CA2710988A1 - Magnetic polymer pellets and their application methods - Google Patents
Magnetic polymer pellets and their application methods Download PDFInfo
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- CA2710988A1 CA2710988A1 CA2710988A CA2710988A CA2710988A1 CA 2710988 A1 CA2710988 A1 CA 2710988A1 CA 2710988 A CA2710988 A CA 2710988A CA 2710988 A CA2710988 A CA 2710988A CA 2710988 A1 CA2710988 A1 CA 2710988A1
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/50—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls
- C09K8/504—Compositions based on water or polar solvents
- C09K8/506—Compositions based on water or polar solvents containing organic compounds
- C09K8/508—Compositions based on water or polar solvents containing organic compounds macromolecular compounds
- C09K8/512—Compositions based on water or polar solvents containing organic compounds macromolecular compounds containing cross-linking agents
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
- C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
- C08J3/075—Macromolecular gels
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/12—Powdering or granulating
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
- C08L1/08—Cellulose derivatives
- C08L1/26—Cellulose ethers
- C08L1/28—Alkyl ethers
- C08L1/286—Alkyl ethers substituted with acid radicals, e.g. carboxymethyl cellulose [CMC]
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L5/00—Compositions of polysaccharides or of their derivatives not provided for in groups C08L1/00 or C08L3/00
- C08L5/04—Alginic acid; Derivatives thereof
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L5/00—Compositions of polysaccharides or of their derivatives not provided for in groups C08L1/00 or C08L3/00
- C08L5/06—Pectin; Derivatives thereof
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2305/00—Characterised by the use of polysaccharides or of their derivatives not provided for in groups C08J2301/00 or C08J2303/00
- C08J2305/04—Alginic acid; Derivatives thereof
Abstract
The invention is related to polymer pellets and the methods of their application for controlled release of active substances into the application environment, for example, substances for the initiation, acceleration or inhibition of physico-chemical processes like gellation, cementation etc. As per the invention, the polymer pellet is a gel matrix of an anionic polymer cross-linked with multivalent metals' cations in which at least one active substance and ferromagnetic particles are dispersed with the concentration of ferromagnetic micro-particles from 0.5 to 5%. As per this invention, the polymer pellets may be used for the controlled release of the active substance into the application medium, for obtaining polymer gels and for the generation of locking gel plugs.
Description
MAGNETIC POLYMER PELLETS AND THEIR APPLICATION METHODS
This invention relates to magnetic polymer pellets comprising a polymer matrix with a solid filler, as well as to the methods of their application for a controlled release of active substances to the application medium, for example, substances for the initiation, acceleration or inhibition of physico-chemical processes like gellation, cementation etc.
Polymer (alginate) pellets with para- and ferromagnetic properties and methods for their obtaining are described in the scientific literature. They are gels cross-linked with calcium ions (Lee, D.Y. et al., Ieee Transactions on Magnetics 2004, 40, 2961; Roger, S. et al., Journal of Magnetism and Magnetic Materials 2006, 305, 221) or iron ions (Llanes, F. et al., International Journal of Biological Macromolecules 2000, 27, 35; Nishio, Y. et al., Polymer 2004, 45, 7129; Naik, R. et al., Journal of Applied Physics 2005, 97, ), and containing magnetic particles or substances: barium ferrite (Lee, D.Y. et al., Ieee Transactions on Magnetics 2004, 40, 2961), iron oxide (Llanes, F. et al., International Journal of Biological Macromolecules 2000, 27, 35; Nishio, Y. et al., Polymer 2004, 45, 7129; Naik, R. et al., Journal of Applied Physics 2005, 97, ) H MarxeTHT (Tyagi, R. et al., Biocatalysis and Biotransformation 1995, 12, 293; Roger, S. et al., Journal of Magnetism and Magnetic Materials 2006, 305, 221).
The procedure to produse magnetic alginate pellets includes introduction of cross-linking ions into the mixture of sodium alginate solution and ferrofluid.
Different introduction options have been described: "internal" and "external".
As applied to calcium-alginate gels the "external" method makes use of the instillation of the sodium alginate and ferrofluid mixture into the calcium chloride solution (Lee, D.Y. et al., Ieee Transactions on Magnetics 2004, 40, 2961; Roger, S. et al., Journal of Magnetism and Magnetic Materials 2006, 305, 221). In the "internal" method, first "inactive" calcium as complex with EDTA
This invention relates to magnetic polymer pellets comprising a polymer matrix with a solid filler, as well as to the methods of their application for a controlled release of active substances to the application medium, for example, substances for the initiation, acceleration or inhibition of physico-chemical processes like gellation, cementation etc.
Polymer (alginate) pellets with para- and ferromagnetic properties and methods for their obtaining are described in the scientific literature. They are gels cross-linked with calcium ions (Lee, D.Y. et al., Ieee Transactions on Magnetics 2004, 40, 2961; Roger, S. et al., Journal of Magnetism and Magnetic Materials 2006, 305, 221) or iron ions (Llanes, F. et al., International Journal of Biological Macromolecules 2000, 27, 35; Nishio, Y. et al., Polymer 2004, 45, 7129; Naik, R. et al., Journal of Applied Physics 2005, 97, ), and containing magnetic particles or substances: barium ferrite (Lee, D.Y. et al., Ieee Transactions on Magnetics 2004, 40, 2961), iron oxide (Llanes, F. et al., International Journal of Biological Macromolecules 2000, 27, 35; Nishio, Y. et al., Polymer 2004, 45, 7129; Naik, R. et al., Journal of Applied Physics 2005, 97, ) H MarxeTHT (Tyagi, R. et al., Biocatalysis and Biotransformation 1995, 12, 293; Roger, S. et al., Journal of Magnetism and Magnetic Materials 2006, 305, 221).
