DE2133723A1 - Corrosion inhibitors for metals - consisting of salts of imidazolines and carboxylic acids - Google Patents

Abstract

The salts are of formula (I) (in which R is the acid gp. of tall oil fatty acid or a 15-20C polymerised fatty acid, A is -(CH2)2- or -(CH2)3-, m is 1-6, p is 1 or 2, R' is a satd. aliphatic gp. with 0-2C atoms when p is 1, and 1-7C atoms when p is 2, q is 1 when p is 1, and 1 or 2 when p is 2)., in aq. soln. at concs. of 10-200 ppm, they are corrosion inhibitors for metals, esp. steel, at =150 degrees C. They are suitable for protection of oil and gas pipes, storage equipment, etc., for metal parts in contact with petroleum-contg. bore-hole fluids as used to displace oil from rock strata.

Description

Compounds with corrosion-inhibiting effect and methods for Manufacture of the Same The present invention relates to corrosion inhibition of metals that are in contact with petroleum-containing borehole fluids or are present during natural gas production. In particular, the invention relates to improved water-soluble mixtures of normal or acidic salts of imidazolines and saturated, aliphatic mono- and dicarboxylic acids to prevent corrosion of metals, especially ferrous metals, in oil and gas production, in storage, in the distribution bodies and in the refinery.

The major corrosive substances found in petroleum-bearing wellbore fluids and occur in natural gas production are H2S, 002, 02, organic acids and dissolved salts. These substances may be alone or mixed with each. Valves, fittings, pipes, pumps, separators, oil pipes, pump shafts and other parts of the drilling and production equipment are particularly susceptible to corrosion. Deposits of rust, scale, corrosive by-products, paraffin and other substances offer ideal conditions for concentration elements and the formation of holes under the Deposits. Acid condensates that are found on the metal pipes of gas condensation systems deposit can also give rise to pitting.

Furthermore, it usually occurs with sulfur-containing gas or oil deposits a sulphide attack hit the pump shafts and delivery lines under Formation of deep holes, cracks or even complete breaks. Temperatures above Approx. 150 ° C can occur in the drilling depths - and accelerate the corrosion.

The one that occurs in primary pumping and in water injection processes Corrosion is complex. Assessing the effectiveness of corrosion inhibitors for such applications the following variables should be considered: height of the wellbore fluids; Type and speed of promotion; Water-oil ratio; Wettability of the oil; pH of the borehole fluids; Temperatures at the bottom of the borehole; H2S, C02, 02 components and components of other gases present; Formation of protective coatings from, for example, paraffin, which comes from the oil, or from calcium carbonate from the water; Composition of the inhibitor and method of its use.

Water flooding is a secondary oil production process and is used for improved economic exploitation of a deposit applied. This is done brine or water is injected under pressure through a borehole, whereby the oil from the Reservoir rock is displaced in production wells, where production is carried out using primary methods he follows. Within the more importantaiVariables that have an impact on the results of water flooding are the permeability, porosity and shape of the pore openings in the reservoir rock, as well as the viscosity, specific weight and surface tension of the oil.

When choosing the fluids intended for water flooding it is important to check for chemical inactivity and absence of sediment that covers the Pore spaces of the reservoir rock could clog, to watch out for. So far have been the commercially available inhibitors of the brine or water intended for water flooding added, whereupon cloudiness occurred. Peeling organic materials became as a result, the pore spaces of the deposit rock surrounding the injection probe "clog".

This would reduce the water injection speed and the Reduce oil production per 4G, 5 a. In practice it fluctuates The relationship from the oil produced to the amount of water injected in the case of effective water flooding between 1:10 and 1:18.

To reduce the use of materials, lower costs through bulk purchases and to achieve maximum process effects, the product of the invention was developed. It; is a class of corrosion inhibitors and their mixtures which have a represent effective metal protection for a variety of corrosive influences.

A main object of this invention is to make a water soluble one Corrosion inhibitor as an additive to sweet and sour oil-containing borehole fluids and as an additive to brine used in water flooding to prevent corrosion and degradation of metals that come into contact with the liquids.

Another object of the invention is to develop one improved process for corrosion protection of metals in crude oil and natural gas production, Storage, distribution and in the refinery.

Another object of the invention is to produce a improved cheaper water-soluble corrosion inhibitor that acts as a corrosion inhibitor of ferrous metals in oil production plants against aqueous carboxylic acids, sulfides and soluble aliphatic acids found in hot petroleum borehole fluids and are available in natural gas production.

