NO155509B - PROCEDURE FOR TREATING A PARTICULAR MATERIAL, SPECIFICALLY AN UNDERGRADUATE, PARTICULAR FORM. - Google Patents

Description

The present invention relates to a method of treating a particulate material to change the surface properties, fluid flow and attraction/repulsion properties of the particulate material, particularly when treating an underground particulate formation to change the relative mobilities between soil and water in and through the formation, where the particulate material is brought into contact with a branched, organic polymer that is dissolved or dispersed in a carrier fluid, the branched organic polymer being a polymer with a molecular weight of 900-50,000,000.

Numerous methods have been used to treat soil formations and especially underground formations that are penetrated by an oil well that produces water as well as oil or hydrocarbon. Production of the water or brine reduces the value of the well as water is usually undesirable and requires expensive disposal methods. Likewise, the penetration of aqueous liquids into soil formations is often undesirable, particularly during the drilling, completion or restoration phases of an oil well in which the filtrate entering certain formations from liquids used in the well can damage the formation. When treating underground formations for these and other purposes, aqueous gels are often used for stimulation (e.g. acidification and fracturing), completion (e.g. cementing, gravel packing and perforating^ drilling, restoration, injection molding, mobility control and water control. Several systems are also available for increasing the viscosity of aqueous liquids, such as pickling liquids, However, the prior methods and compositions present problems such as being temporary, unstable or having other problems.

Several of the numerous methods that have previously been used to slow the flow of aqueous fluids into or out of such formations are described in the following U.S. Pat. patents: 3,393,912, 3,868,999, 3,830,302, 3,826,311, 3,820,603 and 3,779 3l6. In the U.S. patent 3 393 912 describes a method for reducing the production of water from oil wells by injecting into the well a viscous oil containing a coupling agent selected from phenolic and uranium resins. In the U.S. patent 3 868 999 describes a method for reducing the water permeability of a formation in relation to the oil permeability by injecting in a formation a plug of liquid containing a hydrocarbon solvent, colloidal silicon oxide, water and a polymeric material. In the U.S. patent 3 830 302 describes a method for reducing the water-oil ratio of a producing well by treating a formation with a combination of an aqueous organic polyelectrolyte such as polyacrylamide and a cationic surfactant. In the U.S. patent 3,826,311 describes the use of a certain copolymer of (3-acrylamido-3-methyl)-butyl-trimethyl-ammonium chloride and acrylamide having a molecular weight of at least lOO.OOO to reduce the water production of fingering in a waterflooding process using emulsions of a water-soluble anionic vinyl addition polymer and a water-soluble cationic polymer.

In addition to the publications described above, there are many publications that describe methods for the application, production and use of polymers for the treatment of soil formations. Selected patents and articles are as follows:

1. Canadian Patent No. 731,212

2. Canadian Patent No. 864,433

3. U.S. RE 29,595 4. u.s. in 877 5o4 5. u.s. 2,138,763 6.U.S. 2,222,208 7.U.S. 2,223,930 8.U.S. 2,223,933 9. u.s. 2,265,759 10. u.s. 2,272,489 11.U.S. 2,296,225 12.U.S. 2,296,226 13. u.s. 2,331,594 14. u.s. 2,345,713 15. u.s. 2,382,185 16. u.s. 2 57o 895 17.U.S. 2,663,689 18.U.S. 2,677,679 19.U.S. 2 731 4l4 20. U.Sc 2 745 815 21. U.S 2,758,970 22. u.s. 2,761,843 23.. u.s. 2,771,138 24.U.S. 2,772,179 25.U.S. 2,801,984 26.U.S. 2,801,985 27.U.S. 2,823,191 28.U.S. 2,924,861 29.U.S. 2,827,964 30. u.s. 2,842,338 31. u.s. 2,842,492 32. u.s. 2,852,467 33. u.s. 2,864,448 34th U.S. : 2,908,641 35th U.S. 2,940,729 36. u.s. 2 94o 889 37. u.s. 2,985,609 38. u.s. 3,002,960 39. u.s. 3,020,953 40.U.S. 3,023 76o 41. u.s. 3,025,237 42.U.S. 3,028,351 43. u.so 3,039,529 44. u.s. 3,042,641 45. u.s. 3,050,493 46. u.s. 3,051,751 47. u.s. 3,053,765 48.U.S. 3,057,798 49. u.s. 3,070,158 50. u.s. 3,087,543 51. u.s. 3,102,548 52. u.s. 3,108,069 53. u.s. 3,116,791 54. u.s. 3,179,171 55. u.s. 3,210,310 56. u.s. 3,254,719 57. u.s. 3,283,812 58.U.S. 3,284,393 59.U.S. 3,305,016 60.U.S. 3,308,885 61.U.S. 3,317,442 62.U.S. 3,334,689 63.U.S. 3,349,032 64.U.S. 3,367,418 65.U.S. 3,370,647 66.U.S. 3,370,650 67.U.S. 3,376,924 68.U.S. 3,380,529 69.U.S. 3,382,924 70.U.S. 3,399,725 71. U,S. 3,415,673 72.U.S. 3,418,239 73.U.S. 3,419,072 74.U.S. 3,422,890 75.U.S. 3,434,971 76.U.S. 3,451,480 77.U.S. 3,483,121 78.U.S. 3,483,923 79.U.S. 3,491,049 80.U.S. 3,494,965 81.U.S. 3,500,929 82.U.S. 3,510,342 83.U.S. 3,516,944 84.U.S. 3,537,525 85.U.S. 3,545,130 86.U.S. 3,562,226 87.U.S. 3,565,941 88.U.S. 3,567,659 89.U.S. 3,572,416 90.U.S. 3,578,781 91.U.S. 3,603,399 92.U.S. 3,609,191 93.U.S. 3,624,019 94.U.S. 3,625,684 95. U.S., 3,635,835 96.. U.S. 3,640,741 97.U.S. 3,660,431 98.U.S. 3,666,810 99.U.S. 3,734,873,100.U.S. 3,738,437,101.U.S. 3,741,307,102.U.S. 3,744,566,103.U.S. 3,779,316,104.U.S. 3,729,914,105.U.S. 3,781,203,106.U.S. 3,791,446,107.U.S. 3,820,603,108.U.S. 3,822,749,109.U.S. 3,826,311,110.U.S. 3,827,495,111.U.S. 3,827,500 112.U.S. 3,830,302,113.U.S. 3,833,718

114th U.S. 3,842,911,115.U.S. 3,845,824,116.U.S. 3,868,328,117.U.S. 3,868,999,118.U.S. 3,888,312,119.U.S. 3,893,510,120.U.S. 3,768,566,121.U.S. 3,898,165,122.U.S. 3,909,423,123.U.S. 3,922,173,124.U.S. 3,939,912,125.U.S. 3,974,220,126.U.S. 3,994,344,127.U.S. 4,021,355,128.U.S. 4,033,415,129.U.S. 4,029,747,130.U.S. 4,058,491,131.U.S. 4,069,365,132.U.S. 4,073,763,133.U.S. 4,079,027,134.U.S. 4,079,059

135th U.S. 3,878,895

136. U.S. 4,094,795

137th U.S. 4,094,831

Articles and books

1. Barkman, J.H.; Abrams, A.; Darley, H. C. H.; & Hill, H.J.; "An Oil Coating Process to Stabilize Clays in Fresh Water Flooding Operation," SPE-4786, SPE of AIME Symposium on

Formation Damage Control, New Orleans, La., Feb. 7-8, 1974. 2. Coppel, Claude F.; Jennings, Harley X.; & Reed, M.G.; "Field Results From Wells Treated With Hydroxy-Aluminum, 11 JOURNAL OF PETROLEUM TECHNOLOGY (Sept. 1973) pp. 1108-1112. 3. Dow Chemical Company, "PEI Polymers...Infinite

Modifications, Practical Versatility," Copyrighted 1974.

4. Graham, John W.; Monoghan, P. H.; & Osoba, J.S.; "Influence of Propping Sand Wettability of Productivity of Hydraulically Fractured Oil Wells," PETROLEUM TRANSACTIONS, AIME, Vol.

216 (1959).

5. Hower, Wayne F.; "Influence of Clays on the Production of Hydrocarbons," SPE-4785, SPE of AIME Symposium on Formation

Damage Control, New Orleans, La., Feb. 7-8, 1974.

6. Hower, Wayne F.; "Adsorption of Surfactants on Mont-morillonite," CLAYS AND CLAY MINERALS, Pergamon Press

(1970) Vol. 18, pp. 97-105. 7. Hoover, M.F., & Butler, G.B.; "Recent Advances in Ion-Containing Polymers," J. POLYMER SCI, Symposium No. 45, 1-37 (1974). 8. Jackson, Kern C.; TEXTBOOK OF LITHOLOGY, McGraw-Hill Book Company (1970) (Library of Congress Catalog Card No. 72-958LO) pp. 95-103. 9. Theng, B.K.G.; THE CHEMISTRY OF CLAY-ORGANIC REACTIONS,

John Wiley & Son (1974) (Library of Congress Catalog Card No. 74-12524) pp. 1-16.

10. Veley, C. D.; "How Hydrolyzable Metal Ions Stabilize Clays To Prevent Permeability Reduction," SPE-2188,'43rd Annual Fall Meeting of SPE of AIME, Houston, Texas (Sept. 29-

October 2, 1968). 11. Milchem Incorporated, "Milchem's SHALE-TROL Sticky Shale Can't Stop You Anymore," DF-5-75-1M. 12. Chemergy Corporation, "Maintain Maximum Production With PermaFIX and PermaFLO Treatments for CLAY/FINE and SAND CONTROL." 13. ENCYCLOPEDIA POLYMER SCIENCE AND TECHNOLOGY, Suppl. No. 1, "Alkylenimine Polymers," Interscience Publ., N.Y., Copyrighted 1976, pp. 25-52. 14. Roberts, John D. & Caserio, Marjorie, C, BASIC PRINCIPLES OF ORGANIC CHEMISTRY, Pub. W. A. Benjamin Inc., N.Y., 1965. 15. Mettzer, Yale L.; WATER SOLUBLE RESINS AND POLYMERS, Noyes Data Corp., Park Ridge, N.J., 1976 16. Whistler, Roy L.; INDUSTRIAL GUMS, Academic Press, N.Y. , 1973. 17. Hoover, Fred M.; "Cationic Quaternary Polyelectrolytes— A Literature Review," J. MACROMOL. SCI-CHEM., A4(6), October, 1970, pp. 1327-1418. x 18. Robinson and Stokes, "Electrolyte Solutions," Butterworth Scientific Publications, 1959. 19. "Enhanced Oil and Gas Recovery & Improved Drilling Methods," 4th Annual DOE Sumposium, Vol. IA (Oil) of Proceedings, Aug. 29-31, 1978; pp B-l/l-B-1/25; Tulsa, Okla.;

Published by The Petroleum Publishing Co., Box 1260, Tulsa, OK 74104.

In addition to the above publications, pending patent application USSN 901,664 filed May 4, 1978> describes the use of various polymers to stabilize clays in earth formations, particularly in an underground formation. The above publications and other publications mentioned here are incorporated herein by reference to the extent necessary.