The procedure to produse magnetic alginate pellets includes introduction of cross-linking ions into the mixture of sodium alginate solution and ferrofluid.
Different introduction options have been described: "internal" and "external".
As applied to calcium-alginate gels the "external" method makes use of the instillation of the sodium alginate and ferrofluid mixture into the calcium chloride solution (Lee, D.Y. et al., Ieee Transactions on Magnetics 2004, 40, 2961; Roger, S. et al., Journal of Magnetism and Magnetic Materials 2006, 305, 221). In the "internal" method, first "inactive" calcium as complex with EDTA
is added to the mixture of sodium alginate and ferrofluid mixture and then the calcium is slowly released by the medium acidification using gluco-6-lactone hydrolysis (Roger, S. et al., Journal of Magnetism and Magnetic Materials 2006, 305, 221). With iron-alginate gels "internal" administration method is applied which is based on alkaline oxidation of ferrous iron in calcium alginate solution (Llanes, F. et al., International Journal of Biological Macromolecules 2000, 27, 35). It was demonstrated that in "internal" method of administering the crosslinking ions more homogenous particles are obtained.
The use of magnetic alginate pellets for biological separation and treatment of enzymes and cells in the magnetic field has also been described (Tyagi, R. et al., Biocatalysis and Biotransformation 1995, 12, 293; Ames, T.T.
et al., Biotechnology Progress 1997, 13, 336; Liu, C.Z. et al., Journal of Bioscience and Bioengineering 2000, 89, 420), for effluents treatment of heavy metals (Nestle, N. et al., Colloids and Surfaces A-Physicochemical and Engineering Aspects 1996, 115, 141; Ngomsik, A.F. et al., Water Research 2006, 40, 1848).
The examples of releasing active substances from polymer pellets using controlled magnetic field are not numerous.
Thus, U.S. Patent No. 4,652,257 describes the method of obtaining manetically localized polymerizing lipidic vesicles, containing the target substance (medicine), and the method of the vesicles' destruction and release of the contents thereof under the magnetic field effect. The therapeutic substance and ferromagnetic particles are encapsulated in the lipidic vesicle, generated by the polymerizing lipids. The lipids are polymerized under the effect of ultraviolet radiation with the formation of the membrane resistant to chemical and physical effects. Any ferromagnetic substance, preferably single-domain magnets of bacterial origin, magentites, ferrites or fine-grain iron sawdust may be used as magnetic particles. The vesicles are delivered to the target organ under the effect of the external constant magnetic field. After localization in the proper location the vesicle membrane is destroyed or destabilized due to the application of the variable magnetic field. Frequency and duration of the variable magnetic field action determine the rate of the vesicle-encapsulated therapeutic substance release.
U.S. Patent No. 5,019,372 proposes a method of producing solid polymer pellets filled with stainless steel particles and containing the target biologically active substance (water-soluble medicine), the release of which is accelerated in the variable magnetic field. The polymer pellet is made of bio-compatible plastic material non-soluble in the application field, e.g., of ethylene-vinyl acetate copolymer. The biologically active substance and magnetic particles are dispersed in the monomers methylene chloride solution, after which polymerization and pelletization are conducted. The pellets are places in the aqueous medium where the target substance is released effected by the oscillating magnetic field with the intensity of 0.5 to 1,000 Gauss. The rate of the release stimulated by the magnetic field is by factor 30 higher than without this stimulation and amounts to about 400 micro-Gauss per hour. A water-soluble substance with the molecular weight exceeding 150 D may be used as the target substance.
In the proceeding Z. Lu et al. (Langmuir, 2005, 21, 2042-2050) a method of obtaining magnetically sensitive polyelectrolyte multi-layer micro-pellets was proposed. The capsule membrane consists of several layers formed by sodium phosphonated polystyrene and polyallylamine hydrochloride with a layer of cobalt nano-particles coated with gold between them. The capsule membrane permeability for dextrane marked with a fluorescent tag was researched. It was demonstrated that the variable magnetic field with the frequency of 100-300 Hz and intensity of 1200 Gauss causes intensive rotation of the cobalt nano-particles which significantly damages the capsule membrane integrity. The optimum magnetic sensitivity of the membrane sensitivity was observed in the capsules with the walls formed of 10 layers of polyelectrolytes and 1 layer of ferromagnetic nano-particles.
The polymer pellets described are used for bio-medical application in the systems of targeted transport of medicines. Their application in other technologies is limited by the process complexity and their high cost.
The use of polymers for controlled generation of the plug for zone insulation is described in Patent RU 2276675. The invention describes the method of forming a gel plug by gellation of the fluid containing hydrophobically associating substances and water-soluble gellation inhibitor.
In case of contact between the fluid and hydrocarbons the inhibitor retains its properties whereas in case the fluid's contact with the water medium the inhibitor is dissolved which results in gellation. Therefore, the method enables monitoring water influxes in the oil-producing wells by gel plugs' formation.
However, this method has its disadvantages: 1) gellation with the use of this fluid is irreversible and starts from the first contact with water which could occur on the surface which creates significant difficulties during the injection of water into the well, 2) the already formed gel plugs in certain conditions may also lock oil-bearing formations making hydrocarbons' production more difficult.
The invention claimed covers polymer pellets containing magnetic particles and at least one active substance and having optimum mechanical properties enabling the pellets destruction both as a result of swelling and under effect of the magnetic field of admissible intensity, as a result of displacement and change of orientation of ferromagnetic particles. The pellets destruction ensures rather complete and fast release of the active substance (substances) into the application medium and its dissolution. Such medium may be, for example, the solution of polymer capable to gel formation under the influence of the soluble form of the encapsulated substance - gellation initiator. In this case polymer gel formation is attained (thus, the polymer pellets may be used wherever the zonal insulation is required, in the gels used for hydraulic fracture etc.). A substance destroying the structure of the already cross-linked gel may also be encapsulated into the structure of the already cross-linked gel for its removal from the working zone. Under the action of a magnetic field such pellets move and/or localize in the area where active substance (gellation initiator, hardening accelerator or another component) introduction is needed, and are destroyed under the action of the magnetic field which results in their release. The most important advantage of such delivery of the encapsulated substance is complete control over its location and release which significantly improves control over the processes in which it participates.
