Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B33/00—Sealing or packing boreholes or wells
  • E21B33/10—Sealing or packing boreholes or wells in the borehole
  • E21B33/13—Methods or devices for cementing, for plugging holes, crevices or the like
  • E21B33/138—Plastering the borehole wall; Injecting into the formation
• • 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
  • 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
  • C09K8/42—Compositions for cementing, e.g. for cementing casings into boreholes; Compositions for plugging, e.g. for killing wells
  • C09K8/426—Compositions for cementing, e.g. for cementing casings into boreholes; Compositions for plugging, e.g. for killing wells for plugging
• • 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
  • C09K8/516—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls characterised by their form or by the form of their components, e.g. encapsulated material
• • 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
  • C09K8/56—Compositions for consolidating loose sand or the like around wells without excessively decreasing the permeability thereof
  • C09K8/57—Compositions based on water or polar solvents
  • C09K8/575—Compositions based on water or polar solvents containing organic compounds

Definitions

• the present invention relates to a method of reducing fluid loss in formations such as a subterranean formation or water or sewer systems. More particularly the present invention relates to a method of providing a barrier in a fracture-containing system.
• the invention is contemplated to having utility not only in the oil-drilling industry but also in the plugging of fractures in sewer drains etc.
• HPAM Hydrolyzed polyacrylamide
• WO 2007/141519 A2 discloses silicone-tackifier matrixes and methods of use thereof by providing a treatment fluid that comprises a base fluid and a silicone-tackifier matrix composition that comprises at least one silicone polymer component, at least one tackifying agent, and at least one curing agent and/or at least one cross linking agent, placing the treatment fluid in a subterranean formation, and allowing the silicone-tackifier matrix to form at least one silicone-tackifier matrix therein.
• WO 2007/010210 discloses a method of servicing a wellbore in contact with a subterranean formation comprising placing a sealing agent and a nonaqueous carrier fluid in the wellbore, placing a nonaqueous activating fluid in the wellbore, and contacting the sealing agent with the nonaqueous activating fluid to form a sealant composition.
• WO 2008/009957 discloses a method of forming a barrier for a fluid in a subterranean area penetrated by a wellbore, comprising depositing of particulate material in a fracture, wherein the particulate material comprises at least some particles made from material that swells when contacted with said fluid.
• US 2008/0017376 discloses a method of reducing fluid loss in a subterranean formation comprising placing a lost circulation composition comprising a base fluid and a swellable elastomer and allowing the swellable elastomer to swell upon contact with a fluid.
• US 2006/234871 A1 discloses a sealant composition for servicing a wellbore comprising at least one gel system, a leak off prevention material and water.
• U.S. Pat. No. 4,649,998 discloses a method of treating a subterranean, unconsolidated sand and petroleum containing formation penetrated by at least one well, which is in fluid communication with at least a portion of the unconsolidated sand containing subterranean formation, in order to form a flexible, permeable barrier around the well which restrains the movement of sand particles into the well while permitting the passage of formation fluids including petroleum there through.
• an elastomeric material comprising at least one polymer capable of crosslinking into an elastomer together with at least one crosslinking agent in a base fluid and allowing the elastomeric material to crosslink with itself and with the crosslinking agent an efficient barrier is created.
• the present invention relates to a method of providing a barrier in a fracture-containing system, comprising:
• the present invention relates to a treatment fluid comprising:
• the present invention relates to a use of a treatment fluid according to the invention for fracture blocking.
• the term “elastomer” refers to compositions of matter that have a glass transition temperature, T g , at which there is an increase in the thermal expansion coefficient, and includes both amorphous polymer elastomers and thermoplastic elastomer (thermoplastics).
• T g glass transition temperature
• An elastomer exhibits an elasticity deriving from the ability of the polymer chains of the elastomer to reconfigure themselves to distribute an applied stress.
• elastomeric material refers in the present context to a material, which may, in addition to elastomer, include fillers and additives.
• fillers are e.g. reinforcing fillers such as silica and carbon black as well as fillers with color enhancement such as titanium dioxide.
• crosslinking agent and “crosslinker” are used interchangeably and in the present context means a material capable of forming bonds between one polymer chain and another.
• thermoplastic material in the present context means a polymer that turns to a liquid when heated and solidifies to a rigid state when cooled sufficiently.
