NO963601L - Process for the treatment of oil producing systems - Google Patents

Description

The present invention relates to methods for dewaxing oil in steel systems without causing corrosion of the steel. More particularly, the invention relates to methods for providing aqueous solutions of dithiocarbamates with aqueous acids to form mixtures which are non-corrosive to mild steel.

When producing oil from underground formations penetrated by a well, paraffins are often deposited from the oil and tend to clog the pores in the reservoir rock, well casings and pipelines through which the oil flows to the surface. Problems including clogging and lost production yields can be caused by the formation of solid, waxy, asphaltenic and/or colloidal sulfur deposits. In the case of a two-phase oil-water system, further interface problems may arise which adversely affect separation processes.

Different techniques have been used in removing these paraffin deposits from underground formations, and wells and pipelines passing through these formations. These techniques include the use of heating devices, mechanical scraping, special polymers and solvents. Various types of solvents that have been used to dissolve the paraffins include benzene, xylene, toluene, gasoline and heavier distillates, carbon tetrachloride and carbon disulfide.

Carbon disulphide is considered one of the most effective solvents for paraffins with very different compositions. Carbon disulphide is known to prevent the deposition of waxes, asphaltenes and/or sulfur and to remove these deposits as soon as they are formed. Improved oil recovery is also obtained when carbon disulphide is used. Although some of these systems are made of special steel types, the vast majority of the worldwide systems are made of mild steel.

Carbon disulfide is also identified as suitable in many other applications. Some of the applications include: viscose rayon substances, cellophanes, production of carbon tetrachloride and sulfur-containing chemicals such as xanthates and thiocarbamates, agricultural fungicides, rodenticides, insecticides, nematicides, smoke disinfectants, soil conditioners, pharmaceuticals, rubbers, polymer industrial preparations, electroplating, metal treatment, waste water treatment, semiconductors, photography, food preservation, ore flotation, papermaking and catalysts. In addition to petroleum production, carbon disulphide can also exercise its useful solvent properties in such areas as petroleum refining, iodine extraction, sulfuric acid recovery, sulfur extraction and recycling of plastics. Most of these applications take place in systems made of metals, especially steel.

However, the use of carbon disulfide is difficult and dangerous. Its hazards include flammability and toxicity, which have led to certain prohibitions regarding its use. An aqueous carbon disulfide precursor will provide all of the above utility while being safer to handle. Dithiocarbamates represent a class of chemicals that can be water-based and can give carbon disulfide under regulated conditions. Acidification of dithiocarbamate salts is usually necessary to liberate the carbon disulfide agent. Aqueous, acidic solutions are generally corrosive to the vast majority of mild steel types present in the above-mentioned carbon disulfide industries and applications, which will require special metallurgy or periodic replacement of steel pipe lines.

It is an object of the present invention to provide a method for the safe release of carbon disulfide for oil field dewaxing, improved oil recovery and other uses without the need for special precautions, metallurgy or periodic replacement of steel pipelines. It is a further object of the invention to provide mixtures of aqueous dithiocarbamates and acids which are not corrosive to mild steel systems.

Contrary to what might be expected, the addition of aqueous acids to certain aqueous dithiocarbamate salts produces compositions that are non-corrosive, and in some cases corrosion-inhibiting, even though the resulting pH of these compositions is acidic. These results are also found for mixtures containing excipients such as surface-active agents and alcoholic winter equipment agents.

The dithiocarbamates have the formula

The dithiocarbamates can also have polymer form and can further be homopolymers or copolymers.

The method comprises the steps of forming an aqueous solution of the dithiocarbamate, mixing in an acid and supplying the mixture to the oil production system to be dewaxed. The acid is added in a quantity that is sufficient to provide approx. 0.5-7.0 equivalents of acid for each equivalent of carbon disulfide in the dithiocarbamate. This means that approx. 90% or more of the carbon disulfide can be released. The liberated carbon disulfide may be present as a pure phase, dissolved in a hydrocarbon phase, dissolved in an aqueous cosolvent phase, or distributed among any of the above. The mixture can be added to mild steel systems without causing corrosion of the mild steel.