As per this invention, a polymer pellet is a gel matrix of an anionic polymer crosslinked with cations of multivalent metals in which at least one active substance and ferromagnetic particles are dispersed at the concentration of ferromagnetic micro-particles of 0.5 - 5%. The concentration of ferromagnetic particles below 0.5% does not provide the particles' required ferromagnetic properties whereas the particles' concentration of >5% results in heavier pellets which swell worse. Anionic polysaccharide with the concentration from 0.1 to 2% is used as the anionic polymer. The anionic polysaccharide may be sodium alginate, pectin with etherification degree of maximum 30%, carboxymethyl cellulose or oxyethylcarboxymethyl cellulose.
As the ferromagnetic particles spherical or bar-shaped particles of iron or oxides thereof with the minimum size of 40 - 300 nm, e.g., magnetite or magenite are used. The active substance may be the initiator of the physico-chemical conversion or the passive form thereof insoluble in the matrix, for example, gellation initiator which may be represented by, for example, boric acid or calcium carbonate.
The polymer pellets, as per this invention, provide controlled release of the active substance into the application medium. In accordance with the invention, the method of controlled release of an active substance into an application medium includes producing polymer pellets, each being a gel matrix of anionic polymer cross-linked with multivalent metals' cations, in which at least one active substance and ferromagnetic particles are dispersed with the concentration, with the concentration of ferromagnetic particles from 0.5 to 5.5%, delivery of the produced polymer pellets to the application place with the release of the active substance into the application medium. The polymer pellets are destroyed by increasing the application medium pH and/or by means of application of an external magnetic field causing displacement and change of orientation of the ferromagnetic particles. The polymer pellets may be transferred to the application location under the effect of the external magnetic field.
The polymer pellets, as per this invention, may be used to produce a polymer gel. In accordance with the invention, the method of polymer gel production includes preparing of concentrated solution of a first anionic polymer capable of ionotropic gellation, adding of a gellation initiator passive form into the prepared solution, activation of the gellation initiator and gel formation resulting from the interaction of the active form of the gellation initiator with the polymer. The gellation initiator passive form is added into the polymer solution with the polymer pellets each being a gel matrix of a second anionic polymer cross-linked with multivalent metals' cations, in which a gellation initiator and ferromagnetic particles are dispersed with the concentration of ferromagnetic particles from 0.5 to 5.5%. The activation of gellation initiator is performed as a result of dissolution of the initiator passive form in the dispersion medium of the obtained polymer pellets suspension in the polymer solution after the pellets' destruction.
The polymer pellets are destroyed by means of increasing pH of the obtained suspension of the polymer pellets in the polymer solution and/or by applying an external magnetic field to the obtained suspension of the polymer pellets in the polymer solution; the magnetic field causes displacement and change or ferromagnetic particles' orientation, particularly, the external magnetic field with the intensity of 5,000-20,000 Oersted.
As per one of the embodiments of the invention, polyvinyl alcohol with the concentration of minimum 5% may be used as the first polymer capable of ionotropic gellation and used to obtain the polymer gel, boric acid is used as the passive form of the gellation initiator, and the gellation initiator activation is attained by alkalinization of the dispersion medium of the polymer pellets suspension to pH 8 - 10.
The pellets' drying after their fabrication significantly facilitates their storage and transportation as a result of the substantial reduction of their size and weight; it also allows their loading into the well with drilling mud or other blends used without any risk of the equipment damage. Drying may be performed using any method to the pellets residual humidity of 15-25%.
As per this invention, the polymer pellets are used to form the blocking gel plug, e.g., to provide the formation insulation. In accordance with the invention, the method of making the blocking gel plug includes delivery of the gellating compound made as polymer pellets to the gel plug formation place;
each pellet being a gel matrix of an anion polymer cross-linked with the cations of multivalent metals in which ferromagnetic particles are dispersed with the ferromagnetic particles' concentration from 0.5 to 5%. The delivery may be performed by applying a magnetic field ensuring the displacement of the polymer pellets to the gel plug formation place and the blocking gel plug is formed due to the destruction of the polymer pellets resulting from their swelling and/or under the influence of external magnetic field followed by the gellation initiator release into the environment.
The pellets may also be used to deliver the substance destroying the gel used for the formation fracturing, for example, guar gel, cross-linked with boric acid. After passing the perforation zone the pellets containing ammonium persulfate, are activated, the guar gel is destroyed, which enables the well cleaning of polymer and unimpeded oil seepage out of the formation. Therefore, the pellets may be used in the technologies applied for the cementation, blocking plug generation, formation fracture etc., both for the delivery of the agent activating polymerization or hardening and for the delivery of the agent destroying the polymer structure as well as for any catalysts, inhibitors or other substances participating in the process.
The polymer pellets, as per this invention, may be produced by dispersing ferromagnetic particles and an active substance by stirring in the water solution of anionic polysaccharide capable of ionotropic gellation after which the suspension obtained is dripped into the water solution of the multivalent metal salt. As the multivalent metal salts water-soluble salts of calcium, barium or aluminum may be used.
The essence of the invention may be illustrated by the following non-limiting examples.