• carrier in a fracture-containing system in the present context means a physical obstruction of the passage of material through said fracture so that at most 5% of the original area is available for passage, preferably at most 3%, more preferably at most 1%, even more preferably less than 0.1% of the original area.
• particle size of an elastomeric material or a crosslinking agent means the average diameter of the particles in question without any coating or outer layer.
• integrator in the present context refers to a material that accelerates the breakdown of the first and/or second thermoplastic material layer.
• thickness of a layer refers to the average thickness thereof.
• activation in the present context refers to the action of removal of the layer of the first and/or second thermoplastic material in order to expose the interior of the particles in question for reaction, such as crosslinking.
• curing in the present context refers to the process of cross-linking of polymer chains.
• partial curing in the present context refers to a cross-linking process wherein only a proportion of the reactive groups of the polymer chains of the elastomeric material available for reaction are crosslinked.
• neutral buoyancy in the present context means that the density of the particles of the elastomeric material and/or the crosslinking agent is the same as the density of the base fluid so that said particles will float in the base fluid and thus will neither sink nor rise. That the density of the particles of the elastomeric material and/or the crosslinking agent is the same as the density of the base fluid means that the numerical values of the densities in g/ml is the same ⁇ 5%, such as ⁇ 3%, and preferably deviates no more than 1% from each other.
• the elastomeric material and/or the crosslinking agent are of neutral buoyancy with regard to the base fluid or in other words are present under isopycnic conditions. This secures that the elastomeric material and/or the crosslinking agent will be transported to the desired place of action.
• the presence of isopycnic conditions provides for plug flow of the treatment fluid and thereby a controlled and specific delivery to the intended place of action without loss or premature leakage of treatment fluid.
• the density of the elastomeric material and/or the crosslinking agent may be controlled, if desired, via addition of e.g. fillers, such as silica.
• At least one of the elastomeric material or the crosslinking agent is present in the form of particles.
• the elastomeric material is present in the form of particles of elastomeric material.
• the elastomeric material comprises one or more components selected from the group consisting of natural rubber, acrylate butadiene rubbers, polyacrylate rubbers, isoprene rubbers, chloroprene rubbers, butyl rubbers, brominated or chlorinated butyl rubbers, chlorinated polyethylene, neoprene rubbers, styrene butadiene copolymer rubbers, sulphonated polyethylene, ethylene oxide copolymers, ethylene-propylene rubbers, ethylene-propylene-diene terpolymer rubbers, ethylene vinyl acetate copolymers, fluorosilicone rubber, silicone rubbers, poly 2,2,1-bicyclo heptane, alkylstyrene, crosslinked substituted vinyl acrylate copolymers and diatomaceous earth, nitrile rubbers, hydrogenated nitrile rubbers, fluoro rubbers, perfluoro rubbers, tetrafluoro
• the elastomeric material comprises one or more components selected from the group consisting of natural rubber, acrylate butadiene rubbers, polyacrylate rubbers, isoprene rubbers, chloroprene rubbers, butyl rubbers, fluorosilicone rubber, silicone rubbers, and acrylic polymers, more preferably silicone rubbers such as RTV (Room Temperature Vulcanizing) silicone rubbers, HTV (High Temperature Vulcanizing) silicone rubbers or LSR (Liquid Silicone Rubbers).
• a preferred silicone rubber is an RTV silicone such as silica-reinforced PDMS (PolyDiMethylSiloxane).
• An example of a commercially available silica-reinforced PDMS is SylgardTM 184 from Dow Corning or Elastosil RT625 from Wacker Chemie AG.
• silicone rubbers In contrast to traditional hydrocarbon based polymers silicone rubbers lack the C—C bond in their polymeric backbone structure which makes them less susceptible to ozone, UV, heat, chemical degradation, and other ageing factors than hydrocarbon based polymers. Other advantages of silicone rubbers are generally good resistance towards water, acids, aliphatic hydrocarbons, and oils. Furthermore silicone rubbers generally possess low gas permeability, large spreadability in the prereacted state, a very wide temperature range of operation ( ⁇ 150 to 550° C.) and a density similar to brine which makes delivery possible without any phase separation due to differences in densities.
• the particle size of the particles of the elastomeric material is in the range of 0.1-1000 ⁇ m, preferably in the range 1-500 ⁇ m, more preferably in the range 5-300 ⁇ m, such as 10-200 ⁇ m, more preferably 10-100 ⁇ m.
• the particle size is chosen to allow an efficient plugging of a fracture while not allowing the particles to seep into the pores of a subterranean formation.
