MXPA98000953A - Improved process for thermoquimic desparafination of large dsion ducts - Google Patents

Abstract

The present invention relates to an improved process for thermo-chemical dewaxing of hydrocarbon conductive ducts, by the use of a Nitrogen / Emulsion Generating System. The process involved the introduction of an emulsion in the pipeline by dewaxing. The emulsion comprises an internal aqueous phase and an external organic phase. The aqueous phase comprises an oxidant nitrogenous salt, a reducing salt and water. The organic phase encompasses a non-polar organic liquid, such as kerosene, and a delayed action activator to induce the reaction of the oxidizing nitrogenous salt and the reducing nitrogenous salt. The refinement encompasses a delayed action activator, which may be a copolyanidride such as poly (adipic-cosecosic acid) anhydride solubilized in a polar organic solvent such as chloroform. The solubilized delayed action activator is easily and precisely pumped into the pipeline by dewaxing. The emulsion is maintained in the pipeline until the delayed action activator induces the reaction of the nitrogenous salts to generate nitrogen and heat, in order to fluidize the paraffin present in the duct.

Description

"PERFECTED PROCESS FOR DESPARAFINATION OF THE CHEMICAL THERAPY OF LARGE DIMENSIONS" FIELD OF THE INVENTION This invention deals with an improved process for thermo-chemical dewaxing of large hydrocarbon conductive ducts and internal diameter. More specifically, this invention deals with a thermo-chemical process of dewaxing conductive hydrocarbon ducts of greater than 10 and up to 50000 meters or more and an internal diameter of more than 4 to 12 inches or more, to be applied from the same platform of production or equivalent equipment. In this process, the treatment fluid is constituted by a water / oil emulsion, which contains, in the internal phase, nitrogenous nitrogen and heat generating salts and, in the external phase, a delayed action activator as a copolyanidride solubilized in a polar organic solvent. The copolyanidride has controlled hydrodegradability, which allows a marked delay in the start of the generation of nitrogen and heat reaction. The solubilization of the copolyanidide in a polar organic solvent makes the use of the activator much more accurate and simple, taking into account the greater pumping facility of an activator solution compared to the state of the art, where the activator used to be pumped in the form of of a suspension in aliphatic hydrocarbon solvent - Considered broadly, the present application concerns an improved process and composition for fluidizing and removing paraffinic deposits from a hydrocarbon conductive pipeline by the combination of thermal, chemical and mechanical effects provided simultaneously by the hydraulic fluid. dewaxing in the form of an emulsion, the improvement consisting in providing a delayed action activator, which is a copolyanidride solubilized in a polar organic solvent, making the pumping of the activator easier and more accurate than pumping the activator suspension in an aliphatic hydrocarbon solvent of the state of technique.

BACKGROUND OF THE INVENTION The application BR BR 9004200 (US 5183581) of the petitioner and here fully incorporated as reference teaches the use of a Nitrogen / Emulsion Generating System useful for the dewaxing of production formations, so that an increase in temperature caused by the reaction of combined nitrogenous salts in the presence of an organic solvent in the external phase of the emulsion allows the removal of paraffin from the reservoir. The salts used are an oxidizing nitrogenous salt and a reducing nitrogenous salt.

In the privilege application Pl BR 9301171-7 (US 5639313) here completely incorporated as reference and directed to the dewaxing of pipelines for the transport of hydrocarbons, the aqueous solutions containing the selected nitrogen reagents are prepared individually in mixing tanks and then added, even individually, to suitable volumes of selected hydrocarbon organic solvent to promote the dissolution of the specific type of paraffinic deposit found in the pipeline. The addition of an emulsifying agent and / or dew point reducers is foreseen. The activation of the chemical reaction between the nitrogen reagents is achieved by the addition of a weak organic acid solution, such as acetic acid, to the emulsion containing, in the internal phase, the nitrogenous salt resistant to slightly acidic medium, it is say, with pH between 3 and 6. The external phase is constituted by an organic solvent or mixtures of organic solvents of the hydrocarbon type. The breaking of the emulsion causes the nitrogen and heat generation reaction, called the Nitrogen Generating System, to start.

Based on the results of the pipeline by dewaxing, suitable volumes of the two emulsions are prepared, which are injected simultaneously into the pipeline, in the direction of the production flow through surface pumping systems. The terminals for the injection of the treatment fluid - inlet - and the recovery of the mixture of spent fluid and fluidized paraffin - outlet - are made up of backup vessels.

Activation of the treatment fluid is carried out with acetic acid. The fluid thus prepared is then pumped, with maximum permissible discharge, from a vessel installed above the pipeline under treatment. The mixture of emulsions C (ammonium chloride) and N (sodium nitrite) produces, exclusively in flow, the nitrogen generating system, SGN, emulsified. The solutions are pumped in necessarily equal and displaced discharges with a small mattress from which the aircraft and seawater are drained to position the fluid in the second half of the pipeline. After a time of rest necessary for the fluid, the simultaneous pumping of emulsions C and N is resumed, in which you will treat the first half of the pipeline. After a new rest period, the SGN treatment fluid is removed and the dewaxed duct basin is measured in order to evaluate the treatment carried out. Therefore, the treatment fluid with Generator System Nitrogen acts from top to bottom in the pipeline by dewaxing, and with almost complete removal of the paraffin deposits. However, as mentioned above, activation with acetic acid limits the use of this system to lines up to 4000 meters long and internal diameter up to 4 inches, since the release of H + ion is relatively fast and the emulsion breaks quickly , starting the generation of nitrogen and heat reaction.

