/40 4.3 10000 2000 92TOB WeakVII 52155 60/40 4.3 20000 2000 100TOB StrongVII 52197 60/40 3.8 20000 2500 90JSI RigidII 63197 60/40 3.8 10000 2500 90JSI RigidII 63198 60/40 3.7 20000 2500 100JSI RigidII 65156 50/50 3.5 20000 2000 100TOB WeakVII 49______________________________________ .sup.a AM = acrylamide, AMP = Nacryloyl-Nmethyl piperazine .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d 2500 ppm .sup.e HMTA = hexamethylenetetramine .sup.f Weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
TABLE V__________________________________________________________________________ Polymer Phenol/ Gel height (G) Inherent conc. HMTA.sup.c and Liquid height (L) after agingRun AM/NAM.sup.a Viscosity (ppm) in (ppm of at 120.degree. C. in SNSW forNo. Feed Ratio.sup.b dl/g SNSW.sup.c each) 30 days 55 days 70 days__________________________________________________________________________179 80:20 4.4 5400 2500 G = 30 mm G = 28 mm G = 28 mmJSI L = 5 mm L = 7 mm L = 7 mmII 11 Rigid Rigid Rigid179 80:20 4.4 10300 2400 G - 27 mm G = 27 mm G = 27 mmJSI L = 5 mm L = 5 mm L = 5 mmII 11 Rigid Rigid Rigid179 80:20 4.4 20000 2400 G = 26 mm G = 34 mm G = 24 mmJSI L = 3 mm L = 5 mm L = 5 mmII 11 Rigid Rigid Rigid__________________________________________________________________________ .sup.a Am = acrylamide, NAM = Nacryloyl morpholine .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d HMTA = hexamethylenetetramine
TABLE VI______________________________________ Polymer Phenol/ Inherent conc HMTA.sup.d Weight % gel.sup.eRun Am/NAM.sup.a Viscosity (ppm) in (ppm of Gel CharacterNo. Feed Ratio.sup.b dl/g SNSW.sup.c each) 5 months______________________________________179 80/20 4.4 5400 2500 0.8JSI RigidII 11179 80/20 4.4 10300 2400 0.9JSI RigidII 11179 80/20 4.4 20000 2400 0.9JSI RigidII 11______________________________________ .sup.a Am = acrylamide, NAM = Nacryloyl morpholine .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d HMTA = hexamethylenetetramine .sup.e Weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
TABLE VII______________________________________ Am/ Polymer Phenol/ NAM.sup.a Inherent conc. HCHO.sup.dRun Feed Viscosity (ppm) in (ppm of Weight % gel.sup.eNo. Ratio.sup.b dl/g SNSW.sup.c each) Gel Character______________________________________170 80/20 6.2 10000 500 30JSI StrongI 79170 80/20 6.2 10000 2500 28JSI StrongI 79171 70/30 3.7 10000 1000 100JSI RigidI 81172 60/40 3.3 20000 1000 92JSI RigidI 8371 20/80 2.5 20000 2500 100 70TOB Strong StrongV 85125 20/80 1.1 30000 4000 42 35TOB Strong StrongVII 17125 20/80 1.1 30000 2000 55TOB StrongVII 17______________________________________ .sup.a Am = acrylamide, NAM = Nacryloyl morpholine .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d HCHO = formaldehyde .sup.e Weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
TABLE VIII______________________________________ Weight % gel.sup.f Am/ Polymer Gel Character NAM.sup.a Inherent conc. Phenol.sup.d / 30 daysRun Feed Viscosity (ppm) in HMTA.sup.e Parallel ParallelNo. Ratio.sup.b dl/g SNSW.sup.c (ppm) 1 2______________________________________150 70/30 2.2 20000 2000 93 94JSI Rigid WeakI 59150 70/30 2.2 10000 2000 100JSI RigidI 59151 60/40 2.2 20000 2000 96 80JSI Rigid WeakI 61152 50/50 2.5 20000 2000 90 100JSI Strong WeakI 63______________________________________ .sup.a Am = acrylamide, NAM = Nacryloyl morpholine .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d 2500 ppm .sup.e HMTA = hexamethylenetetramine .sup.f weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