Other objects, features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description. It must be understood, however, that the detailed description and specific examples, while setting forth preferred embodiments of the present invention, are provided by way of illustration and not by way of limitation. Many changes and modifications can be made within the scope of the present invention without deviating from its principle, and the invention includes all such modifications.

Aqueous solutions of dithiocarbamate salts can be used as mixtures with aqueous acids to provide mixtures which are not corrosive to mild steel. Some mixtures are even corrosion-inhibiting. Both uniform corrosion and pitting corrosion are affected by the dithiocarbamate mixtures. As a result of this, petroleum production is made easier, which is demonstrated by the reduction of solidification points, reduction of pressure in the flow lines, reduction in separation problems and increased crude oil yields.

The dithiocarbamates which are suitable in the present invention have the formula

where R and Rx are independently hydrogen, an alkyl radical or an aryl radical. An example of an aryl radical is benzyl. M can be any cation, with preferred cations being an alkali metal such as lithium, sodium, potassium, cesium or rubidium, or a substituent compound of the formula NR 2 R 3 R 4 R 5 . R 2 , R 3 , R 4 and R 5 can independently be hydrogen, an alkyl radical or an aryl radical. Preferred dithiocarbamates are sodium salts of N-methyldithiocarbamate and N,N-dimethyldithiocarbamate.

The process comprises the steps of preparing an aqueous solution of the dithiocarbamate, mixing an acid with the dithiocarbamate solution to form a mixture, and transferring the mixture to oil production equipment in a mild steel system. The amount of acid mixed with the aqueous dithiocarbamate will vary depending on the strength of the acid and the equivalents of carbon disulfide in the dithiocarbamate. Generally, the amount of acid mixed with the dithiocarbamate will be an amount sufficient to provide approx. 0.5-7.0 equivalents of acid per one equivalent of carbon disulphide in the dithiocarbamate, preferably approx. 1.5-3.0 equivalents of acid per equivalent of carbon disulfide in the dithiocarbamate. Most preferably, the added amount of acid gives approx. 2.0 equivalents of acid per equivalent of carbon disulfide in the dithiocarbamate. In this way, at least 90% of the theoretical amount of carbon disulphide is released and is available for treating the oil. The liberated carbon disulfide may be present as a pure phase, dissolved in a hydrocarbon phase, dissolved in an aqueous cosolvent phase, or distributed among any of the above.

The decomposition or reformation reaction in which carbon disulfide is released from the mixture of a dithiocarbamate with acid (HA) can be represented by the equation

When sodium N-methyldithiocarbamate is used, a methylamine salt is formed together with the liberation of carbon disulphide. Methyl amine salts are listed in the tables published by the National Association of Corrosion Engineers as agents known to cause corrosion in mild steel. Likewise, the use of sodium N,N-dimethyldithiocarbamate releases known corrosive agents, dimethylamine salts, by the carbon disulfide release reaction.

It has surprisingly been discovered that acids can be mixed with the aqueous dithiocarbamates of the present invention liberating carbon disulfide and known corrosive agents, and yet the resulting mixtures are not corrosive to mild steel.

The dithiocarbamates according to the present invention preferably have a low molecular weight. Lower molecular weight dithiocarbamates will be water soluble and have a high proportion of carbon disulphide potential. Dithiocarbamates of formula I wherein R or Rx each have six carbon atoms or less are preferred. The reaction products from the re-conversion of these dithiocarbamates have a correspondingly low molecular weight and are known corrosive agents in mild steel systems. However, the resulting compositions according to the present invention do not cause corrosion in mild steel.

The dithiocarbamates used in the present invention can also be polymer materials with the formula

or where n is an integer higher than 1. R 6 , R 7 , R 8 and R 9 are each independently hydrogen, an alkyl radical or an aryl radical. These radicals again have a relatively low molecular weight, with 1-6 carbon atoms. For both formulas II and III, Z is an alkyl radical, for example methylene or ethylene, an aryl radical, for example phenylene, or it need not be present in formula II. The dithiocarbamate of formula I, II or III can also be a polymer where M has the formula Furthermore, the dithiocarbamate of formula I, II or III can be polymers where M has the formula

and p is greater than 1.