The present method of the type mentioned at the outset is characterized by the fact that a branched, organic polymer is used with a base chain of polymer units and at least one branch chain connected to the base chain formed by two or more polymer units, the polymer units being the same or different and being from the group consisting of of such with the structural formula

wherein R 1 and R 2 may be the same or different and consist of hydrogen or an alkyl group,

R4 is hydrogen or a hydrocarbon radical which may contain alkyl groups or alkyl groups and heterogroups or combinations thereof, each hydrocarbon radical containing 1-10 carbon atoms, X.^ and X_ are the same or different and consist of heteroradicals derived from nitrogen, oxygen, phosphorus or sulfur , and R^g consists of a hydrocarbon radical which may contain alkyl groups or alkyl groups and heterogroups or combinations thereof, each hydrocarbon radical containing 1-10 carbon atoms, and R-^gf R20 0<3 R21 can be the same or different and independently of each other be absent and consist of hydrogen or hydrocarbon radicals which may contain alkyl groups or alkyl groups and heterogroups or combinations thereof, each hydrocarbon radical containing 2-50,000 carbon atoms, provided that the ratio between carbon atoms and heteroatoms in the organic polymer is 6:1 or less and that the organic polymer is hydrophilic.

Fluid is understood to mean aqueous or organic fluids or combinations thereof. "Aqueous fluids" is used here to denote any fluid containing some water. It may also contain other components such as hydrocarbons (such as alcohols, ethers and other miscible or partially miscible solvents), acids, water-soluble or water-dispersible salts, easily gasifiable components (such as CC>2 and N2) or solids (such as sand , Portland cement and propellants), or other plastics or polymers such as resins. These materials may include those which are curable to a rigid or semi-rigid solid as well as those which are not curable. The fluid may also contain particulate material such as sand, clay or acid-soluble particles (e.g. carbonate). These fluid properties are primarily viscosity and the resulting apparent viscosity of the fluid in various media. This alteration of fluid properties is useful for producing viscosity-enhanced and gelled fluids and for treating various substrates to alter the properties of the substrate such as its surface-active nature or the interaction between a treated substrate and various fluids. The preparations used in the present invention to change fluid properties or treat different substrates can be combined to give the desired combination of preparation properties, e.g. solubility, affinity or repulsion towards different fluids and/or solids; stability against or degradation of constituents such as oxygen, acids and water at different temperatures; or viscosity properties that vary with time, temperature, concentration, etc. These methods have particular application in the thickening of various fluids such as aqueous fluids and acids for the treatment of soil formations, especially those that are cut through by a well such as those used to produce water, oil, gas, steam and other resources. The preparations use a specific type of polymer as an essential component. This type of polymer is a branched organic polymer with a main chain with an average of at least one branch chain per main chain, and where said branch chain averages at least two polymer units in length. In the branched polymer, up to approx. 98 P^. 100 main chain polymer units have one or more branches. The branched polymer can have one or more branch chains on each polymer unit in the main chain if polymerization or grafting conditions, polymer units, economy and the like allow it. A polymer unit as used herein denotes the portion of a polyene chain derived from a monomer either in the main chain, the branch chain, or both, and whether it is derived directly from a polymer or whether it is partially polymerized or reacted to form a polymer precursor, oligomer - or polymer chain.

A preferred used group of polymers within the broad group of branched polymers are branched water-

soluble polymers. The branched polymers may contain polymer units, segments or parts in various arrangements that are oleophilic, oleophobic, hydrophilic, hydrophobic or combinations thereof. A preferred group of branched polymers contains large parts, concentrations or amounts of hydrophilic units or segments "The branched polymers used according to the invention generally comprise combinations of hydrocarbon groups and heterogroups. Hydrocarbon groups as used herein, generally denoted by R, contain hydrogen and carbon and may also contain heteroatoms or groups, but usually hydrogen and carbon are the predominant number of atoms. For example, the hydrocarbon group may include, but is not limited to:

Another preferred group of used branched polyesters according to the invention are those containing ionic groups. These ionic groups can be cationic, anionic, amphoteric, neutral or ionically balanced, or combinations thereof. The ionic groups are usually or usually contain heteroatoms or groups which, as used herein, are oxygen, nitrogen, sulphur, phosphorus, metals such as the alkali metals, the alkaline earth metals, the metals in groups IV, V and VII of the periodic table, combinations thereof and comominations thereof with carbon and/or hydrogen. Ionic groups can be included in or with aromatic groups, heterocyclic groups, unsaturated bonds, carboxyl, carbonyl, keto, amide, imide, sulfo, hydroxyl and the like.

Thus, the invention can be broadly regarded as the application of certain types of branched polymers and the discovery of certain branched polymers that have unexpected stability and efficiency. For example, when treating a soil formation or changing the properties of an aqueous fluid using a water-dispersible polymer, the treatment or change can be improved by using one of these branched polymers with a molecular weight of 900-50,000,000 with an average of at least one branch chain per main chain and where the branch chain has an average length of at least two polymer units. The branched polymer may optionally be ionic or contain ionic and/or non-ionic segments depending on the particular effect and application that is desired. The branched polymer may be prepared by any of several methods or variations and may be prepared to contain the particular combination of segments and properties desired in light of the teachings herein. Likewise, the branched<1> polymer can be used or used in any of a number of methods or variations thereof.

In one aspect of the invention, branched ionic polymers are used to treat particulate or fibrous formations, particularly soil particles, to change the fluid flow properties and/or surface properties of the particles or soil formation. The branched polymers

used to change the viscosity or gel structure of many aqueous liquids and change the surface properties, the liquid flow

and the attraction/repulsion properties of many formations.

The same or different mechanisms may cause the changes

in the various applications. The formations can consist of loose or consolidated particles or fibers. The formation can also be suspended particles, fibers or masses. A formation

may be a solid impermeable mass that has been etched or leached to form a porous permeable formation equivalent to a porous permeable formation formed by compression of particles or fibers. Compacted formations may be loose or consolidated by natural or artificial binders such as resins, inorganic cements, including silicate and Portland types. As used herein, particulate and particulate formation shall include all of the above types of particles, formations or structures. The fluid flow or surface properties mean the net response of the particles or formation to flow or resistance to flow relative to a particular fluid and to the attractive, repulsive or relatively inert nature of the particles or formation to one or more fluids or materials suspended in the fluids. The particles may be suspended in a liquid or packed either loosely or solidly into a mass. Within this aspect of the invention, a particular method relates to the treatment of particles packed into a formation to reduce the permeability of the formation to the flow of water or an aqueous liquid. The method merely comprises placing or contacting a liquid phase next to the formation containing an effective amount of a polymer to treat at least a portion of the adjacent formation.

The treated zone should preferably have a minimum thickness of

25 mm. Of course, in applications to alter the properties of aqueous fluids, such as altering the fluid loss of a treatment or drilling fluid, the penetration of aqueous fluid and branched polymer should be a minimum or only a fraction of 25 mm. The polymer is preferably a branched organic polymer with a molecular weight of 900-50,000,000 with a main chain with reactive regions on which a branch chain can be or has been attached, since branch chains

is bound with the main chain at a concentration of V*

0.1-99% of the reactive areas. The branched organic polymer also contains a hydrophilic part in a concentration sufficient to produce the desired hydrophilic-hydrophobic balance within the formation and to change the hydrophilic properties of the formation. This liquid phase flows or is pumped or injected into the formation and the polymer is allowed to contact the formation. For this use, the preferred groups of polymers have binding groups, i.e. ionic groups for binding or attachment

to the formation. For example, when the formation has a general anionic nature, a preferred polymer will be a cationic polymer so that the cationic groups can attach or connect with the anionic areas in the formation. The higher molecular weight polymers and polymers with high concentrations of ionic groups also tend to make the treatment more permanent and to have improved efficiency.

In yet another aspect of the invention, another group of polymers can be used which have some hydrophobic and/or oleophilic parts, branches or overall nature so that these polymers can be attached to formations or suspended in liquids in the formation to produce a surface effect on the particles or formation which slows the flow of organic fluids or hydrocarbon fluids and increases the permeability of the formation to aqueous fluids or would tend to gel hydrocarbon fluids or organic-based fluids. As used herein, hydrocarbon fluids include both oil, gas and mixtures thereof. One aspect of the change in permeability of the formation is the change in the water-oil ratio (WOR). As used herein, WOR shall include the ratio of aqueous fluid to hydrocarbons including oil, gas or mixtures thereof. The production of various polymer groups to achieve the desired modification, produce the desired attractive, repulsive or suspending properties, and produce the desired viscosity increase, gelation or preference for organic or aqueous liquids can be produced in light of what is stated herein.

For example, a preferred group of cationic polymers which are hydrophilic and have strongly hydrophilic branch chains can be used to treat or attach to a formation with anionic regions. This attachment is long-lasting or essentially permanent, as the effect is not easily removed by washing or flowing through the formation with acids, bases, organic or aqueous liquids. These polymers are also useful for clay stabilization. The hydrophilic part of the polymer hydrates in the presence of water, brine or most aqueous liquids which is believed to cause pseudostructure in the aqueous liquid leading to an apparent increase in viscosity. Or, in other words, the net effect is to increase the resistance to flow or pressure required to produce a given flow of aqueous fluid. The hydrophilic part is believed to be partially dehydrated, shrink or form a smoother flow channel in the presence of hydrocarbons or other organic liquids, thereby increasing the permeability to organic liquids or not significantly changing the permeability to hydrocarbons. Certain preferred polymers used herein are effective to produce at least a 10% change in relative permeability to an aqueous fluid in most loose or consolidated particulate formations, either packs or cores. This hydrophilic nature of the branched polymer also provides an aqueous gelling agent with an unexpectedly high efficiency and high stability even in aqueous and especially acidic liquids. The effectiveness of gelling an aqueous liquid is indicated by a significant increase in viscosity such as at least a 10% increase compared to similar polymers which are linear.

Moreover, certain groups of polymers have long-term stability, which means that this effect will last even after 1000 pore volumes of a normally harmful fluid has been passed through the treated formation. This stability will be affected by the nature of the polymer and the particular formation being processed. For example, in siliceous or anionic formations, a cationic polymer is preferred, and for cationic or neutral formations such as limestone or dolomite, an anionic or amphoteric polymer is preferred. For formations and/or which do not have a clear ionic character or where the ionic nature is weak, stability or longevity can often be improved by increasing the molecular weight of the polymer (eg cross-linking) and/or the length or number of branch chains.

Another preferred group of polymers have an essentially neutral, non-ionic or amphotic nature so that they are adsorbed preferably weakly on the host formation and/or other solids, e.g. suspended particulate solids. Also, this polymer can be solvated and/or swelled with both aqueous and organic liquids depending on the exact hydrophilic/hydrophobic nature of the polymer to provide the desired resistance to flow. These polymers can be used for acidification, fracturing, gravel or sand packing, shut-off of fluid flow in a formation, diversion of fluids, drilling, well completion, cement injection, flooding or tertiary recovery or a combination thereof. They are particularly useful for mobility control as in polymer flocculation and other enhanced recovery methods.