TABLE IX______________________________________ Am/NAM/ Polymer Phenol/ AMP.sup.a Inherent conc. HMTA.sup.d Weight % gel.sup.eRun Feed Viscosity (ppm) in (ppm of Gel CharacterNo. Ratio.sup.b dl/g SNSW.sup.c each) 30 days______________________________________188 70/15/15 4.6 10000 2500 100JSI RigidII 21188 70/15/15 4.6 20000 2500 95JSI RigidII 21188 70/15/15 4.6 10000 1000 47JSI StrongII 21______________________________________ .sup.a Am = acrylamide, NAM = Nacryloyl morpholine, AMP = Nacryloyl-Nmethyl piperazine .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d HMTA = hexamethylenetetramine .sup.e Weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
TABLE X______________________________________ Am/ Inherent Polymer Phenol/ AMPPS.sup.a Vis- conc. HCHO.sup.d Weight % gel.sup.cRun Feed cosity (ppm) in (ppm of Gel CharacterNo. Ratio.sup.b dl/g SNSW.sup.c each) 5 days 30 days______________________________________162 80/20 2.2 10000 2500 100JSI StrongI 65162 80/20 2.2 20000 1000 100JSI RigidI 65162 80/20 2.2 10000 2000 100JSI RigidI 65132 80/20 1.8 30000 4000 100 41JSI Rigid StrongI 28132 70/30 1.8 30000 2000 32JSI StrongI 28130 60/40 1.6 30000 4000 100 62JSI Strong StrongI 26130 60/40 1.6 30000 2000 75JSI StrongI 26100 50/50 20000 2500 94 60TOB Weak WeakVI 68120 50/40 1.5 30000 4000 100 88TOB Strong StrongVII 15120 50/50 1.5 30000 2000 77TOB StrongVII 15______________________________________ .sup.a Am = acrylamide, AMPPS = Nacryloyl-N(3-sulfopropyl)-Nmethyl piperazinium inner salt .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d HCHO = formaldehyde .sup.e weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
TABLE XI______________________________________ Polymer Phenol/ Inherent conc. HMTA.sup.d Weight % gel.sup.eRun Am/AMPPS.sup.a Viscosity (ppm) in (ppm of Gel CharacterNo. Feed Ratio.sup.b dl/g SNSW.sup.c each) 30 days______________________________________202 80/20 3.5 10000 2500 RigidJSI 90II 67202 80/20 3.5 20000 2500 RigidJSI 70II 67______________________________________ .sup.a Am = acrylamide, AMPPS = Nacryloyl-N(3-sulfopropyl)-Nmethyl piperazine inner salt .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d HMTA = hexamethylenetetramine .sup.e weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
TABLE XII__________________________________________________________________________ Polymer Phenol/ Inherent conc. HCHO.sup.d Weight % gel.sup.eAm/DMAMSPS.sup.a Viscosity (ppm) in (ppm of Gel CharacterRun No. Feed Ratio.sup.b dl/g SNSW.sup.c each) 5 days 30 days__________________________________________________________________________149 90/10 1.0 10000 2500 81JSI StrongI 55149 90/10 1.0 20000 2500 88JSI StrongI 5565 80/20 0.9 10000 2500 100 79TOB Weak WeakV 79137 80/20 2.0 30000 4000 93 72TOB Strong StrongVII 23137 80/20 2.0 10000 1000 77TOB StrongVII 23137 80/20 2.0 10000 2500 100TOB RigidVII 23__________________________________________________________________________ .sup.a Am = acrylamide, DMAMSPS = N,Ndimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl)-ammonium inner salt .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d HCHO = formaldehyde .sup.d Weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
TABLE XIII______________________________________ Polymer Phenol/ Am/ Inherent conc. HMTA.sup.d Weight % gel.sup.eRun DMAMSPS.sup.a Viscosity (ppm) in (ppm of Gel CharacterNo. Feed Ratio.sup.b dl/g SNSW.sup.c each) 30 days______________________________________137 80/20 2.0 10000 2000 81TOB Weak gelVII23137 80/20 2.0 20000 2000 100TOB WeakVII23______________________________________ .sup.a Am = acrylamide, DMAMSPS = N,Ndimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl)-ammonium inner salt .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d HMTA = hexamethylenetetramine .sup.e Weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