The repeating units in the polymeric dithiocarbamates should have a high proportion of latent carbon disulphide. These polymeric dithiocarbamates may also have a comonomer character which improves their water solubility. An example of a polymeric dithiocarbamate with comonomer character is a compound of the above formula which has a skeleton with attached ammonium groups.

The polymeric dithiocarbamates with one of the formulas I, II or III can also be used with a copolymer. These copolymers can be, for example, methacrylic acid, acrylic acid, allyl alcohol, methacrylamide, acrylamide, alkyl methacrylates, alkyl acrylates, crotonic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, styrene, butadiene, vinyl acetate, carboxyethyl methacrylate, carboxyethyl acrylate, sulfoethyl methacrylate, sulfoethyl acrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, oxyalkylated methacrylates, oxyalkylated acrylates, oxyalkylated allyl alcohol and acrolein. The oxyalkylation may comprise ethylene oxide, propylene oxide or butylene oxide or mixtures thereof.

Although fully aqueous dithiocarbamate solutions are preferred, it may be advantageous to use a co-solvent and/or emulsifier with the dithiocarbamate to provide additional benefits. Examples of such co-solvents include organic materials which are miscible with water, exemplified by alcohols, glycols, ketones, ethers, esters, amides, amines and chalcogenide and phosphorus derivatives thereof. Examples of emulsifiers are surfactants, dispersants, suspending agents and the like. The surface-active compounds can be non-ionic, anionic or cationic.

The dithiocarbamate for use in the present method can further comprise each combination or mixture of dithiocarbamates indicated above.

When the acidic materials used in the present invention are water-soluble enough to produce concentrated aqueous solutions, these acidic solutions are also known to be corrosive to mild steel. The corrosive tendencies of specific acids in various systems are shown in tables published by the National Association of Corrosion Engineers (NACE) Corrosion Data Survey, 5th ed., National Association of Corrosion Engineers, 1981. The compositions of the present invention, which contain aqueous dithiocarbamates and acid, but, surprisingly, are not corrosive to mild steel systems.

The acidic materials liberate carbon disulfide from the aqueous dithiocarbamate salts. These acidic materials can be typical mineral acids such as hydrochloric acid, hydrofluoric acid, sulfuric acid, phosphoric acid, boric acid, fluoroboric acid or sulfuric acid. Typical polyacids such as polyphosphoric acid or polysilicic acid can also be used.

Organic acids such as acetic acid, hydroxyacetic acid, oxalic acid, citric acid, tartaric acid, maleic acid, acrylic acid and benzoic acid are also used in the present invention. A preferred acid is acetic acid. Likewise, polyorganic acids such as polyacrylic acid or polymethacrylic acid can be used.

Although fully aqueous acid solutions are preferred, it may be advantageous to use a co-solvent and/or emulsifier with the acid to provide additional benefits. For example, acidic materials with low or no water solubility can be emulsified with surfactants and used in the present invention. Examples of such co-solvents include organic materials which are miscible with water, exemplified by alcohols, glycols, ketones, ethers, esters, amides, amines and chalcogenide and phosphorus derivatives thereof. Examples of emulsifiers are surfactants, dispersants, suspending agents and the like. Non-ionic, anionic and cationic surfactants can be used. These agents can also be monomeric (such as oleic acid) or polymeric (such as polyfatty acids). The added acidic materials can also be a buffering material with an acidic pH when diluted in water.

It will be understood that mixtures of any combination of the aforementioned acidic materials and dithiocarbamates may also be used.

Since the predominantly aqueous solutions according to the present invention are usually used in cold climates where wax formation is a problem, it is advantageous to add a winterizing agent to the dithiocarbamate, the acid or the mixture thereof. Winter equipment agents lower the solution's freezing point, which makes pumping the material easier. Commonly used winter equipment agents are alcohols, which can be either monomeric or polymeric. Examples are methanol, isopropanol, ethylene glycol, propylene glycol, polyethylene glycol and mixtures of these.

