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EP-4739746-A1 - METHOD FOR THE ENHANCED RECOVERY OF HYDROCARBONS BY SEQUENTIAL INJECTION OF POLYMER COMPOSITIONS

EP4739746A1EP 4739746 A1EP4739746 A1EP 4739746A1EP-4739746-A1

Abstract

The present invention relates to a method for the enhanced recovery of hydrocarbons, involving flushing a subterranean formation with an injection fluid comprising a polymer P1 in salt water A1, then with an injection fluid comprising a polymer P2 in salt water A2, the polymers P1 and P2 being distinct.

Inventors

  • RIVAS, Christophe
  • DUPUIS, GUILLAUME
  • BLONDEL, Frédéric

Assignees

  • SNF Group

Dates

Publication Date
20260513
Application Date
20250616

Claims (15)

  1. 1. Method for the enhanced recovery of hydrocarbons in a subterranean formation comprising one or more injection wells and one or more production wells, the method comprising at least the following steps: a) preparing an aqueous injection fluid SI by dissolving a polymer Pl in salt water Al having a total salinity [TDSJi and a concentration of divalent cations [Div+]i, the polymer Pl comprising: - xi mol% of nonionic hydrophilic monomer, with 0 < xi < 85, - yi mol% of anionic hydrophilic monomer comprising at least one partially or totally salified carboxylic acid function, with 0 < yi < 85, and - zi mol% of anionic hydrophilic monomer comprising at least one partially or totally salified sulfonic acid function, with 15 < zi < 100; with xi + yi + zi = 100 b) injecting the aqueous injection fluid SI into one or more injection wells Pu of a subterranean formation and flushing the subterranean formation using this aqueous injection fluid SI; c) preparing an aqueous injection fluid S2 by dissolving a polymer P2 in salt water A2 having a total salinity [TDSJi and a concentration of divalent cations [Div+Ji, with [TDSJi < [TDSJi and [Div+] 2 < [Div+]i/2, the polymer P2 containing: - xi mol% of nonionic hydrophilic monomer, with 50 < xi < 92.5, - y 2 mol% of anionic hydrophilic monomer comprising at least one partially or totally salified carboxylic acid function, with 0 < y 2 < 50, and - zi mol% of anionic hydrophilic monomer comprising at least one partially or totally salified sulfonic acid function, with z 2 < zi/2; with xi + yi + zi = 100 d) stopping the injection of the aqueous injection fluid SI; e) injecting the aqueous injection fluid S2 into the well(s) Pu and flushing the subterranean formation using this aqueous injection fluid S2; f) recovering an aqueous mixture and hydrocarbons from one or more production wells in the subterranean formation wherein for the polymers Pl and P2, independently from each other: - the nonionic hydrophilic monomer is selected from the group consisting of: acrylamide, methacrylamide, N-alkyl acrylamides, N-alkyl methacrylamides, N,N-dialkyl acrylamides, N,N-dialkyl methacrylamides, alkoxylated esters of acrylic acid, alkoxylated esters of methacrylic acid, N-vinylpyrrolidone, N-methylol (meth)acrylamide, N-vinylcaprolactam, N-vinylformamide (NVF), N-vinylacetamide, N-vinylimidazole, N-vinylsuccinimide, acryloyl morpholine (ACMO), glycidyl methacrylate, glyceryl methacrylate, diacetone acrylamide, methacrylic anhydride, acrylonitrile, maleic anhydride, itaconic anhydride, itaconamide, vinylpyridine, hydroxyalkyl (meth)acrylates, thioalkyl (meth)acrylates, isoprenol, alkoxylated derivatives of isoprenol, hydroxyethyl (meth)acrylates, alkoxylated derivatives of hydroxy ethyl (meth)acrylates, hydroxypropyl acrylate, alkoxylated derivatives of hydroxypropyl acrylate, vinyl acetate, and mixtures thereof, the alkyl groups being C1-C3 hydrocarbon chains; - the anionic hydrophilic monomer comprising at least one partially or totally salified carboxylic acid function is selected from the group consisting of: acrylic acid, methacrylic acid, dimethylacrylic acid, itaconic acid, C1-C3 itaconic acid hemiesters, crotonic acid, maleic acid, fumaric acid, and mixtures thereof; - the anionic hydrophilic monomer comprising at least one partially or totally salified sulfonic acid function is selected from the group consisting of: allylsulfonic acid, methallylsulfonic acid, 2-methylidenepropane-l,3-disulfonic acid, styrenesulfonic acid, 2- acrylamido-2-methylpropanesulfonic acid (ATBS), 2-acrylamido-2- methylpropanedisulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, and mixtures thereof.
  2. 2. Method according to claim 1, characterised in that the polymers Pl and P2 have weight-average molecular weights of greater than 0.5 million daltons.
  3. 3. Method according to one of the preceding claims, characterised in that - for Pl when xi 0, and for P2, the nonionic hydrophilic monomer is acrylamide, - when yi 0 and/or yi 0, the anionic hydrophilic monomer comprising at least one partially or totally salified carboxylic acid function is acrylic acid.
  4. 4. Method according to one of the preceding claims, characterised in that, for the polymers Pl and P2, the anionic hydrophilic monomer comprising at least one partially or totally salified sulfonic acid function is 2-acrylamido-2-methylpropanesulfonic acid.