Although the field results achieved with the technique described in Pl BR 9301171 (US 5639313) are excellent, since the paraffin is almost completely removed, the process presents some drawbacks related, on the one hand, with the relatively short time of the beginning of the nitrogen and heat generation reaction, which limits the length and diameter of the line by dewaxing, and, on the other hand, and the need to operate with backup vessels. much more expensive the process, since it represents around 70% of the total costs. Thus, it was necessary to develop a process for thermo-chemical dewaxing of conductive pipelines of hydrocarbons, that could act in lines of great extension and volumetric capacity, and in which the pumping of the fluid constituted of a single solution could be made from the production platform, with great economy of costs. Pumping a single solution would represent the The additional advantage of eliminating the difficulty represented by the pumping of two solutions to constant and identical discharges, which is very difficult in practice. In the application of the SGN to large pipelines it used to be necessary to delay the start of the generation of heat and nitrogen reaction. Thus, the Mexican application 96.5725 of the petitioner and here fully incorporated by reference describes a polymer matrix based on a homopolyanidride capable of acting in a delayed manner in the activation of the reaction chemistry of the Nitrogen Generating System (SGN) specifically adapted for hydrocarbon conductive ducts of great extension and volumetric capacity. The process of thermochemical dewaxing of large ducts made in the presence of the homopolyanidride is described in the Mexican application 96.5725, here fully incorporated as reference. However, since the polyanidide of the Mexican application 96.5725 was used in suspension in an aliphatic solvent and taking into account the volumes of several cubic meters necessary to activate the SGN reaction when applied in the field, the pumping of the polyanhydride in suspension form it became difficult and imprecise due to the lack of homogeneity or sedimentation of the product in suspension, which, finally, could have as a consequence alterations in the hydrolysis rate of the polyanidide. The petitioner developed, then, new linear aliphatic copolyanadrids solubilized in polar organic solvent. The use of copolyanidrids solubilized in polar organic solvent makes the pumping of these products more uniform, accurate and simple, in addition to allowing a better control of the hydrolysis rate of the delayed action activator. The application of these copolyanidrides as activators of delayed action in SGN reactions constitutes the improvement in the process for the thermo-chemical deparametry of large ducts, described and claimed in the present application.

SUMMARY OF THE INVENTION An improved process for thermo-chemical dewaxing of hydrocarbon conductive pipelines containing a paraffinic deposit is presented.; the process covers the following stages: (a) introducing an emulsion into the pipeline, which includes an internal aqueous phase and an external organic phase, with the aqueous phase comprising an oxidizing nitrogenous salt, a nitrogenous reducing salt and water, with the organic phase comprising a delayed action activator for the purpose of inducing the reaction of the nitrogenous oxidant salt with the reducing nitrogenous salt, wherein the delayed action activator is a linear aliphatic copolyanidocide solubilized in a polar organic solvent; (b) maintaining the emulsion in the pipeline under conditions sufficient to fluidize the paraffinic deposit and generate nitrogen gas and heat from the reaction between the oxidizing nitrogenous salt and the reducing nitrogenous salt; and (c) removing the fluidized paraffin tank from the pipeline.Like the Mexican application 96.5725, the present process is especially useful for thermo-chemical deparaffinization of large ducts, where a limb is connected to a production platform.

Prior to the dewatering treatment, the oil can be removed from the pipeline or line by dewaxing. The treatment fluid can be prepared in the production platform or in any equivalent equipment and be pumped into the pipeline or line. The treatment fluid contains the Nitrogen Generating System, SGN. The delayed action activator of the nitrogen and heat generating reaction is a linear aliphatic copolyaridide, such as the copolymer of adipic acid and a diacid in C.-C14. The treatment fluid is introduced into the duct. After the period necessary for the treatment fluid to carry out the treatment, the spent fluids and the emulsified paraffin can be recovered and the production of the well can be resumed. The linear aliphatic copolyanhydride used as a delayed action activator in the present invention typically encompasses between 95 and 15 mol% of a diacid, such as adipic acid, and from 5 to 85 mol% of a comonomer which is a diacid in C "- C ,, as the sebacic acid. A preferred proportion is between 25 and 75 mol% of the comonomer. The delayed action activator of the present invention must be dissolved in a polar organic solvent, such as chloroform, in a proportion of 8 to 40 parts by weight of activator for 100 parts by volume of polar organic solvent. The preferred ratio is 10 to 30 weight / volume of activator / solvent. A limiting feature of the copolyanidridides of this invention is that, by hydrolysis, the pH of the medium, that is, the aqueous solution of nitrogenous salts that must generate heat and nitrogen, must be maintained at values equal to or less than S, 0. Copolymers which, by hydrolysis, carry a pH higher than 5.0 in the aqueous solution do not belong to the field of the present invention, because, under conditions of pH higher than 5.0, the SGN reaction does not start. Therefore, this invention provides an improved process for thermal-chemical dewaxing of hydrocarbon conductive ducts of great extension and internal diameter, using a nitrogen and heat generation reaction, SGN, activated by a copolyanidride derivative solubilized in a polar organic solvent. , the copolyanidride having an improved degree of controlled hydrodegradability, which very precisely promotes the degree of delay suitable for the start of the generation reaction of heat and nitrogen. The present process also provides new copolyanidrides prepared from adipic acid and a comonomer that is an organic diacid in Cfj-C, such as sebacic acid, having between 5 and 85 mole% of the comonomer at C8-C14, said copolyanidrides being , when solubilized in a polar organic solvent, capable of producing an activator for the SGN reaction, which, when pumped, has improved characteristics in terms of precision in the pumped volumes, homogeneity of the pumped material and fully controlled hydrolysis rate. The present process provides delayed action activators based on linear aliphatic copolyanidridges solubilized in polar organic solvent, whose hydrodegradability can be controlled by the type of comonomer tenor used also by the molecular weight of the copolyanidride.

