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  • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
  • C09K8/60—Compositions for stimulating production by acting on the underground formation
  • C09K8/62—Compositions for forming crevices or fractures
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  • C09K8/60—Compositions for stimulating production by acting on the underground formation
  • C09K8/62—Compositions for forming crevices or fractures
  • C09K8/70—Compositions for forming crevices or fractures characterised by their form or by the form of their components, e.g. foams
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  • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
  • C09K8/60—Compositions for stimulating production by acting on the underground formation
  • C09K8/62—Compositions for forming crevices or fractures
  • C09K8/66—Compositions based on water or polar solvents
  • C09K8/68—Compositions based on water or polar solvents containing organic compounds
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  • C09K8/60—Compositions for stimulating production by acting on the underground formation
  • C09K8/62—Compositions for forming crevices or fractures
  • C09K8/72—Eroding chemicals, e.g. acids
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  • C09K8/60—Compositions for stimulating production by acting on the underground formation
  • C09K8/84—Compositions based on water or polar solvents
  • C09K8/86—Compositions based on water or polar solvents containing organic compounds
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  • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
  • C09K8/60—Compositions for stimulating production by acting on the underground formation
  • C09K8/84—Compositions based on water or polar solvents
  • C09K8/86—Compositions based on water or polar solvents containing organic compounds
  • C09K8/88—Compositions based on water or polar solvents containing organic compounds macromolecular compounds
  • C09K8/882—Compositions based on water or polar solvents containing organic compounds macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
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  • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
  • C09K8/60—Compositions for stimulating production by acting on the underground formation
  • C09K8/84—Compositions based on water or polar solvents
  • C09K8/86—Compositions based on water or polar solvents containing organic compounds
  • C09K8/88—Compositions based on water or polar solvents containing organic compounds macromolecular compounds
  • C09K8/887—Compositions based on water or polar solvents containing organic compounds macromolecular compounds containing cross-linking agents
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  • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
  • C09K8/60—Compositions for stimulating production by acting on the underground formation
  • C09K8/92—Compositions for stimulating production by acting on the underground formation characterised by their form or by the form of their components, e.g. encapsulated material
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH DRILLING; MINING
  • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
  • E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH DRILLING; MINING
  • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
  • E21B43/25—Methods for stimulating production
  • E21B43/26—Methods for stimulating production by forming crevices or fractures
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH DRILLING; MINING
  • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
  • E21B43/25—Methods for stimulating production
  • E21B43/26—Methods for stimulating production by forming crevices or fractures
  • E21B43/267—Methods for stimulating production by forming crevices or fractures reinforcing fractures by propping
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  • C09K2208/00—Aspects relating to compositions of drilling or well treatment fluids
  • C09K2208/08—Fiber-containing well treatment fluids
• • C—CHEMISTRY; METALLURGY
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  • C09K2208/00—Aspects relating to compositions of drilling or well treatment fluids
  • C09K2208/10—Nanoparticle-containing well treatment fluids
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH DRILLING; MINING
  • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
  • E21B43/02—Subsoil filtering
  • E21B43/04—Gravelling of wells

Definitions

• the present invention relates to filamentary polymer particles useful for the recovery of oil, condensate or gas from underground locations as hydraulic fracturing fluids, diverting fluids, fluids to improve the distribution and the flow profiles of fluids or products injected (hereinafter referred to as compliance fluids) or permeability control, gravel filter placement fluids for sand control, acidic fracturing fluids and the like.
• compliance fluids fluids or products injected
• permeability control gravel filter placement fluids for sand control
• acidic fracturing fluids and the like.
• These fluids are stimulation fluids injected into wells that also serve as production wells for the hydrocarbons initially present in the underground formations.