• a typical cross section of a subterranean fracture is in the range 0.5-5 mm, while the diameter of the pores of a subterranean formation is typically in the range 1-10 ⁇ m.
• particle sizes in the above range are able to create an efficient fracture plug while being of a size larger than the typical pore sizes.
• the elastomeric material is partially cured before mixing of said material with the crosslinking agent and the base fluid to form the treatment fluid.
• said partial curing is obtained by reaction with at least one curing agent in an amount in the range 10-70% by mole, such as 20-60% by mole, such as 25-50% by mole of the stoichiometric amount of the reactive groups of the elastomeric material.
• said partial curing is obtained by mixing the elastomer and the curing agent to obtain an emulsion using a mixer speed depending on the desired final particle size.
• a speed in the range 500-2000 rpm may be used, such as 700-1500, such as 800-1200, such as about 1000 rpm.
• said curing agent is a crosslinking agent as disclosed further below.
• said crosslinking agent is a hydride-vinyl crosslinking agent as disclosed further below.
• the elastomeric material may be partially cured by adding a curing agent, such as a crosslinker, in deficit compared to the molar amount of elastomeric material, to an elastomeric material.
• a curing agent such as a crosslinker
• the mixture obtained may be added to an aqueous phase formed by dissolving a surfactant, or a mixture of surfactants, in water with stirring.
• the surfactant may be any surfactant suitable for the treatment fluid in question and is selected from the group consisting of anionic, cationic, non-ionic or zwitter-ionic surfactants.
• Non-limiting examples of suitable surfactants include an anionic surfactant such as sodium dodecyl sulphate (SDS), a cationic surfactant such as polyvinyl alcohol (PVA), a nonionic surfactant such as a polyoxyethylene glycol(PEG) alkyl ether, a polyoxypropylene glycol(PPG) alkyl ether or a polyoxyethylene-polyoxypropylene glycol(PEG-PPG) alkyl ether, and a zwitterionic surfactant such as Lecithin.
• SDS sodium dodecyl sulphate
• PVA polyvinyl alcohol
• PPG polyoxypropylene glycol
• PEG-PPG polyoxyethylene-polyoxypropylene glycol
• a particularly preferred surfactant is selected from the group consisting of SDS, PVA and a polyoxyethylene-polyoxypropylene glycol(PEG-PPG) alkyl ether or a mixture thereof, such as a mixture of SDS and PVA.
• a polyoxyethylene-polyoxypropylene glycol(PEG-PPG) alkyl ether is commercially available under the trade name Pluronic, such as PluronicTM F-108.
• the partial curing may be obtained by means of irradiation.
• Irradiation may be obtained by heating, such as heating to a temperature in the range 50-100° C., such as in the range 60-80° C.
• the partial curing may be obtained by means of irradiation by means of electromagnetic or particle radiation.
• Secondary gamma radiation may take place by means of supplying an electric current. Any other source of radiation that may be switched on electrically may be of operational advantage.
• the partially cured elastomeric material is present in the form of particles and may be used without any protective layer of a first thermoplastic material.
• the particles of partially cured elastomeric material are provided with a protective layer of a first thermoplastic material.
• a surfactant such as any one of the surfactants mentioned above, such as polyvinyl alcohol (PVA), sodium dodecyl sulphate (SDS) or a polyoxyethylene-polyoxypropylene glycol(PEG-PPG) alkyl ether or a mixture thereof, and adding said solution to an oil phase of a first thermoplastic material, such as PMMA, in an organic solvent to form an oil-in-water emulsion.
• PVA polyvinyl alcohol
• SDS sodium dodecyl sulphate
• PEG-PPG polyoxyethylene-polyoxypropylene glycol
• Non-limiting examples of suitable solvents include acetone, dichloromethane (DCM), tetrahydrofuran (THF), and dimethylformamide (DMF).
• DCM dichloromethane
• THF tetrahydrofuran
• DMF dimethylformamide
• Coated particles of elastomeric material may e.g. be obtained by rotary evaporation of solvent.
• the particles of elastomeric material are provided with a protective layer of a first thermoplastic material without any preceding partial curing of the elastomeric particles.
• an elastomeric material and a first elastomeric material, such as PMMA may be dissolved in an organic solvent, such as dichloromethane, tetrahydrofuran, or dimethylformamide, to form an oil phase.
