IMPROVED FOAMING FORMULATIONS FOR OIL RECOVERY.

Abstract

The invention relates to a composition comprising, in an aqueous medium, at least one ethoxylated alkylamine and at least one amphoteric or bipolar surfactant. The invention further relates to the use of such compositions as foaming agents, particularly for enhanced oil recovery.

Description

IMPROVED FOAMING FORMULATIONS FOR OIL RECOVERY The present invention relates to the enhanced recovery of crude oil from underground formations, particularly carbonate-based formations, and more specifically to improved oil recovery techniques using foaming compositions. During oil extraction from a hydrocarbon reservoir (an oil reservoir such as a rock formation), the first step, called primary recovery, involves extracting oil from a production well using the natural overpressure within the reservoir. This primary recovery only allows access to a small amount of the oil contained in the reservoir, typically around 10 to 15% at most. To allow for the continued extraction of oil after this primary recovery, secondary production methods are employed when reservoir pressure becomes insufficient to displace the oil still in place. Typically, a fluid (such as produced water reinjection, diluted or undiluted, seawater or river water injection, or even gas injection) is injected into the hydrocarbon reservoir to create sufficient excess pressure to drive the oil toward the production well(s). A common technique in this context is water injection (also called flooding or water injecting) or gas injection (gas injection), in which large volumes of water or gas, respectively, are injected under pressure into the reservoir via injection wells. This injection induces the entrainment of some of the oil by the water or gas toward one or more production wells.Secondary production methods such as water or gas injection, mentioned above, however, allow for the extraction of only a relatively small portion of the hydrocarbons in place (typically around 30%). This partial sweep is due in particular to oil entrapment by capillary forces, differences in viscosity and density between the injected fluid and the hydrocarbons in place, as well as heterogeneities at micro- or macroscopic scales (at the pore scale and also at the reservoir scale). To try to recover the rest of the oil, which remains in underground formations after the implementation of primary and secondary production methods, several techniques called enhanced oil recovery (or enhanced hydrocarbon recovery RAH), more commonly known as EOR (for its acronym Enhanced OR Recovery - Enhanced Oil Recovery), have been proposed. Among the EOR techniques, some use compositions QCQcnn / zznza / YiAi capable of forming foams. These techniques can use preformed foams before their injection into a hydrocarbon reservoir or alternatively foaming compositions capable of forming a foam in situ in the underground formation where they are injected, in the presence of a gas (post-injected coo) or present in the underground formation). The use of foams or foaming compositions in oil recovery (OOR) is primarily aimed at maximizing the sweep of the underground formation, particularly to access less accessible zones that would be poorly or not at all swept by non-foaming compositions. The use of foams or foaming compositions is especially advantageous in naturally fractured reservoirs. These naturally fractured reservoirs are distinguished from conventional reservoirs, which may have some fractures, by the density and dimensions of the fractures, which form a true network, thus creating a particularly complex oil recovery challenge. Typically, the foaming agents used in oil extraction and resuspension (OER) comprise anionic surfactants. Although relatively effective in general, these anionic surfactants have limitations when used in certain hydrocarbon reservoirs, particularly carbonate-based formations: in fact, when anionic surfactants are used in carbonate-based formations, they tend to interact Qcocnn / zznz / a / γΐΛΐ strongly with carbonates and therefore must be retained within the reservoir. In general, the use of cationic surfactants does not prove to be an acceptable alternative to anionic surfactants in this context: it is true that cationic surfactants have a lower affinity for carbonates, but the foams formed from these cationic surfactants are generally very unstable, especially at high temperatures. An objective of the present invention is to provide suitable foaming compositions particularly for EOR operations in carbonate-based hydrocarbon reservoirs (naturally fractured or not) and this in particular at relatively high temperatures, typically between 80 and 120°C. For this purpose, foaming compositions of a particular type are proposed according to the present invention, comprising at least one cationic surfactant (more precisely cationic surfactant) of a specific type, namely, of the ethoxylated alkylamine type, which is also used in combination with at least one amphoteric or bipolar surfactant. More precisely, according to a first aspect, the