The invention relates to a compound of the formula where R is the acid residue of a tall oil fatty acid or a polymerized fatty acid with 15-70 carbon atoms, A -CH2-0H2- or -CH2CH2-CH2-m is an integer from 1 to 6, p is 1 or 2, R 'is a saturated aliphatic A radical with 0 to 2 carbon atoms when p is 1 and with 1 to 7 carbon atoms, when p is 2 and q is 1 when p is 1 and 1 or 2 when p is 2.

Water-soluble corrosion inhibitors for metal protection against petroleum-containing Well fluids are made by adding an aliphatic saturated monocarboxylic acid with 1 - 3 carbon atoms or an aliphatic saturated dicarboxylic acid with 3 - 9 carbon atoms reacts with substituted imidazolines to form normal or acidic salts. The imidazolines are produced by reacting either a tall oil fatty acid from the group linoleic acid, conjugated linoleic acid, oleic acid, palmitic acid, stearic acid and mixtures thereof or a polymerized carboxylic acid such as dimerized Linoleic acid.

with a PolyaSkylenpolyamin, such as diethylenetriamine (DETA), triethylenetetramine (TETA) and tetraethylene pentamine (TEPA).

The life of metal pipes or any carbon steel equipment in contact with "sweet" and sour petroleum-bearing wellbore fluids at temperatures up to 15000 can be extended by treating the fluids with the inhibitors will. Permanent or temporary treatment results in a permanent one Protective film of these organic inhibitors on the metal surfaces and keeps the Corrosion away from these.

According to the invention, novel water-soluble corrosion inhibitors free of dispersion media are produced (1Ur (8h reaction of water-soluble saturated aliphatic mono- and dicarboxylic acids with a substituted imidazoline to form derivatives from the class of salts of imidazoline and aliphatic acids with the general formula: Explanation of the formula: 1. The radical R on the C atom no. 2 of each imidazoline ring represents a fatty acid from the tall oil fatty acid group and a polymerized carboxylic acid with 15 - 70 carbon atoms.

2. A on N atom No. 1 of each imidazoline ring is an ethylene or Propylene group, where m is an integer from 1-6.

3. p indicates the valence of R 'and is 1 for monocarboxylic acid and 2 for dicarboxylic acid.

4. Rt is a saturated aliphatic radical with 0-2 C atoms, if p is 1 and with 1 - 7 carbon atoms when p is 2.

5. q is 1 when p is 1.

q is 1 or 2 when p is 2.

In a preparation according to the invention, a 1-aminoalkyl-2-alkyl-2-imidazoline is used by reaction of stoichiometric amounts of monocarbonic acid with high molecular weight with 17 - 32 carbon atoms with a polyalkylene polyamine of the formula H2N- (A-NH) xH, whereby A is a divalent radical from the group containing ethylene and propylene and x is a is an integer from 2 to 7. In particular, one or more of the Fatty acids from tall oil with a polyalkyl polyamine, such as diethylenetriamine, triethylenetetramine and tetraethylene pentamine reacted to form 1-aminoalkyl-2-alkyl-2-imidazoline will. Finally, this imidazoline is saturated with mono- or dicarboxylic acids neutralized with the formation of a salt, which is the corrosion inhibitor. The term tall oil fatty acids as used here refers to the following fatty acids or their mixtures: oleic acid, linoleic acid, conjugated linoleic acid, palmitic and Stearic acid.

As water-soluble saturated aliphatic monocarboxylic acid adducts, which are suitable for neutralizing the imidazolines, ant, vinegar and propionic acid can be used. Water soluble aliphatic saturated dicarboxylic acids, which are suitable for neutralization are: malonic, amber, glutar, adipine, Pimelic, suberic and azelaic acids.

In another preparation according to the invention, an imidazoline is used polymerized by condensation of at least one of the carboxyl groups Fatty acid prepared with at least 1 mole of the polyalkylene polyamine described above. The term polymerized carboxylic fatty acid as used refers to the following polymeric acids and their mixtures: dimer and trimer fatty acids as well as polymers High molecular weight fatty acids. Complex imidazoline structures can by Condensation of two or more carboxyl groups of a polymeric polycarboxylic fatty acid can be made with two or more moles of polyalkylene polyamine.

The radical R in the general structural formula represents the remainder Proportion of the acid molecule after condensation between the carboxyl and polyalkylenepolyamine groups The radical R 'in the general structural formula is the hydrocarbon anteal of Acid molecule without the carboxyl groups.

While the new imidazoline compounds are primarily in use for water-soluble corrosion inhibitors in oil wells and in water flooding processes It was found that these were also intended as dispersants and surface active agents Substances are useful.