• An aqueous solution of a surfactant, such as polyvinyl alcohol may be prepared by stirring, and the oil phase may be added over a period of time, such as 30-120 min, in particular 45-90 min, such as 60-80 min, to the aqueous solution to form an oil-in-water emulsion.
• Coated particles of elastomeric material may be obtained by rotary evaporation of solvent.
• the crosslinking agent is selected from the group consisting of carboxyl-to-amine crosslinking, amine-reactive crosslinking, sulfhydryl-reactive crosslinking, carbonyl-reactive crosslinking, photoreactive crosslinking, hydroxyl-reactive crosslinking, and hydride-vinyl crosslinking agents.
• Carboxyl-to-amine Carbodiimides such as crosslinking 1-Ethyl-3-[3- dimethylaminopropyl]carbodiimide hydrochloride (EDC), dicyclohexylcarbodiimide (DCC), N-hydroxysuccinimide (NHS) and N-hydroxysulfosuccinimide (Sulfo-NHS) amine-reactive N-Hydroxysuccinimide Esters (NHS Esters) crosslinking Imidoesters such as dimethyl adipimidate (DMA) dimethyl pimelimidate (DMP) dimethyl suberimidate (DMS) sulfhydryl-reactive Maleimides, haloacetyls, disulfides crosslinking carbonyl-reactive Hydrazides such as sulfonylhydrazides crosslinking photoreactive Aryl azides (also called phenylazides), cinna
• crosslinking agent is present in the form of particles.
• the particle size of the particles of the crosslinking agent is in the range of 0.1-1000 ⁇ m, preferably in the range 1-500 ⁇ m, more preferably in the range 5-300 ⁇ m, such as 10-100 ⁇ m.
• the particles of the crosslinking agent comprise an outer layer of a second thermoplastic material.
• Preparation of particles of crosslinking agent comprising an outer layer of a thermoplastic material may take place by dissolving a crosslinking agent and a thermoplastic material in a conventional organic solvent, such as dichloromethane, to form an oil phase which is added to an aqueous phase formed by dissolving a surfactant, such as polyvinyl alcohol, in water.
• suitable surfactants include an anionic surfactant such as sodium dodecyl sulphate (SDS), a nonionic surfactant such as a polyoxyethylene glycol(PEG) alkyl ether, a polyoxypropylene glycol(PPG) alkyl ether or a polyoxyethylene-polyoxypropylene glycol(PEG-PPG) alkyl ether, and a zwitterionic surfactant such as Lecithin.
• a particularly preferred surfactant is selected from the group consisting of SDS, PVA and a polyoxyethylene-polyoxypropylene glycol(PEG-PPG) alkyl ether or a mixture thereof, such as a mixture of SDS and PVA.
• An oil-in-water-emulsion may be formed by adding the oil phase with stirring to the aqueous phase. Coated particles of crosslinking agent may be obtained by rotary evaporation of solvent.
• the elastomeric material is a silicone rubber and the crosslinking agent is a hydride-vinyl crosslinking agent.
• the hydride-vinyl crosslinking agent is selected from the group consisting of methylhydrosiloxane-dimethylsiloxane copolymers, polymethylhydrosiloxanes, and vinylmethylsiloxane-dimethylsiloxane copolymers.
• the elastomeric material is a Polydimethylsiloxane (PDMS) rubber and the crosslinking agent is a methylhydrosiloxane-dimethylsiloxane copolymer.
• PDMS Polydimethylsiloxane
• Poly(dimethyl siloxane) is an inert elastomer that have unique properties such as elastic behaviour and resistance to high temperatures, chemical attack and light degradation. Additionally, the reactive groups on the siloxane surface groups can be used as convenient chemical “handles” for particle functionalization. Moreover, PDMS presents high permeability to various solvents and gases allowing PDMS particles to promptly absorb selected agents from the local environment.
• partly cured PDMS microspheres with reactive handles are subjected to a hydrosilylation addition reaction to prepare cross-linked PDMS elastomers where linear PDMS polymers with two vinyl terminated groups react with a multifunctional cross-linker leading to a three-dimensional cross-linked network.
• the elastomeric material is a silicone rubber and the crosslinking agent is an organic peroxide selected from the group consisting of Di(2,4-dichlorobenzoyl) peroxide (Perkadox PD), Di(4-methylbenzoyl) peroxide (Perkadox PM), Dibenzoyl peroxide (Perkadox L) and tert-Butyl peroxybenzoate (Trigonox C).