In addition, this invention provides delayed action activators based on linear aliphatic copolyanidrids solubilized in polar organic solvent, with these copolyanidrides producing, by hydrolysis in the presence of nitrogen and nitrogen generating solutions of heat and nitrogen, pH values equal to 5.0 or less, for temperatures between 10 and 25 * C. Such pH values are necessary for the start of the heat and nitrogen generating reaction at rates useful in the conditions of industrial operations.

SOMERA DESCRIPTION OF THE DRAWINGS FIGURE 1 is a graph illustrating the time delay of SGN reactions using the homopolyidid from the Mexican application 96.5725 in suspension and in solution at 30% weight / volume in chloroform. The attached FIGURE 2 is a graph illustrating the delay time for SGN reactions, using a copolyanidride of the present invention, comprising 50 mole% - of sebacic acid, the copolyanidide being used in suspension and in solution at 30 ° C. weight / volume% in chloroform. The attached FIGURE 3 is a graph illustrating the delay time for the polyanidide of Mexican application 96.5725 and for the copolyanidride of the present invention, which encompasses 50 moles of sebacic acid, both used in suspension in kerosene. The accompanying FIGURE 4 illustrates the delay time for SGN reactions, using the homopolyanidide of Mexican application 96.5725 as well as the delay time for a copolyanidride of the present invention, which encompasses 50 mole% of sebacic acid solubilized in chloroform at 30 % weight / volume. The attached FIGURE 5 is a graph illustrating the delay time for SGN reactions, where the delayed action activator is used in chloroform solution at 30% weight / volume and with different molar tenors in sebacic acid.

The appended FIGURE 6 is a graph illustrating the hydrodegradability of copolyanidrides according to the present invention, which contain different sebacic acid contents.

DETAILED DESCRIPTION For the preparation process of the copolyanidrids useful as activators of delayed action in the chemical reaction of the SGN, a polymer matrix was developed based on aliphatic polyanidridos synthesized from the condensation of two diacids, the condensation product being solubilized in an organic solvent polar, whose main characteristic is its exactly controlled hydrodegradability, useful in the process of the present invention. Mainly it was found that poly (adipic-co-sebacic anide) of several molecular weights or its hydrodegradation products solubilized in a polar organic solvent, are not only activators capable of providing long delay times in the generation of nitrogen and heat by chemical reaction , but also, the manipulation of the activator as a solution of a copolyanidride in a polar organic solvent has a series of advantages. The delay achieved allows the deparaffinization of lines or ducts of large dimensions, that is, of great extension and / or volumetric capacity, while the use of the copolyanidride activator solubilized in a polar organic solvent, by increasing the accuracy, is of the activator volumes added also of the hydrolysis rate of the activator, have consequently the best performance of the dewaxing process as a whole. The process of obtaining the polyanidridides that make possible the process proposed in the present report and claims consists in the reaction of copolycondensation of two carboxylic diacids, preferably the adipic acid and a comonomer diacid in CC -, in the presence of excess acetic anhydride , in order to obtain the copolyanidride. The acetic acid by-product of the reaction and the excess of acetic anhydride are removed from the reaction medium by distillation under reduced pressure.

Although Mexican application 96.5725 mentions that adipic acid could be used in combination with other diacids, such as glutaric acid, pimelic acid, subic acid and sebacic acid, these products were supposed to be used in suspension. However, since the petitioner's purpose was a homo- or copolyanidide to be dissolved in an organic solvent, when the use of some of these copolyanidrides in solution was tried experimentally, it was found that the rate of hydrolysis had become extremely rapid and, therefore, the available products simply solubilized in a polar organic solvent would be unsuitable as delayed action activators for thermo-chemical dewaxing of large ducts, since the rapidity of the hydrolysis rate would cause the nitrogen and heat generation reaction to occur without control. In addition, when using copolyanidrids in solution in a polar organic solvent, a determining factor is that, in the release stage of hydrogen ion, which triggers the nitrogen and heat generation reaction of the SGN system, the pH to reach as a consequence of the hydrolysis of the anhydride is equal to or less than 5.0 for temperatures between 10 and 250C; otherwise the SGC does not happen. Thus, among all the possible pairs of diacid carboxylic monomers, it was necessary to develop a copolyanhydride system that would satisfy, when solubilized in a polar organic solvent, the required level of pH in the hydrolysis as well as the delay required for the activation of the reaction of SGN. Thus, the applicant prepared copolyanidrides containing from 95 to 15 mol% of adipic acid and from 5 to 85 mol% of a diacid comonomer in C-C14, such as sebacic acid, the copolyanidridides being solubilized in a polar organic solvent such as chloroform, with the polar organic copolyanidride-solvent composition presenting the desired characteristics as regards the pH level in the hydrolysis, homogeneity in the pumping as well as the desired delay in the SGN reaction times. It was found that the delay times were a function of the chain length of the comonomer, the molar tenor of the comonomer and the molecular weight of the copolymerid composition to be obtained.

The copolyanidride object of the present application can be prepared as a composition of linear polyanidridos, in batch, from the reaction of dicarboxylic acids in the presence of excess acetic anhydride, by which a pre-polymer forms, under atmospheric pressure and temperature of reflux. Then the prepolymer is cooled and reduced pressure is used to remove the acetic acid which also forms the excess of added acetic anhydride. The temperature is then raised to 1000-200 * C to effect the polymerization. In order to avoid hydrolysis, the copolyanidride product is kept in an organic solvent. Alternatively, the preservation of the product at low temperatures also prevents hydrolysis. The fundamental parameters of the reaction are the molar ratio of the charge, the reduced pressure, the temperature and the reaction time. By controlling these parameters, linear aliphatic copolyanidide compositions of controlled molecular weights, particularly useful as delayed action activators in the SGN reaction, can be prepared. The compositions of copolianidridos as! prepared have different bands of molecular weights, which advantageously affects the rates of hydrolytic degradation and the delay of the SGN reaction. It is believed that controlled release of the H + ion occurs as a result of hydrolysis of the copolyanidide. The copolyanidride can be hydrolyzed at a controlled rate with release of an H * ion, which acts either as a catalyst or as a pH modifier. The chemical equation below summarizes the copolymerization process of the anhydrides used in the present process, starting, for example, from adipic acid and sebacic acid: HOOCR COOH + HOOCR COOH + (CH, CO) t0 - - - - > -O-CO-Ra-CO; -CO-R -CO -CO-R -CO- + CH COOH + (CH 3 CO): O where R is - (CH 2) 4 (adipic acid) y 2 R is -2 (£ H) (sebacic acid).