• Fracturing fluids are commonly used today to fracture rocks to allow or increase the communication of fluids between the subterranean formation and the wells. Fluids in the subterranean formation include water containing salts, gases, condensates and oil. Without the use of fracturing fluids, some rocks, which have very low permeability, are unable to produce hydrocarbons, such as those associated with shale oil and shale gas. Some other rocks already produce hydrocarbons, but we want to increase their yield. In order to keep the fractures open, solid particles, the "proppants”, are dispersed in the fluid above the surface and transported to the fractures during a pumping operation. The proppants are conducted and placed between the walls of the fractures.
• the fracturing fluid has a shear thinning behavior: a high viscosity at low shear so that the proppants do not settle in low turbulence areas of the system injection and in the subterranean formation, and a low high shear viscosity to reduce the energy required to pump the fracturing fluid.
• Shear fluidification means the decrease in viscosity under the effect of an increase in the stress, shear and / or deformation that are applied to the studied system.
• Acid fracturing is a technique used to dissolve rocks in order to increase hydrocarbon permeability.
• a solution Viscous water is injected into the subterranean formation to break rocks to create the desired height, width and fracture length.
• the acid is pumped and is introduced into the fracture by digitation to attack the walls of the fracture and create a conductivity of the fracture.
• the fluids are then pumped to the surface with the same well and the pumping of the hydrocarbons begins.
• the acid is normally viscous or gelled or crosslinked or emulsified to maintain the width of the fracture and minimize fluid leakage, with shear thinning behavior.
• the most commonly used fluid for acid fracturing is 15% hydrochloric acid (HCl). To obtain more acid penetration and more etching, a more concentrated HCl solution is sometimes used as the primary acidic fluid.
• formic acid HCOOH
• acetic acid CH 3 COOH
• Hydrofluoric acid HF
• HF Hydrofluoric acid
• Diversion fluids, compliance fluids and permeability control aim to reduce the permeability of certain parts of the underground formation.
• the formations sometimes have interesting zones containing hydrocarbons but with different permeabilities or different volume fractions of water.
• the injected water sometimes finds the fastest path to reach the production wells. that is, it passes through areas with a high water volume fraction in voids and / or high permeability, flowing around other hydrocarbon-rich areas without pushing them to the production wells.
• Compliance fluids and permeability control are injected into such high permeability and / or high water content areas to replace the fluids in place and reduce their water permeability due to their high viscosity.
• High low shear viscosity is required so that slowly moving upstream fluids can not penetrate and low shear viscosity is required to reduce the energy required to pump fluids for compliance and control.
• permeability The diversion fluids are injected into high permeability and / or high water content zones to replace the fluids in place and reduce their permeability to water thanks to their high viscosity.
• High low shear viscosity is required so that laterally injected fracturing fluids that are subsequently injected can not penetrate and low shear viscosity is required to reduce the energy required to pump the diverting fluid.
• a technique consists in placing a gravel filter of specific size in the annular space between the reservoir rock and the production unit.
• the gravel acts as a filter allowing the formation fluids to flow from the formation to the production tube while filtering sand grains and other fines from the formation.
• the gravel filter placement fluid for sand control exhibits shear thinning behavior: high viscosity at low shear so that gravel does not settle in low turbulence areas of the injection system, and a low high shear viscosity to reduce the energy required to pump the placement fluid.
• hydrophilic polymers are added to the water.
• Said polymers include polygalactomannan, guar or polymers derived from guar such as for example carboxymethylguar, hydroxyethylguar, hydroxypropylguar. Examples are given in the following patents: US5305832, US4488975 and US4579670.
• oxygen sensors can be used, such as sodium thiosulfate, methanol, thiourea, sodium thiosulfite.
• Other additives such as pH buffers, wetting agents, foaming agents, corrosion inhibitors, defoamers or anti-corrosion agents foams, scale inhibitors, biocides, crosslinking agents, gel breakers, non-emulsifiers, fluid loss control additives may be used.
• a gas may also be injected to produce gas bubbles in the fracturing fluid, such as nitrogen and carbon dioxide.
• Clays stabilizers are used to prevent swelling and / or dislodgement of clays in the formation.
• the formation contains water that is thermodynamically balanced with the rocks. It therefore contains dissolved salts.