TABLE XIV______________________________________ Am/ Polymer Phenol/ APDAPS.sup.a Inherent conc. HMTA.sup.d Weight % gel.sup.eRun Feed Viscosity (ppm) in (ppm of Gel CharacterNo. Ratio.sup.b dl/g SNSW.sup.c each) 30 days______________________________________193 80/20 5.3 5000 2500 80TOB RigidVII 89193 80/20 5.3 10000 2500 80TOB RigidVII 89193 80/20 5.3 20000 2500 90TOB StrongVII 89______________________________________ .sup.a Am = acrylamide, APDAPS = N,Ndimethyl-N-(3-sulfopropyl)-3-(acryloylamino)-1-propanammonium inner salt .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d HMTA = hexamethylenetetramine .sup.e weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
TABLE XV__________________________________________________________________________ Polymer Phenol/ Phenol/ Am/AMP/ Inherent conc. HCHO.sup.d HMTA.sup.e Weight % gel.sup.fRun DMAMSPS.sup.a Viscosity (ppm) in (ppm of (ppm of Gel CharacterNo. Feed Ratio.sup.b dl/g SNSW.sup.c each) each) 30 days__________________________________________________________________________195 60/20/20 2.4 10000 2500 100TOB StrongVII 87195 60/20/20 2.4 20000 2500 100TOB RigidVII 87195 60/20/20 2.4 20000 2500 100TOB RigidVII 87__________________________________________________________________________ .sup.a Am = acrylamide, AMP = Nacryloyl-Nmethyl piperazine, DMAMSPS = N,Ndimethyl-N-(3-sulfopropyl)-N-(4-vinylbenzyl)-ammonium inner salt .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d HCHO = formaldehyde .sup.e HMTA = hexamethylenetetramine .sup.e Weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
TABLE XVI______________________________________ Polymer Phenol/ Am/AMP/ Inherent conc. HMTA.sup.d Weight % Gel.sup.eRun APDAPS.sup.a Viscosity (ppm) in (ppm of Gel CharacterNo. Feed Ratio.sup.b dl/g SNSW.sup.c each) 30 days______________________________________196 100TOB 70/25/5 4.4 5000 2500 RigidVII 85196 83TOB 70/25/5 4.4 10000 2500 RigidVII 85196 86TOB 70/25/5 4.4 20000 2500 RigidVII 85203 85IBV 60/30/10 3.5 10000 2500 RigidI 49203 85IBV 60/30/10 3.5 20000 2500 RigidI 49______________________________________ .sup.a Am = acrylamide, AMP = Nacryloyl-Nmethyl piperazine, APDAPS = N,Ndimethyl-N-(3-sulfopropyl)-3-(acryloylamino)-1-propanammonium inner salt .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d HMTA = hexamethylenetetramine .sup.e weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
TABLE XVII______________________________________ Polymer Phenol/ Am/AMP/ Inherent conc. HMTA.sup.d Weight % Gel.sup.eRun APDAPS.sup.a Viscosity (ppm) in (ppm of Gel CharacterNo. Feed Ratio.sup.b dl/g SNSW.sup.c each) 30 days______________________________________184 70JSI 70/15/15 1.9 10000 2500 RigidII 25184 100JSI 70/15/15 1.9 20000 2500 RigidII 25______________________________________ .sup.a AMP = Nacryloyl, AMP = N' = methyl piperazine, AMPPS = Nacryloyl-N(3-sulfopropyl)-Nmethyl piperazinium inner salt .sup.b mole % ratio of monomers in the aqueous solution .sup.c synthetic sea water .sup.d HMTA = hexamethylenetetramine .sup.e Weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
TABLE VIII______________________________________ Polymer Phenol/ AOMPC/ Inherent conc. HCHO.sup.d Weight % gel.sup.cRun AMPS.sup.a Viscosity (ppm) in (ppm of Gel CharacterNo. Feed Ratio.sup.b dl/g SNSW.sup.c each) 30 days______________________________________189 100IBV 50/50 1.1 10000 2500 Strong143______________________________________ .sup.a AOMPC = Nacryloyl-N(2-amino-2-oxoethyl)-Nmethyl piperazinium chloride, AMPS = 2acrylamido-2-methyl-propanesulfonic acid .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d HCHO = formaldehyde .sup.e weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