Example 1 Making Alginate Pellets Containing Magnetite and Boric Acid 0.3 g of magnetite (powder of irregular shape Fe304 particles with the size of about 300 nm) and 0.3 g of fine boric acid powder is dispersed by stirring in 9.7 g of 0.7 %-solution of sodium alginate in 0.01 M solution of the buffer mixture tris-(hydroxymethyl)-aminomethane - HC1 with pH 7.4. The magnetite suspension obtained is dripped into 100 ml of 3 % solution of calcium chloride in the buffer mixture tris-(hydroxymethyl)-aminomethane -HC1 above at pH 7.4. The 3-mm diameter spherical pellets' suspension is kept at 4 C for 24 hours and then washed five times with 20 ml of bidistilled water and stored in the refrigerator for further use.
Example 2 Initiation of Physico-Chemical Conversion Exemplified by Polyvinyl Alcohol Gel Obtaining To 40 ml of 5% water solution of polyvinyl alcohol 4 ml of 0.5% water solution of sodium bicarbonate is added by dripping with energetic stirring, three alginate pellets containing magnetite and boric acid are also added.
Under the influence of homogenous magnetic field with the intensity of 2,000 -20,000 Oersted the microspheres are destroyed and boric acid is released. The boric acid reacts with the sodium bicarbonate generating sodium tetraborate which influences the generation of polyvinyl alcohol gel.
Example 3 Drying of Alginate Pellets Containing Magnetite at Room Temperature The magnetic pellets made as shown in Example 1 are dried at the room temperature for 24 hours. Hereby the average weight of one pellet is reduced from 12.8 to 1.1 micrograms within the first 3 hours and then virtually does not change. The pellets retain spherical shape. Weight reduction during the drying is accompanied by the diameter reduction from 3.1 mm to 0.7-0.9 mm.
Example 4 Drying of Alginate Pellets Containing Magnetite at 80 C
The magnetic pellets made as shown in Example 1 are dried at 80 C B for 1 hour. Hereby the average weight of one pellet is reduced from 12.8 to 1.1 micrograms within the first 0.5 hours and then virtually does not change. The pellets retain spherical shape. Weight reduction during the drying is accompanied by the diameter reduction from 3.1 mm to 0.7-0.9 mm.
Example 5 Drying of Alginate Pellets Containing Magnetite using Sublimation Dehydration Method The magnetic pellets made as shown in Example 1 are frozen at -50 C
and then dried in the sublimation dehydration unit at the residual pressure of 1.1 Pa (Martin Chrict model ALFA 1-2 LD; Osterode am Harz, W, Germany) for 14 hours. Hereby the average weight of one pellet is reduced from 12.8 to 1.1 micrograms within the first 5 hours and then virtually does not change. The weight loss during the drying is accompanied by the pellets' shape change, they become disc-shaped (diameter 2.4 mm and thickness 0.25 mm).
Example 6 D ing of Alginate Pellets Containing Magnetite at Room Temperature in Vacuum The magnetic pellets made as shown in Example 1 are dried at the room temperature in vacuum (1-10-3 mm Hg) for 22 hours. Hereby the average weight of one pellet is reduced from 12.8 to 1.1 micrograms within the first 5 hours and then virtually does not change. The pellets retain spherical shape.
The weight loss during the drying is accompanied by the pellets' diameter reduction from 3.1 mm to 0.9-1.0 mm.
The use of magnetic alginate pellets for biological separation and treatment of enzymes and cells in the magnetic field has also been described (Tyagi, R. et al., Biocatalysis and Biotransformation 1995, 12, 293; Ames, T.T.
et al., Biotechnology Progress 1997, 13, 336; Liu, C.Z. et al., Journal of Bioscience and Bioengineering 2000, 89, 420), for effluents treatment of heavy metals (Nestle, N. et al., Colloids and Surfaces A-Physicochemical and Engineering Aspects 1996, 115, 141; Ngomsik, A.F. et al., Water Research 2006, 40, 1848).
The examples of releasing active substances from polymer pellets using controlled magnetic field are not numerous.
Thus, U.S. Patent No. 4,652,257 describes the method of obtaining manetically localized polymerizing lipidic vesicles, containing the target substance (medicine), and the method of the vesicles' destruction and release of the contents thereof under the magnetic field effect. The therapeutic substance and ferromagnetic particles are encapsulated in the lipidic vesicle, generated by the polymerizing lipids. The lipids are polymerized under the effect of ultraviolet radiation with the formation of the membrane resistant to chemical and physical effects. Any ferromagnetic substance, preferably single-domain magnets of bacterial origin, magentites, ferrites or fine-grain iron sawdust may be used as magnetic particles. The vesicles are delivered to the target organ under the effect of the external constant magnetic field. After localization in the proper location the vesicle membrane is destroyed or destabilized due to the application of the variable magnetic field. Frequency and duration of the variable magnetic field action determine the rate of the vesicle-encapsulated therapeutic substance release.
U.S. Patent No. 5,019,372 proposes a method of producing solid polymer pellets filled with stainless steel particles and containing the target biologically active substance (water-soluble medicine), the release of which is accelerated in the variable magnetic field. The polymer pellet is made of bio-compatible plastic material non-soluble in the application field, e.g., of ethylene-vinyl acetate copolymer. The biologically active substance and magnetic particles are dispersed in the monomers methylene chloride solution, after which polymerization and pelletization are conducted. The pellets are places in the aqueous medium where the target substance is released effected by the oscillating magnetic field with the intensity of 0.5 to 1,000 Gauss. The rate of the release stimulated by the magnetic field is by factor 30 higher than without this stimulation and amounts to about 400 micro-Gauss per hour. A water-soluble substance with the molecular weight exceeding 150 D may be used as the target substance.
In the proceeding Z. Lu et al. (Langmuir, 2005, 21, 2042-2050) a method of obtaining magnetically sensitive polyelectrolyte multi-layer micro-pellets was proposed. The capsule membrane consists of several layers formed by sodium phosphonated polystyrene and polyallylamine hydrochloride with a layer of cobalt nano-particles coated with gold between them. The capsule membrane permeability for dextrane marked with a fluorescent tag was researched. It was demonstrated that the variable magnetic field with the frequency of 100-300 Hz and intensity of 1200 Gauss causes intensive rotation of the cobalt nano-particles which significantly damages the capsule membrane integrity. The optimum magnetic sensitivity of the membrane sensitivity was observed in the capsules with the walls formed of 10 layers of polyelectrolytes and 1 layer of ferromagnetic nano-particles.