Although not linked to any particular theory, the petitioner speculates that the delayed activation mechanism of the SGN reaction initially consists of a step of migrating the anhydride polymer from the organic phase to the aqueous phase of the emulsion. The slow step of hydrolysis of the polymer occurs in the aqueous phase, with generation of the dicarboxylic acid corresponding to the monomeric unit. The diacid is then dissociated and the H 'ion is formed, then allowing the start of the reaction with nitrogen generation and heat release. The following sequence of chemical reactions illustrates steps of the theoretical mechanism of delayed activation of the SGN in the presence of a linear aliphatic copolyanidide such as poly (adipic-cosebracic anhydride). These stages include the following reactions: 1 'STAGE: POLYMER MIGRATION H [OOCR.-CO], - (OOCR2COI MOH> H [OOCR, -COI n- [OOC R2COImOH (OIL OR ORGANIC PHASE) (AQUEOUS PHASE) where n may be the same as or different from m, R, is ( CH2) 4 (adipic acid) and R2 is - (CH2) T (sebacic acid) 2a STAGE: POLYMER HYDROLYSIS .H [OOCR? -C?] N- [OOCR: CO) mOH + H2O > HOOCRTCOOH + HOOCR COOH 3 STAGE: DISASSOCIATION OF DI CIDOS TO GENERATE IONS E * HOOCR.COOH > 2H + + -OOCR ^ OO- HOOCR COOH ~ > 2H + + -OOCR-COO - 4A STAGE: ACTIVATION OF THE REACTION OF THE SYSTEM OF GENERATION OF NITROGEN H + NH4 Cl + NaNO, > N2 + NaCl + 2H2 0 In you will make the 4th stage of the reaction may occur According to the delay times required for the conditions of the present invention, it is important that the hydrolysis of the copolyanidridides produces a pH of the nitrogenous salt solutions in the range of 5.0 or less for temperatures between 10 and 250C.

Analogously to Mexican application 96.5725, in the present application the delay time is controlled by the stability to hydrodegradation, since it is the hydrodegradation of the copolyanidride that is going to generate the hydrogen ion that initiates the generation reaction of heat and nitrogen. Thus, longer delay times will be achieved with the use of more stable copolyanidrids.

Therefore, in the case of the Mexican application 96.5725 the first stage of the proposed mechanism is slower, since the polymer is in the solid state and in suspension in aliphatic hydrocarbon solvent. Already in the case of the present application is the second stage that controls the process (slower stage), because the polymer is in the liquid state. This is an important mechanistic difference between the Mexican application 96.5725 and the present application. Thus, unlike Mexican application 96.5725, in the present application, taking into account that the solubilization in a polar organic solvent puts the copolyanidide at the molecular level, the stage of phase migration (the stage in the sequence above) is facilitated , while in Mexican application 96.5725 this stage is slower. This explains why the delay times of the SGN reactions, carried out with the delayed action activator solubilized in a polar organic solvent, are normally reduced in relation to the delay times of the activator used in the form of suspension in kerosene as in the application Mexican 96.5725. This applies to the activator of Mexican application 96.5725 as well as to the activators of the present invention (see FIGURES 1, 2, 3 and 4).

DETAILED DESCRIPTION OF THE DRAWINGS FIGURE 1 shows that, for large ducts that require a delay time of 50 to 80 minutes or more, the simple solubilization of a homopolyanidide from the state-of-the-art dissolved in a polar organic solvent does not satisfy those delay times .

FIGURES 1 to 4 show that, whether in suspension or solubilized in a polar organic solvent, the copolyanidridides of the present invention invariably entail longer delay times than those delay times achieved with the hydrophobicized ones of Mexican application 96.5725. Thus, the choice of the copolyanidrides of the present invention is a natural choice as delayed action activators in dewatering operations of large ducts.

FIGURES 5 and 6 show that the hydrodegradability is a function of the type and tenor of the comonomer used, likewise of the MP of the copolyanidride. FIGURE 5 illustrates the delay time achieved as a function of the molar tenor of sebacic acid in the copolyanidride. FIGURE 6 shows the hydrodegradability according to the comonomer tenor. For higher tenors in sebacic acid, the reduction in pH is less pronounced, thereby allowing more marked delay. The same trend can be observed in the curves of FIGURE 6.

PREFERRED MODALITIES As described above, the Applicant developed a delayed action activator for the nitrogen generation reaction from the emulsion, containing the nitrogenous salts as ammonium traps and alkali metal nitrites, especially ammonium chloride and sodium nitrite. The activator can be based on a poly (adipic-co-sebacic anide) polymer matrix, which has slow hydrolysis times. The hydrolysis rate can be controlled from the polymer preparation conditions. Accordingly, the desired delay of the nitrogen and heat generation reaction, which is believed to result from the hydrolysis of the copollanidide and release of hydrogen ion, can be precisely planned according to the extension and internal diameter of the pipeline to be dewaxed.

