FRACTURING FLUIDS BASED ON ASSOCIATIVE POLYMERS AND LABILITY SURFACTANTS

Description

[0001] The present invention relates to the field of fracturing techniques used in the context of oil extraction.

[0002] Hydraulic fracturing is a technique commonly used in the field of oil and gas recovery in hydrocarbon reservoirs, which aims to create fractures within the reservoir to increase the exchange interfaces between the extraction fluids and the hydrocarbons contained in the reservoir.

[0003] Fracturing generally involves the injection under high pressure of aqueous fracturing fluids comprising polymers giving the fluid a high viscosity. The injection of these fluids into hydrocarbon reservoirs (the term hydrocarbon reservoir includes, in the sense of the present description, in particular reservoir rocks) generally involves the implementation of considerable pressures which, on the one hand, involve energy expenditure in terms of pumping and on the other hand can degrade the polymers under the effect of shearing. Indeed, typically, a fracturing fluid is injected from the surface into a hydrocarbon reservoir over distances of the order of a few thousand meters.

[0004] GB 2 383 355 A and US2006 / 128846 describe aqueous treatment fluids comprising a hydrophobically modified hydrophilic polymer combined with a surfactant.

[0005] An aim of the present invention is to provide fracturing fluids based on viscosifying polymers which have an effectiveness similar to known fluids, but which are more easily injectable, by making it possible, among other things, to reduce the energy required for their injection, and for which the phenomena of degradation of the viscosifying polymers under shear are preferably reduced or even zero.

[0006] For this purpose, the present invention proposes a new type of fracturing fluid, which comprises, in an aqueous medium: (i) associative polymers which are intrinsically capable of increasing the viscosity of the aqueous medium, or even of gelling it; and (ii) at least one labile surfactant carrying a cleavable function which is an ester function present in an amount sufficient to reduce or inhibit the viscosity-increasing effect induced by said associative polymers during injection and which degrades after injection under the temperature and pH conditions of the hydrocarbon reservoir into which it is introduced, whereby the viscosity of the fluid increases after injection.

[0007] More specifically, according to a first aspect, the present invention relates to a fracturing fluid comprising, in an aqueous medium: an associative polymer; and a labile surfactant carrying a cleavable function which is an ester function in an amount sufficient to reduce or inhibit the viscosity increasing effect induced by said associative polymers; in which the labile surfactant has the following formula: wherein the associative polymer comprises a hydrophilic backbone and includes, along the chains and / or at all or part of the ends thereof, quantities of the order of 0.001% to 10% by mole of hydrophobic functions; wherein the associative polymer is present at a level of 0.1% to 3% by mass relative to the total mass of the fracturing fluid; and wherein the associative polymer and the concentration of the labile surfactant are chosen so that the viscosity of the fracturing fluid is kept reduced during the injection of the fracturing fluid to an area where fracturing is to be carried out, the viscosity being kept reduced relative to the viscosity that the fracturing fluid would have without the labile surfactant.

[0008] According to another aspect, the invention relates to the use of the aforementioned fluids as fracturing fluid. In this context, the invention relates in particular to a method for recovering hydrocarbons in a hydrocarbon reservoir, comprising a step where a fracturing fluid of the aforementioned type is injected into a hydrocarbon reservoir where the temperature and / or pH conditions are suitable for lysing all or part of the labile surfactant.

[0009] For the purposes of the present description, the term "associative polymer" means a polymer capable of increasing the viscosity of an aqueous medium by associations involving hydrophobic-hydrophobic interactions between the polymers. Such polymers are also sometimes referred to as "water-soluble, hydrophobically associative polymers" (PHA) or even "amphiphilic polymers". In the context of the definition according to claim 1, these are polymers comprising a hydrophilic backbone and including, along the chains and / or at all or part of the ends thereof, quantities of the order of 0.001% to 10% by mole, and generally a few mole percent at most, of hydrophobic functions.When such polymers are placed in an aqueous medium, they form, in a manner known per se, hydrophobic bonds (the hydrophobic functions group together to reduce the energy of the system, in the same way that surfactant micelles form in an aqueous medium).