The polymer pellets described are used for bio-medical application in the systems of targeted transport of medicines. Their application in other technologies is limited by the process complexity and their high cost.
The use of polymers for controlled generation of the plug for zone insulation is described in Patent RU 2276675. The invention describes the method of forming a gel plug by gellation of the fluid containing hydrophobically associating substances and water-soluble gellation inhibitor.
In case of contact between the fluid and hydrocarbons the inhibitor retains its properties whereas in case the fluid's contact with the water medium the inhibitor is dissolved which results in gellation. Therefore, the method enables monitoring water influxes in the oil-producing wells by gel plugs' formation.
However, this method has its disadvantages: 1) gellation with the use of this fluid is irreversible and starts from the first contact with water which could occur on the surface which creates significant difficulties during the injection of water into the well, 2) the already formed gel plugs in certain conditions may also lock oil-bearing formations making hydrocarbons' production more difficult.
The invention claimed covers polymer pellets containing magnetic particles and at least one active substance and having optimum mechanical properties enabling the pellets destruction both as a result of swelling and under effect of the magnetic field of admissible intensity, as a result of displacement and change of orientation of ferromagnetic particles. The pellets destruction ensures rather complete and fast release of the active substance (substances) into the application medium and its dissolution. Such medium may be, for example, the solution of polymer capable to gel formation under the influence of the soluble form of the encapsulated substance - gellation initiator. In this case polymer gel formation is attained (thus, the polymer pellets may be used wherever the zonal insulation is required, in the gels used for hydraulic fracture etc.). A substance destroying the structure of the already cross-linked gel may also be encapsulated into the structure of the already cross-linked gel for its removal from the working zone. Under the action of a magnetic field such pellets move and/or localize in the area where active substance (gellation initiator, hardening accelerator or another component) introduction is needed, and are destroyed under the action of the magnetic field which results in their release. The most important advantage of such delivery of the encapsulated substance is complete control over its location and release which significantly improves control over the processes in which it participates.
As per this invention, a polymer pellet is a gel matrix of an anionic polymer crosslinked with cations of multivalent metals in which at least one active substance and ferromagnetic particles are dispersed at the concentration of ferromagnetic micro-particles of 0.5 - 5%. The concentration of ferromagnetic particles below 0.5% does not provide the particles' required ferromagnetic properties whereas the particles' concentration of >5% results in heavier pellets which swell worse. Anionic polysaccharide with the concentration from 0.1 to 2% is used as the anionic polymer. The anionic polysaccharide may be sodium alginate, pectin with etherification degree of maximum 30%, carboxymethyl cellulose or oxyethylcarboxymethyl cellulose.
As the ferromagnetic particles spherical or bar-shaped particles of iron or oxides thereof with the minimum size of 40 - 300 nm, e.g., magnetite or magenite are used. The active substance may be the initiator of the physico-chemical conversion or the passive form thereof insoluble in the matrix, for example, gellation initiator which may be represented by, for example, boric acid or calcium carbonate.
The polymer pellets, as per this invention, provide controlled release of the active substance into the application medium. In accordance with the invention, the method of controlled release of an active substance into an application medium includes producing polymer pellets, each being a gel matrix of anionic polymer cross-linked with multivalent metals' cations, in which at least one active substance and ferromagnetic particles are dispersed with the concentration, with the concentration of ferromagnetic particles from 0.5 to 5.5%, delivery of the produced polymer pellets to the application place with the release of the active substance into the application medium. The polymer pellets are destroyed by increasing the application medium pH and/or by means of application of an external magnetic field causing displacement and change of orientation of the ferromagnetic particles. The polymer pellets may be transferred to the application location under the effect of the external magnetic field.
The polymer pellets, as per this invention, may be used to produce a polymer gel. In accordance with the invention, the method of polymer gel production includes preparing of concentrated solution of a first anionic polymer capable of ionotropic gellation, adding of a gellation initiator passive form into the prepared solution, activation of the gellation initiator and gel formation resulting from the interaction of the active form of the gellation initiator with the polymer. The gellation initiator passive form is added into the polymer solution with the polymer pellets each being a gel matrix of a second anionic polymer cross-linked with multivalent metals' cations, in which a gellation initiator and ferromagnetic particles are dispersed with the concentration of ferromagnetic particles from 0.5 to 5.5%. The activation of gellation initiator is performed as a result of dissolution of the initiator passive form in the dispersion medium of the obtained polymer pellets suspension in the polymer solution after the pellets' destruction.
The polymer pellets are destroyed by means of increasing pH of the obtained suspension of the polymer pellets in the polymer solution and/or by applying an external magnetic field to the obtained suspension of the polymer pellets in the polymer solution; the magnetic field causes displacement and change or ferromagnetic particles' orientation, particularly, the external magnetic field with the intensity of 5,000-20,000 Oersted.
As per one of the embodiments of the invention, polyvinyl alcohol with the concentration of minimum 5% may be used as the first polymer capable of ionotropic gellation and used to obtain the polymer gel, boric acid is used as the passive form of the gellation initiator, and the gellation initiator activation is attained by alkalinization of the dispersion medium of the polymer pellets suspension to pH 8 - 10.
The pellets' drying after their fabrication significantly facilitates their storage and transportation as a result of the substantial reduction of their size and weight; it also allows their loading into the well with drilling mud or other blends used without any risk of the equipment damage. Drying may be performed using any method to the pellets residual humidity of 15-25%.