In this report and claims, the following terms have the meanings below: TREATMENT FLUID is the aqueous solution of oxidizing nitrogenous salt and reducing nitrogenous salt in equimolar stoichiometry emulsified in an organic solvent; EMULSION is a water / oil emulsion, where: the internal phase is constituted by the oxidizing nitrogenous salt and the reducing nitrogenous salt; and the external phase is the oil phase constituted by the organic solvent; The DELAYED ACTION ACTIVATOR is the polyanidide that is used to provide the desired delay at the beginning of the heat and nitrogen generation reaction. In a general way, the improved process for the thermo-chemical dewaxing of large extension and large internal diameter ducts according to the present invention includes: - empty the oil or other hydrocarbon contained in the large pipeline to be dewaxed; preparing and pumping the treatment fluid based on the emulsion, containing nitrogenous nitrogen and heat generating salts, determining the start control of the nitrogen and heat generation reaction by a delayed action activator, which is an asphalt copolyanhydride, as the poly (adipic-co-sebacic aniderido) solubilized in polar organic solvent; leaving the treatment fluid acting on the duct for the time necessary to fluidize the paraffinic deposit; after fluidization, recover the spent fluids and the emulsified paraffin; - replace the well in production.

Therefore, the main differences of the present process in relation to the state-of-the-art, as described in the Mexican application 96.5725, are: - the delayed action activator of the nitrogen and heat generation reaction to be added to the The organic phase of the emulsion is an aliphatic copolyanhydride, such as the poly (adipic-cosebracic anhydride) solubilized in a polar organic solvent, the hydrodegradability of the copolyanidride being controlled by the type and molar tenor of comonomer also used by the molecular weight of the copolyanidride. The copolyanidride preferably comprises adipic acid and a comonomer of an organic diacid in C.-C141 constituting the comonomer of a 5 to 85 mol% of the total copolymer. The copolyanidride is used in the proportion of 8 to 40 parts by weight per 100 parts by volume of polar organic solvent. The preferred polar organic solvent for the purposes of the present invention is chloroform.

The advantage of the use of the copolyanidride is that, being solubilized in a polar organic solvent, the manipulation of the delayed action activator is facilitated and becomes more accurate, since the necessary volumes are pumped more accurately than in the case of the activator in suspension in aliphatic solvent, in addition to the hydrolysis rate is also more reliable.

As in the Mexican application 96.5725, the solution of nitrogenous salts and the resulting emulsion can be prepared in the same production platform, in a single tank, stabilizing the solution by the addition of NAOH up to pH 7, 07.5, adding the activator poly (adipic-co-sebacic anide) solubilized in a polar organic solvent in flux to the aqueous emulsion of nitrogenous salts.

Likewise, the pumping of the treatment fluid does not require backup vessels, resulting in the elimination of these vessels at a cost reduction of around 70%.

The treatment fluid used in the present thermo-chemical process consists basically of a solution of nitrogenous salts, which are in general ammonium chloride and sodium nitrite, emulsified in organic solvent, preferably a low-hazard organic solvent, such as maritime diesel and others. As already described in the previous Brazilian applications of the petitioner, Pl 9004200-0 and Pl 9301171-7 and here integrated integrally as reference, the solutions of nitrogenous salts emulsified in organic solvent are prepared in concentrations that optimize the production of nitrogen and heat of according to the need for dewaxing. Generally the solution is between 3.0 and 4.5 molar for each of the nitrogenous salts. In the present process, a mixing vessel is used for the preparation of the solution of nitrogenous salts. In order to keep the solution stable, the pH remains between 7.0 and 7.5 with the help of NAOH. The solution is emulsified in organic solvent, such as aviation kerosene, marine diesel, xylene or other organic solvents, chosen according to the type and nature of the paraffinic deposit to be fluidized. The emulsified solution is prepared on the same production platform.

The amount of treatment value to be used in the present process is generally determined based on a numerical simulation that calculates the deposited paraffin content.

The present process also provides that, when necessary, the pipeline of the duct to be dewaxed with the help of a contrast fluid mattress, as described in the application of Pl 9301171-7.

The delayed aliphatic copolyanidide action activator can be poly (adipic-cosebracic anide). The aliphatic copolyanidides useful in the present invention encompass those achieved by the copolymerization of adipic acid, that is, an aliphatic carboxylic diacid in -C and a comonomer which is an aliphatic dicarboxylic acid in C-C14, such as sebacic acid. According to the present invention, the delay times to be achieved by the heat and nitrogen generation reaction can be controlled by the size of the comonomer chain, the molar tenor of comonomer present in the copolyanidride and the molecular weight of the copolyanidride. Delay times are in the band between 20 and 120 minutes, preferably between 60 and 100 minutes, depending on the extension of the pipeline or line to be dewaxed, as taught in the Mexican application 96.5725. As is known to the experts, the delay time is a function of the hydrolytic stability of the copolyanidride, so that optimum delay times are achieved by the appropriate combination of chain size and comonomer content present in the copolyanidride.

The type and maximum tenor of comonomer used in the copolyanidride will be chosen so that the pH value is limited to equal to or less than 5.0, when the copolyanidride is hydrolyzed in contact with aqueous solutions generating heat and nitrogen.

In the case that the delay time prior to the start of the required SGN reaction is in the band of 3, 4 or more hours, a suitable comonomer for the activator is an aliphatic dicarboxylic acid in C 0 Cl] rt since the Molar tenor of the long chain comonomer has influence on the hydrodegradability, same delay times can be achieved by the use of larger molar tenors of a shorter chain comonomer. Therefore, lower tenors of long chain comonomers or smaller tenors of shorter chain comonomers can produce the same delay times, with the choice of one of the comonomers being a function of cost and availability of the products. Likewise, as discussed above, the molecular weight of the copolyanidride is an important characteristic of the rate of hydrodegradability, with the higher molecular weight copolyanidrides being more stable to hydrolysis.