  5. 5. Method according to one of the preceding claims, characterised in that - for Pl when xi 0, and for P2, the nonionic hydrophilic monomer is acrylamide, - when yi 0 and/or yi 0, the anionic hydrophilic monomer comprising at least one totally salified carboxylic acid function is sodium acrylate.
  6. 6. Method according to one of the preceding claims, characterised in that - for Pl and for P2 when Z2 0, the anionic hydrophilic monomer comprising at least one totally salified sulfonic acid function is sodium 2-acrylamido-2-methylpropanesulfonate.
  7. 7. Method according to one of the preceding claims, characterised in that the aqueous injection fluid SI contains between 0.1% and 2% by weight of polymer Pl and in that the aqueous injection fluid S2 contains between 0.1% and 2% by weight of polymer P2.
  8. 8. Method according to one of the preceding claims, characterised in that the method comprises, between steps d) and e): - injecting an aqueous injection fluid Sint into the injection well(s) Pu and - flushing the subterranean formation using this fluid Sint, said aqueous injection fluid Sint comprising a water-soluble polymer Pint dissolved in salt water Aint having a total salinity [TDSJint and a concentration of divalent cations [Div+]int, with [TDS]i < [TDSJint < [TDSJi and [Div+]2 < [Div+]int < [Div+]i, the water-soluble polymer Pint comprising: - xint mol% of nonionic hydrophilic monomer, with 0 < xint < 92.5, - yint mol% of anionic hydrophilic monomer comprising at least one partially or totally salified carboxylic acid function with 0 < yint < 92.5, and - zint mol% of anionic hydrophilic monomer comprising at least one partially or totally salified sulfonic acid function with Z2<zint<zi and xint + yint + zint= 100, the injection of the aqueous injection fluid Sint into the well(s) Pu being stopped before the injection of the aqueous injection fluid S2, wherein, for the water-soluble polymer Pint: - the nonionic hydrophilic monomer is selected from the group consisting of: acrylamide, methacrylamide, N-alkyl acrylamides, N-alkyl methacrylamides, N,N-dialkyl acrylamides, N,N-dialkyl methacrylamides, alkoxylated esters of acrylic acid, alkoxylated esters of methacrylic acid, N-vinylpyrrolidone, N-methylol (meth)acrylamide, N-vinylcaprolactam, N-vinylformamide (NVF), N-vinylacetamide, N-vinylimidazole, N-vinylsuccinimide, acryloyl morpholine (ACMO), glycidyl methacrylate, glyceryl methacrylate, diacetone acrylamide, methacrylic anhydride, acrylonitrile, maleic anhydride, itaconic anhydride, itaconamide, vinylpyridine, hydroxyalkyl (meth)acrylates, thioalkyl (meth)acrylates, isoprenol, alkoxylated derivatives of isoprenol, hydroxyethyl (meth)acrylates, alkoxylated derivatives of hydroxy ethyl (meth)acrylates, hydroxypropyl acrylate, alkoxylated derivatives of hydroxypropyl acrylate, vinyl acetate, and mixtures thereof, the alkyl groups being C1-C3 hydrocarbon chains; - the anionic hydrophilic monomer comprising at least one partially or totally salified carboxylic acid function is selected from the group consisting of: acrylic acid, methacrylic acid, dimethylacrylic acid, itaconic acid, C1-C3 itaconic acid hemiesters, crotonic acid, maleic acid, fumaric acid, and mixtures thereof; - the anionic hydrophilic monomer comprising at least one partially or totally salified sulfonic acid function is selected from the group consisting of: allylsulfonic acid, methallylsulfonic acid, 2-methylidenepropane-l,3-disulfonic acid, styrenesulfonic acid, 2- acrylamido-2-methylpropanesulfonic acid (ATBS), 2-acrylamido-2- methylpropanedisulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, and mixtures thereof.
  9. 9. Method according to one of the preceding claims, characterised in that: - the total salinity [TDSJi of the saline solution Al is between 1,000 ppm and 330,000 ppm by weight.
  10. 10. Method according to one of the preceding claims, characterised in that: - the total salinity [TDSJi of the saline solution A2 is between 100 ppm and 50,000 ppm by weight.
  11. 11. Method according to one of the preceding claims, characterised in that: - the total salinity [TDSJint of the saline solution Aint is between 500 ppm and 150,000 ppm by weight.
  12. 12. Method according to one of the preceding claims, characterised in that: - the concentration of divalent cations [Div+]i in the salt water Al is between 100 ppm and 30,000 ppm by weight.
  13. 13. Method according to one of the preceding claims, characterised in that: - the concentration of divalent cations [Div+] 2 in the salt water A2 is between 0 ppm and 6,000 ppm by weight.
  14. 14. Method according to one of the preceding claims, characterised in that: - the concentration of divalent cations [Div+]int in the salt water Aint is between 100 ppm and 20,000 ppm by weight.
  15. 15. Method according to one of the preceding claims, characterised in that: Pl is a polymer of acrylamide and sodium 2-acrylamido-2-methylpropanesulfonate, P2 is a polymer of acrylamide and sodium 2-acrylamido-2-methylpropanesulfonate or a polymer of a polymer of acrylamide and sodium acrylate.

