DRAG REDUCING AGENT FOR WATER-IN-OIL EMULSION

Abstract

A drag reducing agent for a water-in-oil emulsion is provided. The agent comprises a water-soluble powder component and a fat-soluble powder component. The weight ratio of the water-soluble powder component to the fat-soluble powder component in the agent ranges from 1:2 to 1:4. The water-soluble powder component is made of polyacrylamide, and the fat-soluble powder component is made of polyacrylate. By using the powder form of the water-soluble and fat-soluble components, it is possible to mix them into the water-in-oil emulsion, which may significantly reduce the hydrodynamic drag of the water-in-oil emulsion. In a preferred embodiment, the fat-soluble powder component is made of polyacrylate latex. In an optional embodiment, the agent may further comprise an anti-agglomeration agent to prevent the fat-soluble and water-soluble powder components from agglomerating with each other.

Claims

1. A drag reducing agent for a water-in-oil emulsion, comprising: a water-soluble powder component; a fat-soluble powder component; wherein a weight ratio of the water-soluble powder component to the fat-soluble powder component in the drag reducing agent ranges from 1:2 to 1:4, and wherein the water-soluble powder component is made of polyacrylamide, and the fat-soluble powder component is made of polyacrylate.

2. The agent of claim 1, wherein the fat-soluble powder component is made of polyacrylate latex, and wherein the fat-soluble powder component has a particle size of 25-600 microns and a molecular weight equal to or more than one million g/mol.

3. The agent of claim 1, further comprising an anti-agglomeration agent configured to prevent the fat-soluble powder component and the water-soluble powder component from agglomerating with each other.

4. A method for reducing the hydrodynamic drag of a water-in-oil emulsion by using the drag reducing agent according to claim 1, comprising: preparing the water-soluble powder component of the drag reducing agent; preparing the fat-soluble powder component of the drag reducing agent; stirring the water-soluble powder component and the fat-soluble powder component in a weight ratio raging from 1:2 to 1:4; based on properties of the water-in-oil emulsion, calculating an amount of the drag reducing agent to be added to a pipeline through which the water-in-oil emulsion is pumped; and feeding the calculated amount of the drag reducing agent to the water-in-oil emulsion pumped through the pipeline.

5. The method of claim 4, wherein the water-in-oil emulsion has a water cut ranging from 15% to 75%.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0020] The invention is explained below with reference to the accompanying drawings in which:

[0021] FIGS. 1A and 1B show two types of emulsions: oil-in-water (FIG. 1A) and water-in-oil (FIG. 1B);

[0022] FIG. 2 shows a dissolution diagram of a drag reducing agent according to the invention in the water-in-oil emulsion at +60 C. and 25% water cut;

[0023] FIG. 3 shows a dissolution diagram of the drag reducing agent according to the invention in the water-in-oil emulsion at +60 C. and 50% water cut;

[0024] FIG. 4 shows a dissolution diagram of the drag reducing agent according to the invention in the water-in-oil emulsion at +60 C. and 75% water cut; and

[0025] FIG. 5 shows a flowchart of a method for reducing the hydrodynamic drag of the water-in-oil emulsion according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0026] This section describes the main embodiment of the invention, which, however, does not limit other possible embodiments explicitly described herein and apparent to those skilled in the art.

[0027] The embodiments disclosed herein relate to an agent for reducing the hydrodynamic drag of a flow of liquid hydrocarbons in pipelines. This agent is hereinafter referred to as the drag reducing agent. The drag reducing agent is in the form of a solid two-component powder additive comprising water-soluble and fat-soluble polymer particles which are stirred in a proper weight ratio in accordance with the embodiments disclosed herein.

[0028] The agent may be prepared according to the following main procedure.