The corrosion inhibitor mixtures used are in concentrations of around 10-200 ppm extremely and surprisingly useful in protecting oil and gas pipelines and of storage equipment, even down to temperatures of 1,500C.

The corrosion inhibitor is believed to be an adhesive protective film forms on the metal surface that resists the penetration of corrosive substances. The polar parts (N and O) of the inhibitor molecule have metal affinity and bind the rest of the macromolecule to the metal surface.

The bulky organic residue contributes to the thickness and size of the film at. The NH groups in the chains offer a buffer option for acidic compounds in sweet and sour petroleum borehole fluids.

Among the many methods of treating wells with corrosion inhibitors be two of the most common, the periodic and the continuous treatment, mentioned.

Periodic or batch treatment of the drilling probes includes the Entering the corrosion inhibitor through the piping and lines and the Flow through to the bottom of the borehole by shunting the probe current through the Openings of piping and lines is guided. The fluids being pumped dilute and tear the inhibitors with it, causing a crack on the metal surfaces Protective coating is achieved. In the continuous process, a small proportion of the inhibitor is used entered into the flow rate that drives the hydraulic Tuachpumps, so to maintain a predetermined inhibitor concentration.

The invention is further illustrated in the following examples: example I For the production of a corrosion inhibitor consisting of a salt of an imidazoline and an aliphatic carboxylic acid, a 1-aminoalkyl-2-alky1-2-imidazoline 57.6 g (0.2 mole) of Acintol FA 1 tallow fatty acid and 20.6 g (0.2 mole) of diethylenetriamine refluxed at 280tC for approximately 1.75 hours. During that time were 71% of the theoretically calculated water was formed and collected in the reaction.

The temperature was then increased to 2900C and after about 1 72.6% of the theoretically calculated water was obtained. The amine equivalent, which is the basicity of the reaction product in mg. KOH / gram sample expresses, can vary between 185 - 225. The response was measured by measuring the Amount of water and the amide and imide bands in the IR spectrum (1660 - 1676 -1 and 1606 - 1620 cm 1) tracked.

The imidazoline can, if preferred, at a lower temperature with Using an alternate method, using a toluene azeotrope to remove just about anything to remove theoretical water of reaction, are produced. The response time for this procedure is about 2 hours at a maximum temperature of 24,000.

In a preferred embodiment of the invention, tall oil imidazoline acetate is used by neutralizing the 1-aminoalkyl-2-alkyl-2-imidazoline with a stoichiometric Amount of acetic acid, dissolved (1: 1) in nethanol-isopropanol, prepared.

By varying the reaction conditions and in the presence of excess acid can have one or more intermediate amines in the - (A-NH) -, - 1 chain with saturated aliphatic acid to form internal salts. Further can the all-oil imidazoline basic structure with saturated aliphatic dicarboxylic acids, such as adipic and azelaic acid, with the formation of the salt of imidazoline will.

One mole of these dicarboxylic acids becomes one mole of the tall oil imidazoline backbone neutralized, an acidic imidazoline salt is obtained. The neutral salt is formed if each carboxyl residue of the dicarboxylic acid with the imidazoline group reacted.

The salt of imidazoline and aliphatic acid can be used without a dispersant can be used as a water-soluble corrosion inhibitor. However, solution, Dispersing, weighting and other agents with the salt of imidazoline and the aliphatic acid for the formulation of various heat-resistant corrosion inhibitors for special applications, e.g. B. Piping protection for oil wells can be used.

Effective water soluble corrosion inhibitor mixtures for treatment of brine before it is pressed into formations with low permeability is made from tall oil imidazoline acetate by diluting an alcoholic solution with Water can be prepared, the total alcohol concentration eventually being around 15 - 25% by weight and the tall oil imidazoline acetate is about 25-32% by weight. A 1% Solution of this composition in distilled water is clear and shows only slight Tendency to "salt out" in the brine. In the endurance test described later, 25 ppm Uall Oil Imidazoline Acetate Inhibitor tested in 10% light gas oil and 90% brine and resulted in corrosion penetration rates of 0.033 mm / year and 0.145 mm / Year for “sweet” and “sour” media. For comparison, the xorrosion rates tested for unprotected samples under the same conditions. It turned out Values of 0.376 mm / year or 1.29 mm / year. That in the production of the basic framework Acintol FA1 used represents and is a mixture of liquid tall oil fatty acids from Arizona Chemical Co.

