WO2017137786A1

WO2017137786A1 - Paraffin removal formulations

Info

Publication number: WO2017137786A1
Application number: PCT/IB2016/000125
Authority: WO
Inventors: Fernanda GRIGOLETTO; Sergio Martins; Suelbi Silva
Original assignee: Rhodia Poliamida E Especialidades Ltda
Priority date: 2016-02-12
Filing date: 2016-02-12
Publication date: 2017-08-17

Abstract

The present invention generally relates to a paraffin removal formulation. More specifically the present invention describes the use of glycerol ketals and/or acetals for removing paraffin deposits in oilfield equipment.

Description

PARAFFIN REMOVAL FORMULATIONS

TECHNICAL FIELD

The present invention generally relates to a paraffin removal formulation. More specifically, the present invention describes the use of glycerol ketals and/or acetals for removing paraffin deposits in oilfield equipment.

PREVIOUS ART

Paraffin deposition in oilfield equipment has been recognized as one of the main challenge faced in oil operations, during production, transportation and storage. These paraffinic materials contain as major constituents high molecular weight aliphatic hydrocarbons, generally found between the hydrocarbon chain of Ci₈H₃₈ and C₇₈Hi₄₂ and with high melting points. In addition, they also contain petroleum resins, asphaltic and asphaltene materials, aromatic hydrocarbons, water, and inorganic components (such as calcium and magnesium carbonates and sulfates, sand, clay and silicates, rust, iron sulfide and chlorides).

These waxy compounds readily crystallize out upon cooling of the oil fraction containing them. When the temperature of crude drops falls to a critical level, called wax appearance temperature (WAT), and/or when the low-molecular-weight hydrocarbons evaporate, the dissolved waxes begin to form clusters. Under those conditions, wax molecules continue to attach and detach from these clusters until they reach a critical size, become stable and then start depositing on the equipment.

In more details, this deposition process basically involves two distinct stages: nucleation and growth. Nucleation is the generation of these critical sized clusters, called nuclei, which are stable in the hydrocarbon fluid. This insoluble wax itself tends to disperse in the crude oil. Once the nuclei are formed and the temperature remains below WAT, the crystal growth process occurs as further molecules are laid down in laminar or plate-like structure. Wax deposition on the production system ("growth") generally requires a nucleating agent, such as asphaltenes and inorganic solids. Temperature, pressure and composition play an important role in wax deposition, temperature being a predominant factor. In the production of certain types of petroleum or oil from subterranean formations penetrated by a well, paraffin can precipitate and deposit under certain environmentaf conditions as explained above. It is common that the pores of the reservoir rock, well casing, perforations, screen and tubing through which the oil flows to the surface tend to clog, restricting the flow and leading to a reduced production and transportation rate, equipment damage, and production shut down.

Several methods such as mechanical, thermal and chemical methods have been utilized to remove and prevent the formation of paraffin deposits. However, so far no suitable solution has been found to overcome this problem.

The first solution is preventing or inhibiting the deposition using heat. Electric heaters can be employed to raise the crude oil temperature as it enters the wellbore. Limitations are the maintenance costs of the heating system and the availability of electrical power. Maintaining a sufficiently high production level may also keep the upper-wellbore temperature above the WAT because high flow rates tend to minimize wax adherence to metal surfaces because of the shearing action of the flowing fluid.

Wax deposition can also be prevented, delayed, or minimized by the use of dispersants or crystal modifiers. Dispersants are generally surfactants and may also keep the pipe surface water wet, minimizing the tendency of the wax to adhere. Paraffin-crystal modifiers are chemicals that interact with the growing crude-oil waxes by co-crystallizing with the native paraffin waxes in the crude oil that is being treated. These interactions result in the deformation of the crystal morphology of the crude-oil wax and once deformed, these crystals cannot undergo the normal series of aggregation steps. However, these inhibitors must be delivered into the crude oil at temperatures above the WAT and the paraffin is not truly dispersed and can again quickly return to a solid form after the heat dissipates.