[0010] Furthermore, the concept of "labile surfactant" (or "cleavable surfactant" in English) here designates a surfactant which is capable of lysing, typically by cleaving into two distinct molecules, under pH and temperature conditions where at least a portion of the associative polymers with which it is associated in the composition are not degraded. The cleavable surfactants used according to the invention are surfactants carrying a cleavable function which is an ester function, which degrade after injection, under conditions where the associative polymers are not degraded. Labile surfactants of this type are well known in the literature. For further details, reference may be made in particular to "Cleavable surfactants" Alireza Tehrani-Bagha, Krister Holm.

[0011] The specific use of a labile surfactant gives the fracturing fluid according to the invention the advantages of known fracturing fluids while overcoming their disadvantages. Indeed, due to the presence of this labile surfactant, the fracturing fluid has, when injected, a reduced viscosity which facilitates its injection, and the viscosity is restored in the area where the fracturing is to be carried out.

[0012] The reduction in viscosity obtained by the presence of the labile surfactant makes it possible to significantly reduce the phenomena of pressure loss and, in the case where polymers sensitive to degradation are used, a reduction in the degradation of the polymers under shear.

[0013] Furthermore, the nature of the associative polymers present in the fracturing fluids of the present invention is highly modulatable.

[0014] In particular, according to an interesting embodiment, the fracturing fluids of the invention can advantageously comprise, as associative polymers, amphiphilic polymers of relatively low molecular weight (for example less than 1,000,000 g / mol, or even 500,000 g / mol, for example less than 100,000 g / mol) which make it possible to induce high viscosities after lysis of the labile surfactant, and this from relatively low concentrations, and which are furthermore less sensitive to degradation under shear than larger polymers.

[0015] In practice, almost all associative polymers can be used according to the invention. In this regard, it should be noted that in addition to the aforementioned advantages, the labile surfactant present in the compositions of the invention makes it possible to improve the hydration of the polymers in an aqueous medium, which makes it possible to use in the compositions of the invention any type of associative polymer, including those known to be the least hydratable. The invention thus opens the way to the use of numerous amphiphilic polymers in fracturing liquids.

[0016] Given the wide range of polymers that can be used in combination with the surfactants as defined in claim 1 within the scope of the invention, the fracturing method described here is extremely flexible. By making a suitable choice of polymer, it is possible to provide according to the invention both fracturing fluids for which a high viscosity will be recovered after only a few meters and fluids for which the viscosity remains low up to the fracturing zone.

[0017] It is possible to finely modulate the behavior of the fracturing fluid to adapt the evolution of its viscosity along the injection zone. Depending on the polymer and surfactant used, it is within the skills of the person skilled in the art to adapt the concentrations of the two compounds to obtain the desired viscosity evolution profile. Before the lysis of the labile surfactants, the associative polymers and the surfactants interact according to a known mechanism, described in particular in " Interactions between hydrophobically modified polymers and surfactants" B. Magny, I. Iliopoulos, R. Audebert, L. Piculell, B. Lindman Progress in Colloid & Polymer Science Volume 89, 1992, pp 118-121.

[0018] The interactions between associative polymers and surfactants vary in a known manner depending on the surfactant content. When a very small amount of surfactant is added, this small amount of surfactant increases the number of hydrophobic bonds, which increases the viscosity. At low surfactant content, the viscosity thus increases to a maximum as more surfactant is added. Beyond the limiting surfactant content for which this maximum is observed, the trend is reversed and the addition of surfactant, on the contrary, causes the interactions between the polymers and therefore the viscosity to decrease more and more. For any pair of surfactant and polymer, there is a minimum surfactant concentration beyond which a systematic decrease in viscosity is obtained, this minimum concentration being very easy to determine.

[0019] According to the first aspect of the present disclosure, the associative polymer and the concentration of the labile surfactant are chosen so that the viscosity of the fracturing fluid is kept reduced when injecting the fracturing fluid to an area where fracturing is desired to be carried out, the viscosity being kept reduced relative to the viscosity that the fracturing fluid would have without the labile surfactant.

[0020] In addition to the aforementioned advantages, the associative polymers used in the context of the present invention generally induce rheological properties of the fracturing fluid which make it suitable for ensuring effective control of the fracturing.

[0021] The particular rheology of the fracturing fluids of the invention are also generally very well suited to effectively conveying suspended proppants. These proppants are particles intended to consolidate and keep fractures open by sliding into them during their formation (they are typically calibrated sand).