As per this invention, the polymer pellets are used to form the blocking gel plug, e.g., to provide the formation insulation. In accordance with the invention, the method of making the blocking gel plug includes delivery of the gellating compound made as polymer pellets to the gel plug formation place;
each pellet being a gel matrix of an anion polymer cross-linked with the cations of multivalent metals in which ferromagnetic particles are dispersed with the ferromagnetic particles' concentration from 0.5 to 5%. The delivery may be performed by applying a magnetic field ensuring the displacement of the polymer pellets to the gel plug formation place and the blocking gel plug is formed due to the destruction of the polymer pellets resulting from their swelling and/or under the influence of external magnetic field followed by the gellation initiator release into the environment.
The pellets may also be used to deliver the substance destroying the gel used for the formation fracturing, for example, guar gel, cross-linked with boric acid. After passing the perforation zone the pellets containing ammonium persulfate, are activated, the guar gel is destroyed, which enables the well cleaning of polymer and unimpeded oil seepage out of the formation. Therefore, the pellets may be used in the technologies applied for the cementation, blocking plug generation, formation fracture etc., both for the delivery of the agent activating polymerization or hardening and for the delivery of the agent destroying the polymer structure as well as for any catalysts, inhibitors or other substances participating in the process.
The polymer pellets, as per this invention, may be produced by dispersing ferromagnetic particles and an active substance by stirring in the water solution of anionic polysaccharide capable of ionotropic gellation after which the suspension obtained is dripped into the water solution of the multivalent metal salt. As the multivalent metal salts water-soluble salts of calcium, barium or aluminum may be used.
The essence of the invention may be illustrated by the following non-limiting examples.
Example 1 Making Alginate Pellets Containing Magnetite and Boric Acid 0.3 g of magnetite (powder of irregular shape Fe304 particles with the size of about 300 nm) and 0.3 g of fine boric acid powder is dispersed by stirring in 9.7 g of 0.7 %-solution of sodium alginate in 0.01 M solution of the buffer mixture tris-(hydroxymethyl)-aminomethane - HC1 with pH 7.4. The magnetite suspension obtained is dripped into 100 ml of 3 % solution of calcium chloride in the buffer mixture tris-(hydroxymethyl)-aminomethane -HC1 above at pH 7.4. The 3-mm diameter spherical pellets' suspension is kept at 4 C for 24 hours and then washed five times with 20 ml of bidistilled water and stored in the refrigerator for further use.
Example 2 Initiation of Physico-Chemical Conversion Exemplified by Polyvinyl Alcohol Gel Obtaining To 40 ml of 5% water solution of polyvinyl alcohol 4 ml of 0.5% water solution of sodium bicarbonate is added by dripping with energetic stirring, three alginate pellets containing magnetite and boric acid are also added.
Under the influence of homogenous magnetic field with the intensity of 2,000 -20,000 Oersted the microspheres are destroyed and boric acid is released. The boric acid reacts with the sodium bicarbonate generating sodium tetraborate which influences the generation of polyvinyl alcohol gel.
Example 3 Drying of Alginate Pellets Containing Magnetite at Room Temperature The magnetic pellets made as shown in Example 1 are dried at the room temperature for 24 hours. Hereby the average weight of one pellet is reduced from 12.8 to 1.1 micrograms within the first 3 hours and then virtually does not change. The pellets retain spherical shape. Weight reduction during the drying is accompanied by the diameter reduction from 3.1 mm to 0.7-0.9 mm.
Example 4 Drying of Alginate Pellets Containing Magnetite at 80 C
The magnetic pellets made as shown in Example 1 are dried at 80 C B for 1 hour. Hereby the average weight of one pellet is reduced from 12.8 to 1.1 micrograms within the first 0.5 hours and then virtually does not change. The pellets retain spherical shape. Weight reduction during the drying is accompanied by the diameter reduction from 3.1 mm to 0.7-0.9 mm.
Example 5 Drying of Alginate Pellets Containing Magnetite using Sublimation Dehydration Method The magnetic pellets made as shown in Example 1 are frozen at -50 C
and then dried in the sublimation dehydration unit at the residual pressure of 1.1 Pa (Martin Chrict model ALFA 1-2 LD; Osterode am Harz, W, Germany) for 14 hours. Hereby the average weight of one pellet is reduced from 12.8 to 1.1 micrograms within the first 5 hours and then virtually does not change. The weight loss during the drying is accompanied by the pellets' shape change, they become disc-shaped (diameter 2.4 mm and thickness 0.25 mm).
Example 6 D ing of Alginate Pellets Containing Magnetite at Room Temperature in Vacuum The magnetic pellets made as shown in Example 1 are dried at the room temperature in vacuum (1-10-3 mm Hg) for 22 hours. Hereby the average weight of one pellet is reduced from 12.8 to 1.1 micrograms within the first 5 hours and then virtually does not change. The pellets retain spherical shape.
The weight loss during the drying is accompanied by the pellets' diameter reduction from 3.1 mm to 0.9-1.0 mm.
Claims (34)
1. A polymer pellet comprising a gel matrix from an anionic polymer cross-linked with cations of multivalent metals wherein at least one active substance and ferromagnetic, particles are dispersed in the matrix with the ratio of weight concentrations of the ferromagnetic particles from 0.5 to 5%.
2. The polymer pellet of Claim 1 wherein the anionic polymer is an anionic polysaccharide with the concentration of 0.1 - 2%.
3. The polymer pellet of Claim 2 wherein the anionic polysaccharide ia sodium alginate or pectin with etherification degree of max. 3 0%.
4. The polymer pellet of Claim 2 wherein the anionic polysaccharide is carboxymethyl cellulose or oxyethylcarboxymethyl cellulose.
5. The polymer pellet of Claim 1 wherein ferromagnetic micro-particles are spherical or bar-shaped iron or iron oxides particles with the minimum size from 40 to 300 nm.