The most common technic for the removal of paraffin deposits is the use of hot oil, normally pumped down the casing and up the tubular. It is intended that the high temperature of the liquid phase heat and melt the wax, which then dissolves in the oil phase. Hot oil treatment is considered expensive because of the energy consumption for heating and pumping, and besides, hot oil has a relatively low solvency for paraffin and can cause permeability damage, if the fluid containing the melted wax enters the formation.

Another alternative used to remove paraffins that have already been deposited is to dissolve the asphaltene and other organic deposits. Various solvents which have been used to dissolve asphaltene include chlorinated solvents, petroleum product distillates and aromatic solvents as describe by Elochukwu, et al (Elochukwu, O. H., Ismail M. Saaid, I.M. and Rasidah M. Pilus, R. M. Organic deposit remediation using environmentally benign solvents: a review, Journal of Engineering and Applied Sciences; Oct2014, Vol. 9 Issue 10, p. 1930-1935). As with asphaltene dissolution, xylene has been the most widely aromatic solvent used to remove paraffin from well tubular and near wellbore region of the reservoir formation. However, these solvents poses health, safety and environment risks due to their physico-chemical properties, i.e. evident toxicity, and their action is limited to the deposit surface.

Apart from these traditional methods, other solutions have been proposed. The US Patent IMS 4,813,482 describes a method to contact a mixture of an alkyl or aralkyl polyoxyalkylene phosphate ester surfactant in free acid form or as a salt with a mutual solvent and water to remove paraffin deposits. This mixture must be at a temperature greater than the melting point of the wax to be effective. Since this process does not melt the wax, it can only slowly act at its surface, this is not fast enough and creates dispersions in water which must be disposed of or otherwise expensively dealt with.

US Patent 6,176,243 teaches the use of a composition comprising limonene, a glycol ether, an ethoxylate alcohol surfactant, an aliphatic alcohol and an organic acid to remove paraffin accumulations in oilfield equipment. However, it is a questionable environmental solution, since the glycol ethers are not renewable and they have certain toxicity, depending on the molecule, such as eye irritation. Still this composition inherently involves lengthy processing and/or mixing times of the chemicals, which are not favored, particularly at the well site or the pipeline. In view of the above, up to now there is no effective solution for removing paraffin in oilfield equipment that combines inherent properties for a potential paraffin deposit remediation and water solubility, low toxicity, low odor, environmental profile and low cost. Furthermore, there is a continued search for "green" solvents as an alternative to the conventional solvents and few green solvents that are available can meet the increasingly demanding technical requirements for paraffin removal formulations.

Therefore, the present invention aims to propose an optimized paraffin removal formulation improving the paraffin deposit remediation by solubilizing these organic deposits.

One of the objects of the invention is to propose an alternative solvent for reducing paraffin deposits from oilfield equipment, which solubilizes and allows increased paraffin removal from the well in a fast and efficient manner, maintaining paraffin build-up low and enhancing the effectiveness of scale and corrosion inhibitors.

The formulation also has the advantage of having water solubility, low odor, adequate volatility, no toxicity, a good environmental profile (non VOC) and low cost.

SUMMARY OF THE INVENTION

The invention thus relates to the use of at least one com ound of formula I below:

wherein

Ri and R₂, independently from one another, are selected in the group consisting of: hydrogen or a linear or branched C1-C12 alkyl, a C4-C12 cycloalkyl or an aryl.

R3 is H, a linear or branched alkyl, a cycloalkyl, a -C(=0)R₄ group, with R₄ being a linear or branched C1-C4 alkyl or a C5-C6 cycloalkyl or -(R₅0)_n— R₆, with R₅ being a linear or branched C1-C12 alkylene group and R₆ being H, a linear or branched C1-C12 alkyl or a C5-C6 cycloalkyi and n=l to 9, as solvent in paraffin removal formulations.