produced. This mixture contains: resin acids% 4.2 unsaponifiables % 1.6 total fat, acid content% 94.2 The fatty acid mixture consists of: Multiple saturated, conjugated linoleic acid% 8 n n, non-conjugated linoleic acid% 36 Oleic acid as difference% 52 saturated fatty acids% 4 Acintol FAl has the following properties: Specific weight 25 ° / 25 ° C 0.91 Acid number 195 Saponification number 197 Iodine number (wijs method) 131 Viscosity Saybolt seconds 37.8 ° C 100 Flash point (open shell) 0 0 193 Soluble in water Corrosion inhibitors can also be made in the following way: First that Basic structure, which consists of mono- or polyimidazolines, / by reaction of a polymerized carboxylic acid from the group of dimeric, trimeric, polymerized Carboxylic acids with a higher molecular weight and their mixtures with 15 - 70 carbon atoms with a polyalkylene polyamine, such as .3. Diethylenetriamine.

Then the mono- or polyimidazoline with an aliphatic Mono- or dicarboxylic acid neutralized.

The polymerized carboxylic acids can be unsaturated by polymerization Fatty acids according to that in the Journal of the American Oil Chemists Society, 24, 65, (1947) described procedures are established. Polymerized acids containing more than 3 Contains acid residues are not available for sale. However, the higher links are with 4 or more acid residues (e.g. tetramers) in the resulting residues the representation of dimeric and trimeric polyacids present. These contain residues also polymerized acids with higher molecular weights. You can too can be used to produce the basic framework. Typical polymerized carboxylic acids are dimerized linoleic and 9,11,13 - octadecatrienoic acids.

A suitable polymerized carboxylic acid is at the Harchem Division, Wallace & Tiernan, Inc., under the trade designation ttcentury D-75 polymerized Fatty Acid ". Ccntury I) - 75 is a polymerized carboxylic acid with a higher molecular weight and consists of approximately 10% monomer, 35% dimer, 55% trimer, as well as other polymerized carboxylic acids with higher molecular weight and the following properties: Free fatty acid (as oleic acid) 70-76% saponification value 175 - 185 iodine number 45 - 48 viscosity, Saybolt seconds at 98.9 ° C 325 - 400 molecular weight, approximately 600 Example II Reacted under similar conditions as in Example 1 equimolar amounts of Oentury D-75 with diethylenetriamine. The reaction product was at room temperature in acetic acid, 16% by weight solution of acetic acid in 1: 1 methanol-isopropanol, solved.

Other water soluble formulations of the salts of imidazoline aliphatic Acid and their corresponding corrosion penetration rates are in the table I stated. The test procedure is described in more detail below.

The reservoir conditions were examined in the dynamic test the corrosion inhibitors according to the invention are simulated by the ability of the inhibitors protecting metals immersed in sweet or acidic liquids has been tested.

Two well treatment methods were simulated in these tests: a. Long-term test or constant concentration b. Forms a permanent protective film by periodically adding high concentrations. The general test method: One sandblown weldable steel sample, '76, 2 x 12.7 x 0.127mm, is weighed and placed in a 4 ounce glass bottle containing 100 ml of a film-forming mixture, placed. 1 ml of 6% acetic acid is added to each of the glass bottles, with respectively There is water or brine in the film blinding mixture.

The bottles are now placed vertically on the spokes of a The wheel (diameter 58.42 cm) is mounted and the wheel is prescribed with a Time of less than 30 rpm.

in an oven at 48.90C for the acidic mixture and 71.1 ° C for the twisted sweet mixture. As the wheel rotates, the film-forming mixture washes away about the test sample. At the end of the trial period, the sample was taken out of the bottle removed, washed with dilute acid, brushed with scouring cleaner and weighed. The test results were obtained from the weight loss of the sample, metal density and treatment time compiled as corrosion penetration speeds in mm / year.

Continuous treatment simulation: a continuous addition of inhibitor is the oldest type of corrosion control process for hydrocarbons Pipes, water probes and water injection systems. The metal to be protected treads continuously in contact with low inhibitor concentrations of about 10 - 100 ppm (based on on the total liquid). In the auertest "the continuous borehole treatment in Laboratory simulates adding a 25 ppm inhibitor concentration in mixtures of 10% light gas oil and 90% artificial brine, as well as 1000 / o artificial brine (100 / o NaCl + 0.5% Carl2) was used. Sweet and sour influences were brought about by satiety the film-forming mixtures with C02 and H2S are simulated. The 25 ppm concentration lies in the 10-100 ppm range mentioned and is a severe test for most people Inhibitors. Steel samples were exposed to the film-forming inhibitor mixtures for 72 hours exposed in accordance with the general test procedure.