[0022] Furthermore, the associative polymers used in the fracturing fluids of the invention have the advantage of being able to be used in the presence of salts (the presence of salts generally improves their associative character), which allows the use of water immediately available in the environment close to the extraction zone without having to worry about its purity or its salt content. The associative polymers of the invention constitute in this respect an interesting alternative to the polymers usually used in fracturing of the polysaccharide type (such as guars crosslinked with borate or zirconate, for which the quality of the water used is decisive).Thus, in particular, the invention lends itself well to the formulation of fracturing fluids based on seawater or production water and more generally any water which may contain salts (including at high contents of up to 25% by mass and / or with significant hardnesses of up to Mg 2+< and Ca 2+< contents of the order of 5000 ppm): according to a particular embodiment, the fracturing fluid of the invention comprises seawater or production water as aqueous medium.

[0023] Various features and more specific embodiments of the invention will now be explained in more detail: associative polymers :

[0024] The polymers employed according to the invention may vary to a fairly wide extent, provided that they fall within the definition of claim 1.

[0025] They may for example be chosen from the polymers described in US4529523, US4432881, US4814096, WO 85 / 03510, US4702319, US4709759, US4638865, US4780517, US4852652 or US4861499. More generally, they may be associative polymers based on a hydrophilic skeleton carrying hydrophobic groups of the type obtained by the HASE type synthesis routes (direct synthesis route) or the HEUR type (post addition of hydrophobic groups on a hydrophilic chain). Examples of synthesis of this type are described in particular in Prog. Color Colorants Coat. Vol 4, pp. 71-77 (2011).

[0026] It is also possible to use associative polymers resulting from so-called "micellar radical polymerization" processes of the type described in US 4,432,881 or even in Polymer, vol. 36, No. 16, pp. 3197-3211 (1996), to which reference may be made for further details, by copolymerization of hydrophilic monomers and hydrophobic monomers within an aqueous dispersing medium (typically water or a water / alcohol mixture) which comprises: hydrophilic monomers in the solubilized or dispersed state in said medium; and hydrophobic monomers within surfactant micelles formed in said medium by introducing this surfactant therein at a concentration greater than its critical micelle concentration (cmc).

[0027] According to a particular embodiment, the hydrophobic monomers present within micelles of surfactants used in micellar polymerization may be monomers which, in themselves, have the property of forming micelles without the need to add additional surfactants (so-called "self-micellizable" monomers in the remainder of the description). According to this particular embodiment, the surfactant used may be the self-micellizable hydrophobic monomer itself, used without any other surfactant, although the presence of such an additional surfactant is not excluded. Thus, within the meaning of the present description, when mention is made of hydrophobic monomers within micelles of surfactants, this notion encompasses both (i) hydrophobic monomers present within micelles of surfactant other than these monomers and (ii) monomers comprising at least one hydrophobic part or block and forming the micelles by themselves in an aqueous medium.The two aforementioned modes (i) and (ii) are compatible and can coexist (hydrophobic monomers within micelles formed by another self-micellizable monomer for example, or even micelles comprising a combination of surfactants and self-micellizable monomers).

[0028] In micellar polymerization, the hydrophobic monomers contained in the micelles are said to be in "micellar solution". The micellar solution referred to is a micro-heterogeneous system which is generally isotropic, optically transparent and thermodynamically stable. According to an interesting embodiment, the associative polymers used according to the present invention are polymers obtained according to a process which comprises a step (E) of micellar radical polymerization in which the following are brought into contact, within an aqueous medium (M): hydrophilic monomers, solubilized or dispersed in said aqueous medium (M); hydrophobic monomers in the form of a micellar solution, namely containing, in the dispersed state within the medium (M), micelles comprising these hydrophobic monomers (this dispersed state being able in particular to be obtained using at least one surfactant); at least one radical polymerization initiator, this initiator typically being water-soluble or water-dispersible; and at least one radical polymerization control agent.

[0029] The aqueous medium (M) used in step (E) is a medium comprising water, preferably at least 50% by mass, or even at least 80%, for example at least 90%, or even at least 95%. This aqueous medium may optionally comprise solvents other than water, for example a water-miscible alcohol. Thus, the medium (M) may be, for example, a hydroalcoholic mixture. According to a possible variant, the medium (M) may comprise other solvents, preferably in a concentration where said solvent is miscible with water, which may in particular make it possible to reduce the quantity of stabilizing surfactants used. Thus, for example, the medium (M) may comprise pentanol, or any other additive making it possible to modulate the aggregation number of the surfactants. Generally, it is preferable that the medium (M) is a continuous phase of water and consisting of one or more solvents and / or additives miscible with each other and in water in the concentrations where they are used.