The above described solutions according to the present invention can be used in steel systems without corrosion occurring. The steel types can be mild steel types, cast iron and galvanized, with mild steel being the most preferred.

The invention is further described by the following non-limiting examples.

Example 1

The amount of acid relative to the amount of winterized aqueous sodium N-methyldithiocarbamate can be determined by examining various ratios of acid to dithiocarbamate and measuring the point at which the maximum theoretical amount of carbon disulfide is released upon mixing.

25 ml of a solution of 39% sodium N-methyldithiocarbamate, 24% ethylene glycol and 36% water was mixed with an equal volume of acetic acid in varying strengths, and the amount of carbon disulfide converted was determined. The following data were obtained.

The theoretical carbon disulphide value is 5.5 ml. Distillation of the aqueous layer when 30% acetic acid was used gave 2.5 ml of carbon disulphide, bp. 45°C. This shows that the carbon disulfide was kept in the aqueous solution by means of the ethylene glycol.

These data show that 2 5 ml of approx. 30% aqueous acetic acid will convert 39% sodium N-methyldithiocarbamate to the theoretical amount of carbon disulfide.

It was observed that the pH went from 11 to 3.6 upon addition of the acid to the dithiocarbamate, followed by a rise to 7.0. Aqueous acetic acid is known to be corrosive to mild steel.

Example 2

The corrosive nature of dithiocarbamates, acids and mixtures thereof was determined under dynamic conditions using a recirculating flow loop. In this case, a reservoir was connected to a corrosion test cell via a pump. The test cell housed a Corrater probe equipped with mild steel elements (supplied from Rohrback-Cosasco, Santa Fe Springs, CA). Flow meters, thermometers and a pH probe were also part of the system. The entire loop contained at least 300 ml of fluid and was run at speeds of 15-38 liters per minute. hour. Normally the flow rate was 22.7 liters per hour. The data relating to the sodium N-methyldithiocarbamate/acetic acid system are shown in the following Table 1.

<1>pH (am) is the value just after mixing the system, and

pH (eq) is the value after the system reached equilibrium. The corrosion rates were determined after Corrater-

the equipment reached a stable reading.

These data show that the sodium N-methyldithiocarbamate in glycol/water with the equivalent amount of 50% aqueous acetic acid is not corrosive. This is evident from comparisons with the acetic acid systems which contain equivalent amounts of sodium hydroxide and methylamine, which are obtained by the re-conversion process which simultaneously produces carbon disulphide.

Example 3

A petroleum-producing well was chosen as the site for the application of aqueous sodium N-methyldithiocarbamate containing ethylene glycol as a winterizing agent described in example 1. An equal volume of 30% acetic acid was applied at the same time. The well produced a gross quantity of 12,000 liters per year. day with a 5% water reduction ("water cut"). The crude oil had an API specific gravity of 28.2° and contained approx. 8.1% wax and approx. 4.0% asphaltenes. The brine produced had a pH of 7.2 and a total dissolved solids level of 6,400 ppm (parts per million). The chemicals were pumped down the back of the well using a beam driven pump equipped with two heads. Each chemical was pumped separately and mixed after the pump heads before entering the well pipe. No flushing was used. In terms of experience, approx. 10-14 days for the product's performance to show at the wellhead at gross production. The data for this application are shown in Table 2. The corrosion measurements were made on a Corrosometer probe (Rohrback-Cosasco, Santa Fe Springs, CA).

These data show that the sodium N-methyldithiocarbamate can be applied with the simultaneous use of acetic acid, and provides a pour point reduction for this crude oil. Furthermore, no change was observed in the corrosive nature of the production when the awaxing process was observed.