• Perkadox PD Di(2,4-dichlorobenzoyl) peroxide
• Perkadox PM Di(4-methylbenzoyl) peroxide
• Perkadox L Dibenzoyl peroxide
• Trigonox C tert-Butyl peroxybenzoate
• the first and second thermoplastic material is selected from the group consisting of polyalkyl methacrylate, such as polymethyl methacrylate (PMMA), fluorinated polyalkyl methacrylate, such as heptafluorbutyl methacrylate (HFBMA), copolymers of polyalkyl methacrylate and fluorinated polyalkyl methacrylate, such as copolymers of polymethyl methacrylate (PMMA) and heptafluorbutyl methacrylate (HFBMA), polyester, polyurethane, polyvinyl acetate, polyvinyl chloride (PVC), poly(acrylonitrile), poly(tetrahydrofuran) (PTHF), styrene-acrylonitrile, polyethylene terephthalate, polycyclohexylene dimethylene terephthalate, polyhydroxyalkanoates, chlorinated polyethylene, polyimide, polylactic acid, polyphenylene oxide, polyphthalamide
• the aim of the first and the second thermoplastic material, respectively, if present, is to protect the particles of the crosslinking agent and the elastomeric material, respectively, until the point of use, and at that point in time to be able to be removed quickly and efficiently to activate the particles by exposing the interior of said particles, i.e. the particles without a layer of thermoplastic material.
• a preferred thermoplastic material should have a glass transition temperature in the range 80-110° C. which is close to the typical operation temperature of an oil well.
• Encapsulating or coating of particles may be obtained by several techniques, which can be broadly divided into two major groups: Physical and chemical methods.
• Physical methods include air suspension, coacervation phase separation, centrifugal extrusion, spin coating, spray drying and pan coating, whereas solvent evaporation and polymerization are non-limiting examples of methodologies well recognized as chemical processes for coating/encapsulating particles.
• encapsulation is obtained by the solvent evaporation technique, where a coating polymer (PMMA) may be dissolved in a volatile organic solvent that is immiscible with water, such as dichloromethane (DCM), or in a water-soluble solvents, such as THF and/or acetone, whereby the coating polymer (PMMA) will be in the same phase as the cured PDMS particles.
• a mixture of solvents may be used, such as acetone and THF.
• encapsulation is obtained by spin coating.
• the first and second thermoplastic materials are both PMMA.
• PMMA has a glass transition temperature of 90-100° C. which is close to the operation temperature of an oil well. Thereby it is possible, optionally with further addition of energy, to melt the PMMA layer and subject it to shear forces which will remove the protective layer of thermoplastic material.
• PMMA is also degradable by gamma-radiation which will cause “scissioning”, i.e. cutting of the polymer chains of PMMA.
• a further activation method is solvent dissolution, wherein the particles are flushed by a solvent which gradually removes the polymer chains of PMMA. Thus several activation mechanisms may be used, either separately or in combination.
• a minor amount, such as from 1-5% by weight, such as about 3% by weight, of an oil, such as silicone oil, may be added to the thermoplastic material in order to assist the thermoplastic material in the coating of the elastomeric material.
• an oil such as silicone oil
• silicone oil may assist e.g. PMMA in the coating of particles of an elastomeric material, such as PDMS microspheres, due to the high interaction parameter between silicone oil and the elastomeric material, and its non-reactive property.
• PMMA is water resistant and will not swell at the typical temperatures of use.
• the thickness of the layer of the first thermoplastic material is in the range of 0.01-20 ⁇ m, preferably in the range of 0.1-5 ⁇ m.
• the thickness of the layer of the second thermoplastic material is in the range of 0.01-20 ⁇ m, preferably in the range of 0.1-5 ⁇ m.
• the thickness of the outer protective layer of the first and/or second thermoplastic layer is a balance between on the one hand the wish for efficiency of the system, as a consequence of which the thickness needs to be low such that the activation initiates a fast and efficient removal of the protective layer, and on the other hand the desire for a complete coating of the individual particles.
• the thickness of the protective outer layer is too small the particles may very well have unprotected spots which can react prematurely and cause irreversible agglomeration of the particles in the treatment fluid.
• the base fluid is a gas, an aqueous fluid or an oleaginous fluid, preferably water or a hydrocarbon fluid, more preferably water.
• a readily available base fluid material is water in the form of brine.
• Non-limiting examples of a gas to be used as base fluid according to the invention include air, methane or natural gas.