Particular applications for preferred groups of branched polymers include (1) water-to-oil ratio (ie WOR) reduction in wells, (2) reduction of water flow, (3) enhancement of the flow or production of hydrocarbons including oil, gas or mixtures thereof, either alone or in the presence of an aqueous fluid, (4) plugging or diversion of aqueous fluid flow in or into parts of a formation, (5) increasing viscosity and/or fluid loss control fluids used in a well as in carrier or treatment fluids , gravel packing fluids, drilling, restoration or completion fluids, (6) diversion of well or formation fluids, e.g. to change mobility or injection profile or to regulate fluid injection, (7) decrease or increase the resistance to flow of aqueous fluids, organic fluids, mixtures thereof or a component thereof in a formation, (8) increase the viscosity of aqueous or organic liquids and especially when these liquids enter or encounter certain types of formations, (9) rejection of certain liquids, salts, solids or materials in a formation or structure, or suspended in a liquid, (10) gelation of aqueous liquids , particularly acidic liquids, (11) as carrier liquids for particulate solids, e.g. gravel packing, breaking up, acidification or a combination thereof, (12) clay stabilization, (13) as a flocculant for suspended particles, (14) treatment of surfaces to cause them to attract or repel aqueous or organic liquids or ionic materials, (15 ) as an acid extender or retarder, (l6) fluid loss control and/or viscosity enhancer for breaking up and/or acidification, (17) prevention or breaking of certain emulsions, especially water and hydrocarbon emulsions commonly found in formations, (18) formation of an aqueous sealing gel around conduits such as pipelines, wells, tunnels, mine shafts, sewers, hydrocarbon storage pits, (19) acting as a surfactant or binding agent between solids and liquids; one or more liquid phases such as to increase adhesion of resins or consolidation materials to certain surfaces; or one or more solid phases such as between solids suspended in a fluid or a formation, and (2o) embedding uncoated or poorly coated silicon oxide surfaces in a resin consolidation of solids (eg, gravel packs, formation particles, and the like) to make the consolidation more resistant to water degradation.

Thus, generally speaking, a preferred application of the present invention comprises one or more methods with one or more polymer preparations for changing the surface properties of and/or fluid flow properties or a substrate or a formation, which includes bringing said formation into contact with a highly branched organic polymer which has a fastening part and a modification part. The attachment part of the polymer generally has ionic groups which provide the desired ionic bond or repulsion in the formation. The modifying part of the polymer has the hydrophilic-hydrophobic balance desired to provide the desired formation surface properties and/or interaction with liquids such as gelling and increasing or decreasing permeability to certain liquids.

Preferred polymers can be classified according to the main properties, in the formation to be processed or used, the type of polymer attachment or adsorption mechanism, the type of modifying polymer moiety, polymer solubility or suspending properties and the functions that the polymer can perform as shown in the following table.

In one embodiment of the invention, a simple one-step, one-phase, or one-agent treatment process is provided to modify the surface properties, wettability or fluid flow properties of a soil formation, in particular an underground formation intersected by a well which a producing oil or gas well. The treatment can also be carried out by grafting or the formation of branched polymers in situ. This treatment is essentially permanent and very stable against acids, oxygen and temperatures up to at least 93-177°C. For some preferred polymers even higher temperatures can be tolerated. The treatment is also very stable in the presence of most electrolyte solutions such as salt or brine which usually affect other polymers (e.g. polyacrylamides and derivatives) previously used for such treatments. These acrylamide polymers are prone to desorb or break down in the formation. In this treatment process, a certain group of branched organic polymers with a molecular weight in the range 900-500.000.000 is brought into contact with or added to a fluid carrier medium, preferably an aqueous liquid phase, for the formation. The polymeric carrier fluid can also be an emulsion, aqueous solution of inorganic salts, a hydrocarbon liquid, a polar solvent such as polar and/or oxygenated hydrocarbons or mixtures thereof. The polymer has certain ionic and hydrophilic properties. Depending on the surface properties or wettability properties desired for the treated soil or particle formation, the polymer may be non-ionic, amphoteric, neutral, anionic, cationic or a combination thereof. For the treatment of most sandstone formations and especially underground oil-producing formations, the cationic polymer is preferred. For some formations such as those having a high concentration of carbonate, the anionic polymer or the amphoteric polymer is preferred. Where weak or reversible adsorption is preferred, non-ionic polymers can be used, such as for polymer flocculation or in tertiary flocculation to change the mobility ratio of the liquid phases in the formation. The ionic polymer preferably has a calculated ionic concentration of approx. 5 x IO<-2> - <1> x IO"<10> or preferably 5 x lo"<2> - 1 x IO-<5> ionic areas per gram atomic weight.

The ionic concentration of certain preferred polymers is calculated by adding the number of charges in the form of ionically charged atoms, radicals or groups including both the main unit, pendant groups and branch chains, and then dividing this number of charges by the gram atomic or molecular weight of the repeating polymer unit or representative part of the polymer. This gives the number of charges per representative weight unit of the polymer. For example, polyethyleneamine with one nitrogen for each repeating polymer unit, e.g.

one positively charged nitrogen or cation per repeating unit and a molecular weight of 44 giving a charge density of 1/44 or

-2

about. 2.3 x 10 . This does not include the counter ion (A ). For polymers such as polyalkylamines, the ionic charge or degree of ionization can be varied or changed by adjusting the pH, solvent or salts in the solution. For ionic concentration calculation purposes, all atoms, radicals, or groups that might normally be charged under the same conditions of use can be considered charged for the calculation except when settings to ionize some groups would deionize or interfere with others.

Another example of charge density calculation for a branched copolymer with units A, B and C as:

Calculation of gram atomic or molecular weight Calculation of the number of l charges per unit

G j.snitti, charge concentration = 2010 charges/224,630

-■a

weight = 8.9 x 10 charges per gram atomic weight.

A preferred type of branched polymers has a substantially linear main chain with active sites on which branch chains can be attached. This essentially linear main chain can be a homopolymer or a copolymer with the reactive regions in the main chain or on pendant groups. Essentially linear is used here to also include polymers with pendant groups that are no more than approx. two polymer units in length. The monomer units of this main chain may be or contain aliphatic, aromatic, hetero groups, or combinations thereof. As used herein, "homopolymer" refers to a polymer prepared by using monomers at a concentration of at least

98% of one type of monomer, and copolymer covers polymers prepared using more than one type of monomer in concentrations of at least approx. 1%, i.e. significant amounts. The term copolymer as used herein includes copolymers, terpolymers, etc., with 2-8 types of monomers in various concentrations

or homopolymers where some monomer units or polymer units have been derivatized as hydrolyzed acrylamide. Both homopolymers and copolymers or parts thereof can be produced in a one-step regular or a random polymerization of monomers, oligomers, polymers or mixtures thereof, or by multi-step polymerization of monomers, oligomers, prepolymers or mixtures thereof. The branched polymers may include randomly polymerized parts, regularly polymerized parts, block polymerized parts or combinations thereof. The branched polymer or portions thereof may be prepared by any of a number of conventional batch or continuous polymerization processes or may be polymerized in situ as in an underground formation where it is to be applied or used. The effectiveness of the branched polymer for a specific application, its structure and viscosity, degree of branching, length of polymer chains and the like, are sensitive to polymerization conditions and the precise control of factors such as temperature, diluents or solvents, pressure, pH, electrolyte type and concentration, agitation and other common variables.

Each branch chain can be substantially linear, even highly branched or with the desired degree of branching as indicated herein.

The stability of the branched polymer is a function of the polymer bonds and the environment to which they are exposed. The polymer should be stable when exposed to high temperature, acid, oxidation, hydrolysis and shear. For WOR applications, high stability is desirable. For other applications such as gelation of acids, the polymer need not be as stable over long periods of time. Preferred main chain linkages include C-C, C-N-C, C-O-C and combinations thereof. The stability of the bonds in the branch chain and pendant groups is also critical, and the stability should be high for most applications. To alter fluid flow properties in formations, certain preferred branched polymers contain polyamine and polyether linkages in the branches.

It is believed that the branching also increases the backbone stability of certain polymers such as those containing ester linkages. Certain preferred polymers with C-C linkage, ester linkage and polyether branches have remained surprisingly effective at temperatures above about 177 C. This gives a highly stable preferred polymer. In the case of the carbon-to-carbon bond, the ionic groups and hydrophilic or water-solubilizing groups are in attached groups or in branched chains. For sufficient water solubility, there should be at least one ionic or hydrophilic group for approximately every 5 or 6 carbon atoms. that the carbon-to-heteroatom or group ratio should be less than approx. 7:1. The nature of the ionic or hydrophilic groups and the type of carbon or hydrocarbon groups present will affect the solubility and ratio of carbon to hydrophilic groups. A preferred group of polymers are water-soluble polymers, but all polymers need not be water-soluble depending on their application or function. "Water solubility" is used here to denote a solubility of at least 5 parts per million (ppm), preferably approx. 1% by weight, in an aqueous liquid. In order for polymers to become ionically bound to a charged formation or structure being treated, the polymer must be at least dispersible in a fluid and at least partially ionizable in the presence of a solvent such as water, a polar solvent, or mixtures thereof. It may be desirable to use hydrocarbon liquids, substituted or polar hydrocarbons such as oxygenated hydrocarbons. These hydrocarbon solvents include alcohols (methanol, ethanol, isopropanol), glycol ethers and ethylene glycol and the like. Easily gasifiable carrier fluids useful according to the invention include, but are not limited to, carbon dioxide, ammonia, nitrogen, low molecular weight hydrocarbons or substituted hydrocarbons. These materials can also be used as an easily gasifiable component of a liquid system or as a main component of a mist or foam carrier. These fluids can be used as solvents, carrier fluids, pre-flushes, post-flushes or a combination thereof to place or suspend the polymer. The degree of branching, crosslinking, molecular weight and stereoconfiguration must also be taken into account along with the chemical constituents, e.g. hydrophilic groups and ionic nature, to determine the solubility, attraction, repulsion, suspension, adsorption and other properties that determine the strength of attachment to the formation or suspension in a fluid, as well as the fluid properties including adsorption, hydration and resistance to or promotion of fluid flow for either aqueous or organic fluids. For some applications it may be desirable to have a polymer or parts thereof that repel, suspend or disperse solids, the surrounding formation and/or other polymer chains. A high molecular weight polymer with a high concentration of hydrocarbon groups would tend to give a highly viscous fluid and be less soluble in aqueous fluids. This polymer could also be soluble or dispersible in organic fluids. A high concentration of hydrophilic groups would tend to increase water solubility, hydration or solvation. It is believed that for a given molecular weight, a highly branched hydrophilic polymer would tend to trap or affect more water than a more linear hydrophilic polymer, and would more effectively hydrate or swell to

increase the viscosity of an aqueous fluid in which it was dissolved or with which it was united while bound to a formation or structure. That is that the randomly branched polymer would have a larger hydrodynamic volume or associate with more water and be more effective in reducing aqueous fluid flow.

However, a polymer with longer hydrophilic branches would be

more effective for gelling aqueous fluids or reducing WOR than one with shorter branches, particularly in highly permeable formations or those with large pores.