Example 4

The amount of numerous acids relative to the amount of winterized aqueous sodium N,N-dimethyldithiocarbamate can also be determined by examining the various ratios between acid and dithiocarbamate and measuring the point where the maximum amount of carbon disulfide occurs upon mixing. In this case, the precursor contained 33% sodium N,N-dimethyldithiocarbamate, 20% ethylene glycol and 47% water. Divided tubes were filled with 6.5 g of dithiocarbamate solution and mixed with different amounts of acids in different concentrations. The theoretical amount of carbon disulfide is 0.9 ml. The data are shown in Table 3.

As will be seen, several inorganic and organic acids can be used to liberate carbon disulphide from the sodium N,N-dimethyldithiocarbamate. Most of these acids are corrosive to mild steel types, which can be easily verified according to the Corrosion Data Survey issued by the National Association of Corrosion Engineers.

Example 5

The mixtures of acid and sodium N,N-dimethyldithiocarbamate at acid levels sufficient to produce maximum amounts of carbon disulfide were examined for their corrosion tendencies using the test loop described in Example 2. The data are described in Table 4.

The above examples show that the use of acids with sodium N,N-dimethyldithiocarbamate in ethylene glycol/water mixtures results in lower rates of uniform corrosion for all the indicated acids. There are some increases when it comes to pitting corrosion for the acrylic, methacrylic and phosphorous cases. In the case of 25% acetic acid, the rates of uniform corrosion were significantly altered when a 25% increase in acid was used, but the observed values were below the water blank.

Example 6

The winter-equipped design of sodium N,N-dimethyl-dithiocarbamate was supplied in an amount of 3.8 liters per day with a simultaneous quantity of 20% acetic acid, at the petroleum-producing well under the conditions described in example 3. After 51 days with 3.8 liters per day, the quantities were increased to 5.7 liters per day. The data is shown in Table 5.

The data show that the mixture of acetic acid and sodium N,N-dimethyldithiocarbamate can be applied down the well and that no corrosion increases were found during the periods when waxing was observed in total production.

Example 7

An oil well with a gross production of oil and water quantity of approx. 15,900 liters per day, with an oil content of approx. 6360 liters per day of a crude oil of the type API 20°, was treated with a solution of 33% aqueous dithiocarbamate mixed with a 25% acetic acid in a ratio of 1:1. The treatment included pressing in 318 liters of solution (equivalent to approx. 27 litres, carbon disulphide) at a pH of approx. 4.5 in the borehole, after which the well was closed for approx. 24 hours. Twelve months before this treatment, total production in the well was approx. 9 54 0 liters per day. Production resumed in the first 24 hours after the injection. The gross production rate had increased to approx. 21,460 liters per day, comprising approx. 11,760 liters of crude oil per day (an improvement of 187%), and after approx. 1 month, gross production had decreased to approx. 17,170 liters per day, while the amount of crude oil was approx. 7,630 liters per day (120% improvement). The corrosion rate before this pressure application was approx. 1-2 mpy. At the time of restarting crude oil production after the shutdown condition and during the following month, no change in corrosion rate was observed.

Example 8

The corrosion test loop described in example 2 was used to evaluate different winterized mixtures of acid and sodium dithiocarbamate. The data is described in Table 6, and 235 g of 33% sodium dimethyldithiocarbamate and 200 g of 20% acetic acid are used, with the winterizing agent at a level of 25% in the 235 g dithiocarbamate solution.

These data suggest that alcohol-based winterizing agents do not affect the low levels of corrosion obtained with mixtures of acid and dithiocarbamate.

Claims (41)