• the treatment fluid further comprises one or more additives conventionally used in the art, such as fillers, flow or viscosity modifiers, anti-foaming agents, suspending agents, dispersing agents, buffers, and surfactants.
• additives conventionally used in the art, such as fillers, flow or viscosity modifiers, anti-foaming agents, suspending agents, dispersing agents, buffers, and surfactants.
• the treatment fluid comprises a filler in the form of e.g. sand, grit or the like which may increase the strength of the treatment fluid.
• the treatment fluid comprises one or more surfactants.
• Surfactants are known in the art and non-limiting examples thereof include sodium dodecyl sulphate (SDS), polyvinyl alcohol (PVA) and surfactants of the PluronicTM series, such as PluronicTM F-108.
• the treatment fluid comprises a viscosity modifier as known in the art.
• Viscosity modifiers include viscosifiers from MI SWACO, such as viscosifiers marketed under the tradenames DUROGELTM and SAFE-VISTM.
• the accelerator is a capsule comprising a core and a coating.
• the core is made of a material suitable as solvent for the first and/or second thermoplastic material.
• the coating is made of a copolymer of the first and/or second thermoplastic material and a polymer compatible with the core material of the capsules.
• the accelerator is an organic solvent.
• organic solvent Non-limiting examples include hydrocarbons such as hexane and heptane and silicone oils, preferably low molecular weight silicone oils such as Dow Corning® OS10, OS20 or OS30.
• the accelerator comprises a catalyst in an organic solvent, such as the solvents mentioned above.
• catalysts include platinum or tin or complexes thereof.
• the accelerator is an inorganic salt, such as CaSO 4 or MgSO 4 , which is encapsulated by a thermoplastic material such as the first and/or second thermoplastic material as defined above.
• a thermoplastic material such as the first and/or second thermoplastic material as defined above.
• the particles of the elastomeric material are present in an amount in the range of 10-75% by volume of the treatment fluid, preferably in the range 25-50% by volume, such as in the range 30-40% by volume.
• a pumpeable solution is generally obtained such that the particles can pass the pump without destruction as well as be delivered at the desired place of use.
• the particles of the crosslinking agent are present in an amount in the range of 0.1-50% by volume of the treatment fluid, preferably in the range 0.5-20% by volume, such as 2-10% by volume.
• a pumpeable solution is obtained such that the particles can pass the pump without destruction as well as be delivered in the right place.
• step iii) the elastomeric material is allowed to crosslink with the addition of energy.
• Energy input is believed to be necessary at least for an initiation of the crosslinking reaction of the elastomeric material.
• said energy is provided in the form of irradiation.
• Irradiation may be provided by means of thermal irradiation.
• Thermal irradiation may penetrate relatively deeply into a formation but may be a relatively slow form of energy input. Thus heat may be supplied or may be present as thermal energy from the ground.
• energy input may be provided by means of electromagnetic or particle radiation.
• the effect of activation by means of particle radiation may be applied relatively fast compared to for instance the effect of activation by means of thermal radiation.
• Radiation may be supplied in the form of ⁇ radiation. Activation may thus be performed by means of supplying an electric current.
• energy input may be provided by a combination of e.g. thermal irradiation and electromagnetic or particle radiation.
• the order of energy required is generally believed to be in the range of 0.1-100 J/g of active silicone, (i.e. the reactive part of the total elastomer mixture excluding any fillers and additives).
• the treatment fluid is prepared by mixing elastomeric material, crosslinking agent and a base fluid and heating to an elevated temperature, such as in the range 60-100° C., preferably in the range 70-80° C. in order to obtain crosslinking of the elastomeric material to obtain a plug thereof.
• a first proportion of treatment fluid comprises particles of the elastomeric material of a particle size in the range 500-1000 ⁇ m
• a second proportion of treatment fluid comprises particles of the elastomeric material of a particle size in the range 10-100 ⁇ m.
• said first and said second proportion of particles of the elastomeric material are provided simultaneously or consecutively to the treatment fluid.
• a tailoring of the fracture to be blocked is more efficiently obtained.
• the latter may fill out any interstices formed between the larger particles in order to obtain an efficient blocking of a fracture.
• a first proportion of treatment fluid comprises particles of the elastomeric material of a particle size in the range 10-100 ⁇ m
• a second proportion of treatment fluid comprises particles of the elastomeric material of a particle size in the range 500-1000 ⁇ m.