• the cations of these salts are balanced between the aqueous phase and the clays. If the injected water does not contain enough dissolved cations, when it comes into contact with the rocks of the formation, the cations present in the clays of the clays diffuse into the injected water, leaving the leaflets with a reduced cationic charge. As a result, negatively charged leaflets repel each other and clays are said to swell, limiting the permeability that has been created by fractures.
• the injected water contains enough salts to avoid this unbalanced diffusion of cations between water and clays.
• the dissolved salts act on the viscosity of the fracturing fluid.
• the most common clay stabilizers are KCl, NaCl, quaternary ammonium salts such as NH 4 Cl, used at a dose of about 1% to about 5% by weight.
• Water recycling means the treatment of water containing large amounts of salts, such as NaCl, KCl, CaCl 2 , BaCl 2 and the like.
• US20091 1 1716 discloses water-soluble polymers, especially polyelectrolytes which are salt-sensitive in terms of rheology collapse during salt increase, and discloses a solution for increasing the resistance to salts of water.
• water-soluble polymers comprising a water-soluble polymer, zwitterionic surfactants and inorganic salts, and their use as hydraulic fracturing fluid.
• Figure 8 of US20091 1 1716 shows the impact of 5% by weight of KCl on the viscosity of an aqueous 0.3% anionic guar solution as a function of the shear rate.
• Viscosity without KCI is 0.4 Pa.s to 0.5 Pa.s and 0.09 Pa.s is equal to a concentration of 5% by weight of KCI at a shear rate of 0.1 s " 1. The decrease is thus 75%.
• the addition of 2% of a specific surfactant allows an increase in viscosity of 0.35 Pa.s at 0.1 s "1 in the presence of 5% by weight of KCI.
• This patent does not describe the sensitivity of the polymer / surfactant mixture as a function of the concentration of KCl, and the addition of the surfactant is another step to prepare the fracturing fluid.
• PE Dresel and AW Rose (Pennsylvania Geological Survey, Fourth Series, Harrisburg, (2010) pp. 1-12, http://www.marcellus.psu.edu/resources/PDFs/brines.pdf) teach that Formation waters in the oil and gas fields in Pennsylvania are difficult to analyze because the amount produced is sometimes very low, and the data are therefore not available or are of poor quality.
• PE Dresel and AW Rose also teach that the salt content of the formation water can vary widely in Pennsylvania from 7% w / v to 35% w / v and also over short distances from 2 to 3 kilometers, for example for points 19 and 21 on the diagram on page 1 1 for a sodium concentration ranging from 3 g / L to 17.4 g / L and for a calcium concentration ranging from 0.9 g / L at 6.1 g / L. If we consider that sodium and calcium are associated with the chloride which is always the dominant anion, the variations in terms of NaCl and CaCl 2 are respectively 7.5 g / l at 44 g / l and 2, 5 g / L to 16.8 g / L.
• the calculated total amount of dissolved solids varies between 1% and 6.7%. This means that the choice of the salt content of the fracturing fluid is difficult and the current hydraulic fracturing fluid can be below the formation water salinity expressed in terms of total dissolved solids.
• WO2012 / 085415 describes the preparation of specific filamentous particles by controlled radical emulsion polymerization of hydrophobic monomers, using as initiators live macroinitiators derived from nitroxide.
• the particles may be crosslinked.
• US2007213232 also discloses a direct technique for the preparation of filamentous particles which does not require the use of an organic cosolvent. Filamentous polymer aggregates are said to be of increasing attraction, particularly in biomedical applications as systems for drug delivery. These filamentous polymer particles are illustrated with 35 g / L NaCl in water. However, no use for the extraction of oil and gas from underground reservoirs is described.
• WO2012 / 085473 describes the increase in viscosity of the water injected into a well for the improved recovery of hydrocarbons with the aid of specific filamentous polymer particles.
• the injected aqueous phase maintains the pressure in the reservoir and displaces the hydrocarbons to the production wells.