The present invention also proposes a paraffin removal formulation comprising at least one compound of formula I below:

wherein

Ri and R₂, independently from one another, are selected in the group consisting of: hydrogen or a linear or branched C1-C12 alkyl, a C4-C12 cycloalkyi or an aryl.

R₃ is H, a linear or branched alkyl, a cycloalkyi, a -C(=0)R₄ group, with R₄ being a linear or branched C1-C4 alkyl or a C5-C6 cycloalkyi or -(R₅0)_n— R₆, with R₅ being a linear or branched C1-C12 alkylene group and R₆ being H, a linear or branched C1-C12 alkyl or a C5-C6 cycloalkyi and n=l to 9, as solvent in paraffin removal formulations. DETAILED DESCRIPTION OF THE INVENTION

The present invention thus concerns the use of at least one compound of formula I below:

wherein

R₃ is H, a linear or branched alkyl, a cycloalkyi, a -C(=0)R₄ group, with R₄ being a linear or branched C1-C4 alkyl or a C5-C6 cycloalkyi or -(R₅0)_n— R₆, with R₅ being a linear or branched C1-C12 alkylene group and R₆ being H, a linear or branched C1-C12 alkyl or a C5-C6 cycloalkyl and n=l to 9, as solvent in paraffin removal formulations.

In one embodiment, Ri and R₂, independently from one another, are selected in the group consisting of: hydrogen, methyl, ethyl, isopropyl, n-propyl, isobutyl, n-butyl, tert-butyl, n- pentyl, cyclopentyl, cyclohexyl or phenyl.

In a preferred embodiment, Ri and R₂, independently from one another, are selected in the group consisting of: methyl, ethyl, isopropyl, n-propyl, isobutyl, n-butyl, tert-butyl, n-pentyl, cyclopentyl, cyclohexyl or phenyl.

Advantageously, in formula I above R₃ is H or a -C(=0)R₄ group, with R being methyl, ethyl, isopropyl, n-propyl, isobutyl, n-butyl or tert-butyl, or -(^R50)_n— R6, with R₅ being -CH₂-, - (CH₂)₂-, -CH(CH₃)-, -(CH₂)₃-,-C(CH₃)₂-, -CH(CH(CH₃)₂)-, -(CH₂)₄- or -CH(C(CH₃)₃)- and R₆ being H, methyl, ethyl, isopropyl, n-propyl, isobutyl, n-butyl or tert-butyl and n=l to 3.

One preferred embodiment is when Ri and R₂ are methyl and R₃ is H. In this case, the compound is commercially available, for example under the name Augeo^® Clean Multi, Augeo^® SL191 or Solketal. This compound can be synthesized by reaction between glycerol and acetone, under well-known classical conditions.

In another embodiment, Ri is methyl, R₂ is isobutyl and R₃ is H. In this case, the compound is commercially available, for example under the name Augeo^® Clean Plus. This compound can be synthesized by reaction between glycerol and methyl-isobutyl ketone, under well-known classical conditions.

In a third embodiment, Ri is methyl, R₂ is phenyl and R₃ is H. In this case, the compound is commercially available, for example under the name Augeo^® Film HB. This compound can be synthesized by reaction between glycerol and acetophenone, under well-known classical conditions. In a fourth embodiment, Ri is isopropyl and R₂ and R3 are H. In this case, the compound is 2- isobutyl-2-methyl-l,3-dioxolane-4-methanol. This compound can be synthetized by reaction between glycerol and isobutyraldehyde, under well-known classical conditions. Another possibility is to have Ri and R₂ are methyl and R₃ is a -C(=0)R₄ group, with R₄ being methyl. In this case, the compound is commercially available, for example under the name Augeo^® ACT. This compound can be synthesized by transesterification of Solketal with an alkyl acetate under well-known classical conditions. Still another possibility is to have Ri is 2-ethylhexyl and R₂ and R3 are H. In this case, the compound is (2-(heptan-3-yl)-l,3-dioxolan-4-yl)methanol. This compound can be synthetized by reaction between glycerol and 2-ethylhexanal, under well-known classical conditions. Glycerol can be obtained as a coproduct from biodiesel production during the transesterification of triglycerides.