present invention relates to a composition C, suitable as a foaming composition, particularly suitable for EOR, comprising, in an aqueous medium M: Qcocnn / zznz / a / γΐΛΐ at least one ethoxylated alkylamine and at least one amphoteric or bipolar surfactant. The inventors have now established that, although based on cationic surfactants, the particular foaming compositions of the invention surprisingly allow the formation of stable foams, even at relatively high temperatures, particularly between 80 and 120°C and in the presence of hydrocarbons. In this context, it turns out that the bipolar surfactant used according to the present invention induces the same type of advantages as in the case of foams based on anionic surfactants and surfactants such as betaines known in the prior art. Very high foam stability is obtained according to the invention. This effect is much more unexpected in the case of the compositions of the invention, which are based on cationic surfactants of the tertiary amine type, which are generally not recommended in combination with amphoteric or bipolar surfactants. The stability of the foam referred to herein can be measured in particular by the half-life of the foam formed by expansion of the foam by a gas (typically dinitrogen used as a model gas), with or without the presence of hydrocarbons (typically dodecane used as a model hydrocarbon); this half-life is all the longer the Qcocnn / zznz / a / γΐΛΐ is more stable than foam. This half-life is typically measured by forming the foam in a cylindrical container where the height of the foam formed above the liquid reaches an initial height h and then allowing the foam to evolve, the half-life corresponds to the duration after which the height of the foam above the liquid goes from the value to half of this value, i.e. h / 2. It is found that the compositions of the invention result in foams that have longer half-lives than the half-lives of foams formed from the same compositions but that do not comprise the bipolar surfactant. Another advantage of the cationic surfactants employed according to the present invention is that they generally have relatively high thermal stability, as do many amphoteric or bipolar surfactants. According to one particularly interesting embodiment of the invention, composition C uses surfactants that are stable at least up to 80°C, preferably at least up to 100°C, or even at least up to 120°C and more preferably at least up to 150°C (which is the case for most ethoxylated alkylamines and bipolar surfactants), making it possible to use the composition of the invention at relatively high temperatures (typically between 40 and 140°C, for example, between 80 and 150°C). QCQcnn / zznza / YiAi 120°C). The surfactants used according to the invention are particularly suitable (especially in terms of solubility) when composition C comprises salts, which is almost always the case for compositions used in EOR, where the aqueous medium is typically seawater or formation water. The surfactants used according to the invention have the advantage of being usable in compositions C with high salinity, for example, with a total salt content of more than 50 g / L, for example, at least 80 g / L of salts or even at least 100 g / L; this content typically reaches 200 g / L or even 300 g / L. According to another aspect, the present invention relates to a method for enhanced oil recovery from an underground formation comprising the following steps: A composition C of the type mentioned above is injected into such an underground formation, by means of at least one injection well; the composition is in the presence of a gas (CO2, nitrogen, water vapor or hydrocarbon gas, for example) within the underground formation; then, by means of at least one production well, a fluid is recovered which carries the oil that comes out of the underground formation. Qcocnn / ζζηζα / γ According to an interesting embodiment, the method of the invention is implemented to extract a hydrocarbon from an underground carbonate-based formation, in particular a naturally fractured underground carbonate-based formation. In the context of the method of the invention, the joint presence of composition C and a gas (CO2, nitrogen, water vapor or hydrocarbon gas, for example) in the underground formation, suitable for forming a foam, can be obtained according to different methods, which include in particular: the prior formation of a foam by expansion of composition C with a gas and injection of this foam into the underground formation or the joint injection of composition C, in non-foamed form and gas into the underground formation or the injection of composition C into the underground formation, followed by injection of a gas that will then come into contact with composition C in the underground formation or the injection of composition C into the underground formation that previously contains a gas (for example, naturally present in the formation and / or previously injected into the formation). According to a particular modality, the method comprises: the joint injection of