• the particles may be crosslinked.
• the shape and structure of the filamentous polymer particles according to WO2012 / 085473 are maintained in a dispersed medium, regardless of their concentration in the medium, variations in its pH or salinity.
• the example given in FIG. 10 has a NaCl concentration of 35 g / l of water.
• WO2012 / 085473 teaches therefore that the shape and structure of the polymer particles are not modified to a salinity of 35 g / L (3.5%) NaCl.
• the mass fraction of the particles is between 100 ppm and 10,000 ppm (i.e., a maximum of 1%).
• the term "brine" is used, but without definition, and the behavior with a higher amount of salt or different salts and a higher amount of particles is therefore unknown.
• WO2012 / 085473 does not show a change in the rheology as a function of the salt concentration, because it teaches that the shape and the structure are not modified with the salt.
• WO2012 / 085473 claims an improved hydrocarbon extraction process. This means that the rocks already produce hydrocarbons and that the claimed technique increases the yield.
• the method of the invention mentioned above is implemented by means of a polymer additive, said additive being mixed with water or brine in a proportion of at least 500 ppm of additive, and this mixture is then injected under pressure into the rock.
• US8347960 discloses an electrocoagulation treatment above the surface of the return water or source water from a hydraulic fracturing operation to remove contaminants, reuse the water and reduce the transport of water. the water. This process allows the recycling of water for the following hydraulic fracturing operations. However, it is said that chloride and sodium contaminants are not reduced by this process. Other contaminants are extracted from the return water, but must be removed.
• This reduced sensitivity would allow an increase in the salt content, such as for example NaCl, KCl, CaCl 2 , BaCl 2 and / or ammonium salts, in the hydraulic fracturing fluid while maintaining a fluidification behavior. by shearing.
• the density of the fluid would be increased, which would increase the pressure in the underground formation to a constant pumping power and therefore the effectiveness of the fracturing.
• the water of the formation may have different salinities at different locations of the same underground reservoir and since the water of the formation mixes with the hydraulic fracturing fluid, thus changing its salinity, and since the salinity would have a reduced impact on the viscosity of the new hydraulic fracturing fluid at low shear rates (eg 0.1 to 1 s -1 ) compared to conventional fluids, so the viscosity of the new fracturing fluid would have a reduction the ability of the new hydraulic fracturing fluid to carry the proppants into the fractures would be greater and fractures would be maintained at a wider opening or this would reduce the amount of water and fracturing additives needed to obtain the same hydrocarbon quantities and flows (yields).
• low shear rates eg 0.1 to 1 s -1
• the viscosity of the return fluid decreases essentially due to the dilution of the shear thinning additive. It is then necessary to add the missing concentration of the shear thinning additive.
• the viscosity is low when the salinity is high and because of the water dilution of the formation, the relative missing concentration is higher than for the Filamentous polymer particles that have a lower sensitivity to salt.
• the viscosity return fluid decreases due to dilution of the shear thinning additive. But this effect will be limited due to the increase in the salt content from the formation water and which tends to increase the viscosity.
• shear thinning fluid containing gravel in the case of gravel filter placement fluid for sand control
• shear rate viscosity 0.1 s -1 to 1 s
• 1 decreases more slowly than the viscosity of existing fluids, or even increases when its Salt content increases up to 30% with the salts generally found in the water of the formation, at a constant concentration of the shear thinning additive.
• a first object of the present invention is a composition comprising water, dissolved salts, filamentary polymer particles and solid particles.
• the salts may be inorganic salts such as those found in an underground formation water, such as NaCl, KCl, MgCl 2 , CaCl 2 , SrCl 2 , BaCl 2 , or synthetic salts such as ammonium salts.
• the solid particles may be specific solid particles referred to as proppants by those skilled in the art, and are small inorganic particles, e.g. ex. rock particles, such as sand, gravel, coated sand, bauxite, ores, tailings or metal particles.