Therefore, the delayed action activator, which is a copolyanidride solubilized in a polar organic solvent, according to the present invention makes possible, by the correct manipulation of the various parameters involved in the copolymerization, the desired delay times for each SGN reaction are achieved with a precision and facility unknown in the prior art.

The copolyanidridides useful as delayed action activators of the present invention therefore encompass those achieved by the copolymerization of aliphatic carboxylic acids, where one monomer is adipic acid and the comonomer is an aliphatic carboxylic dicarboxylic acid at C-C14 as sebacic acid, acid dodecanoic or tetradecanoic acid. Other longer chain dicarboxylic acids may be used; however, the delay times achieved would be outside the scope of the present invention.

The polar organic solvents useful in the present invention are those capable of rapidly and completely solubilizing the copolyanidride at temperatures between 20 and 30C. The polar organic solvent must be completely free of water and analytical grade. The polar organic solvents are chloroform and carbon tetrachloride.

The delayed action activators of the present invention are obtained by dissolving the copolyanidridides in the polar organic solvent in proportions of 8% up to 40% weight / volume, preferably 10% up to 30% weight / volume.

The proportion of activator to be added to the solution of heat-generating salts and nitrogen emulsified in an aliphatic solvent SGN / Emulsion - varies between 0.1% and 1.0% by weight of active material, depending on the type, tenor and nonolecular weight of the comonomer in C8 -C14. Throughout the present application, expressions "Controlled hydrodegradability" and "stability to hydrolysis" should be understood as the possibility of, by means of the control of variables such as comonomer type and tenor and molecular weight of the obtained copolyanidride, to precisely establish the delay times of the copolyanidride compositions solubilized in a polar organic solvent used in SGN reactions for dewaxing conductive hydrocarbon ducts, for example, large ducts.

The copolymerization process used to prepare the copolyanidridides to be solubilized in a polar organic solvent and thus , producing the delayed action activators useful in the present invention does not differ fundamentally from the anhydride homopolymerization process taught in Mexican application 96.5725.

Generally, the process for preparing the copolyanidridides of the present invention encompasses the condensation of aliphatic dicarboxylic acids in the presence of excess acetic anhydride to form a prepolymer, under atmospheric pressure and reflux temperature, followed by cooling and reduction of pressurization for removal. of the acetic acid formed and the excess acetic anhydride, and then raising the temperature to 100"2000C to effect the copolymerization step The obtained copolyanidride product is kept at low temperature or in suspension in an aliphatic organic solvent, such as kerosene , to minimize depolymerization and hydrolysis reactions that occur at room temperature in the presence of moisture.

The determining parameters in the polymerization process are the molar ratio of the load (RM), vacuum or pressure (P), temperature (T) and time (t). The control of these parameters makes it possible for linear aliphatic copolyanidide compositions to be prepared, these compositions having the most suitable molecular weight for each desired application of SGN.

It should be clearly understood that, as stated in the present application, the term "linear aliphatic copolyanidide compositions" means that, unlike the biodiesel applications of similar products, in the present process mixtures or copolymer-nidride compositions are obtained. different bands of molecular weights, which represents one of the controlling parameters of hydrolytic degradation: the other parameters are the carbon chain size of the comonomer as well as the molar tenor of comonomer.

Taking into account the controlled hydrodegradability of the delayed action activators of the present invention solubilized in a polar organic solvent such as chloroform, these activators will be useful in all cases in which the monomeric products resulting from the hydrolysis of those copolyanidrids release H1 ions checked. These situations include those in which a compound soluble in an organic solvent and insoluble in water are required, and, additionally, hydrolysable at controlled rates with liberation of a hydrogen ion, which may play a catalytic role or act as a pH modifier of the medium.

In a general manner, the copolymerization process comprises contacting adipic acid and an aliphatic dicarboxylic carboxy comonomer in C.C1, in a molar ratio of 5% to 85%, but preferably of 25 to 75 mol% of the comonomer, a sufficiently high temperature to obtain a pre-polymer, and, then, distilling, under reduced pressure, the acetic acid by-product of the reaction and the excess of added acetic anide, and finally allowing the polymer chain to grow under reduced pressure and temperature Sufficiently high Thus, adipic acid and the comonomer are dissolved in acetic anhydride under heating. The molar proportions of acetic anhydride for the comonomer charge vary between 3 and S. The mixture is then heated to the boiling temperature, that is, between 100 and 150OC, preferably between 120 and 1500C. In order to obtain the pre-polymer, the reaction conditions with respect to temperature are maintained for up to 60 minutes, preferably 20 to 40 minutes.

Then, without any separation or treatment of the pre-polymer obtained, the reaction mixture is cooled and the top of the reactor is directed to a condenser provided with a condensate collection bottle and a vacuum pump located above. Reduced pressure is used, between 160 and 10 mm Hg. The reactor is then heated, in order to vaporize the acetic acid and acetic anhydride present in the reaction mixture, maintaining the same level of reduced pressure, the reaction mixture is rapidly heated up to the polymerization temperature. Temperatures between 130 and 1900C can be used. The total reaction time is between 5 and 20 hours.

During the copolymerization reaction the distillation of acetic acid and acetic anhydride is continued.

The present process leads to controlled hydrodegradability copolyanidides, useful as delayed action activators in SGN reactions.

The copolyanidic reaction products are characterized in terms of melting point with the aid of DSC (Differential Scanning Calorimetry / Differential Calometry Scanning) and a Perkin Elmer DSC7 apparatus. The nitrogen purge discharge is 30 ml / min. , and the heating rate is 10OC / min. The melting points refer to the beginning of the melting temperature.