In the case of polymers with high solubility in aqueous fluids or those with a high ionic concentration, it is desirable to have heteroatoms or groups such as nitrogen, oxygen, phosphorus, sulphur, carboxyl, carbonyl, carbinol, cyano, ether, acetal, carboxyamide, alkylidene, alkylene or substituted aromatic groups in the branched polymer. The first 11 atoms and groups are preferred. The heterogroups and branch chains should be chosen for the desired stability. They can also be chosen to reduce the stability of the polymer for some applications such as hydrolysis, attack by acid or oxygen, or thermal degradation.

By a method for producing the branched

polymer, the main chain must contain reactive areas that will react with a corresponding reactive area in the monomer or in the branch chain to be bonded. The branching can also be achieved by homopolymerisation where the monomer reacts with other monomers, oligomers

or polymers during random branching or a branched polymer as in the case of certain alkylenimines (e.g. a

the aziride to form PEI) in which the alkylene group preferably contains approx. 2-3 carbon atoms. In another method, the branch chain can be attached to a monomer unit and then a type or a mixture of monomers is polymerized to form the main chain, the branch chain or both. Branching can also be achieved by reaction with or grafting of a branched polymer chain onto a linear main chain, a weakly branched main chain or a main chain with pendant groups. The branch chain can be attached at corresponding reactive sites to the linear main chain or to what can be considered a pendant branch or a pendant group on the branch chain. After the branch chain or branch chain monomers are attached, the reactive regions can be considered no longer reactive. As with the main chain, the branch chain or pendant groups may contain heteroatoms or groups such as oxygen, nitrogen, phosphorus and sulphur. The branched polymer can also be prepared by reacting or polymerizing one or more monomers at reactive sites in or on the backbone to form branches of random length at different locations on the backbone polymer and/or on different branch chains.

In one method, the reactive regions in the polymer main chain, branch chain or monomer can be any atom, radical or group that will react with a corresponding reactive group in the main chain, branch chain or monomer to bind the branch chain to the main chain. When forming, branching or grafting the polymer, there must be at least one reactive region in the main chain to connect a branch chain, but there can be one or more reactive regions in the branch chain as long as cross-linking is not a significant problem. The reactive region(s) can be considered a branching agent. The branching agent can also be a complete monomer or polymer unit with one or more reactive areas that will react or polymerize to form the branched polymer or part thereof. Especially for in situ grafting or polymerization, the branching agent would be considered a monomer, oligomer or polymer, and not just the reactive region or group of such as epichlorohydrin bound to the branching or cross-linking polymer0 Some cross-linking can be tolerated and in some cases as low ionic attraction, high formation porosity and high temperature environments, extensive cross-linking along with branching is useful for stability and efficiency, particularly for WOR reduction, cement injection, flow diversion, etc. The polymer formed should still be water soluble.

The reactive sites may be selected from one or more of the following chemical groups to react with a corresponding reactive site: (1) alcohol, (2) aldehyde or ketone, (3) alkene, (4) alkyl halide, (5) alkyne, (6) amine, (7) an acid or acid equivalent including an ester, anhydride or an acyl halide,

(8) amide, (9) epoxide, (10) acetal or ketal, (11) nitrile,

(12) sulfides and similar or equivalent reactive groups.

The effectiveness of branched polymers to reduce water flow and/or alter aqueous fluid properties appears to involve several molecular variables. Special properties can be incorporated into branched polymers to suit different applications such as degree of branching, length of branches, ionic nature of the main chain and branches, molecular weight of main chain and branches, and degree of cross-linking.

In order to bind the polymer to particulate solids, it is generally preferred that the predominantly ionic charge on the surfaces of a substrate or solids is reacted with a branched polymer having opposite ionic charges in the main chain, but the effect is not limited to this mechanism. High molecular weight branched polymers also tend to adhere to surfaces that may have the same predominant surface charge as the polymer. Some degree of cross-linking of the branched polymers also tends to increase this molecular weight and give it improved properties. The mechanism or mechanisms involved in coating these surfaces is not fully understood.

Greater effectiveness in reducing water permeability is associated with a higher degree of branching and with the higher molecular weight of hydrophilic branches and main chain structure.

Some cross-linking may be advantageous as the molecular structure is enlarged' Sufficient open-ended branches are, however, necessary to effect the reduction in water production and/or mobility.

For binding to predominantly anionic sandstone (siliciura oxide) formations, certain preferred polymer structures should contain sufficient cationic (+) sites to effect strong attraction of the polymer to sandstone surfaces or other particulate solids (anionic surface properties). These highly cationic polymers will also stabilize clays

and fine materials in a surface or subsurface structure while imparting desirable properties (described above) to the formation or particulate solids. These polymers stabilize sensitive formations such as those containing clay so that they are less susceptible to swelling, dispersion, erosion or other damage from fluids such as hydrocarbon fluids (especially gas), aqueous fluids or other formation fluids that can result in migration, plugging or other types of damage that reduce permeability. These polymers also increase the stability of a resin consolidated formation. These polymers can also modify the surface properties of particles such as sand, silica flour, asbestos and the like.

In another situation, it is desirable that predominantly cationic particulate solids consisting of calcium constituents (cationic (+) surfaces) e.g. CacO^, CaMg^O^^ dolomite), FeCOg (siderite, etc.) are treated with polymers containing a sufficient amount of anionic (-) sites to lead to strong attraction of the polymer to the solids. Limestone formations represent the calcium-containing structures described above.

Formations often contain particulate solids of varying or mixed composition and ionic surface properties. The formations can be treated separately with two or more polymer types, for example a treatment can involve a cationic (+) polymer structure to promote attraction to the anionic (-) (sand, clays, silicon oxide, etc) surfaces.

A simultaneous subsequent treatment with a polymer containing anionic regions can be used to effect strong attraction to the cationic surfaces. The above example describes a method for treating a formation with different ionic surfaces. Branched polymers with different ionic groups or mixtures of different ionic properties can also be used on a formation with a predominantly ionic property. Alternatively, a polymer used according to the invention may contain anionic, cationic or other types of ionic groups, parts or segments so that formations with a mixed composition or several formations of varying nature can be treated with one type of polymeric material in one or more steps or applications. However, the scope of the invention includes other methods and modifications that represent the stated basic idea.

For some applications, it is desirable that the polymeric molecules are characterized by little or no chemical cross-linking of polymer segments. Some cross-linking may be desirable in other areas. The polymers must have sufficient hydrophilic properties to cause some thickening of aqueous liquids. In general, for a given branched polymer family, it has been observed that polymers with higher viscosity are more effective than those of the same family that have lower viscosity at the same concentration.

For certain preferred polymers, the main chain, if definable, may be linear, branched, irregularly shaped, or otherwise, and may be composed of a homopolymer or copolymer structure. Sufficiently reactive sites must be available on the main chain for chemical attachment of desirable polymer chains. Side chains may also be represented by a homopolymer or copolymer structures and may assume a linear, branched, irregularly shaped or other type of configuration. The branched chain may also be attached to pendant groups of a polymer main chain. The resulting polymeric structure must contain the necessary ionic charges, flexibility, and balance to facilitate strong and long-lasting ionic bonding between it and the particulate solids. It should provide sufficient hydrophilic (water-loving) segments of sufficient ionic nature to effect substantially effective resistance to flow. of aqueous fluids through porous media, but cause little or no resistance to the flow of hydrocarbons through them. The polymeric material can also provide long lasting surface properties to the particulate solids such as increasing oil flow by increasing oil permeability. Polymeric structures should have the following additional properties. The ionic character of the polymer can be of one or more types, e.g. a polymeric molecule may have only cationic properties, while another polymeric structure may contain nonionic, cationic, anionic, neutral, amphoteric segments, or combinations thereof. Ionic disorder or interaction within the molecule or between polymers can create problems with different types of ionic segments.

For a preferred group of highly branched, water-soluble cationic polymers, the main chain will contain the cationic groups or radicals, and the branch chains may contain further groups, amphoteric groups, non-ionic groups and/or be a neutral group. For substantially linear main chains, the molecular weight of the main chain should be in the range of 10O0-5.OO0.O00.

The polymer unit of the branch chains may be one or more of the polymer units specified for the polymer main chain. As indicated above, the branch chains may contain the same polymer units for randomly polymerized homo- or copolymers. For randomly polymerized main chain, branch chain or both, the polymer chain can be chosen arbitrarily so that even the branch chains would have branches. For graft polymerization or separate attachment of the branch chain to a main chain, the branch chain can also have several branches attached over one or more reactive sites. The branch chains may also comprise different random polymer units which may be made up of one type of repeating units or one or more different repeating units. Branch chains can also be graft polymerized onto the polymer backbone as a separate polymerization step. More than one type or length of branch chain can be grafted onto the main chain. The branch chain can also be another homo- or copolymer chain containing a reactive region which will bind to a corresponding reactive region in the main polymer chain. The molecular weight range for these branched chains may be 100-5.0O0.000 or preferably

300-10OOO0OOO for water-soluble WOR reduction or aqueous liquid-gelation polymers.

The polymer chain may contain hydrophilic or hydrophobic groups, oleophilic or oleophobic groups, heterogroups and/or ionic groups including amphoteric, non-ionic, cationic, neutralized or anionic. Either the polymer main chain or the branch chain or both may contain ionic groups. The number or concentration of each of these groups, their location and the surrounding medium, solvent or fluid, will determine the net or total properties and performance of the branched organic polymer. The branched polymers used according to the invention can be produced by conventional methods as described in the references referred to above, The main chain, the branch chain or both can be regular homopolymers, random copolymers of two or more monomers, block copolymers, segmented random copolymers or combinations thereof .

The branched polymers used according to the invention have a molecular weight in the range of 900-50,000,000. The molecular weight is generally not critical except for a minimum value for each polymer family depending on the application and other polymer properties such as the degree of branching, ionic nature, degree of cross-linking, as well as the desired efficiency and stability. In general, the higher the molecular weight, the more effective the polymer is in increasing viscosity and reducing permeability to liquid flow. Polymers with a molecular weight near the lower critical limit for a given application may be effective for a short time, but are usually less stable to damaging liquid flow or adverse conditions. A higher degree of branching and/or cross-linking generally makes the lower molecular weight polymers more effective for most applications. Preferred groups of branched polymers have an average molecular weight of 100,000-5,000,000 for most applications; higher aqueous viscosities are obtained with molecular weights up to 10,000,000-15,000,000. Polymers with molecular weights of 10,000-2,000,000 are effective for several applications and are easier to handle than higher molecular weight polymers. For certain applications where high viscosity or efficiency is not critical, or for less permeable formations, low molecular weight polymers such as those on

1,000-9,000,000 are used. Some polymers can also be used and branched or cross-linked in situ for easier processing and/or greater efficiency.

The main chain polymers can have a molecular weight from 800

to nearly 50,000,000, preferably 1,000-5,000,000 for WOR reduction, and 10,000-10,000.OOO for use as an aqueous viscosity enhancer or fluid loss control agent. These main chain polymers can be used to produce branched polymers with a molecular weight of 9,000-9,000,000,

100,000-20,000,000, or up to 50,000,000 of

depending on the number and size of associated branch chains and the degree of possible cross-linking.