• use of the treatment fluid according to the invention is for fracture blocking in an oil drilling well.
• use of the treatment fluid according to the invention is for fracture blocking in sewer drains.
• the method according to the invention may be performed by means of a sealing device for sealing fractures or leaks in a wall or formation surrounding a tube-shaped channel, such as a drain, pipeline or well bore, the sealing device including an elongated body having a longitudinal direction and being adapted to be introduced into the tube-shaped channel, the elongated body including a sealing fluid placement section arranged between a first and a second annular flow barrier adapted to extend from a circumference of the elongated body to the wall or formation surrounding the tube-shaped channel, and the sealing fluid placement section including a sealing fluid outlet port.
• the sealing device is disclosed in more detail in the Applicants' copending patent application of same date entitled “Sealing device and method for sealing fractures or leaks in wall or formation surrounding tube-shaped channel”, EP No. 12194965.5.
• SylgardTM 184 silicone elastomer which is provided from Dow Corning as a two-parts kit of a polydimethylsiloxane (PDMS) elastomer and a “curing agent” comprising a crosslinker were mixed at a ratio of 20:1 at 1000 rpm for 2 mins in order to form a mixture S resulting in an elastomer with excessive amounts of vinyl groups as the “curing agent” was added in deficit (the recommended ratio of SylgaardTM 184 is 10:1 PDMS: curing agent). The bubbles formed were removed from the mixture S with a vacuum pump for 10 mins.
• PDMS polydimethylsiloxane
• mixture S was added to 60 g aqueous solution containing 0.06 g of the surfactant PluronicTM F-108 from BASF, a copolymer consisting of PEG-PPG-PEG, average Mn ⁇ 14,600).
• PluronicTM F-108 from BASF, a copolymer consisting of PEG-PPG-PEG, average Mn ⁇ 14,600.
• the mixture was ultrasonicated for 5 mins to disperse the mixture S in the aqueous solution and cured at 60° C. for 4 h.
• the yield for this process was about 66% of particles with a mean diameter of approximately 1 micrometer.
• 0.272 g of hard silicone microspheres according to example 1.1 were added to 25 ml of 1% polyvinyl alcohol (PVA) solution.
• PVA polyvinyl alcohol
• the aqueous solution was sonicated for 15 min and then let to cool to room temperature.
• 25 ml of a 1.3% PMMA solution in acetone was added to form an oil-in-water emulsion. Agitation was maintained for 2 h and then the solution was rotary evaporated for 20 min, with the temperature being ramped from 20 to 65° C. over this period of time. Later, the vacuum was switched off and the solution was kept at 65° C. for further 40 min. The rotary speed was 260 rpm.
• the dispersion of coated microspheres was cleaned with distilled water and filtered.
• First PDMS microspheres were prepared in a separate step. In order to obtain small partly cured PDMS microspheres with a large surface area with reactive handles the initial speed of mixing was assessed.
• Several PDMS mixtures with different viscosities were prepared by mixing the prepolymer base elastomer and the curing agent in several weight ratios (10:1, 20:1 and 25:1). Then, the resulting mixtures were mechanically stirred and subjected to vacuum for 15 min and finally transferred to a syringe. 1 ml PDMS mixture was poured into 250 ml of an aqueous solution that contained anionic SDS (3% w/w) and polymeric (1% w/w) PVA surfactants.
• the emulsification process was basically divided into a three-step procedure. Firstly, the dispersion was mechanically stirred intensively for approximately 2 min at varying initial speeds (2000, 1200, 800 and 500 rpm, respectively). Secondly, the speed for all procedures was reduced to 500 rpm for 10 min. Finally, the rotation speed was reduced further to 110 rpm and the temperature was increased up to 85° C. for 2 hours for faster curing of the PDMS microspheres. The cured PDMS microspheres were filtered and washed with distilled water.
• 0.3 g of cured PDMS microspheres (20:1) was added to 25 ml of 1% (w/w) PVA solution.
• the aqueous solution was sonicated for 10 min to provide as little aggregation as possible since the spheres physically adhere together.
• the mixture was allowed to cool down to room temperature before adding 25 ml of 1.3% (w/w) PMMA solution in DCM. Agitation was maintained for 2 h.
• the solution was rotary evaporated for 20 min, with the temperature being ramped from 20 to 65° C. during this time, after which the vacuum was switched off and the solution was kept at 65° C. for further 45 min.
• the rotary speed was set to 260 rpm.