composition C, in non-foamed form, and gas into the underground formation and / or Qcocnn / zznz / a / γΐΛΐ injection of composition C into the underground formation, followed by the injection of a gas that will then come into contact with composition C in the underground formation. According to another modality, particularly appropriate for an underground formation with a dense fracture network, the method comprises: the prior formation of a foam by expansion of composition C with a gas and injection of this foam into the underground formation and / or the joint injection of composition C, in non-foamed form and gas into the underground formation. The following section describes in more detail different aspects and possible modalities of the invention. ethoxylated alkylamine A composition C according to the invention typically comprises a cationic surfactant that is an ethoxylated alkylamine. More specifically, it is a cationizable species, typically employed under pH conditions in which the alkylamine is at least partially in its protonated form. A composition C according to the invention can be used, for example, at a pH far removed from the pKa of the ethoxylated alkylamine (typically at least one or even two pH units), for example, between 4 and 7, particularly between 5 and 6. According to an advantageous modality, the alkylamine The ethoxylated Qcocnn / zznz / a / γΐΛΐ used according to the invention corresponds to the following formula (I) (which corresponds to the protonated form of the amine, the amine possibly being present alternatively in non-protonated form): H (0 where: n is a non-zero number, typically greater than or equal to 1, typically between 1 and 12, for example, between 1 and 10; m is a non-zero number, usually greater than or equal to 1, usually between 1 and 12, for example, between 1 and 10; the sum of n + m is preferably less than 20, for example, less than 10; [A] is a group comprising an alkyl group, this group [A] is preferably: an alkyl group R typically comprising 8 to 22 carbon atoms, typically between 10 and 18, or an ethoxylated alkylamine group of formula: Qcocnn / zznz / a / γΐΛΐ where: R' is an alkyl group, typically comprising 8 to 22 carbon atoms, typically between 10 and 22, especially between 12 and 18; R is an alkenyl group, typically a -(CH2)q- group where q is an integer between 2 and 5, for example, equal to 3. p is a non-zero number, usually greater than or equal to 1, for example, between 1 and 10 the sum of n + m + p is preferably less than 20, for example 10. The values ​​of n, myp given below are in general average values ​​given for a population of molecules of formula (I). Likewise, composition C typically employs mixtures of various ethoxylated alkylamines of formula (I) with different alkyl groups R (and possibly R'). In this case, mixtures of compounds of formula (I) comprising R groups derived from specific vegetable oils or petroleum fractions are typically used (for example, mixtures of various alkyl groups comprising 12 to 14 carbon atoms or mixtures of alkyls present in coconut oil, known as coco alkyls). Thus, according to a first variant, a composition C according to the invention may comprise, for example, an ethoxylated alkylamine corresponding to formula (a) a QCQcnn / zznza / YiAi continued: QCQcnn / zznza / YiAi (la) where n, my R have the above meanings. Ethoxylated alkylamines of formula (la) can be, for example, ethoxylated cocoalkylamines. Advantageously, in ethoxylated alkylamines of formula (la), it is preferred that the sum of n + m be between 2 and 8 According to a particular modality, it is possible, for example, to use in composition C at least one ethoxylated alkylamine of formula (la) where m + m = 2 According to another embodiment, it is possible to use in composition C at least one ethoxylated alkylamine of formula (la) where n + m is strictly greater than 2, in particular where m = 3, 4, 5 or 6, for example, where n + m = 5. This embodiment is particularly advantageous in terms of ease of solubilization of the amine in composition C. According to another variant, compatible with the above, a composition C according to the invention may comprise, for example, an ethoxylated alkylamine employed at least partly in the protonated form corresponding to formula (Ib) below: Qcocnn / ζζηζα / γ R' H (Ib) where n, m, p, R' and R have the above meanings. Ethoxylated alkylamines of formula (Ib) can be, for example, ethoxylated cocoalkylamines. Advantageously, in ethoxylated alkylamines of formula (Ib) , it is preferred that the sum of n + m + p be between 3 and 6. Furthermore, in ethoxylated alkylamines of formula (Ib), the R' group typically comprises a number of carbon atoms between 12 and 18, for example, on the order of 16. By way of non-limiting examples of ethoxylated alkylamines that may be used in the context of the present invention, the commercial products FENTACARE® CO2 and FENTACARE® C05, available from Solvay, may be cited in particular. Other non-limiting examples of ethoxylated alkylamines suitable for implementation of the invention include the product