Advantageously, the compound of formula I is chosen from the group comprising: 2,2- dimethyl-l,3-dioxolane-4-methanol, 2,2-diisobutyl-l,3-dioxolane-4-methanol, 2-isobutyl-2- methyl-l,3-dioxolane-4-methanol, 2-isopropyl-l,3-dioxolane-4-methanol, 2-butyl-2-ethyl- l,3-dioxolane-4-methanol, 2-phenyl-l,3-dioxolane-4-methanol and 2-methyl-2-phenyl-l,3- dioxolane-4-methanol, 2,2-dimethyl-l,3-dioxolane-4-acetate, (2-(heptan-3-yl)-l,3-dioxolan- 4-yl)methanol and mixtures thereof. In one embodiment of the invention, at least two, more preferably two or three, compounds of formula I can be used as blend of solvents in paraffin removal formulations. As preferable examples of such blends include a blend of 2,2-dimethyl-l,3-dioxolane-4- methanol and at least a glycerol ketal and/or acetal chosen from the following group: 2,2- diisobutyl-l,3-dioxolane-4-methanol, 2-isobutyl-2-methyl-l,3-dioxolane-4-methanol, 2- isopropyl-l,3-dioxolane-4-methanol, 2-butyl-2-ethyl-l,3-dioxolane-4-methanol, 2-phenyl- l,3-dioxolane-4-methanol, 2-methyl-2-phenyl-l,3-dioxolane-4-methanol, 2,2-dimethyl-l,3- dioxolane-4-acetate, (2-(heptan-3-yl)-l,3-dioxolan-4-yl)methanol and mixtures thereof. According to this embodiment, the blend can comprise from 15 to 95% by weight, preferably from 25 to 50% by weight of 2,2-dimethyl-l,3-dioxolane-4-methanol, based on the total weight of the blend. In this case, the compound is commercially available, for example under the name Augeo^® Clean Multi, Augeo^® SL191 or Solketal. This compound can be synthesized by reaction between glycerol and acetone, under well-known classical conditions.

The preferred blends according to the invention are the following:

- A blend of 2,2-dimethyl-l,3-dioxolane-4-methanol and 2,2-diisobutyl-l,3- dioxolane-4-methanol, preferably comprising from 50 to 80% of 2,2-dimethyl-l,3-dioxolane- 4-methanol and from 20 to 50% of 2,2-diisobutyl-l,3-dioxolane-4-methanol, and even more preferably a blend comprising from 60 to 70% of 2,2-dimethyl-l,3-dioxolane-4-methanol and from 30 to 40% of 2,2-diisobutyl-l,3-dioxolane-4-methanol,

- A blend of 2,2-dimethyl-l,3-dioxolane-4-methanol and 2-isobutyl-2-methyl-l,3- dioxolane-4-methanol, preferably comprising from 50 to 70% of 2,2-dimethyl-l,3-dioxolane- 4-methanol and from 30 to 50% of 2-isobutyl-2-methyl-l,3-dioxolane-4-methanol, and even more preferably a blend comprising from 55 to 65% of 2,2-dimethyl-l,3-dioxolane-4- methanol and from 35 to 45% of 2-isobutyl-2-methyl-l,3-dioxolane-4-methanol,

- A blend of 2,2-dimethyl-l,3-dioxolane-4-methanol and 2-isopropyl-l,3-dioxolane-4- methanol, preferably comprising from 40 to 60% of 2,2-dimethyl-l,3-dioxolane-4-methanol, and from 40 to 60% of 2-isopropyl-l,3-dioxolane-4-methanol, and even more preferably a blend comprising from 45 to 55% of 2,2-dimethyl-l,3-dioxolane-4-methanol and from 45 to 55% of 2-isopropyl-l,3-dioxolane-4-methanol,