• PMMA coated cured PDMS microspheres were washed with distilled water and finally the microspheres were filtered. The same procedure was repeated but replacing DCM with THF and acetone, respectively. Hot plate heating with magnetic stirring was also used instead of the rotavapor to study if the agglomeration of microspheres upon solvent removal could be avoided.
• PMMA was dissolved in DMF to yield a solution of 1%, 3%, or 5% (wt) DMF, and 3% (wt) silicone oil was also dispersed into the solution.
• the polystyrene glass watch was covered with a lid and subjected to a spin coater. Spin coating was performed at 5000 rpm for 1 min with an acceleration of 1000 rpm/s from 0 to 5000 rpm. Then the polystyrene glass watch was inserted into an oven at 80° C. to remove the residual DMF.
• thermogravimetric analysis TGA
• PMMA (1 g) was dissolved in dichloromethane (DCM) (75 ml) and then 2 g of the SylgardTM 184 polydimethylsiloxane elastomer from Dow Corning was added.
• An aqueous surfactant solution (77.5 g of 1% PVA) was prepared and added to a 250 ml conical flask. The aqueous phase was mechanically stirred at 2000 rpm for 2 min, and the oil phase was added over 60 s to form an oil-in-water emulsion. The agitation was kept for 1 h at 1000-750 rpm before pouring the emulsion into a further 120 ml of aqueous surfactant solution (1% PVA).
• the diluted emulsion was rotary evaporated for 25 min (20° C. and 65° C.), after the vacuum was turned off and the dispersion was kept at 65° C. for a further 1 h. The rotary speed was 250 rpm.
• the dispersion of microspheres was filtered by using filtration pump and qualitative filter paper, 413 (particle retention: 5-13 mm). The product was cleaned with distilled water ( ⁇ 1.5 L) and afterwards it was washed three times with heptane.
• PMMA (1 g) was dissolved in dichloromethane (DCM) (75 ml) and then the crosslinking agent HMS-301 (methyl-hydrosiloxane-dimethylsiloxane) from Gelest, Inc., (1.5 g) was added to form an oil phase.
• An aqueous surfactant solution (77.5 g of 1% PVA) was prepared and added to a 250 ml conical flask. The aqueous phase was mechanically stirred at 2000 rpm for 2 min, and the oil phase was added over 60 s to form an oil-in-water emulsion.
• the agitation was kept for 1 h at 1000-750 rpm before pouring the emulsion into a further 120 ml of aqueous surfactant solution (1% PVA).
• aqueous surfactant solution 1% PVA.
• the diluted emulsion was rotary evaporated for 25 min (20° C. and 65° C.) after the vacuum was turned off and the dispersion was kept at 65° C. for a further 1 h.
• the rotary speed was 250 rpm.
• the dispersion of microspheres was filtered by using filtration pump and qualitative filter paper, 413 (particle retention: 5-13 mm). The product was cleaned with distilled water ( ⁇ 1.5 L) and afterwards it was washed three times with heptane.
• microspheres (20:1) according to Example 1.1 were added to 50 ml of 1% PVA solution in a 100 ml beaker. The mixture was sonicated for 15 min and afterwards cooled to room temperature. Then the solution with microspheres was poured into a 250 ml beaker and 50 ml of 1.3% PMMA solution in acetone was added to the mixture with mechanical stirring at 150 rpm. The agitation was kept for 2 hours. After that time the mixture was heated for the next 2 hours (65° C.) on a hot plate in a water bath. The agitation speed remained the same. The microcapsules were left in a fume hood overnight while stirring at room temperature. After that time all acetone had evaporated and only a small amount of water was left. The microspheres did not agglomerate. In the end, the microspheres were filtered and cleaned with deionized water.
• PMMA and the crosslinking agent HMS-301 from Gelest, Inc. were dissolved in dichloromethane (DCM) to provide an oil phase. Then the oil phase was added to equal volumes of surfactant solution, either PVA or PMAA. In some cases acetone was added to the oil phase. While adding the oil phase the emulsion was mechanically stirred at 2000 rpm. After that the speed was decreased to 750 rpm and the emulsion was stirred for another 1 hour. The mixture was then diluted with 120 ml of surfactant solution and DCM was removed by using rotary evaporator. The particles were then washed with deionized water and heptane on a filter paper and dried at room temperature.
• DCM dichloromethane
• the different PMMA coated particles appear from table IV below.

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