[0030] By "radical polymerization control agent", For the purposes of the present description, this means a compound capable of extending the lifetime of the growing polymer chains in a polymerization reaction and of giving the polymerization a living or controlled character. This control agent is typically a reversible transfer agent as used in controlled radical polymerizations designated under the terminology RAFT or MADIX, which typically implement a reversible transfer process by addition-fragmentation, such as those described for example in WO96 / 30421, WO 98 / 01478, WO 99 / 35178, WO 98 / 58974, WO 00 / 75207, WO 01 / 42312, WO 99 / 35177, WO 99 / 31144, FR2794464 or WO 02 / 26836.

[0031] According to an interesting embodiment, the radical polymerization control agent used in step (E) is a compound which comprises a thiocarbonylthio group -S(C=S)-. Thus, for example, it may be a compound which comprises a xanthate group (carrying -SC=SO- functions), for example a xanthate. A suitable xanthate is Rhodixan A1 available from Solvay. Other types of control agent may be envisaged (for example of the type used in CRP or ATRP).

[0032] According to a particular embodiment, the control agent used in step (E) may be a polymer chain resulting from a controlled radical polymerization and carrying a group capable of controlling a radical polymerization (polymer chain known as "living" type, of a type well known per se). Thus, for example, the control agent may be a polymer chain (preferably hydrophilic or water-dispersible) functionalized at the end of the chain by a xanthate group or more generally comprising a -SC=S- group, for example obtained according to the MADIX technology.

[0033] Alternatively, the control agent used in step (E) is a non-polymeric compound carrying a group ensuring the control of radical polymerization, in particular a thiocarbonylthio group -S(C=S)-.

[0034] According to a particular variant, the radical polymerization control agent used in step (E) is a polymer, advantageously an oligomer, of a water-soluble or water-dispersible nature and carrying a thiocarbonylthio group -S(C=S)-, for example a xanthate group -SC=SO-). This polymer, capable of acting both as a polymerization control agent and as a monomer in step (E), is also designated by "pre-polymer" in the remainder of the description. Typically, this pre-polymer is obtained by radical polymerization of hydrophilic monomers in the presence of a control agent carrying a thiocarbonylthio group -S(C=S)-, for example a xanthate.Thus, for example, according to an interesting embodiment which is illustrated at the end of the present description, the control agent used in step (E) can advantageously be a pre-polymer carrying a thiocarbonylthio group - S(C=S)-, for example a xanthate group - SC=SO-, obtained at the end of a step (E 0< ) of controlled radical polymerization prior to step (E). In this step (E 0< ), it is typically possible to bring into contact hydrophilic monomers, advantageously identical to those used in step (E); a radical polymerization initiator; and a control agent carrying a thiocarbonylthio group - S(C=S)-, for example a xanthate.

[0035] The implementation of the aforementioned step (E 0< ) prior to step (E) makes it possible, schematically, to hydrophilize a large number of control agents carrying thiocarbonylthio functions (for example xanthates, which are rather hydrophobic by nature), by converting them into soluble or dispersible prepolymers in the medium (M) of step (E). Preferably, a prepolymer synthesized in step (E 0< ) has a short polymer chain, for example comprising a chain of less than 50, or even less than 25 monomer units, for example between 2 and 15.

[0036] Unexpectedly, it turns out that the conditions of step (E) make it possible to combine the advantages of both controlled radical polymerization and micellar polymerization. In this context, the inventors have now demonstrated in particular that the presence of micelles in the polymerization medium does not affect the action of the control agents, which make it possible to carry out a controlled polymerization of the monomers present in the aqueous medium in a manner similar to a controlled radical polymerization carried out in a homogeneous medium, which makes it possible to predict and control very easily the average molar mass of the synthesized polymer (this mass is all the higher as the initial concentration of control agent in the medium is low, this concentration dictating the number of growing polymer chains).At the same time, the presence of the control agent also does not harm the interesting effect observed in polymerization, namely the precise control of the size of the hydrophobic blocks.

