Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F228/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a bond to sulfur or by a heterocyclic ring containing sulfur
  • C08F228/02—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a bond to sulfur or by a heterocyclic ring containing sulfur by a bond to sulfur
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F212/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring
  • C08F212/02—Monomers containing only one unsaturated aliphatic radical
  • C08F212/04—Monomers containing only one unsaturated aliphatic radical containing one ring
  • C08F212/14—Monomers containing only one unsaturated aliphatic radical containing one ring substituted by heteroatoms or groups containing heteroatoms
  • C08F212/30—Sulfur
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
  • C09K8/52—Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning
  • C09K8/528—Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning inorganic depositions, e.g. sulfates or carbonates

Definitions

• the present invention concerns inorganic deposit inhibitors, and particularly of calcium carbonate and barium sulphate in oil wells. It also concerns certain copolymers particularly suitable for this application, particularly in high pressure/high temperature conditions (HP/HT).
• HP/HT high pressure/high temperature conditions
• Patent application EP-A-792998 suggests inhibiting in particular the formation of barium sulphate by introducing, into the aqueous fluid, a water soluble polymer comprising units derived from an unsaturated sulphonic acid and its soluble salts (5 to 35%), from an unsaturated monocarboxylic acid (0 to 85%), from an unsaturated dicarboxylic acid (0 to 80%) and from a non-ionisable unsaturated monomer (0 to 20%), the aqueous fluid containing calcium, barium, strontium and sulphate ions.
• this treatment applies in particular to the so-called “squeeze” process.
• This process generally consists in injecting sea water into the well, then injecting the fluid containing the inhibitor into the reservoir and injecting once again a new flow of water, with the aim of spreading out the inhibitor in the reservoir in order for it to be adsorbed on the rock.
• European patent application EP-A-459 661 relates to a process for controlling the formation of deposits of silica or silicate in an aqueous system, in which is used (a) certain water soluble, low molecular weight copolymers or terpolymers of (meth)acrylic or maleic acid, (b) a magnesium ion, (c) a mixture of said copolymers or terpolymers with an aluminium or magnesium ion, or (d) poly(meth)acrylic or polymaleic acid of low molecular weight with an aluminium or magnesium ion.
• U.S. Pat. No. 4,566,972 relates to a process for preventing deposits of scale in an aqueous system, by the introduction into the water of a specific amino-carboxylate and a water soluble copolymer that may possess sulphonated units.
• European patent application EP-A-184 894 relates to a process for preventing corrosion and the formation of scale and iron oxide deposits in aqueous systems, in which are introduced, into aqueous systems, a water soluble polymer prepared from an unsaturated carboxylic acid, an unsaturated sulphonic acid and an unsaturated poly(alkylene oxide).
• a first aim of the invention is inorganic deposit inhibitors that can be used in high pressure/high temperature conditions.
• a further aim of the invention is inorganic deposit inhibitors that can be used in the “squeeze” process.
• an aim of the invention is inhibitors with good adsorption on the rock allowing slow desorption, as water is produced.
• a yet further aim of the invention is inhibitors that are particularly efficient against the deposition of calcium carbonate and/or barium sulphate.
• the invention thus firstly relates to inorganic deposit inhibitors, characterized in that they comprise a water soluble copolymer comprising (in mole % of polymerised monomers):
• the invention relates to inhibitors, characterized in that they comprise a water soluble copolymer comprising (in mole % of polymerised monomers):
• the invention also relates to water soluble copolymers such as those mentioned in the previous paragraphs.
• the aforesaid sulphonic or polycarboxylic acids may be replaced partially or totally by their salts, particularly alkali metal salts such as sodium or potassium or ammonium or quaternised amine salts.
• styrenesulphonic acids and their salts
• 4-styrenesulphonic acid is preferably used.
• the copolymer comprises units derived from unsaturated polycarboxylic acids (or their salts)
• maleic acid or its anhydride fumaric, itaconic, citraconic acids or cis 1, 2, 3, 6 tetra-hydrophthalic anhydride or water soluble sodium, potassium or ammonium salts of said acids are preferably used.
• Such monomers when they are present, represent preferably up to 30% in mole % of the polymerised monomers.
• non-ionisable unsaturated monomers non-substituted or (C1-C8) alkyl or hydroxy (C1-C8) alkyl substituted (meth)acrylamides; non-substituted or (C1-C8) alkyl- or hydroxy alkyl substituted (meth)acrylic esters; vinyl acetate, styrene, vinyltoluene, may, in particular, be cited.
• Such monomers when they are present, represent up to 10% in mole % of the polymerised monomers.