6. The polymer pellet of Claim 5 wherein ferromagnetic micro-particles are magnetite or magenite particles.
7. The polymer pellet of Claim 1 wherein the active substance is an initiator of physico-chemical conversion or the matrix-insoluble passive form thereof.
8. The polymer pellet of Claim 7 wherein the physico-chemical conversion initiator is a gellation initiator.
9. The polymer pellet of Claim 8 wherein the gellation initiator passive form is boric acid or calcium carbonate.
10. Method for a controlled release of an active substance into an application medium comprising the steps of:
production of polymer pellets, each pellet being a gel matrix of an anionic polymer cross-linked with multivalent metals' cations, in the gel matrix at least one active substance and ferromagnetic micro-particles are dispersed with the ferromagnetic particles' concentration from 0.5 to 5%, delivery of the produced polymer pellets to the place of their application, and subsequent destruction of the pellets with the active substance release into the application medium.
production of polymer pellets, each pellet being a gel matrix of an anionic polymer cross-linked with multivalent metals' cations, in the gel matrix at least one active substance and ferromagnetic micro-particles are dispersed with the ferromagnetic particles' concentration from 0.5 to 5%, delivery of the produced polymer pellets to the place of their application, and subsequent destruction of the pellets with the active substance release into the application medium.
11. Method for a controlled release of an active substance of Claim 10 wherein the polymer pellets are delivered by the action of an external magnetic field.
12. Method for a controlled release of the active substance of Claim 10 wherein the produced polymer pellets are dried before the delivery.
13. Method for a controlled release of the active substance of Claim 12 wherein the dried polymer pellets are delivered by the action of an external magnetic field.
14. Method for a controlled release of the active substance of Claim 10 wherein the polymer pellets are destroyed by applying an external magnetic field causing the ferromagnetic particles' displacement and orientation change.
15. Method for a controlled release of the active substance of Claim 14 wherein the external magnetic field has the intensity of 5,000 - 20,000 Oersted.
16. Method for a controlled release of the active substance of Claim 14 wherein the polymer pellets are destroyed by increasing application medium pH to pH >
7.
7.
17. Method for a controlled release of the active substance of Claim 16 wherein the polymer pellets' destruction is additionally accelerated by applying an external magnetic field causing the ferromagnetic particles' displacement and orientation change.
18. Method for a controlled release of the active substance of Claim 17 wherein the external magnetic field has the intensity of 5,000 - 20,000 Oersted.
19. Method for a polymer gel production comprising the steps of:
preparation of a concentrated solution of a first anionic polymer capable of ionotropic gellation, adding of the polymer pellets into the prepared solution, each pellet being a gel matrix of a second anionic polymer cross-linked with cations of multivalent metals in which a gellation initiator passive form and ferromagnetic particles are dispersed with the ferromagnetic particles concentration from 0.5 to 5%, activation of the gellation initiator due to a dissolution of the initiator passive form in the dispersion medium of the obtained suspension of the polymeric pellets in the prepared polymer solution after their destruction and a gel formation due to a reaction between the gellation initiator active form and said first polymer.
preparation of a concentrated solution of a first anionic polymer capable of ionotropic gellation, adding of the polymer pellets into the prepared solution, each pellet being a gel matrix of a second anionic polymer cross-linked with cations of multivalent metals in which a gellation initiator passive form and ferromagnetic particles are dispersed with the ferromagnetic particles concentration from 0.5 to 5%, activation of the gellation initiator due to a dissolution of the initiator passive form in the dispersion medium of the obtained suspension of the polymeric pellets in the prepared polymer solution after their destruction and a gel formation due to a reaction between the gellation initiator active form and said first polymer.
20. Method for a polymer gel production of Claim 19 wherein the polymer pellets are destroyed by applying an external magnetic field to the obtained suspension of the polymer pellets in the prepared polymer solution causing displacement and change or orientation of the ferromagnetic particles.
21. Method for a polymer gel production of Claim 20 wherein the external magnetic field has the intensity of 5,000 - 20,000 Oersted.
22. Method for a polymer gel production of Claim 19 wherein the polymer pellets are destroyed by increasing pH of the obtained suspension of the polymer pellets in the polymer solution to pH > 7.
23. Method for a polymer gel production of Claim 22 wherein the polymer pellets' destruction is additionally accelerated by applying an external magnetic field to the obtained suspension of polymer pellets in the polymer solution causing the ferromagnetic particles' displacement and orientation change.
24. Method for a polymer gel production of Claim 23 wherein the external magnetic field has the intensity of 5,000 - 20,000 Oersted.
25. Method for a polymer gel production of Claim 19 wherein the first anionic polymer is polyvinyl alcohol with the concentration of minimum 5%, the passive form of the gellation initiator is boric acid, and the gellation initiator activation is attained by alkalinization of the dispersion medium of the polymeric pellets suspension to pH 8 - 10.
26. Method for a blocking gel plug formation comprising the steps of:
a delivery of the polymer pellets to a place of the blocking plug formation, each pellet being a gel matrix of an anionic polymer cross-linked with the cations of multivalent metals in which a gellation initiator and ferromagnetic particles are dispersed with the ferromagnetic particles' concentration from 0.5. to 5%, and subsequent formation of the blocking gel plug due to the destruction of the polymeric pellets followed by the gellation initiator release into the blocking gel plug formation place.
a delivery of the polymer pellets to a place of the blocking plug formation, each pellet being a gel matrix of an anionic polymer cross-linked with the cations of multivalent metals in which a gellation initiator and ferromagnetic particles are dispersed with the ferromagnetic particles' concentration from 0.5. to 5%, and subsequent formation of the blocking gel plug due to the destruction of the polymeric pellets followed by the gellation initiator release into the blocking gel plug formation place.
27. Method for a blocking gel plug formation of Claim 26 wherein the polymer pellets are delivered to the gel plug formation place by applying an external magnetic field ensuring their displacement.