- A blend of 2,2-dimethyl-l,3-dioxolane-4-methanol and 2-butyl-2-ethyl-l,3- dioxolane-4-methanol, preferably comprising from 50 to 80% of 2,2-dimethyl-l,3-dioxolane- 4-methanol and from 20 to 50% of 2-butyl-2-ethyl-l,3-dioxolane-4-methanol, and even more preferably a blend comprising from 60 to 70% of 2,2-dimethyl-l,3-dioxolane-4- methanol and from 30 to 40% of 2-butyl-2-ethyl-l,3-dioxolane-4-methanol,

- A blend of 2,2-dimethyl-l,3-dioxolane-4-methanol and 2-phenyl-l,3-dioxolane-4- methanol, preferably comprising from 50 to 70% of 2,2-dimethyl-l,3-dioxolane-4-methanol and from 30 to 50% of 2-phenyl-l,3-dioxolane-4-methanol, and even more preferably a blend comprising from 55 to 65% of 2,2-dimethyl-l,3-dioxolane-4-methanol and from 35 to 45% of 2-phenyl-l,3-dioxolane-4-methanol,

- A blend of 2,2-dimethyl-l,3-dioxolane-4-methanol and 2-methyl-2-phenyl-l,3- dioxolane-4-methanol, preferably comprising from 40 to 60% of 2,2-dimethyl-l,3-dioxolane- 4-methanol, and from 40 to 60% of 2-methyl-2-phenyl-l,3-dioxolane-4-methanol, and even more preferably a blend comprising from 45 to 55% of 2,2-dimethyl-l,3-dioxolane-4- methanol and from 45 to 55% of 2-methyl-2-phenyl-l_/3-dioxolane-4-methanol_/

- A blend of 2,2-dimethyl-l,3-dioxolane-4-methanol and 2,2-dimethyl-l,3-dioxolane- 4-acetate, preferably comprising from 50 to 80% of 2,2-dimethyl-l,3-dioxolane-4-methanol and from 20 to 50% of 2,2-dimethyl-l,3-dioxolane-4-acetate, and even more preferably a blend comprising from 60 to 70% of 2,2-dimethyl-l,3-dioxolane-4-methanol and from 30 to 40% of 2,2-dimethyl-l,3-dioxolane-4-acetate,

- A blend of 2,2-dimethyl-l,3-dioxolane-4-methanol and (2-(heptan-3-yl)-l,3- dioxolan-4-yl)methanol, preferably comprising from 50 to 70% of 2,2-dimethyl-l,3- dioxolane-4-methanol and from 30 to 50% of (2-(heptan-3-yl)-l,3-dioxolan-4-yl)methanol, and even more preferably a blend comprising from 55 to 65% of 2,2-dimethyl-l,3-dioxolane- 4-methanol and from 35 to 45% of (2-(heptan-3-yl)-l,3-dioxolan-4-yl)methanol.

The above % are in % by weight based on the total weight of the blend. The use according to the invention promotes the paraffin deposits removing performances of paraffin removal formulations in oilfield equipment, notably when compared to a paraffin removal formulation containing glycol ether instead of one glycerol ketal and/or acetal of formula I. The present invention also concerns a paraffin removal formulation comprising at least one glycerol ketal and/or acetal of formula I described above. All the preferred embodiments detailed before, taken alone or in combination are also applicable to the paraffin removal composition. The paraffin removal formulation according to the invention advantageously comprises from 1 to 20% by weight of at least one compound of formula I, preferably from 3 to 15% by weight based on the total weight of the paraffin removal formulation. In a preferred embodiment of the invention, the formulation comprises at least 2,2- dimethyl-l,3-dioxolane-4-methanol in a proportion from 1 to 20% by weight, preferably from 3 to 15% by weight based on the total weight of the paraffin removal formulation. In this case, the compound is commercially available, for example under the name Augeo^® Clean Multi, Augeo^® SL191 or Solketal. This compound can be synthesized by reaction between glycerol and acetone, under well-known classical conditions.