marketed as EthoDuomeen® T / 13 by AkzoNobel or even FENTACARE® TDO3, of similar structure, available from Solvay. Whatever the nature of the alkylamines used in composition C, it is generally preferred that the total concentration of ethoxylated alkylamine be between 0.05% and 2% by mass, particularly between 0.1% and 1% by mass in composition C (this concentration corresponds to the total sum of ethoxylated alkylamines present in composition C, with respect to the total mass of composition C). Amphoteric or Bipolar Surfactant A composition C according to the invention further comprises at least one amphoteric or bipolar surfactant in a mixture with at least one cationic surfactant of the type mentioned above. This amphoteric or bipolar surfactant can be selected in particular from alkylamidobetaines, alkylamidohydroxysultaines, alkylbetaines, and alkylhydroxysultaines, and mixtures of these compounds. Preferably, when used in a composition C according to the invention, these surfactants have an alkyl chain advantageously comprising 8 to 18 carbon atoms. By way of example, cocoamidohydroxypropyl sultaine may be cited. Other possible compounds are aminosulfonates of the type described in WO 2015 / 173052. Other useful compounds are amphoacetates and amphopropionates. By way of non-limiting examples of amphoteric or bipolar surfactants that can be used in composition C, the commercial products Mackam® CBS 50G, LHS-E, LSB 50, Mackam® 35 or Mackam® CB 35 available can be cited in particular. Qcocnn / zznz / a / γΐΛΐ of the Solvay company. Whatever the nature of the amphoteric or bipolar surfactants used in composition C, it is generally preferred that the total concentration of amphoteric and bipolar surfactants be between 0.05% and 2% by mass, particularly between 0.1% and 1% by mass in composition C (this concentration corresponds to the total sum of amphoteric and bipolar surfactants present in composition C, with respect to the total mass of composition C). Furthermore, it is preferable in a composition C according to the invention that the mass ratio of the total mass of ethoxylated alkylamines to the total mass of amphoteric and bipolar surfactants be between 10 / 90 and 90 / 10, for example, between 20 / 80 and 80 / 20 and more preferably between 30 / 70 and 70 / 30. Other Possible Surfactants According to a first possible embodiment of the invention, composition C can only comprise ethoxylated alkylamines and amphoteric or bipolar surfactants derived from surfactants (binary surfactant system of ethoxylated alkylamine type + amphoteric / bipolar). According to another advantageous embodiment, a composition C according to the invention may comprise, in addition to the aforementioned surfactants, at least one additional anionic surfactant. In this case, the composition in general QCQcnn / zznza / YiAi contains only these three types of surfactants (ternary surfactant system of ethoxylated alkylamine type + amphoteric / bipolar + anionic) In all cases, typically, the total surfactant content in composition C generally remains between 0.05% and 2% by mass with respect to the total mass of composition C, for example, between 0.1 and 1% by mass with respect to the total mass of the composition. When composition C comprises anionic surfactants, these can normally be selected from: sulfonate-type anionic surfactants and in particular: alpha olefin sulfonates, preferably alpha olefin sulfonates from C12 to C20, for example, from C14-16. alkylarylsulfonates and in particular alkylbenzenesulfonate (ABS), wherein the alkyl group preferably contains at least 15 carbon atoms, for example, between 15 and 24 carbon atoms, such as, for example, an alkyl aryl sulfonate with a C15-18 alkyl; sulfosuccinates and sulfosuccinamates; anionic sulfate surfactants; mixtures of these anionic surfactants. When anionic surfactants are used, they are generally a minority in the surfactant mixture present in composition C. Thus, the proportion of the total mass of QCQcnn / zznza / YiAi anionic surfactants with respect to the total mass of surfactants present in composition C typically remains less than 50%, even as low as 40% and this proportion is usually between 5 and 35% when anionic surfactants are used. Other Possible Compounds A composition C according to the invention may advantageously comprise several additives in addition to the aforementioned surfactants. Therefore, it is of particular interest that the aqueous medium M of composition C according to the invention comprises dissolved salts (in this case, the aqueous medium M is typically a brine). More generally, the aqueous medium M preferably has a salinity similar to that of the underground formation into which composition C is to be injected, which tends to improve the efficiency of oil recovery. Typically, the total salt content in a composition C according to the invention is in the range of 1 to 300 g / L, preferably from 80 to 250 g / L. A composition according to the invention generally comprises several different types of salts, and the salt concentration referred to corresponds to