The branched chains can have molecular weights up to 1,000,000 or even higher, generally if the chain is highly hydrophilic and itself highly branched. A group of preferred branched polymers, before binding to the main chain, have molecular weights of

300-50,000. For greater WOR efficiency, higher molecular weights and a higher degree of branching are preferred, even up to a molecular weight of 100,000 or even 1,000,000.

In the case of more soluble, highly branched or compact polymers, polymers with a higher molecular weight are preferred as they are generally more effective and can be processed acceptably. Cross-linking, either during manufacture or in situ, can have the effect of increasing the molecular weight of the branched polymer. This cross-linking can occur during batch or continuous production of the branched polymer or in situ when the branched polymer is applied to a formation. The degree of crosslinking will limit the degree of water solubility or water dispersibility as the polymer tends to become less soluble or dispersible and forms a stiffer gel structure with increased crosslinking. The Geistruk tour is desirable for some applications such as plugging of formations or cement injection in cavities or highly permeable zones around conduits such as wells, caves, tunnels, pipelines and the like. The limiting factor on the molecular weight of the main chain polymer, branch chain polymer and/or formed branched organic polymer is the maximum liquid viscosity that can be handled in the preparation, mixing and application of the components and/or the formed polymer

The polymer's branch chains can be any polymer group with the desirable hydrophilic-hydrophobic properties and a reactive group that will bond with the reactive areas on the main chain. The reactive group is preferably at or near one end of the branched chain, but it may be anywhere in the chain or in a pendant group. For a preferred group of polymers used to reduce the flow of water through soil formations or to reduce the production of water in an oil well, the branched chain and total polymer should be hydrophilic where the branch chain has approx. 2-50,000 repeating polymer units. These branch chains may be substantially linear or themselves branched. In some cases, multi- or di-functionally branched polymers with reactive end groups can be used if one reactive group can be terminated or inactivated to prevent or reduce cross-linking. Some cross-linking, e.g. about. 5%> can be tolerated and is beneficial for certain applications. More preferred groups of branched polymer chains are the polyalkylene imines and polyalkylene oxides in which the alkylene groups contain approx. 1-3 carbon atoms. Examples of other monomer units that can be used to form the branched polymer chains are acrylamide, acrylate, vinyl alcohol, vinyl ethers, hexoses, allyl alcohols, allyl amines, substituted derivatives thereof such as sulphonated acrylamide, as well as copolymers and combinations thereof. In general, monomers, polymers and polymer units that can be used for the main chain can be used for the branch chain.

In one type of preferred hydrophilic branched polymers useful as viscosity enhancers, reducing WOR or reducing the flow of aqueous fluids in, into or within a formation, the predominant ionic groups in or near the main chain will preferably be cationic groups. The preferred repeating units in the polymer branching will be -f-CH2-CH2-0—)--f-<CH>2-<CH>2-<NH>~)-, CH2-CH2-N<=>^<= > or combinations or substituents thereof. These preferred polymer units can be written (R-X} where R is as indicated above, and X is a hetero group such as nitrogen, oxygen or sulfur with at least two bonds. The R group shown above is the C0 alkyl radical ethylene. X can also be another R -group, lack or be inside the R group. These chains will preferably be monofunctional or more reactive at one end such as those that are end-capped or terminated at one end by a relatively unreactive group and at the other end by a branching agent. These { R-X} groups can be acrylate, acrylamide, vinyl alcohol, methylvinyl ether, a C₁-Cg alkyl, aryl, combinations thereof, or combinations thereof with heterogroups, especially in the case of a heteroatom as indicated above as C₁-Cg alkyl with heterogroups. Examples of preferred end groups are alkoxy (e.g. -OCH 3 , -OCH 2 -CH 3 ); aroxy (e.g. -O-(o) ).

Commercially available monomers, equivalents or polymers containing them (either homopolymers or copolymers) which can be used for the branched polymers (either in the main chain, the branch chain or both parts) in the present process are acrylic acid, acrylic ester, methacrylic acid; methacrylate ester maleic anhydride; itaconic acid; 2-acrylamido-2-methylpropane-sulfonic acid; acrylonitrile; sodium vinyl sulfonate; sodium styrene sulfonate; dimethylaminoethyl methacrylate; allyl sulfonate; vinyl acetate; methacryloyloxyethyltrimethylammonium methosulfate; alkenes; vinyl acetamide; vinyl ethers; vinyl phosphonates; vinyl phosphates; vinyl phosphines; diethylaminoethyl acrylate; 3-methacryloyloxy-2-hydroxypropyl-trimethylammonium chloride; 4-vinylpyridine; 2-vinylpyridine; N-methyl-5-methyl-2-vinylpyridinium methosulfate; 1,1-dimethyl-1-(2-hydroxypropyl)-amino-methacrylamide; dimethyl diallylammonium chloride; diallylamine; triallylamine; methyldiallylamine; diallyl ammonium salts; (3-acryloyloxyethyldimethylsulfonium methosulfate; ethylene oxide; propylene oxide; N,N-disubstituted methacrylamides; N-substituted methacrylamides; methacrylamide; N,N-disubstituted acrylamides; N-substituted acrylamides; N-vinylpyrrolidine; acrylamide; diacetone-acrylamide ; ethyleneimine; propyleneimine; ethylene chloride reacted with ammonia; l-vinyl-2,3-dimethylimidazolinium methylsulphate; N-vinylimidazole; glycidyl alcohol; epichlorohydrin; glycidyl methacrylate; vinyl carbonate; allyl glycidyl ether; isoprene and chloroprene.

Conventional methods of polymerisation, grafting or branching, and treatment can be used to prepare and apply the polymers in light of what is stated here

given and the referrals. Typical polymers, polymerization tech-

nods and methods of application are described in U,S. patents RE 29 595, 2223 933, 2 331 594, 2 345 713, 3 500 929, 3 822 749 and 4 058 491 which are incorporated herein by reference to the extent necessary. A preferred method for producing a cationic branched polymer for use according to the invention is the solvent method using an aqueous medium containing a high concentration of electrolyte such as an alkali metal halide, preferably sodium chloride or potassium chloride. In this preferred method, the reaction conditions, time and stirring should be controlled to obtain the branched polymer of the desired molecular weight and structure without unnecessary mechanical cutting of the polymer chain or disturbance of the reaction. For higher degrees of agitation, the reaction time should be extended to obtain the desired polymer size and structure. The molecular weight, structure, and effectiveness of the branched polymer formed for a particular application are sensitive to reaction conditions and conditions to which the polymer is subjected, including pH, temperature, pressure, time, contaminants, solvents or diluents, electrolyte, concentration, agitation, and other typical variables. Typical procedures are described in more detail here as methods. The aforementioned literature also describes various aqueous and organic solvent and emulsion methods that can be used.

The polymers used in this invention can be applied to most particulate solids or formations either by spraying, pouring or applying the polymer directly to the formation or particles. The polymer may be placed in a suitable liquid phase or medium until the formation to be treated, and the liquid phase is allowed, forced, injected or pumped into the formation so that the polymer contacts or treats the formation or the desired portion of the formation to change the wettability or surface properties. of the formation as desired. Particulate matter (eg, sand, silica flour and asbestos) may also be added to or suspended in the polymer or a liquid containing the polymer. For an oil well, this can simply be done by placing an aqueous, organic or mixed liquid phase containing the polymer next to the formation to be treated and displacing or forcing the liquid phase containing the polymer into the formation. The carrier fluid can be one or different mixtures of gas, liquid or solids such as foams, emulsions or slurries. The treatment of a subterranean formation through an oil well may be carried out using one or more fluid spacer plugs, preflushes or postflushes such as a dilute salt solution, preferably ammonium halide and/or an aqueous alkali metal halide dip solution, into the formation to pretreat or clean the formation, then injecting the liquid phase containing the polymer in a concentration of up to 10%, preferably 0.0 to 1.0%,

in an amount calculated to bring the desired portion of the formation into contact with the liquid ice and highly branched ionic polymer. IN

in some cases, a preflush containing an extension agent such as a surfactant, a nonionic polymer, or an ionic linear polymer that will be adsorbed onto the formation may be used to allow displacement of the branched treatment polymer away from the wellbore or formation surface. This pre-flushing works by binding the ionic regions in the formation and allows the branched polymer to pass through this zone with minimal processing by the branched polymer. This zone treated with an extension agent would normally have a high permeability to water. The branched polymer would then treat the adjacent formation zone. This would leave a zone of high permeability to water between the branched polymer treated zone and the wellbore. This would have the effect of increasing the effective radius or bore of the branched polymer treated zone around the well. The polymer can be in a liquid phase which is aqueous, organic or a substituted hydrocarbon such as an alcohol, ester, ether, ketone, aldehyde, amide or an emulsion or mixture of two or more of these liquid phases with water or another organic liquid. A foamed carrier can also be used. The carrier or other fluid phases can be acidic, basic or neutral. Acids or acidic carrier fluids can also be used.

Optionally, the polymer can also be carried in aqueous acid or salt solutions. A preferred acid carrier may contain up to 37% acid, such as a mineral acid, organic acid or mixtures thereof, e.g. hydrochloric acid, hydrofluoric acid, acetic acid, fumaric acid and the like. Other preferred acid concentrations are: for break-up acidification up to 28% or 15-28%} for break-up acidification with a propellant such as sand, 3-5%" and for use in WOR control treatments 0-5%" A preferred aqueous, acidic carrier should have a pH adjusted below 7 or 6.5 with an appropriate mineral or organic acid or equivalent such as hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, acetic acid, formic acid, hydroxyacetic acid, sulfamic acid, citric acid, fumaric acid, oxalic acid, and sodium dihydrogen phosphate. Acid-forming compounds, equivalents or precursors can also be used such as ammonium bifluoride, acetic anhydride and methyl formate. For higher concentrations of certain polymers, high viscosity and pumped jerk can be a problem. The carrier fluid may contain one or more acids, diluents, solvents or other liquid phases as a carrier medium or be injected in sequence with the carrier. When the branched polymer is mixed with an acid or acidic liquid, the mixture can be used for one or more of different purposes such as breaking up, acidification, acid breaking up or removing unwanted material such as deposits, carbonates, rust and other clogging material from wells or a formation.

Some branched polymers also serve to prestretch

or retard the acids or in other words the polymer prolongs the time required for a given acid concentration to react with a given amount of substrate. This would allow injection of an acid containing the polymer deeper into a formation before the acid was used up or would allow a reaction with material deeper into the formation. The carrier fluid can also be a water-in-oil or oil-in-water emulsion, and the carrier fluid can optionally contain components such as particulate material used in breaking up, surface-active agents compatible with the polymer, inhibitors and diversion agents. The polymers can be applied, mixed with other polymers or additives, so that more than one treatment is carried out at the same time. As certain preferred polymer treatments are essentially permanent and stable

against brine and most acids, these polymer phases can be displaced from the wellbore or displaced into the treated formation using additional carrier fluid, acids, aqueous or organic phases. Moreover, the treatment can be carried out in one or more treatment phases with different spacer liquids or other types of treatment liquids between the liquid phase containing the polymer.