1. Procedure for treating oil without causing corrosion in a mild steel system, characterized in that it includes the steps that an aqueous solution of a dithiocarbamate with the formula is prepared where R and Rx independently of each other are H, C 1 -alkyl or aryl, M is Li, Na, K, Cs, Rb or NR2 R3 R4 R5 , R 2 , R 3 , R 4 and R 5 are independently H, C 1 -alkyl or aryl, acid is mixed with the dithiocarbamate solution to form a mixture, the acid being added in an amount effective to provide approx. 0.5-7.0 equivalents of acid for each equivalent of carbon disulfide in the dithiocarbamate; and the mixture is delivered to the oil in the system with the mild steel, the treatment method being selected from the group consisting of awaxing, desulphurisation and deasphalting. 2. Method according to claim 1, characterized in that the acid is added in an amount that is effective for providing approx. 1.5-3.0 equivalents of acid for each equivalent of carbon disulfide in the dithiocarbamate. 3. Method according to claim 2, characterized in that the acid is added in an amount that is effective for providing approx. 2.0 equivalents of acid for each equivalent of carbon disulfide in the dithiocarbamate. 4. Method according to claim 1, characterized in that the acid is in aqueous solution. 5. Method according to claim 1, characterized in that the acid is selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid, boric acid, fluoroboric acid, sulfuric acid, polyphosphoric acid, polysilicic acid, acetic acid, hydroxyacetic acid, oxalic acid, citric acid, tartaric acid, maleic acid, acrylic acid, benzoic acid, polyacrylic acid, polymethacrylic acid, oleic acid, polyfatty acids and combinations thereof. 6. Method according to claim 5, characterized in that the acid is acetic acid. 7. Method according to claim 1, characterized in that the acid is emulsified with an agent selected from the group consisting of non-ionic surfactants, cationic surfactants, anionic surfactants, emulsifiers and dispersants. 8. Method according to claim 1, characterized in that a co-solvent selected from the group consisting of alcohols, glycols, ketones, ethers, esters, amides, amines and chalcogenide and phosphorus derivatives thereof is added to the acid. 9. Method according to claim 1, characterized in that M is Na. 10. Method according to claim 1, characterized in that the dithiocarbamate is emulsified with an agent selected from the group consisting of non-ionic surfactants, cationic surfactants, anionic surfactants, emulsifiers and dispersants. 11. Process according to claim 1, characterized in that a co-solvent selected from the group consisting of alcohols, glycols, ketones, ethers, esters, amides, amines and chalcogenide and phosphorus derivatives thereof is added to the dithiocarbamate. 12. Method according to claim 1, characterized in that it further comprises adding to the mixture a winter equipment agent selected from the group consisting of methanol, isopropanol, ethylene glycol, propylene glycol, polyethylene glycol and mixtures thereof. 13. Method according to claim 1, characterized in that the dithiocarbamate is a polymer with the formula where n is an integer greater than 1; R 6 / R 7 , R 8 and R 9 independently of each other are H, C 1 -alkyl or aryl; and Z is alkyl, aryl or absent. 14. Method according to claim 13, characterized in that the dithiocarbamate polymer has the formula 15. Method according to claim 1, 13 or 14, characterized in that M is a polymer with the formula 16. Method according to claim 1, 13 or 14, characterized in that M is a polymer with the formula 17. Method according to claim 1, 13 or 14, characterized in that M is a polymer with the formula where p is an integer greater than 1. 18. Method according to claim 13 or 14, characterized in that the dithiocarbamate is a copolymer with a compound from the group consisting of methacrylic acid, acrylic acid, allyl alcohol, methacrylamide, acrylamide, alkyl methacrylates, alkyl acrylates, crotonic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, styrene, butadiene, vinyl acetate, carboxyethyl methacrylate, carboxyethyl acrylate, sulfoethyl methacrylate, sulfoethyl acrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, oxyalkylated methacrylates, oxyalkylated acrylates, oxyalkylated allyl alcohol, acrolein and combinations thereof. 19. Method according to claim 1, characterized in that the dithiocarbamate is sodium N-methyldithiocarbamate. 20. Method according to claim 1, characterized in that the dithiocarbamate is sodium N,N-dimethyldithiocarbamate. 