28. Method for a blocking gel plug formation of Claim 26 wherein the polymer pellets are pre-dried.
29. Method for a blocking gel plug formation of Claim 28 wherein the pre-dried polymer pellets are delivered to the gel plug formation place by applying an external magnetic field ensuring their displacement.
30. Method for a blocking gel plug formation of Claim 26 wherein the polymer pellets are destroyed by an external magnetic field ensuring the ferromagnetic particles' displacement and orientation change.
31. Method for a blocking gel plug formation Claim 30 wherein the external magnetic field has the intensity of 5,000 - 20,000 Oersted.
32. Method for a blocking gel plug formation of Claim 26 wherein the polymer pellets are destroyed by increasing the environment pH.
33. Method for a blocking gel plug formation of Claim 32 wherein the polymer pellets destruction is additionally accelerated by applying an external magnetic field causing the ferromagnetic particles' displacement and orientation change.
34. Method for a blocking gel plug formation of Claim 33 characterized in that the external magnetic field has the intensity of 5,000 - 20,000 Oersted.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/RU2007/000754 WO2009088318A1 (en) | 2007-12-29 | 2007-12-29 | Magnetic polymer granules and a method for the use thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2710988A1 true CA2710988A1 (en) | 2009-07-16 |
Family
ID=40853278
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2710988A Abandoned CA2710988A1 (en) | 2007-12-29 | 2007-12-29 | Magnetic polymer pellets and their application methods |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2710988A1 (en) |
| WO (1) | WO2009088318A1 (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9080440B2 (en) | 2007-07-25 | 2015-07-14 | Schlumberger Technology Corporation | Proppant pillar placement in a fracture with high solid content fluid |
| US9133387B2 (en) | 2011-06-06 | 2015-09-15 | Schlumberger Technology Corporation | Methods to improve stability of high solid content fluid |
| US9388335B2 (en) | 2013-07-25 | 2016-07-12 | Schlumberger Technology Corporation | Pickering emulsion treatment fluid |
| US9528354B2 (en) | 2012-11-14 | 2016-12-27 | Schlumberger Technology Corporation | Downhole tool positioning system and method |
| US9803457B2 (en) | 2012-03-08 | 2017-10-31 | Schlumberger Technology Corporation | System and method for delivering treatment fluid |
| US9850423B2 (en) | 2011-11-11 | 2017-12-26 | Schlumberger Technology Corporation | Hydrolyzable particle compositions, treatment fluids and methods |
| US9863228B2 (en) | 2012-03-08 | 2018-01-09 | Schlumberger Technology Corporation | System and method for delivering treatment fluid |
| US10011763B2 (en) | 2007-07-25 | 2018-07-03 | Schlumberger Technology Corporation | Methods to deliver fluids on a well site with variable solids concentration from solid slurries |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4652257A (en) * | 1985-03-21 | 1987-03-24 | The United States Of America As Represented By The Secretary Of The Navy | Magnetically-localizable, polymerized lipid vesicles and method of disrupting same |
| DE4413350A1 (en) * | 1994-04-18 | 1995-10-19 | Basf Ag | Retard matrix pellets and process for their production |
| AUPM807094A0 (en) * | 1994-09-09 | 1994-10-06 | Commonwealth Scientific And Industrial Research Organisation | Polymer beads and method for preparation thereof |
| RU2113841C1 (en) * | 1996-04-16 | 1998-06-27 | Акционерное общество открытого типа Завод "Компонент" | Capsule for per os administering drugs with controlled drug supply |
| RU2167281C2 (en) * | 1999-08-04 | 2001-05-20 | Швецов Игорь Александрович | Method of nonuniform formation development |
| RU2276675C2 (en) * | 2002-10-09 | 2006-05-20 | Физический факультет Московского государственного университета им. М.В. Ломоносова | Method of selectively inhibiting gelation of hydrophobically associating substances |
| RU2298088C1 (en) * | 2005-09-30 | 2007-04-27 | Открытое акционерное общество "Татнефть" им. В.Д. Шашина | Method for non-uniform oil reservoir development |
-
2007
- 2007-12-29 WO PCT/RU2007/000754 patent/WO2009088318A1/en active Application Filing
- 2007-12-29 CA CA2710988A patent/CA2710988A1/en not_active Abandoned
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9080440B2 (en) | 2007-07-25 | 2015-07-14 | Schlumberger Technology Corporation | Proppant pillar placement in a fracture with high solid content fluid |
| US10011763B2 (en) | 2007-07-25 | 2018-07-03 | Schlumberger Technology Corporation | Methods to deliver fluids on a well site with variable solids concentration from solid slurries |
| US9133387B2 (en) | 2011-06-06 | 2015-09-15 | Schlumberger Technology Corporation | Methods to improve stability of high solid content fluid |
| US9850423B2 (en) | 2011-11-11 | 2017-12-26 | Schlumberger Technology Corporation | Hydrolyzable particle compositions, treatment fluids and methods |
| US10351762B2 (en) | 2011-11-11 | 2019-07-16 | Schlumberger Technology Corporation | Hydrolyzable particle compositions, treatment fluids and methods |
| US9803457B2 (en) | 2012-03-08 | 2017-10-31 | Schlumberger Technology Corporation | System and method for delivering treatment fluid |
| US9863228B2 (en) | 2012-03-08 | 2018-01-09 | Schlumberger Technology Corporation | System and method for delivering treatment fluid |
| US9528354B2 (en) | 2012-11-14 | 2016-12-27 | Schlumberger Technology Corporation | Downhole tool positioning system and method |
| US9388335B2 (en) | 2013-07-25 | 2016-07-12 | Schlumberger Technology Corporation | Pickering emulsion treatment fluid |
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| Publication number | Publication date |
|---|---|
| WO2009088318A1 (en) | 2009-07-16 |
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