In one embodiment of the invention, the formulation comprises at least two, more preferably two or three, compounds of formula I. As preferable examples of such blends include a blend of 2,2-dimethyl-l,3-dioxolane-4-methanol and at least a glycerol ketal and/or acetal chosen from the following group: 2,2-diisobutyl-l,3-dioxolane-4-methanol, 2- isobutyl-2-methyl-l,3-dioxolane-4-methanol, 2-isopropyl-l,3-dioxolane-4-methanol, 2- butyl-2-ethyl-l,3-dioxolane-4-methanol, 2-phenyl-l,3-dioxolane-4-methanol and 2-methyl- 2-phenyl-l,3-dioxolane-4-methanol, 2,2-dimethyl-l,3-dioxolane-4-acetate, (2-(heptan-3-yl)- l,3-dioxolan-4-yl)methanol and mixtures thereof.

The paraffin removal formulation of the invention generally further comprises at least one of the following components:

a. limonene,

b. a biodegradable surfactant,

c. an aliphatic alcohol having 1 to 4 carbon atoms or mixture thereof,

d. water. The limonene is a natural cyclic monoterpene and major component of the distilled rind oils of oranges, grapefruits, lemons and other citrus fruit. The limonene of the present formulation is preferably d-limonene and is commercially available from various sources.

In a preferred embodiment of the invention, the paraffin removal formulation comprises from 0.2 to 3% by weight of the limonene, preferably from 0.5 to 1% by weight based on the total weight of the paraffin removal formulation. The paraffin removal formulation according to the invention may include a biodegradable surfactant, generally selected in the group consisting of anionic, cationic, non-ionic, hydrotope and amphoteric surfactants. In particular, it can be chosen among the following components: alkylamine oxides, alkylphenol ethoxylates, linear and branched alcohol ethoxylates, alkylbetaines, primary amine salts, diamine salts, quaternary ammonium salts, carboxylic acid salts, alkylbenzene sulfonates, alkylbenzenesulfonic acid, olefin sulfonates, alkyl sulfates and others.

In one embodiment, the biodegradable surfactant is generally present in an amount varying from 0.5 to 10%, preferably from 1 to 5% by weight based on the total weight of the paraffin removal formulation.

In a preferred embodiment, the biodegradable surfactant is an ethoxylated alcohol surfactant, preferably is lauryl alcohol ethoxylate.

The aliphatic alcohol is generally selected in the group consisting of lower aliphatic alcohol having 1 to 4 carbon atoms, such as methanol, ethanol or mixture thereof. It is generally present in an amount varying from 0.2 to 10%, preferably from 0.5 to 4% by weight based on the total weight of the paraffin removal formulation.

In a preferred embodiment of the invention, the paraffin removal formulation comprises at least 50%, preferably at least 75% and even more preferably at least 90% by weight of water based on the total weight of the paraffin removal formulation. In any case, the amount of water is the amount that is necessary to achieve 100% of the weight of the formulations of the present invention.

Further additives can be added to the formulation like dispersants, anti-corrosion agents, biocides, thickeners, anti-foam agents and others. The total amount of further additives generally remains below 15% by weight of the paraffin removal formulation. Specific language is used in the description so as to facilitate the understanding of the principle of the invention. It should, however, be understood that no limitation of the scope of the invention is envisaged by the use of this specific language. Modifications, improvements and perfections may especially be envisaged by a person skilled in the technical field concerned, on the basis of his own general knowledge.