NMR Hi was used, in order to obtain molecular weight and composition values of the copolyanidrids. The analyzes were carried out under quantitative conditions previously established in a VARIAN Gemini-30 device.

The present invention can be illustrated by examples in laboratory scale, pilot scale and even in field scale, ie the dewaxing of a large duct, where the delayed action activator is a copolyanidride of the present invention solubilized in a solvent polar organic, like chloroform.

EXAMPLES 1 TO 8 These Examples refer to copolyanidride products on a laboratory scale and were obtained by the procedure described above. Copolymerization reactions were effected in a 3.78 liter (gallon) capacity reactor, with the molar ratio of acetic anhydride for adipic acid and sebacic acid being equal to 3.

The comonomer used was sebacic acid (Ció) in molar proportion between 25% and 75%. For each molar ratio, at least two races were carried out.

TABLE (I) below relates data of process parameters to prepare the copolyanidridos, where P is the reduced pressure, T the temperature and t the time. TABLE (I) also shows data regarding the melting point (T, "), molecular weight (MW) of the copolyanidride and the molar percentage of the sebacic polyanidide. Ció means the sebacic acid comonomer. The molar tenor of the sebacic acid in the product was determined by HL NMR.

TABLE 1 Ej.n 'T (' C) t (min) Composition (mol% Cio) in Tm (-C) PM the load / Product 1 142 397 0 0 75.0 2.960 2 150 450 0 0 80.0 9.483 3 150 437 25 28.9 55 75,800 4 170 170 25 26.6 56.0 40,600 5 150 342 50 56, 6 60.0 20,030 6 170 460 50 47.0 59.5 7 170 460 75 79.0 67 , 5 49,700 8 150 507 75 77.0 70.0 7.000 The reactions were effected under reduced pressure of 160 mm Hg.

The data in TABLE (i) show that the variation of operating conditions such as P, T and t leads to products that are compositions of different molecular weights, as mentioned in the Mexican application 96.5725. Thus, due to the longer reaction time and higher reaction temperature, Example 2 has a higher molecular weight than Example 1; due to the longer reaction time, Example 3 shows PM higher than Example 4; and, due to higher reaction temperature, Example 7 shows higher MW than Example 8.

According to the Mexican application 96.5725 and considering the studies that show that the hydrolysis rate of copolyanidrids is a function of the molecular weight, an increase in the time of delay to carry out the hydrolysis of the polyanidide by contact with the aqueous solution generating nitrogen and heat it is expected as a result of an increase in the molecular weight of the copolyanidrids.

It was also found that the rate of hydrolysis is a function of the molar composition of the comonomer, as illustrated in FIGURE 6 in the attached.

The delay time of the SGN reaction is also a function of the pH of the heat and nitrogen generating reaction, as well as the proportion of the copolyanhydride activator added to these solutions.

The SGN reaction is based on the controlled hydrolysis of the copolyanidride in contact with the aqueous solution of nitrogenous salts, the copolyanhydride being hydrolyzed in order to form the original anhydride monomers. Subsequently, these monomers still require a certain time to disassociate in the aqueous phase of the SGN system, releasing hydrogen ion and initiating the generation reaction of heat and nitrogen.

The effect of the copolyanidrids on the delay of the SGN reaction is controlled by a laboratory procedure, as follows: The SGN emulsion is prepared as follows: A 4.5 molar solution of NaN02 and N ^ HCl is prepared, adjusting the pH in the band between 7.0 and 8.0, with the aid of NAOH.

Then, 40 percent by volume of the solution above, 60 percent by volume of aliphatic hydrocarbon solvent, such as aviation kerosene or marine diesel, and 0.1 percent volume of non-ionic lipophilic emulsifier, such as sorbitan ester, are used. for preparing an emulsion in a high shear mixer; then the emulsion is introduced into a three-neck flask followed by the delayed-action copolyanidride activator in chloroform solution or in suspension in kerosene, for purposes of comparative examples. The activator content based on SGN / emulsion is between 0.1% and 1.0% by weight of active material depending on the tenor and molecular weight of the C-C14 comonomer in the copolymer.

The SGN reaction occurs as follows: The reaction is carried out adiabatically, creating a vacuum in a shirt that embraces the bottle of three mouths. The contents of the bottle are agitated with a magnetic stirrer to the point where a nitrogen gas bubble appears. Then the agitation is interrupted; The turbulence generated is exclusively due to the nitrogen gas produced by the reaction.

Performance data are obtained by readings of the temperature of the reacting mass (which should reach numbers higher than the temperature of the paraffin to be fluidized) and by the volume of nitrogen generated, which is read on a test tube containing water and that is connected to the bottle of three mouths.

Using the procedure above, laboratory data illustrated in FIGURES 1 to 5 was obtained. To obtain experimental data, 0.7 ml of solution at 30 w / v% copolyanidide in chloroform was used. For comparative tests, 1.2 ml of a suspension in aviation kerosene with a weight / volume% copolyanidride was used.

EXAMPLE 9 This Example illustrates the preparation of the copolyanidrides in the pilot scale and as a consequence the feasibility that these compounds are prepared on an industrial scale. In a reactor of 100 liters capacity in a pilot plant were loaded: 1.0 kg of adipic acid, 8.0 kg of sebacic acid and 50 kg of acetic anhydride. The heating is started under agitation, keeping the mixture reacting at boiling temperature for 30 minutes, after which the mixture is cooled to 400C and the top of the reactor is connected to a condenser provided with condensing collection bottles and a pump. empty. The pressure is around 20 mm Hg. The reactor is then heated to the final temperature of 160OC, initially to eliminate the excess, be it of added acetic anidrid as the formed acetic acid, and finally to allow the growth of the polymeric chain. The total reaction time was 10.0 hours.