the total amount of all the salts present. Among the salts advantageously present in the composition of the invention, the following may be cited in particular, without limitation: Qcocnn / zznz / a / γΐΛΐ alkali and alkaline earth metal halides, such as NaCl, KCl, MgClz, CaC12 or CaSO^ or iron salts such as FeSCu or FeC12 or even carbonates or bicarbonates. Use of Compositions According to the Invention The compositions C according to the invention are very suitable for forming stable foams and, in particular, prove to be particularly suitable for enhanced oil recovery operations and, in particular, for underground formations that are: Carbonate-based formations, fractured or not, and / or reservoirs with gas mobility control problems, including the existence of preferential trajectories and / or steal zones and / or gravity override phenomena and / or permeability heterogeneity; these reservoirs are preferably not based on sandstones. The foaming compositions of the invention are especially advantageous for forming foams in the presence of supercritical CO2 or not. The examples given below illustrate non-limiting embodiments of the invention and some of its advantages. Examples Foams have been produced from foaming compositions according to the present invention. The foaming capacity and stability of these compositions were evaluated. QCQcnn / zznza / YiAi the foam obtained according to the protocol described below: Each foam was formed in an identical 8 mL flask for each test (cylindrical flask, diameter = 1 cm), at a temperature of 80°C and under atmospheric pressure. Foam formation was achieved by placing 2 mL of the foaming composition to be tested into the flask with a metal rod (optionally plus 200 microliters of dodecane for the examples where foam formation in the presence of oil was evaluated), allowing the system to reach a temperature of 80°C for 1 second, and then placing it in a vortex at 80°C for 15 seconds. Foam was formed under the vibration effect of the metal rod as the liquid came into contact with air. The vortex was then stopped, and the foam was allowed to develop. In each case, the foam lifetime was measured, which corresponds to the time between vortex cessation (when the foam reaches its maximum volume in the flask) and the time when the foam volume in the flask is reduced by half. In practice, since the foam forms in a cylindrical zone, the height of the foam formed at vortex cessation (maximum height) is expected to have been reduced by half. In addition, the foamability, denoted in this case as F (for the term foamability in English), of the foaming composition used was evaluated, which corresponds to the capacity of QCQcnn / zznza / YiAi to create a foam from the considered composition for a certain mechanical energy applied to it. This foamability F (foam-forming capacity) was measured in each case (in the presence of oil or not) by the ratio of the height of the column of air available above the liquid before the application of the vortex (maximum height that the foam can reach in the flask) in relation to the height of the foam actually obtained just before stopping the vortex. The foaming capacity F ranges from 0 to 1 and an F value less than 0.3 is considered low; an acceptable foam composition typically has to exhibit a foaming capacity F of at least 0.5. The results obtained are shown in the following table, which indicates the nature and quantity of surfactants used (ethoxylated alkylamine and amphoteric or bipolar surfactant). The tested compositions comprised these surfactants in a brine solution containing, dissolved in water: 79.71 g / L of NaCl; 2.34 g / L of KCl; 4.38 g / L of MgCl₂; and 22.53 g / L of CaCl₂. The percentages in the table indicate the mass content of the composition relative to the total mass of the composition. For comparison, tests were carried out with three control compositions containing only ethoxylated alkylamines as surfactants. QCQcnn / zznza / YiAi acocnn / zznza / Y Half-life (with or without oil) and foaming capacity F of tested compositions Surfactants present in the formulation Oil-free In the presence of dodecane F half-life (min) F half-life (min) FENTACARE CO2 0.5% - CONTROL - 1 19.3 0.34 4.5 FENTACARE CO2 0.25% MACKAM LSB50 0.25% 1 53.3 0.85 20 FENTACARE CO2 0.25% MACKAM LHS-E 0.25% 1 43 0.91 4.3 FENTACARE CO2 0.25% MACKAM 35 0.25% 1 63.3 0.49 24 FENTACARE CO2 0.25% MACKAM CB35 0.15% 1 50.5 0.69 5.3 FENTACARE CO5 0.5% - CONTROL - 1 2 0.13 2.5 FENTACARE CO5 0.25% MACKAM LSB50 0.25% 1 47.5 0.32 10 FENTACARE CO5 0.25% MACKAM LHS-E 0.25% 1 23.7 - - FENTACARE TD03 0.5% - CONTROL - 1 2 0.17 1 FENTACARE TD03 0.25% MACKAM LSB50 0.25% 1 9.5 - - FENTACARE TD03 0.25% MACKAM LHS-E 0.25% 1 6.5 - - The surfactants used in this example also have good thermal stability. For illustrative purposes, each of these surfactants was subjected to an aging test in the form of a 5 g / L solution in the aforementioned brine, at 120°C for 60 days at pH 5. The concentration remained substantially the same at 5 g / L for the duration of the test for each of the surfactants tested.