• the synthesis and structure of the filamentous polymer particles are described in applications WO 2012/085415 and WO 2012/085473 and are indicated hereinafter.
• the weight percentage of the filamentous polymer particles compared to the weight of the composition without the solids and the proppants is between 0.05% and 20%. and the weight percent of the dissolved salts is 0.1% at the salt saturation concentration.
• the present invention relates to a composition
• a composition comprising water, dissolved salts, filamentary polymer particles and dissolved acids, such as those described hereinabove.
• the dissolved salts may be inorganic salts such as those found in an underground formation water, e.g. ex. monovalent and / or bivalent and / or trivalent ions, such as NaCl, KCl, MgCl 2 , CaCl 2 , SrCl 2 , BaCl 2 , or synthetic salts such as ammonium salts.
• the acids are chosen from hydrochloric acid, hydrofluoric acid, formic acid and acetic acid.
• the synthesis and structure of the filamentous polymer particles are described in applications WO 2012/085415 and WO 2012/085473 and are indicated hereinafter.
• the filamentous particles have a length / diameter ratio greater than 100, said particles being composed of block copolymers synthesized by controlled radical emulsion polymerization carried out from at least one hydrophobic monomer in the presence of a soluble macro-initiator in the water.
• said particles are synthesized from at least one hydrophobic monomer in the presence of a living macro-initiator derived from a nitroxide.
• said filamentous particles are obtained in an aqueous medium from the synthesis of said block copolymers carried out by heating the reaction mixture at a temperature of 60 ° C to 120 ° C, with a percentage of the molar mass of the hydrophilic macro-initiator in the final block copolymer of between 10% and 50%, the degree of conversion of the hydrophobic monomer being at least 50%.
• the initial pH of the aqueous medium can vary between 5 and 10. This direct technique for the preparation of filamentous particles does not require the use of an organic co-solvent.
• a "living macro-initiator” is a polymer comprising at least one end suitable for re-engagement in a polymerization reaction by adding monomers at an appropriate temperature and pressure. Said macroinitiator is advantageously prepared by controlled radical polymerization (CRP).
• a "water-soluble macro-initiator” is a polymer which is soluble in water and comprises at its end a reactive function capable of re-initiating a radical polymerization.
• This macro-initiator is mainly composed of hydrophilic monomers, these being monomers comprising one or more functions capable of establishing hydrogen bonds or an ion-dipole interaction with water.
• hydrophilic monomers these being monomers comprising one or more functions capable of establishing hydrogen bonds or an ion-dipole interaction with water.
• an amphiphilic copolymer will be formed, with a hydrophilic sequence composed of the macro-initiator, while the hydrophobic sequence will be obtained by the polymerization of the hydrophobic monomer or monomers.
• said macro-initiator soluble in preformed water is added to the reaction medium comprising at least one hydrophobic monomer.
• said water-soluble macro-initiator is synthesized in the aqueous reaction medium during a preliminary stage, without isolation of the formed macro-initiator and without elimination of any hydrophilic monomer. residual.
• This second variant is a "monotopic" polymerization reaction.
• the hydrophobic monomers may be chosen from the following monomers:
• aromatic vinyl monomers such as styrene or substituted styrenes, alkyl, cycloalkyl and aryl acrylates, such as methyl, ethyl, butyl, 2-ethylhexyl or phenyl acrylates,
• alkyl, cycloalkyl, alkenyl or aryl methacrylates such as methyl, butyl, lauryl, cyclohexyl, allyl, 2-ethylhexyl or phenyl methacrylates, and
• said filamentary polymer particles are obtained:
• the percentage of the molar mass of the water-soluble macro-initiator in the final block copolymer being between 10% and 30%
• the degree of conversion of the hydrophobic monomer being at least 50%
• hydrophobic monomer being chosen from aromatic vinyl monomers
• crosslinking comonomer being optionally used, the crosslinking monomer comprising divinylbenzenes, trivinylbenzenes, allyl (meth) acrylates, diallyl maleate, polyol (meth) acrylates, alkylene glycol di (meth) acrylates which contain from 2 to 10 carbon atoms in the carbon chain, 1,4-butanediol di (meth) acrylates, 1,6-hexanediol di (meth) acrylates and N, N'-alkylenebisacrylamides.