The poly (adipic-co-sebacic) anidrid composition had the following characteristics: molecular weight by NMR: 14. 230 and melting temperature of 48, OOC.

EXAMPLE 10 The conditions for application of the copolyanidrids of the invention solubilized in a polar organic solvent, such as chloroform, were tested in the paraffin line of a well in the Campos Basin, State of Rio de Janeiro. A sample of poly (adipicoco-sebacic) anidrid was characterized, containing a 25 mole % of sebacic acid in terms of average molecular weight, concentration of active material and melting point.

TABLE (II) below relates the characteristics of the copolyanidride in solution.

TABLE II PROPERTY VALUE Sebacic acid tensor in the copolyanidride (mol%) 25 Active material content * in chloroform solution (% by weight / volume) 23 Average molecular weight (MW) 14,000 Melting point (OC) 48.0 * Active material is the copolyanidride activator.

The main parameters of the SGN / Emulsion used in the treatment were: - Solution of nitrogenous salts: pH - 7,11 concentration: 4,5 molar Volume used: 12 M3 - Solvent for the emulsion: (kerosene) aliphatic hydrocarbon Volume: 18 m3 - Non ionic emulsifier: Sorbitan ester (ATPET 200) Volume used: 10 liters - Delayed Action Activator: adipic acid-sebacic acid copolyanidide @ 25 mol% of sebacic acid solubilized in chloroform Volume used: 210 liters.

The dewaxing line was 7,370 meters long and had an internal diameter of 10.16 cm (4 inches). Paraffinance was estimated at 30% of the volume of the line based on the normal volume of the line, which means practically 11 m3 of paraffin in the line. Using the present process it is possible to achieve a delay of 45 minutes for the SGN reaction. After treatment with SGN, the discharge of oil production increased from 120 M3 / day to 288 M3 / day, that is, an increase of 140%. The pumping of the delayed action activator solubilized in chloroform according to the present invention was smooth and regular, introducing the required volumes in the line in a precise and homogeneous manner.

Therefore, the action of the delayed action activators of the present application is directed towards a wide range of delay times, in addition to making easier and precise the manipulation of large volumes of activator, conditions that are not known in the activators. homopolianidrido of the state-of-the-art.

Claims (1)

1. Improved process for thermo-chemical dewaxing of ducts containing paraffinic deposits through a nitrogen / emulsion generating system, characterized in that it comprises the steps of: introducing an emulsion in the duct covering an internal aqueous phase and an external phase organic, the aqueous phase comprising an oxidant nitrogenous salt, a nitrogenous reducing salt and water, and the organic phase comprising a non-polar organic liquid; the emulsion comprising a delayed action activator to induce the reaction of the oxidizing nitrogenous salt and the reducing nitrogenous salt; maintaining the emulsion in the pipeline under conditions sufficient to fluidize the paraffin deposit and generate nitrogen gas and heat from the reaction of the oxidizing nitrogen salt and the reducing nitrogen salt; and - removing the fluidized paraffinic deposit from the duct, the refinement being characterized as encompassing a delayed action activator, which is a linear aliphatic copolyanidide solubilized in a polar organic solvent. 2 - improved process according to claim 1, characterized by the fact that the delayed action activator solubilized in polar organic solvent is added in flow to the emulsion of nitrogenous salts. 3. Process perfected according to claim 1, characterized in that the polar organic solvent is chloroform. Improved process according to claim 1, characterized in that the linear copolyanidride comprises a linear carboxylic diacid in C8-Ca, and from 5 to 85 mol% of a comonomer which is a linear carboxylic aliphatic diacid in C8C14, the aliphatic copolyanhydride being solubilized in chloroform, the weight ratio of aliphatic copolyanhydride being for each volume of chloroform between 8% and 40%. 5. Process perfected according to claim 4, wherein the preferred proportion of comonomer in C8.C14 is between 25 and 75 mol% and the proportion by weight of linear copolyanidide for each chloroform bulk is preferably between 10% and 30%. 6. Process perfected according to claims 1, 2 or 3, characterized in that the linear aliphatic copolyanhydride is obtained by copolymerization of a linear aliphatic carboxylic acid diacid C6-C8 and a linear aliphatic dicarboxylic carboxy comonomer in C8-C114 in presence of excess acetic anhydride, in order to form a pre-poly ero, under atmospheric pressure and reflux temperature, followed by cooling and reduction of pressure to remove the acetic acid formed and the excess of acetic anide, increasing the temperature to 100 -200"C to effect copolymerization 7. Process perfected according to claim 5, characterized in that the comonomer in C8-C14 can be suberic acid, decanoic acid, dodecanoic acid and tetradecanoic acid. - Process perfected according to claims 1 and 7, characterized in that the preferred dicarboxylic acid in C-C is adipic acid and the comonomer in C.-C, preferred is sebacic acid. 9. Process perfected according to claim 1, characterized in that the linear aliphatic copolyanidrid delayed action activator is added in a proportion of 0.1% up to 1.0% by weight of active material in relation to the volume of aqueous solution of nitrogen and heat generating salts emulsified in an aliphatic hydrocarbon solvent, said proportion being a function of the type and molar tenor of the C8-C14 comonomer and the molecular weight of the linear aliphatic copolyanidide. Process perfected according to claim 1, characterized in that the control of the hydrodegradability of the copolyanidride activators solubilized in chloroform is effected through the choice of the type and molar tenor of C8-C14 comonomer and the molecular weight of the linear aliphatic copolyanidride. The improved process according to claim 1, characterized in that the hydrolysis of the delayed action copolyanhydride, upon contacting the aqueous solution of nitrogenous salts of the SGN / Emulsion, must produce a solution with pH equal to or less than 5, 0 at temperatures between 10 and 25 ° C, so as to start the nitrogen and heat generation reaction.