The preferred corrosion inhibitor mixtures given in Table I. were subjected to the "endurance test". Penetration speeds in mm / year for steel samples, which have been brought into contact with the corrosion-inhibiting liquids and Comparative tests with unprotected steel samples under the three test conditions described are in Table I. listed. A comparison of the test results with the comparison tests clearly shows the effectiveness of these mixtures in the Metal corrosion protection for drilling probes containing oil.

Formulations of water-soluble salts of imidazoline with aliphatic acids and their corrosion rates Corrosion Penetration Rates mm / year - long-term test (25 ppm inhibitor) Imidazoline amine- Saturated 1: 1 methanol- 100% 10% light gas oil- (25 wt.%) Equivalent of aliphatic isopropanol art. 90% artificial Brine Acid water brine sweet / 71.1 ° C sour / 48.9 ° C Name% by weight% by weight by weight acidic 48.9 ° C Acintol FA1 + DETA 211 acetic acid 7.1 47.9 20.0 4.6 1.3 5.7 "211 adipic acid 8.6 46.4 20.0 4.6 1.4 6.8 "211 azelaic acid 11.4 43.6 20.0 4.2 1.0 6.9 Acintol FA1 + TEPA 409 acetic acid 3.7 51.3 20.0 3.8 1.8 0.6 "313" 4.8 50.2 20.0 5.0 1.2 7.6 Century D-75 + DETA 384 "4.0 51.0 20.0 4.4 1.6 7.4 FA1 + D-75 + TEPA 416 "3.6 51.4 20.0 3.4 - - Settlement agreement such (without in- hibitor) 52.8 14.8 50.8

Claims (10)

Claims (1.) Compound of the formula wherein R is the acid residue of a tall oil fatty acid or a polymerized fatty acid with 15-70 carbon atoms, A -CH2-CH2- or -CH2-CH2-CH2-m is an integer from 1 to 6, p is 1 or 2, R 'is a saturated one aliphatic radical with 0 to 2 carbon atoms when p is 1 and with 1 to 7 carbon atoms when p is 2 and q is 1 when p is 1 and 1 or 2 when p is 2. 2. A compound according to claim 1, wherein R is the acid residue of a fatty acid with about 15 to 70 carbon atoms, namely the acid residue of a tall oil fatty acid or a high molecular weight polymeric carboxylic acid, A -CH2-CH2-, m 1 to 6, R 'is the hydrocarbon residue of a water-soluble saturated aliphatic carboxylic acid, namely - if p is equal to 1 - formic acid, acetic acid or propionic acid and when p is equal to 2, the malonic, amber, glutar, adipine, pimeline, suberine or azelaic acid when p is 2 and q is 1 when p is 1 and 1 or 2 when p is 2. 3. A compound according to claim 1, wherein R is the acid residue of a tall oil fatty acid, namely the acid residue of linoleic, conjugated linoleic, oleic or stearic acid, A -CH2-CH2-, m the integer 1 and R 'the acid residue of acetic, adipic or azelaic acid mean. 4. Process for the preparation of a water-soluble salt of an imidazoline and an aliphatic acid, d a -d u -: - r c h g e k e n n n z e i c h n e t that a tall oil fatty acid, a polymerized fatty acid or mixtures thereof with one Polyalkylenepolyamine, which has at least one -HN - CH2 - CH2 - NH - group and at the same time at least three amino groups reacted to form a substituted imidazoline be and the substituted imidazoline with a saturated aliphatic mono- or dicarboxylic acid with 1 to 9 carbon atoms is neutralized. 5. The method according to claim 4, d a d u r c h g e k e n n -z e i c Note that stoichiometric amounts of dimerized linoleic acid and diethylenetriamine to be reacted to form a substituted imidazoline and the substituted Imidazoline neutralized with a stoichiometric amount of acetic, adipic or azelaic acid will. 6. The method according to claim 4, d a d u r c h g e k e n n -z e i c Not that a mixture of linoleic and acidic acids in equimolar proportions with diethylenetriamine implemented and the substituted imidazoline obtained neutralized with acetic acid will. 7. Use of the compounds according to any one of claims 1 to 3 or Mixtures thereof as corrosion inhibitors. 8. Use according to claim 7 in wellbore fluids. 9. Use according to claim 7 or 8 in a 4-barrel, sol-soluble Formulation consisting of a. about 25-32% by weight of the salt, b. about 15 - 25% by weight Low molecular weight alcohols or mixtures thereof, preferably 1: 1 methanol-isopropanol, c. about 43-60% by weight water. 10. Use according to claim 8 and 9, d a d u r c h g e -k e n n z E i h e t that the water-, brine-soluble formulation in a concentration weight Inhlbitor tration of at least 10 ppm are contained in the borehole fluid.