The present invention provides advantages over existing paraffin removal solutions in oil and gas field. The invention proposes a combination of a green solvent, an environmentally friendly surfactant and a biodegradable terpene (d- limonene), which improves their performance to remedy paraffin deposits in oilfield equipment. This formulation has advantageously water solubility, low toxicity, low odor, environmental profile and low cost, and simultaneously exhibit high solvency for organic deposit comparable to aromatic solvents. Other details or advantages of the invention will become more clearly apparent in the light of the examples given below.

EXAMPLE

Methods of measure

For the example below, the paraffin removal parameter have been measured according to time required for complete solubilization of paraffin, through visual observation of the paraffin deposit.

Tests and results

The evaluation of paraffin removal performance was verified by the deposit removing test described below.

In the test it was used paraffin melted at 90°C and 1.5g of said melted paraffin was added in a slab of 7 cm x 3 cm of dimension. In a reactor made of glass and coupled to a water bath at 70°C, 250 mL of a paraffin removal formulation was added and the slab was put within the reactor, so it will be in contact with the formulation during the entire process. An agitator was used inside the reactor at 300 rpm, but always keeping attention so that the slab did not come into contact with the agitator inside the reactor.

The paraffin solubilization was visually evaluated at certain time intervals until its complete removal. The effectiveness of the tested paraffin removal formulations are shown in the table 1 below.

Table 1

Components Comparative Example Example 1

D-limonene 0,7 0,7

Ethyleneglycol Monopropyl Ether 6,0 -

Lauryl Alcohol 10EO 2,0 2,0

Methanol 0,7 0,7

Acetic Acid* 0,7

Augeo Clean Multi 6,0

Water 89,9 90,6

Time to remove paraffin (min) 35 25

*As acetic acid is not compatible with Augeo Clean Multi, it has not been used in Example 1. Anyway, no paraffin removal effect is associated with this compound.

Conclusion

The above results show that the paraffin removal formulation described in this invention (Example 1) solubilizes and removes more quickly the paraffin deposit. Therewith the present formulation saves time in oil operations, since the equipment is returned much sooner to production, transportation and storage, and less damaged.

Claims

1. Use of at least one compound of formula I below:

wherein

Ri and R₂, independently from one another, are selected in the group consisting of: hydrogen or a linear or branched C1-C12 alkyl, a C4-G12 cycloalkyl or an aryl.

R₃ is H, a linear or branched alkyl, a cycloalkyl, a -C(=0)R₄ group, with R₄ being a linear or branched C1-C4 alkyl or a C5-C6 cycloalkyl or -(R₅0)_n— R6, with R₅ being a linear or branched C1-C12 alkylene group and R₆ being H, a linear or branched C1-C12 alkyl or a C5-C6 cycloalkyl and n=l to 9, as solvent in paraffin removal formulations.

2. Use according to claim 1, wherein Ri and R₂, independently from one another, are selected in the group consisting of: hydrogen, methyl, ethyl, isopropyl, n-propyl, isobutyl, n- butyl, tert-butyl, n-pentyl, cyclopentyl, cyclohexyl or phenyl.

3. Use according to claim 1 or 2, wherein R₃ is H or a -C(=0)R₄ group, with R₄ being methyl, ethyl, isopropyl, n-propyl, isobutyl, n-butyl or tert-butyl or -(RsO),,— R₆, with R₅ being -CH₂-, -(CH₂)₂-, -CH(CH₃)-, -(eH₂)₃-,-C(CH₃)₂-, -CH(CH(CH₃)₂)-, -(CH₂)₄- or -CH(C(CH₃)₃)- and R6 being H, methyl, ethyl, isopropyl, n-propyl, isobutyl, n-butyl or tert-butyl and n=l to 3.