21. Procedure for improving the recovery of petroleum from a production well that penetrates a petroleum-bearing formation, without causing corrosion in a mild steel system, characterized in that it includes the steps that an aqueous solution of a dithiocarbamate with the formula is prepared where R and Rx independently of each other are H, C1-6-alkyl or aryl, M is Li, Na, K, Cs, Rb or NR2 R3 R4 R5 , R 2 , R 3 , R 4 and R 5 independently of each other are H, C 1 -alkyl or aryl, acid is mixed with the dithiocarbamate solution to form a mixture, the acid being added in an amount effective to provide approx. 0.5-7.0 equivalents of acid for each equivalent of carbon disulfide in the dithiocarbamate; the mixture is introduced into the petroleum-bearing formation through the system of mild steel; and petroleum is extracted from the petroleum-bearing formation at a daily crude oil production rate. 22. Method according to claim 21, characterized in that the acid is added in an amount that is effective for providing approx. 1.5-3.0 equivalents of acid for each equivalent of carbon disulfide in the dithiocarbamate. 23. Method according to claim 22, characterized in that the acid is added in an amount that is effective for providing approx. 2.0 equivalents of acid for each equivalent of carbon disulfide in the dithiocarbamate. 24. Method according to claim 21, characterized in that the acid is in aqueous solution. 25. Method according to claim 21, characterized in that the acid is selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid, boric acid, fluoroboric acid, sulfuric acid, polyphosphoric acid, polysilicic acid, acetic acid, hydroxyacetic acid, oxalic acid, citric acid, tartaric acid, maleic acid, acrylic acid, benzoic acid, polyacrylic acid, polymethacrylic acid, oleic acid, polyfatty acids and combinations thereof. 26. Method according to claim 25, characterized in that the acid is acetic acid. 27. Method according to claim 21, characterized in that the acid is emulsified with an agent selected from the group consisting of non-ionic surfactants, cationic surfactants, anionic surfactants, emulsifiers and dispersants. 28. Method according to claim 21, characterized in that a co-solvent selected from the group consisting of alcohols, glycols, ketones, ethers, esters, amides, amines, and chalcogenide and phosphorus derivatives thereof is added to the acid. 29. Method according to claim 21, characterized in that M is Na. 30. Method according to claim 21, characterized in that the dithiocarbamate is emulsified with an agent selected from the group consisting of non-ionic surfactants, cationic surfactants, anionic surfactants, emulsifiers and dispersants. 31. Method according to claim 21, characterized in that a co-solvent selected from the group consisting of alcohols, glycols, ketones, ethers, esters, amides, amines and chalcogenide and phosphorus derivatives thereof is added to the dithiocarbamate. 32. Method according to claim 21, characterized in that it further comprises adding to the mixture a winter equipment agent selected from the group consisting of methanol, isopropanol, ethylene glycol, propylene glycol, polyethylene glycol and mixtures thereof. 33. Method according to claim 21, characterized in that the dithiocarbamate is a polymer with the formula where n is an integer greater than 1; R 6 , R 7 / R 8 and R 9 independently of one another are H, C 1 -6 alkyl or aryl; and Z is alkyl, aryl or absent. 34. Method according to claim 33, characterized in that the dithiocarbamate polymer has the formula 35. Method according to claim 21, 33 or 34, characterized in that M is a polymer with the formula 36. Method according to claim 21, 33 or 34, characterized in that M is a polymer with the formula 37. Method according to claim 21, 33 or 34, characterized in that M is a polymer with the formula where p is an integer greater than 1. 38. Method according to claim 33 or 34, characterized in that the dithiocarbamate is a copolymer with a compound from the group consisting of met acrylic acid, acrylic acid, allyl alcohol, methacrylamide, acrylamide, alkyl methacrylates, alkyl acrylates, crotonic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, styrene , butadiene, vinyl acetate, carboxyethyl methacrylate, carboxyethyl acrylate, sulfoethyl methacrylate, sulfoethyl acrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, oxyalkylated methacrylates, oxyalkylated acrylates, oxyalkylated allyl alcohol, acrolein and combinations thereof. 39. Method according to claim 21, characterized in that the dithiocarbamate is sodium N-methyldithiocarbamate. 40. Method according to claim 21, characterized in that the dithiocarbamate is sodium N-methyldithiocarbamate. 41. Method according to claim 21, characterized in that the mixture is delivered to the petroleum-bearing formation in an amount that is sufficient to increase the crude oil production rate by at least approx. 10%.