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EP-3837306-B1 - FLUID FOR CONTROLLING THE PERMEABILITY OF A SUBTERRANEAN FORMATION, AND USE THEREOF

EP3837306B1EP 3837306 B1EP3837306 B1EP 3837306B1EP-3837306-B1

Inventors

  • CARMINATI, STEFANO
  • MADDINELLI, GIUSEPPE
  • Moscatelli, Davide
  • SPONCHIONI, Mattia

Dates

Publication Date
20260506
Application Date
20190819

Claims (14)

  1. Fluid for controlling the permeability of a subterranean formation comprising an aqueous solution of at least one thermo-responsive triblock polymer of block structure A-B-A', wherein: - A and A', the same as or different from one another, are outer blocks and each represent a thermo-responsive oligomer group said A, A' having a defined lower critical solubility temperature (LCST) - B is an oligomer group comprising n repeat units, the same as or different from one another, wherein: (i) at least one of the repeat units has a solubility of the corresponding monomer, in water at 20°C, equal to or greater than 120 g/l, (ii) n is a whole number within the range 30 - 1000; wherein said A block and/or said A' block are selected from the groups consisting of (a) oligomer groups formed by two or more OEGMA compounds having molecular weight different from one another; (b) a co-polymer comprising OEGMA as a first co-monomer and at least one second hydrophobic co-monomer in the form of HEMA-polylactide; and wherein the block B is (c) poly(ethylene glycol) chain (PEG, HO-[CH 2 CH 2 -O] n -H), where n is a whole number comprised between 30 and 300; (d) an oligomer group comprising one or more repeat units selected from: (meth)acrylic acid, polymerisable esters comprising polyoxyethylene chains -[-CH 2 -CH 2 -O] r -H where r is an integer number within the range 10 - 500, oligo(ethylene glycol)methyl ether methacrylate (OEGMA), [2-(methacryloyloxy)ethyl]- trimethylammonium chloride (MADQUAT), [2-(methacryloyloxy)ethyl]- trimethylammonium chloride, potassium 3-sulfopropyl methacrylate, 2-acrylamido-2-methylpropanesulfonic acid, (meth)acrylamide 2-hydroxypropyl methacrylamide, glycerol monomethacrylate, 2-hydroxyethyl methacrylate, methacryloyloxyethyl phosphorylcholine, carboxybetaine, sulfobetaine and combinations thereof. .
  2. Fluid according to claim 1, wherein said A block and/or said A' block has a lower critical solubility temperature (LCST) within the range 30°C - 100°C.
  3. Fluid according to claim 1, wherein said A block and/or said A' block have a degree of polymerisation DP within the range 2 - 1,000, preferably 3 - 500, more preferably 5 - 450, even more preferably 6 - 400.
  4. Fluid according to claim 1 , wherein said OEGMA compound has a mean molecular weight M n within the range 100 - 10,000 Dalton, more preferably within the range 100 - 5,000 Dalton.
  5. Fluid according to claim 1, wherein: - said B block is an oligomer group comprising, as corresponding monomer, poly(ethylene glycol) (PEG) having a mean molecular weight M n within the range 500 - 10,000 Dalton, preferably within the range 1,000 - 5,000 Dalton; - said A block and/or A' block are oligomer groups comprising, as corresponding monomer, oligo(ethylene glycol)methyl ether methacrylate (OEGMA), having a mean molecular weight M n within the range 100 - 1,000.
  6. Fluid according to claim 1, wherein: - said B block is an oligomer group comprising, as corresponding monomer, [2-(methacryloyloxy)ethyl]-trimethylammonium chloride (MADQUAT), - said A block and/or A' block are oligomer groups comprising, as corresponding monomer, OEGMA having a mean molecular weight M n within the range 100 - 1,000.
  7. Fluid according to claim 1, wherein said B block comprises at least one cationic pendant group.
  8. Fluid according to the preceding claim, wherein said B block comprising at least one cationic pendant group comprises one or more monomers selected from: [2-(methacryloyloxy)ethyl]- trimethylammonium chloride (MADQUAT), [2-(acryloyloxy)ethyl]trimethylammonium chloride, (dimethylamino)ethyl methacrylate DMAEMA and 2-aminoethyl methacrylate hydrochloride.
  9. Fluid according to claim 1, wherein said oligomer group of the A block and/or said A' block comprises one or more degradable repeat units.
  10. Method for controlling the permeability of a subterranean formation comprising: a. providing a fluid comprising an aqueous solution of at least one thermo-responsive triblock polymer with block structure A-B-A', as defined in any one of the preceding claims 1 to 9 b. positioning said treatment fluid in a subterranean formation.
  11. Method according to the preceding claim, wherein said polymer A-B-A' is present in said aqueous solution in a concentration within the range 0.5-40% by weight, more preferably within the range 1-20% by weight, with respect to the weight of the aqueous solution.
  12. Method according to claim 10 or 11 , wherein said step b comprises injecting said fluid via at least one extraction well and/or at least one injection well.
  13. Use of a fluid according to any one of claims 1-9 to modify the permeability of a subterranean formation.
  14. Use of a fluid according to any one of claims 1-9 to limit the infiltration of water in a well for extracting a hydrocarbon oil or gas from a subterranean formation.