4. Use according to claim 1 to 3, wherein the compound of formula I is selected in the group consisting of: 2,2-dimethyl-l,3-dioxolane-4-methanol, 2,2-diisobutyl-l,3-dioxolane-4- methanol, 2-isobutyl-2-methyl-l,3-dioxolane-4-methanol, 2-isopropyl-l,3-dioxolane-4- methanol, 2-butyl-2-ethyl-l,3-dioxolane-4-methanol, 2-phenyl-l,3-dioxolane-4-methanol and 2-methyl-2-phenyl-l,3-dioxolane-4-methanol, 2,2-dimethyl-l,3-dioxolane-4-acetate, (2- (heptan-3-yl)-l,3-dioxolan-4-yl)methanol and mixtures thereof.

5. Use according to claim 1 to 4, wherein at least two, more preferably two or three compounds of formula I are used as blend of solvents in paraffin removal formulation.

6. Use according to claim 1 to 5, wherein the blend comprises 2,2-dimethyl-l,3- dioxolane-4-methanol and at least a glycerol ketal and/or acetal chosen from the following group: 2,2-diisobutyl-l,3-dioxolane-4-methanol, 2-isobutyl-2-methyl-l,3-dioxolane-4- methanol, 2-isopropyl-l,3-dioxolane-4-methanol, 2-butyl-2-ethyl-l,3-dioxolane-4-methanol, 2-phenyl-l,3-dioxolane-4-methanol and 2-methyl-2-phenyl-l,3-dioxolane-4-methanol, 2,2- dimethyl-l,3-dioxolane-4-acetate, (2-(heptan-3-yl)-l,3-dioxolan-4-yl)methanol and mixtures thereof.

7. Use according to claim 1 to 6, wherein the blend comprises from 15 to 95% by weight, preferably from 25 to 50% by weight of 2,2-dimethyl-l,3-dioxolane-4-methanol, based on the total weight of the blend.

8. Use according to claim 1 to 4 to promote the paraffin removing performances of the paraffin removal formulations in oilfield equipment.

9. Paraffin removal formulation com rising at least one compound of formula I below:

wherein

R₃ is H, a linear or branched alkyl, a cycloalkyl, a -C(=0)R₄ group, with R₄ being a linear or branched C1-C4 alkyl or a C5-C6 cycloalkyl or -(R₅0)_n— R₆, with R₅ being a linear or branched C1-C12 alkylene group and R₆ being H, a linear or branched C1-C12 alkyl or a C5-C6 cycloalkyl and n=l to 9, as solvent in paraffin removal formulations.

10. Paraffin removal formulation according to claim 9, comprising at least two, preferably two or three, compounds of formula I.

11. Formulation according to claim 9 or 10, further comprising at least one of the following components:

a. limonene,

b. a biodegradable surfactant,

c. an aliphatic alcohol having 1 to 4 carbon atoms or mixture thereof,

d. water.

12. Formulation according to claim 9 to 11, comprising from 1 to 20% by weight of the compound of formula I, preferably from 3 to 15% by weight based on the total weight of the paraffin removal formulation.

13. Formulation according to claim 9 to 12, wherein the compound of formula I is 2,2- dimethyl-l,3-dioxolane-4-methanol.

14. Formulation according to claim 9 to 13, comprising from 0.2 to 3% by weight of the limonene, preferably from 0.5 to 1% by weight based on the total weight of the paraffin removal formulation.

15. Formulation according to claim 9 to 14, comprising from 0.5 to 10% by weight of biodegradable surfactant, preferably from 1 to 5% by weight based on the total weight of the paraffin removal formulation.

16. Formulation according to claim 9 to 15 wherein the biodegradable surfactant is an ethoxylated alcohol surfactant, preferably is lauryl alcohol ethoxylate.

17. Formulation according to claim 9 to 16, comprising from 0.2 to 10% by weight of aliphatic alcohol, preferably from 0.5 to 4% by weight based on the total weight of the paraffin removal formulation.

18. Formulation according to claim 9 to 17 wherein the aliphatic alcohol is methanol, ethanol or mixture thereof.