For applications in well fluids such as for drilling, completion, testing, cementing or cementing preparations, one preferred carrier is an aqueous fluid. This fluid preferably has a basic pH or a pH greater than 6.5 or 7, and preferably above 10 or 12. The pH of most Portland cement preparations is above 12. In these fluids, the branched polymer may serve to treat formations such as comes into contact with the liquid or to treat the liquid itself (eg reduce liquid loss, increase viscosity of the liquid and gel the liquid).

Polymer units which can be used for the branched polymers can be basically any which

any type of polymer unit that can be linked to other polymer units of the same or a different type to form a branched water-soluble polymer. More particularly, polymer units can be prepared or derived from one or more of the classes consisting of (1) vinyl monomers or diene monomers which provide a chain of carbon-to-carbon bonds which may contain a double bond; (2) diallylic monomers which can provide a cyclic or heterocyclic moiety in the polymer chain; (3) imine- or amine-type monomers leading to nitrogen atoms in the polymer chain;

(4) amide type polymers including nylon and protein type polymer unitsj (5) saccharide monomer units, polymers of and derivatives thereof including the starches, guar gums, xanthan gum polymer, cellulose and derivatives thereofj (6) ethers and sulfides including oxygen and sulfur in the polymer chain; (7) carbonates which include the carbonate group in the polymer chain either in a linear chain or in a pendant group; and (8) urethanes which include the urethane bond in the polymer chain either in a linear chain or in a pendant group. These polymer units may be present as a predominant group or united in regular, random, block or other various combinations. With polymer units that are less soluble than desired in a particular fluid, other polymer units, substituents, certain branch chains or a combination thereof can be used to obtain the desired solubility and main polymer properties required for the intended application. The polymers used according to the invention, however, include those in which a considerable part (at least 0.1% and preferably 1%) of the branched polymer units are defined by the above-mentioned groups or at least one of the formulas listed here. The above polymer units can be represented or illustrated by the structural formula given below:

wherein the various substituents are as previously defined.

Examples of polymer units are:

ru - 0-20, but n2 and n^ cannot both be zero.

A preferred class of polymer units are those in which the branched chain polymers contain polymer units which

and combinations thereof where Rg2 is independently defined in each position as alkyl, alkenyl, alkynyl, acyl, aryl, carbonyl, carboxyl, aromatic hydrocarbon, cyclic hydrocarbon, heterocyclic hydrocarbon or combinations thereof which may also contain oxygen, sulphur, nitrogen or phorsphorus, and where

R independently in each position is defined as R „ I this

83

class is a preferred group of polymers those in which the RQO groups are predominantly C 2 -C 4 -alkylidene groups such as ethylene, propylene and/or butylene. These branch chains should preferably have molecular weights up to 50,000, such as 800-30,000. These branch chains can contain an average of 2-25,000, or even up to 50,000 polymer units. The branch chains of any polymer may be substantially uniform or mixtures of different chain lengths and/or configurations.

tions can be used. Certain polyethyleneimine polymers as described herein can be used for clay stabilization or WOR modification. For other applications, these polymers, especially in the lower molecular weights and ranges, should have additional branching or cross-linking. Certain other preferred polymers of these classes are useful in cements, aqueous liquids with a pH below 10 and especially in acidic media with a pH below 6.5 or even 3.0.

These branch chains can be bound to different types

of main chain polymers. The main chain and the branch chain can both contain substantially the same type of polymer units or combination of polymer units. The branched polymer can have significantly different main polymer chain and branch chain polymer units, each of which has significantly different properties such as the hydrophilic-hydrophobic nature, ionic character or solubility in different fluids. For example, the main chain can be strongly ionic (e.g. either anionic, cationic, amphoteric or a mixture thereof), while the branch chain is essentially non-ionic, and yet be strongly hydrophilic or solvatable in the presence of aqueous liquid. The ionic groups can be in the linear main chains, in pendant groups on the main chain or both. Another preferred polymer may have the main chain more hydrophilic, and the ionic groups may be in the branch chains.

Yet another preferred polymer may have portions of the main chain and/or branch chains of the above descriptions. The overall properties of the branched polymer can make it very water-soluble or only slightly water-soluble. It may also be soluble in other fluids such as organic fluids or substituted organic fluids including polar solvents such as alcohols (ci~cig) > organic acids, sulfonated hydrocarbons, oxygenated hydrocarbons or polyol hydrocarbons.

Another preferred class of polymers from the above-mentioned class are those polymers which contain more than one type of polymer unit. These polymers can be those defined by a single formula of the above class or by combining

are two or more formulas from this class. This

class of polymers includes those with at least one type of polymer unit derived from alkyl acrylate, aryl acrylate, alkyl acrylamide, aryl acrylamide, alkyl aziride, aryl aziride, alkoxide, alkylepoxide, the reaction product of ammonia or alkylamine reacted with an alkyl dihalide, an alkyl diepoxide or a combination thereof, or combinations of these polymer units. In these units, the hydrocarbon radicals can contain 1-10 carbon atoms. In certain units such as the acrylate and the acrylamide, the hydrocarbon radical is missing when it has zero carbon atoms. In other units, there may be more than one hydrocarbon substituent, and the substituent may be in one of several positions in each unit. A particularly preferred and surprisingly stable and effective polymer for gelling aqueous liquid, especially acidic aqueous liquid, as well as for reducing WOR, are polymers and copolymers containing considerable amounts of methacrylate units in the main chain. These polymers with alkylidene oxide branches are particularly permanent and stable at higher temperatures, even in high pressure steam. These polymers are also effective in controlling fluid loss from aqueous fluids such as cements, treatment fluids, fracturing fluids and acidizing fluids, to stabilize clays in the presence of aqueous fluids; and to reduce friction losses when pumping different liquids. "Stability" is used here for the use of the polymers to increase the viscosity of aqueous liquids, particularly for gelling acids for breaking up and/or acidification, and means that the polymeric liquid mixture should maintain a substantial part of its viscosity for 2 hours at approx. 6o°C in 5% hydrochloric acid without particular loss of viscosity or formation of sediment.

Further examples of polymer units within the above class are:

Some of these formulas can be written in more general form as:

or

where RgZf, Rg5, Rg6, Rg7,<Rg>8, R^, Rgi, R^, R?3, R^ independently of each other have the meaning given above for R^j where Rgg» R95<»><R>96 <*><R>97' R98 °g <R>99 <u>avnen9i9 of each other have meanings indicated above for Rg2'* 0<3

where X^, Xg and Xy are independent of each other as indicated for X1 and X2.

Several preferred polymer units include the alkyl acrylates and acrylamides and substituted alkyl acrylates and =amides and can be defined by the more general formulas:

where R100 and RiQ2 can be hydrogen, alkyl, aryl, heterogroups or combinations thereof, each hydrocarbon radical containing 1=6 carbon atoms

R101' <R>103 09R104 can be hydrogen, iso- or normal alkyl, aryl, heterogroups or combinations thereof, each hydrocarbon radical being chosen independently and containing 1-6 carbon atoms.

Preferred branch chains or R groups for these polymer units include or tRIo6-°*n

where R-^q^ and is an alkylene unit with 1-10 carbon atoms per hydrocarbon radical, and n is an integer up to 50,000, and preferably up to 2o000o

A particularly preferred class of polymers for modifying the properties of aqueous fluids, such as reducing WOR, gelling aqueous fluids, fluid loss control, and increasing oil production, are those containing alkyl acrylate backbone units and ethylene oxide branches such as those defined by the formulas:

where x is .10 to 60,000, preferably 10 to 15,000,

y is 1 to 90,000, preferably 1 to 5,000| and z is 2 to 25,000, preferably 2 to 10,000 and A~ is an anion associated with the quaternary nitrogen.

These preferred polymer units can also have other substituents, particularly on the carbon and nitrogen atoms. The polyethylene oxide chain, ^OCH2CH2^z, can also be terminally terminated or terminated with hydrogen, hydroxy, -Cg-oxyalkyl, Cg~Cg-oxyaryl, oxy-(2= hydroxy-3-chloropropane) or oxy-(2,3- oxopropane) as well as the methoxy group shown.

Met ode A

Preparation of a branched polymer containing polyacrylamide branches

50 ml of distilled water and 30 g of a commercially available polymer prepared from epichlorohydrin and dimethylamine are added to a three-necked 250 ml flask equipped with a cooler, stirrer, gas inlet tube and temperature gauge.

2" The flask is flushed with nitrogen gas while 0.4 g of isopropyl alcohol and 20 g of acrylamide monomer (as a 40% aqueous solution) are added." The reaction contents are heated to 64°C.

3o 0.27 g of an azobisisobutyronitrile radical polymerization initiator is introduced and the temperature is maintained at 85°C for 3 hours» The product consists of a pale yellow to amber liquid with a viscosity of 2,000 to 80OOO cP on a No. 3 Brookfield spindle at 12 r /min at 25°c.

Method B

Preparation of a main chain polymer and subsequent grafting of branches onto the polymer 1. To a three-necked 500 ml flask equipped with a cooler, stirrer, gas inlet tube and temperature gauge, heating mantle and addition funnel, l6o g of dimethyldiallylamine monomer (as a 40% aqueous solution) and 40 g of diallylamine monomer. The pH of the reaction mixture is set to approx. 4.0.

2. The flask is flushed with nitrogen, while the contents are heated

to 70°C.

3. Dissolve 10 g of ammonium persulphate catalyst in 100 g of water and place in the addition funnel. The catalyst is added in 5 equal portions every 30 minutes, while the temperature is kept at 70°C. The reaction mixture is then kept at 80°C for a further 2 hours. The reaction mixture is cooled, and the nitrogen purge is interrupted. The reaction product is a viscous, yellow liquid. 4. A quantity of the product from step 3 above is taken out which represents 1.76 g of active copoly-(dimethyldiallyl-diallyl)-ammonium chloride. To this is added 2.6 g of active MPEO-epichlorohydrin adduct product prepared as described in method C0. This mixture is diluted with water to a concentration of approx. 4% active polymer 5. The pH is set to approx. 9.5 with 50% sodium hydroxide solution. Salt may be added to reduce viscosity" 6. The polymer mixture is placed in a sealed container and placed in a water bath at 60°C for 2 hours to allow the reaction to proceed. Agitation may be used to keep it pumpable, but agitation may affect the time to produce a given viscosity' product. 7. The branched or grafted copolymer is diluted to a concentration of approx. 2% with water or saline solutions, and the liquid is sheared with a blender (eg a high speed Hamilton Beach Blender) to a constant viscosity. 8. The viscosity is read if desired, and the product obtained is used to test its effectiveness as a WOR chemical or as an acid regulator as described in method E up to and including 0.

Method C

Preparation of a branching medium or a polymeric branch chain

1. A methoxypolyethylene glycol or -oxide (hereinafter referred to as MPEG or MPEO), such as "Carbowax" MPEG 5000, 0.04 mol or 200 g, is added to a three-necked 500 ml flask fitted with a condenser, stirrer, gas inlet tube and temperature gauge. 2. The flask is flushed with nitrogen, while the glycol is melted using a water bath at 65-75°c. 3. The water bath is removed, and 0.12 mol (11.0 g) of epichlorohydrin is added and mixed with stirring for 15 minutes. 4. Boron trifluoride etherate is added, and the temperature is kept between 65 and 75°C during cooling and heating as required. 5. The MPEO-epichlorohydrin reaction product (ie MPEG or MPEO adduct) is stirred for 1 hour. 6. Excess epichlorohydrin is removed with a rotary evaporator, and the branching adduct or branching agent is diluted with an equal amount of water.