Description

The present invention relates to a fluid for controlling the permeability of a subterranean formation, and use thereof. In particular, the present invention relates to an aqueous fluid comprising a thermo-responsive polymer. Once injected into a subterranean formation, through an effect of the geothermal heat of the subterranean formation the fluid comprising the thermo-responsive polymer undergoes in situ a phase transition, becoming a gel of viscosity such as to locally modify the permeability of the formation to fluids. The present invention may be used advantageously in the oil industry, particularly in improved oil recovery operations (IOR) or enhanced oil recovery (EOR), to modify the permeability of a subterranean formation to displacement fluids, for example water or gas, that are used in the production of oils and hydrocarbon gases. As is known, in processes of improved recovery of hydrocarbon fluids (oil and gas) from a subterranean formation, the hydrocarbon fluid initially present in the pores of the reservoir rock is brought to the surface by means of displacement by an immiscible fluid (also called a displacement fluid) that takes its place. To this end, wells are drilled within the oil field for the injection of the displacement fluid, generally water, that are arranged in such a way as to create in the subsoil the most uniform possible advancing front to displace the hydrocarbon fluid towards the production well. The technique of displacement by injections of water (water flooding) has long been the simplest and most economical method used to sustain production in an oil field and increase the overall recovery factor of the hydrocarbon fluid. The quantity of hydrocarbon fluid that can be displaced towards the production wells by water injection depends, among other factors, on the degree of heterogeneity of the reservoir rock and the properties of the hydrocarbon fluid (above all the viscosity). In particular, fractures, channels or levels of high permeability (the latter also called thief zones) constitute preferential flow pathways. The natural tendency of fluids to flow through the most permeable portions of the reservoir rock means that, with the passage of time, the water injected into the subsoil continues to flow away along these fractures, channels or levels of high permeability, reaching the producer wells directly without or only minimally infiltrating the zones of the reservoir rock in which the hydrocarbon fluid is still present, thus producing no displacement effect. In these situations, the production of water can increase until it dominates that of the hydrocarbon fluid, thus rendering the production of the latter barely or not at all advantageous from an economic standpoint. Furthermore, the co-production of water implicates the adoption of specific treatment plants so as to be able to safely dispose of the water produced, or of systems for its re-injection into the subsoil. These measures involve high consumption of energy and materials, and increase the overall cost of hydrocarbon extraction. In the state of the art, the problem of undesirable production of water and of the inadequate efficiency of the recovery of the hydrocarbons by displacement with water is dealt with by injecting into the subsoil liquid compositions containing chemical compounds that are capable of modifying the permeability characteristics of the subterranean formation. The compounds most in use for this purpose are generally in the form of polymers, gels or foams. These compounds are here also called "blocking agents". The blocking agents block the pores of the formation zones with the highest permeability, diverting the flow of the displacement fluid towards the zones that are still rich in hydrocarbon fluid, thus increasing the production capacity of the well. US 2009/0264321 describes a method for modifying the permeability of a subterranean formation based on injecting into the subsoil a composition comprising encapsulated expandable polymeric microspheres. Once injected into the subsoil, following an activation event (for example a variation in temperature or pH), the polymeric microspheres escape from the capsules in which they are enclosed and disperse into the formation, where they swell up by absorbing the displacement fluid with which they are in contact. Swelling of the microspheres within the pores of the formation prevents the flow of the displacement fluid, which is thus diverted towards other zones of the formation. However, the properties of the aforesaid encapsulated polymeric microspheres cannot be easily modifiable and therefore optimizable as a function of the specific conditions of the formation. Furthermore, the aforesaid microspheres alter the permeability of the formation irreversibly, so that any errors of injecting the blocking agent are not remediable. Also known in the state of the art are blocking agents composed of thermo-responsive polymers. Thermo-responsive polymers ar