Description

METHOD FOR THE ENHANCED RECOVERY OF HYDROCARBONS BY SEQUENTIAL INJECTION OF POLYMER COMPOSITIONS Field of the invention The present invention relates to a method for the enhanced recovery of hydrocarbons (petroleum and/or gas) using a sequential injection sequence of different injection fluids having distinct compositions (nature of the polymer, salinity of the solution). Prior art The majority of oil fields currently being exploited have reached maturity and have therefore begun to decline in production or are about to do so. The recovery rate (yield) of these fields is currently around 15 to 35% on average, in relation to the initial amount of hydrocarbons (petroleum and/or gas). They therefore offer a production potential which is still considerable. Generally, the hydrocarbons, for example crude petroleum, contained in these deposits is recovered in several stages. The production results first of all from the natural energy of the fluids and the rock which become decompressed. At the end of this depletion phase, the amount of hydrocarbons recovered at the surface represents on average around 5 to 15% of the initial reserve. It is therefore necessary, in a second stage, to use techniques which aim to increase the recovery yield by maintaining the pressure in the field. The most frequently implemented method consists in injecting water into the deposit through injection wells intended for this purpose. This is referred to as secondary recovery. This second phase ends when the water/hydrocarbons ratio is too high, i.e. when the amount of water in the mixture produced by the production wells is too high. This secondary recovery thus makes it possible to obtain an additional recovery rate of around 10 to 20%. The other techniques that can be used are grouped together under the name “enhanced recovery of petroleum or hydrocarbons”, or “enhanced oil recovery” (EOR). Their aim is to recover between 10 and 35% of additional hydrocarbons relative to the initial amount of hydrocarbons. The term enhanced recovery of petroleum or hydrocarbons covers various thermal or non-thermal techniques, such as enhanced electric, miscible, steam or chemical recovery of remaining hydrocarbons (see “Oil & Gas Science and Technology” - Revue IFP, vol 63 (2008) no. 1, pages 9-19). The term “petroleum” denotes any type of oil, namely light oil, heavy oil or even bituminous oil. An oil is usually the result of the natural transformation of organic matter and is composed of a mixture of hydrocarbons. In the description of the prior art or of the invention, the terms "petroleum" (or hydrocarbons) and "oil" are used to denote the same material, unless mentioning the composition of an emulsion or of a dispersion. The efficiency of water injection flushing is generally improved by the addition of water- soluble polymers. The expected and proven benefits of the use of polymers, through the "viscosification" of the injected water, are the improvement in flushing and the reduction in the viscosity contrast between the fluids in order to control their mobility ratio in the field, in order to recover the hydrocarbons quickly and efficiently. The most commonly used polymers for increasing the viscosity of water are polymers based on acrylamide and/or acrylic acid and/or 2-acrylamido-2-methylpropanesulfonic acid (ATBS), and/or the salts thereof. Polymers added to the injection water are generally subject to long residence times in the deposit, between the injection wells and the production wells, which can range from a few months to a few years. During this period of time, they may undergo thermal degradation linked to an increase in their degree of hydrolysis by conversion of acrylamide units into acrylates, or chemical degradation leading to chain breakage (decrease in molecular weight) by radical attack. In both cases, these mechanisms generally result in a decrease in viscosity and therefore a loss of the efficiency of flushing the subterranean formation with the injected aqueous polymer solution. There is therefore a real benefit to developing polymers that are more resistant to these processes encountered at enhanced hydrocarbon recovery sites (petroleum and/or gas). EP 3 770 232 teaches an oil recovery method involving a composition comprising an inverse emulsion of an acrylamide polymer and solid particles of a polymer of acrylamide and ATBS. CA 3 056 975 teaches an oil recovery method involving a polymer of ATBS. FR 2 986 034 teaches an oil recovery method involving a water-soluble polymer of ATBS and a monomer selected from acrylamide, N-Vinylpyrrolidone and acrylamide derivatives. EP 3 816 228 teaches a hydraulic fracturing involving an inverse emulsion of polymer. It is known to those skilled in the art that synthetic water-soluble polymers based on 2- acrylamido-2-methylpropanesulfonic acid (ATBS and/or the salts thereof) or a monomer functionalized with a sulfonic acid group (and/or the salts thereof) are tolerant to divalent s