Method D

Preparation of a branched copolymer from a commercially available copoly-(methyl vinyl ether/maleic anhydride) backbone

1« To a 250 ml three-necked flask equipped with a condenser, stirrer, heating mantle and temperature gauge, add 90 ml of water, 7.3 g of a high molecular weight mixed-oxide polyglycol, and 1.4 g of nonylphenol surfactant. The reaction contents are heated to 5o°c. 2. To the stirred, heated reaction flask contents, 1.3 g of commercially available methyl vinyl ether/maleic anhydride polymer is added, and the reaction mixture is heated for 4 hours. The result is an off-white liquid with 5,800 cP viscosity at 25°C measured with a No. 3 Brookfield spindle at 12 r/min.

Method E

Preparation of a branched copolymer from a commercially available polydimethylamine oethyl methacrylate (ie, PDMAEM) 1. Add the amount indicated in Table 12 of the main chain cationic polymer to a container, add the indicated amount of water and stir until the polymer is dissolved. Add the indicated amount of branched chain adduct polymer and stir for 3 minutes. 2. Set the pH to approx. 9.5 with 50% sodium hydroxide solution. Salt can be added to reduce viscosity.

3. Place the sealed container in a water bath at 6o°C i

2 hours to allow the reaction to proceed. Agitation may be used to keep it pumpable, but agitation may affect the time to form a given molecular weight or viscosity.

4. Dilute the branched or graft copolymer liquid with

75 ml of water and shear the liquid with a mixer (e.g. high speed "Hamilton-Beach" mixer) to a constant viscosity,

5o Measure the viscosity using a model 35

Found Viscometer at 300 r/min, standard weight and sleeve in cP,

6. To test the effectiveness of the polymer in gelling aqueous acid, add the required amount of concentrated acid (see Tables 12, 13, 14> 15 and 16) to the concentrated aqueous polymer mixture. If necessary, dilute to the desired acid and polymer concentration while stirring. Measure the viscosity of the mixture on the Fann Viscometer as before (eg, 1.5% active polymer-solids concentration in 5% hydrochloric acid liquid).

Method F

Preparation of a modified branched polymer (PEI)

1, Add the desired amount of a commercially available branched polyethyleneimine polymer (molecular weight approx. 40,000 to 100,000) to water to prepare a 6% active polymer concentration of FEI„

2, Add an extender or branching agent as described in Table 19 (6% concentration) and stir while heating (pH above 9-10) at 6o°C until gelation occurs. 3. Dilute the viscous gel with hydrochloric acid to the desired acid concentration.

4. Measure the apparent viscosity on a model 35A

Fann Viscometer, No. 1 spring, standard weight and sleeve.

Method G

Assessment of the effectiveness of branched polymer in reducing aqueous fluid flow 1. Place a small amount of glass wool in the bottom of a 100 ml burette.

2. Pour 5o ml of deionized water into the closed burette.

3. Place 5.0 g of 8-12 mesh sand in the bottom of the burette followed by 25.o g of 2o-4o mesh sand. Place 5.0 g of 8-12 mesh sand on top of the 20=40 mesh sand. 4. Gently pound the burette to obtain a 20-4-0 mesh sand pack of length 8-9 cm, 5. Drain excess deionized water to the top of the 8-12 mesh pack and note the level of the meniscus in the burette and use it as zero-level0

6» Place 25 ml of deionized water in the burette (use syringe or pipette) and note the time required for it to pass through the packing and reach the zero level. This is original time,

7, Prepare a (l.OOO ppm polymer solids) branched polymer solution in deionized water and adjust to a pH below about 5.0 with an acid such as hydrochloric acid0

8. Introduce lOO ml of the branched polymer treatment solution and allow it to flow through the buret to the zero level,

9, Follow the treatment with 75 ml of deionized water,

10. Repeat step 6, this is the end time.

11, Divide the initial time by the end time and multiply by 100 to get % of original flow rate,

Method H

Preparation of a branched polymer in situ

An amount of main chain polymer such as polyethyleneimine

[MV 40,000-100,000] in an aqueous liquid is combined with an equal active weight of MPEO-epichlorohydrin adduct (MV approx. 5,000) prepared as described in method c and diluted with water to an approx.

5,000 ppm total polymer concentration. The pH is set to above approx. 7 to 8. This solution is then injected either into the test core or the formation to be treated.

If a test core is processed, method I should be used. If a formation is treated, Method N should be used, except that after the treatment step is completed, the system must be allowed to remain static for a period of time dependent on the temperature, e.g. 24 hours at 71°C. After this curing time, the test medium is returned to production, and changes in flow rates are noted.

Meto de I

Method for judging the effectiveness of branched polymer to

to reduce aqueous fluid flow through a clayey sand pack

A dry mixture of sand was prepared by mixing 88 parts of approx. 70-170 mesh sand with 10 parts fine silica flour (smaller particle size than about 200 mesh) and two parts Smekt it clay0 This mixture (100 g) was packed in a "Teflon" polymer-lined pre-search rabbit (2.38 cm inner diameter ) or a Hassler sleeve test chamber (2.38 cm inner diameter). About. 25 ml of 6.7% brine was passed through the sand pack and the test chamber was either shut off overnight or for 2 hours at 80°C to ensure complete hydration of clays. A salt solution (6.7% sodium chloride) was passed through the sand pack until equilibrium was reached, i.e. no change in differential pressure (&P^) and flow rate (Q^). A solution of the chemical to be investigated was then injected through the sandpack in the opposite direction. Production was then continued until equilibrium conditions again existed and the flow rate (Q^) and differential pressure (APf) were noted. The percentage retention of the original permeability was then obtained by the following formula:

where: Q i <=> initial flow rate} Qf = final flow rate; AP^ = initial pressure drop across the chamber, and APf = final thrust drop or differential thrust.

% reduction = 100 - %K^.

Method J

Comparison of relative oil permeability in a sandpack

After determining the percentage retention of the initial brine permeability (% K ± ) by method I, the kerosene (2.7 CP) was passed through the sand pack. The flow rate and differential thrust were noted. The percentage of oil permeability compared to the initial brine permeability was calculated by

Method K

Determination of branched polymer effectiveness for reduction of aqueous fluid flow through a core

A Berea sandstone or limestone core (2.38 cm outside diameter x 10 cm) was mounted in a Hassler sleeve test chamber (2.38 cm inside diameter). About. 25 ml of 6.7% brine was passed through the core, and the test chamber was either sealed overnight or for 2 hours at 80°C to ensure complete hydration of clays. A 6.7% brine was passed through the core until equilibrium conditions were reached, i.e. no changes in pressure and flow rate. A solution of the chemical to be tested was then obtained. injected through the core in the opposite direction. Production was then continued until equilibrium conditions again existed and the flow rate and differential pressure were noted. The percentage of the original permeability was then obtained by the following expression:

where: Q. = initial flow rate, and Q^. = final flow rate 0

Method L

Determination of relative oil permeability in a core

After the determination of the percentage retention of original brine permeability (% K±) by method K, the kerosene (2.7 cP) was passed through the core. The flow rate and differential pressure were noted. The percent initial brine permeability to oil was calculated by:

Method M

A typical WOR method

A typical WOR method is calculated on 500 1 polymer mixture per m perforations. This is done by diluting a concentrated branched ionic polymer concentrate solution 10:1-70:1 with water (e.g. formation water, brine or 2% potassium chloride solution), and then adding approx. 20° Baume hydrochloric acid to set the pH to approx. 3-6. After the pipeline has been pressure tested and the injection rate determined, the branched polymer solution is pumped in with approx. 2 barrels per minute, followed by water. This method is repeated in sequence until all the branched polymer solution has been injected into the well. After the last stage has been pumped, water is pumped as an overflow.

Method N

A recommended method uses approx. 45 kg branched ionic polymer in a concentrate solution (solids) per running meter diluted approx. 15:1-50:1. The treatment volume depends on the porosity and the radial penetration desired in the formation. Table 22 gives recommended volumes.

If the total water-producing invervall is not known, it is recommended that approx. 3-9 m penetration over the entire producing interval is used to determine treatment volume. If the total water-producing interval is known or a good estimate is available, approx. a 9-15 m penetration in this interval. It can be assumed, for this calculation, that all treatment liquid will enter the water-producing zone. For greater radical penetration, a more diluted solution can be used.

The mixing water can be any compatible brine. Additives (eg corrosion inhibitors, bactericides, surfactants, etc.) must be checked for compatibility.

The polymer should be added while mixing to the carrier liquid.

Passing through a pump, turbine or ribbon mixer 2 to 4 times should provide adequate mixing. The pH should be adjusted to 3-5 with hydrochloric acid or another acid.

An initial injection rate and injection pressure should be determined using water or other available aqueous fluid. The speed should be as high as practicable while maintaining a pressure below the burst pressure. It may be necessary to reduce the injection rate to keep it below the maximum allowable pressure. The branched ionic polymer treatment solution was overpurified using an aqueous liquid, gas or hydrocarbon such as water, nitrogen or crude oil. The well can immediately be put into production again.

Treatment sequence

1. Select a candidate well with an available production history„

2„ Assess proposed carrier fluids such as water, crude oil, etc, and well production information.

3. Mix the branched polymer solution.

4 = Determined the injection rate and pressure using available fluid, 5o Pump branched polymer treatment solution through conduit, the annulus, or both while maintaining a pressure below the formation break-up pressure. 6. Superdisplace branched ionic polymer solution into the formation using an available fluid such as an aqueous liquid, gas, hydrocarbon or mixture thereof.

7» Put the well into production.

Method 0

Example or procedure for a method to reduce WOR (water-gas ratio)

A dry sand pack (65 cm long x 0.72 cm diameter) was prepared from a mixture of 80 parts 70-270 mesh sand, 15 parts silica flour and 5 parts smectite. The flow rate of the equilibrium gas (methane) through the dry pack was 3900 cc/min at 35 kg/cm differential pressure. After saturating the sand pack with a 6.7% sodium chloride solution, a maximum flow rate of 1020 cm^/min methane was obtained at 35 kg/cm<2> differential pressure. This sandpack was then treated with 100 ml of a l.OOO ppm solution of a water-soluble, ionic, branched polymer (PDMAEM) <r>800,000 to l.OOO,000 MV grafted with polyethylene oxide (5.OOO MV) branches 1 :1 main chain-branch weight ratio]. The flow of water was reduced by more than 90% while the flow of gas was 170% of the original. About. 1.OOO 1 methane was required to restore equilibrium purge conditions.

D<g> the above data show the relative effectiveness of a particular polymer used in loose sand packs of different permeabilityero The performance characteristics of other branched polymer structures covered by these specifications will vary with polymer and formation characteristicso Polymeric molecules can vary in molecular weight, degree of polymer branching, length of polymer branches, etc, to achieve different effects and sizes of efficiency depending on the food to be processed.