Claims

1. A composition C, suitable as a foaming composition, characterized in that it comprises, in aqueous medium M: at least one ethoxylated alkylamine and at least one amphoteric or bipolar surfactant.

2. The composition according to claim 1, characterized in that the surfactants present in composition C are stable at least up to 80°C, preferably at least up to 100°C or even up to 120°C and more advantageously at least up to 150°C.

3. The composition according to claim 1 or 2, characterized in that the ethoxylated alkylamine corresponds to the formula (I) below: H [Ab n%h:h24:h2-o-vh (!) where: n is a non-zero number, typically between 1 and 12; m is a non-zero number, normally between 1 and 12, the sum of n + m preferably less than 20; [A] is a group comprising an alkyl group, [A] is preferably: an alkyl group R typically comprising 8 to 22 carbon atoms or an ethoxylated alkylamine group of formula: where: R' is an alkyl group, typically comprising 8 to 22 carbon atoms; R is an alkenyl group, typically a -(Clblq-) group where q is an integer between 2 and 5, p is a non-zero number, typically between 1 and 10, the sum of n + m + p preferably less than 20.

4. The composition according to claim 3, characterized in that the ethoxylated alkylamine corresponds to the formula (la) below: HHH gO~| «“H (la) Qcocnn / zznz / a / γΐΛΐ where n, m and R are as defined in claim 3, the sum of n + m being preferably between 2 and 8.

5. The composition according to claim 3, characterized in that the ethoxylated alkylamine corresponds to the formula (Ib) below: QCQcnn / zznza / YiAi R> H H (Ib) wherein n, m, p, R' and R are as defined in claim 3, the sum of n + m + p being preferably between 3 and 6.

6. The composition according to any of claims 1 to 5, characterized in that the total concentration of ethoxylated alkylamine is between 0.05% and 2% by mass in composition C.

7. The composition according to any of claims 1 to 6, characterized in that the amphoteric or bipolar surfactant is selected from alkylamidobetaines, alkylamidohydroxysultaines, alkylbetaines and alkylhydroxysultaines and mixtures of these compounds.

8. The composition according to any of claims 1 to 7, characterized in that the total concentration of amphoteric and bipolar surfactants is between 0.05 and 2% by mass in composition C.

9. The composition according to any of claims 1 to 8, characterized in that the mass ratio of the total mass of ethoxylated alkylamines to the total mass of amphoteric and bipolar surfactants is between 10 / 90 and 90 / 10, for example, between 20 / 80 and 80 / 20.

10. The composition according to any of claims 1 to 9, characterized in that composition C comprises only ethoxylated alkylamines and amphoteric or bipolar surfactants as surfactants.

11. The composition according to any of claims 1 to 9, characterized in that composition C further comprises at least one additional anionic surfactant.

12. The composition according to claim 11, characterized in that the ratio of the total mass of anionic surfactants to the total mass of surfactants present in composition C typically remains less than 50% or even 40%.

13. An enhanced oil recovery method from an underground formation, characterized in that it comprises the following steps: a composition C according to any of claims 1 to 12 is injected into the underground formation, through at least one injection well, the composition being in the presence of a gas in the underground formation; then, by means of at least one production well, a fluid carrying the oil that comes out of the underground formation QCQcnn / zznza / YiAi 26 is recovered.

14. The method of claim 13, characterized in that it is implemented to extract a hydrocarbon from a carbonate-based underground formation, in particular a naturally fractured carbonate-based underground formation.