• the copolymer only comprises units derived from derivatives of vinylsulphonic acid or its salts and styrenesulphonic acid and, in particular, 4-styrenesulphonic acid or its salts
• the molar percent of vinylsulphonic acid or its salts is preferably between 70 and 90% and, even more preferably, between 80 and 90%.
• the invention especially relates to such water soluble copolymers.
• the water soluble copolymers according to the invention have a molar mass (by number) generally between 3 000 and 50 000 and preferably between 5 000 and 30 000.
• their dispersity index M w /M n is less than or equal to 3.
• the molar mass of copolymers is measured by steric exclusion chromatography (SEC).
• SEC steric exclusion chromatography
• the chromatographic chain used comprises a WATERS 590 pump (WATERS, Milford, USA), a WATERS 717plus injector and a WATERS R410 refractomeric detector.
• the set of columns used comprises 2 columns (POLYMER LABORATORIES PL aquagel-OH; 8 ⁇ m; 300 ⁇ 7.5 mm) filled with rigid, macroporous polymer beads (very hydrophilic, polyhydroxylated surface). Two porosities are used: 40 (resolution field: 10000-200000 eq. PEO/PEG) and 30 (resolution field: 100-30000 eq. PEO/PEG).
• the eluant is composed of 80% water (purified with MILLI-Q ZFMQ 230 04 from MILLIPORE) containing sodium nitrate at a concentration of 0.3M, sodium hydrogen phosphate at a concentration of 0.01M and 20% methanol; the solution thus has a pH of 9.
• the rate at which the solvent is introduced is 1 cm 3 .min ⁇ 1 .
• the copolymer solutions to analyse are prepared at a concentration of 1 g.l ⁇ 1 and 100 ⁇ l of solution are injected.
• the calibration curve is constructed from a set of 8 PULLULAN polysaccharide standards with M w between 5900 and 788000, with a narrow distribution (dispersity index between 1.06 and 1.23).
• copolymers according to the invention may be obtained by polymerising the monomers mentioned previously using conventional methods in the presence of free radical initiators.
• the polymerisation is carried out in aqueous solution or partially aqueous solution, for example a water/alkanol solution, or an alkanol such as ethanol, isopropanol, ethylene glycol, diethylene glycol.
• aqueous solution or partially aqueous solution for example a water/alkanol solution, or an alkanol such as ethanol, isopropanol, ethylene glycol, diethylene glycol.
• the reaction medium is advantageously at acid pH, preferably less than 6.
• free radical initiators include peroxides, such as benzoyl or t-butyl peroxides, azo compounds, such as azo-bis-isobutyronitrile, 2, 2′-azo-bis(2-amidino-propane)dihydrochloride (AIBA) and, preferably, peracid salts, such as potassium or ammonium persulphates.
• peroxides such as benzoyl or t-butyl peroxides
• azo compounds such as azo-bis-isobutyronitrile, 2, 2′-azo-bis(2-amidino-propane)dihydrochloride (AIBA)
• AIBA 2, 2′-azo-bis(2-amidino-propane)dihydrochloride
• peracid salts such as potassium or ammonium persulphates.
• the polymerisation is generally carried out at a temperature between 40 and 120° C., preferably between 45 and 100° C., and the polymerisation time may be several hours, for example 2 to 10 hours.
• copolymers are obtained in solution form and this may be subjected to partial or total evaporation, generally under reduced pressure.
• the copolymers that have undergone partial or total evaporation are re-diluted before their use.
• copolymers in solution may be used as such as inhibitors according to the invention, or purified in accordance with conventional methods such as:
• copolymers according to the invention in which all or part of the acid hydrogens are replaced by cations derived from an appropriate salt forming a base may also be prepared by mixing an aqueous, water/alcohol or alcohol solution of the acid copolymer with an aqueous, water/alcohol or alcohol solution containing a quantity of the required base appropriate to the desired level of substitution.
• the copolymers according to the present invention constitute inorganic deposit inhibitors, particularly of calcium carbonate and barium sulphate, and are particularly efficient when used in the “squeeze” process in oil wells operating under high pressure conditions, in other words around 20 to 150 MPa and high temperature, in other words around 130 to 230°C.
• These copolymers have in fact sufficient thermal stability, have good efficiency in inhibiting the formation of salts (CaCO 3 and BaSO 4 ), are insensitive to high levels of Ca ++ of the reservoir water and have sufficient adsorption on the rock for use in “squeeze” processes. This set of properties is not found in inhibitors known to the prior art, whether they are terpolymers based on sulphonated monomer/acrylic acid/maleic acid or homopolymers of sodium vinyl sulphonate.