[0037] In addition to this control of the polymerization of the monomers, not obtained in the more usual micellar polymerization processes, the implementation of step (E) of the process of the invention also makes it possible, in a completely surprising manner, to access polymers of both large and controlled size, which is particularly unexpected in view of the maximum sizes that can be obtained today by using controlled radical polymerization methods or micellar radical polymerization in the absence of control agents.

[0038] Under the conditions of step (E), it proves possible to control the number-average molar mass of the polymers, which makes it possible, among other things, to produce polymers of low mass.

[0039] According to an interesting embodiment, the associative polymer present in the fracturing fluid of the invention is synthesized according to the aforementioned step (E) and has a mass of between 50,000 and 10,000,000, preferably between 750,000 and 5,000,000 g / mol, in particular between 1,000,000 and 4,000,000 g / mol. Typically, such polymers can be used in a concentration lower than their critical coverage concentration. Due to their small sizes, such polymers can diffuse to the interfaces and participate in modifying the properties of these interfaces or surfaces.

[0040] Whatever its nature, the associative polymer of the fracturing fluids according to the invention is present at a level of 0.1% to 3%, preferably between 0.2% and 1.5%, preferably between 0.3% and 1%, by mass relative to the total mass of the fracturing fluid. labile surfactants :

[0041] The labile surfactants used in the context of the invention are surfactants which have groups having an affinity for the hydrophobic groups present on the associative polymers and on the other hand hydrophilic chains. Advantageously, these are water-soluble surfactants.

[0042] Furthermore, these are compounds carrying a cleavable function. This cleavable function is advantageously an ester function.

[0043] The labile surfactants present in the fracturing fluids of the invention are non-ionic surfactants. They may also be surfactants having the structure of non-ionic surfactants, but possibly carrying functionalized groups, possibly charged, at the chain end.

[0044] The labile surfactant used in the fracturing fluid according to the first aspect is Alkamuls PSML20 (also called polysorbate 20), with the following formula:

[0045] This compound is available from Solvay. other compounds possibly present in the fracturing fluid of the invention : pH control agent(s)

[0046] In combination with labile surfactants carrying an ester cleavable function, the fracturing fluid may comprise pH regulating or controlling agents, in particular buffers, bases or acids. Depending on the desired viscosity evolution profile, the pH range will preferably be close to neutral (between 6 and 8, more preferably between 6.5 and 7.5 if the viscosity is desired to increase slowly. Conversely, the conditions will be acidic (for example less than 4, or even 3) or basic (above 9, or even 10) if a more rapid increase in viscosity is desired. « Breakers »

[0047] According to an interesting embodiment, the injected composition may further comprise one or more amphiphilic compounds called “breakers”, capable of lowering the viscosity in the fractured zones, after the fracturing has been carried out.

[0048] These breakers are typically non-labile surfactants introduced into the formulation in an encapsulated form. One can notably use surfactants in the form of granules that are coated with a protective film of wax, typically by fluidized bed coating.

[0049] When the fracturing fluid contains breaker-type surfactants in encapsulated form, these are generally ineffective until the end of the fracturing operation (they are simply carried by the fracturing fluid, and their encapsulation makes them initially chemically inert). After the pressure injection of the fracturing fluid has stopped, the capsules are found in the fractures, where they are subjected to the pressure of the fracture which tends to close, and they are "crushed", particularly when proppants are present. This induces a release of the surfactants, which then become capable of interacting with the associative polymers to reduce viscosity.The presence of such breakers thus allows the fractures to be freed from the gelled composition it contains following fracturing (thus, the increase in viscosity (formation of a gel) only occurs punctually during fracturing, namely between the lysis of the labile surfactant and the release of the non-labile surfactant, which further minimizes the pumping energy. Another advantage is that this reduces the time before the well is put into production.

[0050] The invention will now be illustrated by the following example. EXAMPLE Synthesis of an associative polymer (polyacrylamide / AMPS / LMA 2000,000 g / mol)

[0051] In a 500 mL flask, 29.3 g of a 30% SDS solution, 89.03 g of distilled water, 1.66 g of lauryl methacrylamide (LMA monomer) were introduced at room temperature (20°C). The mixture was stirred using a magnetic bar for 6 hours, until a clear micellar solution was obtained.