• the crosslinking monomer comprising divinylbenzenes, trivinylbenzenes, allyl (meth) acrylates, diallyl maleate, polyol (meth) acrylates, alkylene glycol di (meth) acrylates which contain from 2 to 10 carbon atoms in the carbon chain, 1,4-butanediol di (meth) acrylates, 1,6-hexan
• reaction medium which mainly comprises water.
• the percentage of the molar mass of the macro-initiator soluble in water in the final block copolymer is preferably between 10% and 30% by weight.
• the implementation of the process according to the invention produces filamentous polymer particles in which the mass fraction of the hydrophilic fraction constituting the block copolymer is less than 25%.
• crosslinked filamentous particles are obtained.
• Said crosslinking agent is a crosslinking comonomer other than the aforementioned hydrophobic monomers.
• a crosslinking comonomer is a monomer which, thanks to its reactivity with the other monomers present in the polymerization medium, is capable of generating a covalent three-dimensional network.
• a crosslinking comonomer generally comprises at least two polymerizable ethylenic functions which, by reacting, are capable of producing bridges between a number of polymer chains.
• crosslinking comonomers may be capable of reacting with the unsaturated hydrophobic monomers during the synthesis of said particles.
• the crosslinking comonomers include divinylbenzenes, trivinylbenzenes, allyl (meth) acrylates, diallyl maleate, polyol (meth) acrylates such as trimethylolpropane tri (meth) acrylates, di (meth) alkylene glycol acrylates containing from 2 to 10 carbon atoms in the carbon chain, such as ethylene glycol di (meth) acrylates, 1,4-butanediol di (meth) acrylates, di (meth) acrylates 1,6-hexanediol and ⁇ , ⁇ '-alkylenebisacrylamides, such as ⁇ , ⁇ '-methylenebisacrylamide.
• Preference will be given to the use of divinylbenzene or dimethacrylate as the crosslinking agent.
• the filamentous particles according to the invention typically have a percentage of the molar mass of the hydrophilic macro-initiator in the final block copolymer of between 10% by weight and 50% by weight.
• these particles may take the form of cylindrical fibers having a length / diameter ratio greater than 100; their diameter is constant over their entire length and is greater than or equal to 5 nm, while their length is greater than 500 nm, preferably greater than 1 ⁇ m, advantageously greater than 5 ⁇ m and, even more preferably, greater than or equal to ⁇ ⁇ ⁇ .
• the filamentary polymer particles are cylindrical fibers having a diameter ranging from 5 nm to 200 nm inclusive, a length ranging from 500 nm to 200 ⁇ m, preferably greater than 1 ⁇ m, advantageously greater than 5 ⁇ m and better still greater than or equal to 10 ⁇ .
• the filamentous particles according to the invention maintain their shape and structure in a dispersed medium, regardless of their concentration in the medium and / or changes in its pH or salinity.
• said filamentous particles are synthesized by addition-fragmentation reversible transfer radical polymerization (RAFT) in water in the presence of a macromolecular RAFT agent (or a macroagent RAFT) which is hydrophilic.
• RAFT addition-fragmentation reversible transfer radical polymerization
• additives may be added such as water-soluble shear thinning polymers such as, for example, polysaccharides, guar, guar derivatives containing hydropropyl, hydroxypropyl, hydroxybutyl, carboxymethyl functions, copolymers containing acrylamide monomers. , partially hydrolysed polyacrylamide, (co) polymers containing (meth) acrylic monomers, oxygen sensors, pH buffers, wetting agents, foaming agents, corrosion inhibitors, defoamers or defoamers, anti-scalers , biocides, crosslinking agents, gel breakers, non-emulsifiers, fluid loss control additives, clay stabilizers.