TABLE XIX______________________________________ Polymer Phenol/ Weight AOVC/AMP/ Inherent conc. HCHO.sup.d % gel.sup.e GelRun AMPS.sup.a Viscosity (ppm) in (ppm of CharacterNo. Feed Ratio.sup.b dl/g SNSW.sup.c each) 30 days______________________________________191 100JSI 15/70/15 1.6 20000 2500 RigidII 33______________________________________ .sup.a AOVC = N(2-amino-2-oxoethyl)-Nvinyl imidazolium chloride, AMP = Nacryloyl-Nmethyl piperazine, AMPS = 2acrylamido-2-methyl-propanesulfonic acid .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d HCHO = formaldehyde .sup.e Weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
TABLE XX______________________________________ Inherent Viscosity Polymer Phenol/ dl/g conc. HCHO.sup.c Weight % gel.sup.dRun AOMPC O.1 (ppm) in (ppm of Gel CharacterNo. Homopol.sup.a weight % SNSW.sup.b each) 30 days______________________________________117 100TOB 1.4 30000 4000 StrongVI 18______________________________________ .sup.a AOMPC = Nacryloyl-N(2-amino-2-oxoethyl)-Nmethyl piperazinium chloride, homopolymer .sup.b SNSW = synthetic sea water .sup.c HCHO = formaldehyde .sup.d Weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
TABLE XXI______________________________________ Polymer Phenol/ Am/AMP/ Inherent conc. HCHO.sup.d Weight % Gel.sup.eRun AMPS.sup.a Viscosity (ppm) in (ppm of Gel CharacterNo. Feed Ratio.sup.b dl/g SNSW.sup.c each) 30 days______________________________________157 100TOB 50/25/25 3.4 20000 1000 100 StrongVII 57157TOB 50/25/25 3.4 20000 2500 100 StrongVII 57______________________________________ .sup.a Am = acrylamide, AMP = Nacryloyl-Nmethyl piperazine, AMPS = 2 = acrylamido2-methyl-propanesulfonic acid .sup.b mole % ratio of monomers in the aqueous solution .sup.c SNSW = synthetic sea water .sup.d HCHO = formaldehyde .sup.e weight % gel of initial weight of the solution after aging at 120.degree. C. in synthetic sea water
EXAMPLE IV
This example is a comparative example showing that gels formed from a commonly employed polyacrylamide do not withstand well under a hostile environment condition as compared to the gels formed from the invention polymers.
A 7000 ppm solution of Dowell J333 polyacrylamide in seawater was crosslinked with phenol and formaldehyde at 120.degree. C. Table XXII shows a summary of the results.
TABLE XXII______________________________________ Gel Height (G) and Liquid Height (L) afterPolymer Phenol/Formaldehyde 6 days aging at 120.degree. C.Concentration (ppm of each) G (mm) L (mm)7000 500 22 65 Rigid7000 1000 20 70 Rigid7000 2000 30 75 Rigid______________________________________
The results shown in Table XXII indicate that much syneresis gels formed from polyacrylamide only after aging for 6 days.
The results shown in the above examples clearly demonstrate that the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned as well as those inherent therein. While modifications may be made by those skilled in the art, such modifications are encompassed within the spirit of the present invention as defined by the disclosure and the claims.

Number	Name	Date
4454114	Strasilla et al.	Jun 1984
4460570	Strasilla et al.	Jul 1984
4928766	Hoskin	May 1990
5003016	Boeder	Mar 1991
5028344	Hoskin	Jul 1991
5270382	Ahmed et al.	Dec 1993
5294691	Ahmed et al.	Mar 1994
5391669	Sulc et al.	Feb 1995

Number	Date	Country
5-179155	Jul 1993	JPX
7-258202	Sep 1995	JPX
7-300513	Nov 1995	JPX

Composition and processes for treating subterranean formations

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