[0052] In a 250 mL flask, 32.9 g of the micellar solution thus prepared, 7.53 g of water, 40.7 g of acrylamide (50% by mass aqueous solution), 32 g of AMPS (51% by mass aqueous solution), 0.454 g of Rhodixan A1 (1.0% by mass ethanolic solution) and 6.00 g of ammonium persulfate (0.67% by mass aqueous solution) were introduced at room temperature (20°C). The mixture was degassed by bubbling nitrogen for 20 minutes. 1.5 g of sodium formaldehyde sulfoxylate, in the form of a 0.13% by mass aqueous solution, was added to the medium all at once. The mixture was degassed by bubbling nitrogen for 15 minutes.

[0053] The polymerization reaction was then allowed to proceed with stirring for 16 hours at room temperature (20°C). viscosity reduction by addition of labile surfactant

[0054] The previously prepared polymer was dissolved at 0.5% by mass in polymer in an aqueous solution of NaCl at 15% by mass in the presence of labile surfactant Alkamuls PSML20 at different concentrations.

[0055] For each concentration, the viscosity of the mixture was measured at 80°C using an AR2000 rheometer (TA Instrument, Surrey, Great Britain), equipped with Couette-type geometry. The results are reported in the table below: concentration (ppm) viscosity at 1s-1 (mPa.s) 0 3430 50 1140 100 360 250 168 500 48 1000 10

[0056] The decrease in viscosity by adding labile surfactant is highlighted here beyond 500 ppm. hydrolysis of the labile surfactant - effect on viscosity

[0057] The polymer of Example 1 was dissolved at 0.5% wt in 15% NaCl in the presence of 0.5% Alkamuls PSML20. Sodium hydroxide is added to obtain a concentration of 83mmol / L. The viscosity of the solution thus obtained is 10cP at 25°C (at 1s -1< ).

[0058] The solution was placed in an oven at 80°C for 16 h. At the end of this treatment, the viscosity of the solution was measured to be 4200cP at 1s -1< (compared to 3600cP for a surfactant-free polymer solution obtained after hydration by heating for 4 h at 80°C).

Claims

1. Fracturing fluid comprising, in an aqueous medium: - an associative polymer; and - a labile surfactant bearing a cleavable function that is an ester function, in an amount sufficient to reduce or inhibit the effect of increasing the viscosity induced by said associative polymer; wherein the labile surfactant is of the following formula: wherein the associative polymer comprises a backbone of hydrophilic nature and includes, along the chains and / or at all or some of the ends thereof, amounts of the order of 0.001 mol% to 10 mol% of functions of hydrophobic nature, wherein the associative polymer is present in an amount of 0.1% to 3% by weight relative to the total weight of the fracturing fluid, and wherein the associative polymer and the concentration of the labile surfactant are chosen so that the viscosity of the fracturing fluid is kept reduced during the injection of the fracturing fluid to a zone where it is desired to carry out the fracturing, the viscosity being kept reduced compared to the viscosity that the fracturing fluid would have without the labile surfactant.

2. Fracturing fluid according to claim 1, wherein the associative polymer is obtained according to a preparation process that comprises a step (E) of micellar radical polymerization in which the following are placed in contact, in an aqueous medium (M): - hydrophilic monomers, dissolved or dispersed in said aqueous medium (M); - hydrophobic monomers in the form of a micellar solution, containing, in the dispersed state within the medium (M), micelles comprising these hydrophobic monomers, this dispersed state being optionally obtained using at least one surfactant; - at least one water-soluble or water-dispersible radical polymerization initiator; and - at least one radical polymerization control agent.

3. Fracturing fluid according to claim 2, wherein the radical polymerization control agent used in step (E) is a compound which comprises a thiocarbonylthio group -S(C=S)-.

4. Fracturing fluid according to claim 3, wherein the polymerization control agent used in step (E) is a xanthate.

5. Fracturing fluid according to any one of claims 1 to 4, wherein the associative polymer is present in an amount of 0.1% to 3% by weight relative to the total weight of the fracturing fluid.

6. Process for recovery of hydrocarbons in a hydrocarbon reservoir, comprising: - a step of injecting a fracturing fluid according to one of claims 1 to 5 into a hydrocarbon reservoir where the temperature and / or pH conditions are suitable for lysing all or some of the labile surfactant.

7. Use of the fracturing fluid according to any one of claims 1 to 5 as a fracturing fluid, comprising the penetration of the fluid into the zone where it is desired to carry out the fracturing and the lysis of the labile surfactant.