Each of the three sand packs consisted of 88slO:2 parts by weight of 70-170 mesh sand, silica flour and smectite. The results of this determination show that this branched, water-soluble polymer, branched methacrylate copolymer (MV-^ 1.OOOo0O0)] was effective in reducing water permeability in 177°C to 26o°C dynamic steam environments. Data also show that deposited branched polymers were resistant to washing away by acidic fluids. These fluids are often used to stimulate fluid production in hydrocarbon-producing formations.

A commercially available PDMAEM (molecular weight ;:6oo,000 - 8OO0OOO) constituted the main chain. The viscosity of the aqueous solution of the main chain is about 20 cP at 25°C at 2% polymer solids. All grafted polymers were a 1:1 weight ratio of MPEO to main chain polymer. Less branching was obtained with 5000 molecular weight MPEO than with 350 molecular weight MPEO grafts. Branched or graft polymers were prepared by methods C and E. Data in Table 5 show that as the branch chain decreases, the number of branches increases, and the %Ki goes from 3»1 to 44, Ki is thus considerably affected by a few long branch chains and even by a large number of short branch chains. Data also show that fewer long molecular branch chains in this particular polymer family are more effective in increasing the viscosity of aqueous and aqueous acid fluids.

All experiments were performed at 66°C using Berea cores. An 8% NaCl solution was used to place the polymer solution.

Data in Table 7 show that some branching is necessary and that for certain polymers a small amount or degree of branching gives a considerable effect. Since the number of branches is increased, the efficiency increases up to a certain optimum point. This shows that each polymer family has a critical range for the ratio of main chain polymer to the number of branch chains. The first, second to last, and last line of data in the three columns are for an unbranched polymer or polymer blend, and they show that the unbranched polymer does not produce the unexpected effect on aqueous fluid permeability that the branched polymer family does.

Data show that at least two different cationic polymers with high molecular weight branches and high molecular weight branched polymers are effective in reducing permeability to aqueous fluid.

where A is an equal molar ratio copolymer of maleic anhydride and methyl vinyl ether (MV~500.OOO) grafted with an equal weight of methoxypolyethylene glycol (MV~5,000); B is an equal molar ratio α-copolymer of maleic anhydride and methyl vinyl ether (MV~5,000) grafted with an equal bulk amount of polyethylene oxide (MV~5.OOO); C is a polymer of dimethylaminoethyl methacrylate (MVMSOO.OOO) grafted with an equal amount by weight of methoxypolyethyleneglycol-epichlorohydrin adduct (MV~5,000).

Partially hydrolyzed polyacrylamide or co-(polyacrylamide-sodium acrylate).

Data in the table show that the branched polymers are effective in reducing the permeability to aqueous fluid flow while the Linear polymers are not.

Data in this table show that the branched cationic polymers are water wetting and have some surfactant properties. Contact angles were measured using a clean glass plate immersed in diesel oil with the polymer or surfactant dissolved in deionized water.

For aqueous liquid treatment with certain branched polymers, the surface tension is lowered, which also usually leads to a lower interfacial tension between aqueous and organic or hydrocarbon liquids.

The core samples were stabilized to flow with produced water, then treated with the pore volumes (PV) of polymer, and permeability was measured with produced water and crude oil.

Data show that the branched polymer treatment decreased the permeability to aqueous liquid and increased the permeability to oily runoff.

Data show that branching is necessary for a stable polymer to gel aqueous and aqueous acid liquids. Data also show that the number of branches affects the effectiveness of the branched polymer in gelling aqueous liquids.

Data show the same effects as in Table 15 plus the effect of higher molecular weight or longer branch chains.

Data show the same effects as Tables 15 and 16 for higher molecular weight branch chains. Data also show that the branched polymer is stable in acid at high temperatures for a longer time.

Data show the effectiveness and stability of various linear polymers in aqueous and vandice acid fluids for extended times at high temperature.

TABLE 23

Pilot well treatment

This experimental production well is located on a water flood project and has been shut down due to excessive water production. It was again put into production to establish initial production data. Liquid inlet examination was carried out before and after WOR polymer treatment. This well was packed with gravel and has 2 55.7 net meters that produce. The treatment with 30 drums of concentrated polymer solution of a cationic polymer with non-ionic branches diluted 1:40 with injection water gave approx. 84 kg/cm 2 increase in injection pressure. This solution was supersaturated with 350 barrels of injection water.

TABLE 24

Pilot well treatment

This trial treatment well is located on a water-flooded project. It has been packed with gravel and has 174 net meters of producing fluid. Several experimental and fluid intrusion studies have been carried out both before and after the WOR polymer treatment. The initial oil production rate varied, the WOR polymer treatment consisted of 24 drums of concentrated polymer solution of a cationic polymer with non-ionic branches, diluted 1:48 with injection water with a 1,200 barrels of injection water overcrowding.

TABLE 25

Pilot well treatment

This well was an old flowing well with a bottom wool static temperature (BHST) of approx. 104°C 1.5 m perforations ed 3488"7 m. Four drums of heated concentrated polymer solution of a cationic polymer with non-ionic branches were applied at a dilution of 1:30. This was superseded with OO barrel "gun barrel water".

Pilot well treatment

This well had 3 m perforated at 3048 m and was on gas rise. The treatment was carried out using 12 drums of concentrated polymer solution of a cationic polymer with non-ionic branches, diluted 1:19 with preheated gun barrel water and overpurged with 300 barrels of gun barrel water.

TABLE 28

Porous well treatment

This well was treated with 8 drums of concentrated polymer of a cationic polymer with nonionic branches dissolved in 150 barrels of NH^Cl water with one 25-barrel standoff and over-displacement with 175 barrels of brine.

Data show that the branched polymer is not particularly affected or exposed to shear by rapid pumping through a perforation.

Claims (1)

1. Procedure for treating a particulate material to change the surface properties, fluid- the flow and the attraction/repulsion properties of it particulate matter, especially when treating a underground, particulate formation to change the relative mobilities between oil and water in and through the formation, where the particulate material is brought in contact with a branched, organic polymer that is dissolved or dispersed in a carrier fluid, as it for branched organic polymer is used a polymer with a molecule weight of 900-50,000,000, characterized in that a for branched, organic polymer with a basic chain of polymer units and with at least one branch chain connected to the base chain formed of two or more polymer units, the polymer units being the same or different and are from the group consisting of such with the structural formula wherein R and R2 may be the same or different and be consists of hydrogen or an alkyl group, R^ is hydrogen or a hydrocarbon radical which may contain holding alkyl groups or alkyl groups and hetero groups or combinations thereof, each hydrocarbon radical contains 1-10 carbon atoms, X-^ and X^ are the same or for scaly and consists of heteroradicals derived from nitrogen, oxygen, phosphorus or sulphur, and P^g consists of a hydrocarbon radical which may contain alkyl groups or alkyl groups and heterogroups or combinations thereof, each hydrocarbon radical containing 1-10 carbon atoms, and R^g, R^q and R21 may be the same or different and independently of each other be absent and consist of hydrogen or hydrocarbon radicals which may contain alkyl groups or alkyl groups and heterogroups or combinations thereof, each hydrocarbon radical containing 2-50,000 carbon atoms, provided that the ratio between carbon atoms and heteroatoms in the organic polymer is 6 :1 or less and that the organic polymer is hydrophilic. <2»>Procedure according to claim <1>» characterized by that. one of R20 and R21 is absent. 3. Method according to claim 1 or 2, characterized in that at least one of Rig, R20 and R2^ contains a heterogroup or combinations thereof and in that the number of radicals connected to each atom is equal to the number of bonds for this atom. 4. Method according to claims 1-3, characterized in that a branched, organic polymer is used with a basic chain formed by polymer units from the group in which Rl' R2°^ R4 ^an be the same or different and consist of hydrogen or an alkyl group with 1-6 carbon atoms, R2 5' R2 7 and R2 8 are mutually absent or consist of hydrogen or an alkyl group with 1-6 carbon atoms, 1*2g is an alkylene group with 1-6 carbon atoms, R29 is absent or is hydrogen or an alkyl group, and when R_q is hydrogen or an alkyl group, it also includes an anion or an anionic active group associated with the quaternary nitrogen group, X^ is oxygen or nitrogen, M is a cation or a cationic active group attached to the oxygen, R^4 is hydrogen or an alkyl group of 1-6 carbon atoms, R35 is absent or consists of hydrogen or an alkyl group of 1-6 carbon atoms, and X^ is nitrogen or oxygen, in that the polymer has at least one branch chain per basic chain, as the branch chain replaces R^g and consists of wherein R^g is an alkylene group of 1-10 carbon atoms, ^27 is hydrogen, a hydroxyl group or an oxyalkyl group of 1-6 carbon atoms, and z is 2 or more.5. Method according to claim 4, . characterized in that R^ and R2 are hydrogen, R4, R27 and R28 are methyl, X3 is oxygen, R25 and R2g are absent, <R>2g is ethylene, R3g is ethylene, and R^ is a methoxy group. 6- Method according to claim 4, characterized in that in the formulas comprising M+ R^ and R^ are hydrogen, and that in the last formula R^ is hydrogen, and is nitrogen. 7. Method according to claim 4 or 5, characterized by atzer 2-10,000. 8. Method according to claim 4, characterized by the use of a branched, organic polymer with the structural formula in which v is a number within the range 10 - 15,000, w is a number in the range 1-5,000, z is a number in the range 2 - 10,000, and Aj is an anion or an anionic active group which is associated with the quaternary nitrogen.<9->Procedure according to claim 4, characterized in that a branched, organic polymer with the structural formula is used where v is a number in the range 10 - 15,000, w is a number in the range 1 - 5,000, x is a number in the range 1 - 5,000, z is a number in the range 2-10,000, A is an anion or an anionic active group that is ^ associated with the quaternary nitrogen, and M<+> is a cation or a cationic group which is 2 associated with the oxygen. 10.. Method according to claim 4, characterized in that a branched, organic polymer with the structural formula 11 is used. Method according to claims 8-10, characterized in that an aqueous carrier fluid is used and a concentration of the polymer in the carrier fluid within the range of 0.005-5 volume% polymer in relation to the carrier fluid, 12. Method according to claims "8-11, characterized in that an aqueous salt solution is used as carrier fluid. 13. Method according to claims 8-12, characterized in that an aqueous, acidic solution of hydrochloric acid, hydrofluoric acid, nitric acid, sulfuric acid, phosphoric acid, acetic acid, formic acid, hydroxyacetic acid, sulfamic acid, citric acid, fumaric acid, oxalic acid, sodium dihydrogen phosphate or mixtures thereof is used as the carrier fluid. 14. Method according to claims 8-13, characterized in that a branched organic polymer is used with a basic chain with a molecular weight of 1,000 - 5,000,000. 15. Method according to claims 8-14, characterized in that a branched, organic polymer with a branch chain with a molecular weight of 300 - 100,000 is used. 16. Method according to claims 1-15, characterized in that a branched, organic polymer is used with a basic chain formed by at least three polymer units.