• the inhibitors according to the present invention are either in powder form, or in solution whose concentration may be around 15 to 30% by weight.
• the solutions intended for continuous injection in the wells have a concentration of around 1 to 100 ppm, whereas the solutions used in “squeeze” processes are injected so that they are placed on the rock at a concentration of around 10% by weight, all of these concentration values being only given by way of indication.
• This test enables the efficiency of the deposit inhibitors used in preventive treatments to be evaluated. Performed on an anti-deposition loop, it consists in measuring the clogging time of a capillary when a mixture of two incompatible waters is injected: one water contains bicarbonates (HCO 3 ⁇ ), the other calcium (Ca ++ Mg ++ ) for a study of the carbonated deposits (calcite, etc.); one water contains sulphates (SO 4 ⁇ ), the other barium (Ba ++ , Sr ++ ) for a study of the sulphated deposits. Each of the waters contains a quantity of inhibitor that may generally vary between 10 and 100 ppm. Measuring the differential pressure enables the evolution of the clogging of the capillary to be monitored.
• the experiments comprise a control test without inhibitor and tests in the presence of inhibitors.
• the principle of the test is to observe the appearance of cloudiness or a deposit by the decrease in the transmittance of distilled water solutions of each inhibitor (at 0.1, 1.5 and 10% by weight at pH 5, 6 and 7 when known quantities of calcium are added. The tests are carried out at ambient temperature.
• This test is used for dimensioning the preventive treatments by the “squeeze” process. It is carried out on a representative core sample from the well in which the treatment will be carried out, and its purpose is to verify that the adsorption (or the precipitation) of the inhibitor on the porous medium is correct and thus that the treatment will have an acceptable lifetime and to verify that the adsorption (or the precipitation) of an important quantity of inhibitor will have no effect on the well productivity (reduction in the permeability).
• the experimental set up employs a “HASSLER” cell in which the core sample is characterised (porosity, etc.) and conditioned to the well conditions (pressure, temperature, presence of oil).
• the sodium 4-styrenesulphonate is dissolved in water and, in a proportion of around 10% by weight of this solution, the sodium vinylsulphonate solution is added.
• the pH is checked and sulphuric acid (96% by weight) is added if necessary in order to obtain a pH of 3.8.
• This solution of monomers is introduced into a stainless steel reaction vessel equipped with a double agitator.
• the vessel is degassed with nitrogen 3 times in a succession of vacuum/nitrogen cycles.
• the temperature is maintained for 1 to 2 hours, or the polymerisation is carried out at two different temperatures (see Table I).
• the SStNa is dispersed and/or dissolved in the VS solution.
• the pH is adjusted to 3.8. It is then heated to the reaction temperature.
• the initiator is added and the solution left for 2 to 10 hours.
• the inhibitors are used in the form of aqueous solutions at different concentrations according to the test and are subjected to the tests described above.
• HVS sodium vinylsulphonate homopolymer
• VS/VSS sodium vinylsulphonate/sodium styrenesulphonate copolymer, with the molar proportions of the monomers polymerised given.
• TROS810 HVS commercialised by the TROS Company
• EC6151A HVS commercialised by the Nalco/Exxon Company.
• the symbol OK signifies a stability verified after 3 weeks at 200° C.
• the term “compatible” signifies the absence of cloudiness or deposit, for a quantity of calcium up to 40 g/l and a pH of the medium from 4 to 7.

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• Chemical & Material Sciences (AREA)
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• Chemical Kinetics & Catalysis (AREA)
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• General Life Sciences & Earth Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)
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• 1999
  • 1999-12-29 FR FR9916654A patent/FR2803304B1/fr not_active Expired - Fee Related
• 2000
  • 2000-12-28 AU AU28611/01A patent/AU2861101A/en not_active Abandoned
  • 2000-12-28 US US10/169,331 patent/US20030149210A1/en not_active Abandoned
  • 2000-12-28 DE DE60022784T patent/DE60022784T2/de not_active Expired - Lifetime
  • 2000-12-28 EP EP00993717A patent/EP1261652B1/de not_active Expired - Lifetime
  • 2000-12-28 WO PCT/FR2000/003712 patent/WO2001049756A1/fr active IP Right Grant
  • 2000-12-28 AT AT00993717T patent/ATE305015T1/de not_active IP Right Cessation
• 2002
  • 2002-06-26 NO NO20023093A patent/NO327144B1/no not_active IP Right Cessation
• 2004
  • 2004-08-12 US US10/916,540 patent/US7378477B2/en not_active Expired - Fee Related

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