• a gas may also be injected to produce gas bubbles in the fracturing fluid, such as nitrogen and / or carbon dioxide.
• Another object of the invention is the use of the aforementioned compositions as stimulation fluids for the production of petroleum, a condensate and gas, as hydraulic fracturing fluids, diverting fluids, fluids for compliance or permeability control, gravel filter placement fluid for sand control, acid fracturing fluids.
• the aforementioned filamentous polymer particles used as a shear thinning additive make it possible to obtain solutions with water which are fluidized by shearing and exhibit a viscosity reduction limited to a shear less than or equal to 1 s -1 when the salt content increases to the saturation concentration, or even the viscosity increases depending on the salt used.
• the saturation concentration is defined as the concentration at which the first crystals of These viscosity variations are also of interest for salt concentrations below saturation, for example from 10% by weight to 40% by weight.
• the low sensitivity of the viscosity to variations in salinity at low shear rates (for example less than 1 s -1 ) for the solution containing the filamentous polymer particles makes it possible to increase the content of salts, such as by NaCI, KCI, CaCl 2 , BaCl 2 , and ammonium salts in the hydraulic fracturing fluid while maintaining shear thinning behavior, and the fluid density is increased, which increases the pressure in the fluid. the underground formation with a constant pumping power and consequently the fracturing efficiency.
• the water of the formation may have different salinities at different locations of the same underground reservoir and since the formation of the water mixes with the hydraulic fracturing fluid, thus changing its salinity, and since the salinity has a reduced impact on the viscosity of the new hydraulic fracturing fluid at low shear rates (for example less than 1 s -1 ) in comparison with conventional fluids, whereas the viscosity of the new fracturing fluid has a reduced reduction and therefore, the ability of the new hydraulic fracturing fluid to carry the proppants in the fractures is greater and the fractures are maintained at a wider opening or this reduces the amount of water and fracturing additives required for obtain the same hydrocarbon yield.
• the viscosity of the return fluid essentially decreases because of the dilution of the additive of shear thinning. It is then necessary to add the missing concentration of the shear thinning additive.
• the viscosity decreases due to the increase in the salt content and dilution by water, the relative missing concentration is higher.
• Another object of the present invention is the use of an aqueous composition extracted from a well of a subterranean formation for the preparation of a composition of the present invention for the preparation of a hydraulic fluid for fracturing of an underground formation.
• Another object of the invention relates to a hydraulic fracturing fluid, a diverting fluid, a compliance fluid, a fluid for controlling the permeability, a grit filter placement fluid for sand control, an acidic fracturing fluid containing a composition of the present invention as previously described.
• the invention also relates to the use of a composition of the present invention as previously described as a hydraulic fracturing fluid, as well as a method of fracturing a subterranean formation using said composition according to the present invention.
• This example details the synthesis of a poly (methacrylic acid-sodium styrene co-sulphonate) living copolymer used as a macro-initiator, a regulating agent and a stabilizer for the synthesis of hairy particles in the form of fibrillar micelles.
• This amphiphilic copolymer is synthesized according to a monotopic reaction.
• the synthesis conditions of the macro-initiator can be modified (during the polymerization, sodium styrene sulfonate concentration and pH) to adapt and modify the composition of the macro-initiator.
• BlockBuilder ® -MA (a) SG1 (b) Nitroxide.
• the BlocBuilder MA solution is introduced into a reactor at room temperature with stirring at 250 rpm.
• the monomer solution is slowly introduced into the reactor.
• the reactor pressure is adjusted to 1.1 bar with N 2 , still stirring.
• the temperature is 65 ° C after 15 min.
• a second reactive system containing hydrophilic monomers is introduced at ambient pressure. and 3 bar of N 2 pressure and stirring at 205 rpm are applied. The temperature is set at 90 ° C for the polymerization.
• Table 1 shows the characteristics of a latex sample prepared during the second stage of the synthesis of the nanoparticles.
• the diameter of the fibers measured by transmission electron microscopy MET is 45.3 nm.
• This microscope is JEOL 100 Cx II 100 keV with a high resolution CDD Camera Keen View camera from SIS.
• Filamentous polymer particle solutions are prepared at 40 ° C using tap water and various salts.
• the salt is first introduced into the tap water and then the resulting polymer solution of the synthesis.
• the mixture is stirred gently at 40 ° C for 60 min.
• the mixture is then poured into a Couette device (air gap 2 mm) of an Anton Paar MCR301 rheometer and left to equilibrate at 20 ° C.
• the mixture is then sheared starting at 10 "2 s" 1 and ending at 10 3 sec "1.
• the indicated polymer dosage is the dosage of the polymer without water from the synthesis.
• Example 2 An aqueous composition containing 5% by weight of non-crosslinked filamentous polymer particles
• composition is fluidized by shearing as shown in Figure 1.
• EXAMPLE 3 An aqueous composition containing 5% by weight of non-crosslinked filamentous polymer particles with KCl in comparison with FIG. 8 of US2007213232
• composition with 5% by weight of EG216 is less sensitive to KCl than the mixture EHAC / IPA at 4.5% by weight.
• EHAC / IPA at 4.5% by weight
• the viscosity begins to decrease at a dose greater than 3% by weight of KCl.
• Example 4 Aqueous compositions containing 5% by weight of non-crosslinked filamentous polymer particles with or without CaCl 2 or with BaCl 2 .
• the aqueous solution of uncrosslinked filamentous polymer particles ECL 13-04 is prepared in the same manner as EG 216 previously.
• ECL 13-04 makes it possible to maintain a constant or increase the viscosity at a low shear rate with amounts up to 40% of salt, depending on the salt. This effect is not taught or even suggested by WO 2012/085415 and WO 2012/085473.
• EXAMPLE 5 An aqueous composition containing 5% by weight of filamentous polymer particles crosslinked with 4% KCl and 15% ethylene diamine tetraacetic acid (EDTA)
• EG227 can be considered as a covalent polymer due to crosslinking, such as guar and its derivatives.
• crosslinking such as guar and its derivatives.
• the viscosity of EG227 increases with the addition of a salt, contrary to what is taught in US20091 1 1716 with respect to polyelectrolytes.
• Example 6 Aqueous compositions containing 0.3% by weight of crosslinked filamentous polymer particles of the aqueous composition ECLR5-13.06, or with KCI, in comparison with US20091 1 1716
• anionic guar + 2% BET-O-30 + 5% KCl + tap water 0.35 (US20091 1 1716 Fig. 8)
• the anionic guar is useful with tap water to produce a hydraulic fracturing fluid that suspends solids. But once this fluid has come into contact with a saline underground formation water, it can lose its viscosity due to the increase of salts (-75% if the concentration of KCl is 5% by weight in water ) and dilution with water and therefore part of its ability to carry proppants in areas with such a salt content.
• Example 7 An aqueous composition containing 5% by weight of crosslinked filamentous polymer particles of the aqueous composition ECLR5-13.06 and BaCI 2 or CaCl 2
• the viscosity with 5% ECLR5-13.06 and 40% CaCl 2 or BaCl 2 is greater than that in tap water. It allows hydraulic fracturing in areas with high salinity, ie greater than 5% of total dissolved solids, more preferably greater than 10% of total dissolved solids. In addition, it facilitates the use of return water, which often has a high salinity and is pumped to the surface after a fracturing operation. Its high salinity is indeed not harmful for use as a new hydraulic fracturing fluid with the filamentous polymer particles of the invention. The water The surface area is thus saved and replaced by the formation water in the hydraulic fracturing fluid.
• PNaA poly sodium acrylate
• BlockBuilder®-MA is (/ V- (2-methylpropyl) -N- (1-diethylphosphono-2,2-dimethylpropyl) -O- (2-carboxylprop-2-yl) hydroxylamine, available from Arkema.

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