[0029] First, a fat-soluble powder component is prepared. The fat-soluble powder component is based on polyacrylates which are known to have drag reduction properties. For example, polyacrylate latex may be used as the fat-soluble powder component. The particles of the fat-soluble powder component can be formed by polymerizing at least one monomer selected from the group comprising acrylates, methacrylates, including, but not limited to, 2-Ethylhexyl methacrylate, isobutyl methacrylate, butyl methacrylate, acrylic acid, and combinations thereof. If polyacrylate latex is used, the latex particles of the drag reducing agent may be formed by polymerizing 2-Ethylhexyl methacrylate, isobutyl methacrylate, butyl methacrylate, acrylates, including, but not limited to, 2-Ethylhexyl acrylate, isobutyl acrylate, butyl acrylate, typically alcohol esters from C1 to C10 of acrylic acid or methacrylic acid, with a small amount of acrylic acid being also added to prepare a terpolymer. The latex particles of the drag reducing agent have a high molecular weight which refers to a value exceeding one million g/mol in the embodiments disclosed herein. The prepared liquid comprising the latex particles is dried by spray drying. The dried material is an active base powder having a particle size of 25-600 microns.

[0030] As a water-soluble component, a commercial high molecular weight polyacridamide powder may be used, such as one of the following: Kemira: Superfloc A-130 or Superfloc C-498, SNF: Flopam AN934 or Flopam FO 4190.

[0031] The two powder components are further mixed in a specified weight ratio until smooth using a stirrer, and at least one anti-agglomeration agent may be added, if required.

Embodiment 1

[0032] The fat-soluble powder component of the drag reducing agent is prepared as follows.

[0033] A 250 ml jacketed three-necked flask is placed on a Heidolph magnetic stirrer, and a circulation thermostat is connected to the flask jacket through silicone hoses.

[0034] A fluoroplastic-coated magnetic stirrer is placed into the flask. Then, 69.3 g of distilled water in a measuring glass are added to the flask, whereupon the magnetic drive of the stirrer is switched on, with the stirrer rotation speed being 800 rpm. While stirring, a rubber septum is placed into the neck of the flask, and a 250 mm veterinary needle is inserted through the septum, to which a nitrogen bottle from a reducer with a pressure of 0.01 MPa is connected through a silicone hose.

[0035] 55 g of 2-Ethylhexyl methacrylate are added to the flask in the process of constant stirring and nitrogen supply. Then, 5 g of sodium lauryl sulfate and 6.4 g of neonol 9-12 (other surfactants, such as synthanol, sulfanol can also be used) are added into the flask. Next, everything is stirred for about 15 minutes until sodium lauryl sulfate dissolves. Then, 0.23 g of monosubstituted potassium phosphate and 0.18 g of disubstituted potassium phosphate are added to the reaction mass. Then, stirring and nitrogen purging are performed for half an hour to remove the residual oxygen in the reaction mass.

[0036] After the nitrogen purging, 0.2 g of ammonium persulphate (a source of radicals) is added to the reaction mass.

[0037] After adding the source of radicals, the circulation thermostat is switched on for the circulation of a heat-transfer medium in the jacket of the flask. A thermocouple is placed into the reaction mass to measure a reaction temperature. The reaction temperature is maintained at 151 C.

[0038] After the reaction mass reaches the above-indicated temperature, a prepared solution of 0.1 g of Mohr's salt (serving as an initiating agent) in 40 g of distilled water with 0.01 mol/l of sulfuric acid is added into the flask. The rate of adding the initiating agent solution is about 8 g/h.

[0039] The stirring and nitrogen purging are continuously performed during the reaction time.

[0040] After the reaction, the prepared latex solution is dried in a laboratory spray dryer at a temperature of 1105 C., after which 2 g of anti-agglomeration agentcalcium stearateare added thereto.

[0041] Then, 3.4 g of octanol and 3.4 g of hexylene glycol are added to the prepared powder, and everything is stirred until smooth.

[0042] The water-soluble powder component of the drag reducing agent is prepared as follows.

[0043] As noted earlier, a commercial high molecular weight polyacridamide powder may be used as the water-soluble powder component. For example, it is possible to use one of the following: Kemira: Superfloc A-130 or Superfloc C-498, SNF: Flopam AN934 or Flopam FO 4190.

[0044] If required, the particles of the water-soluble powder component and/or the fat-soluble powder component may be grinded to make the particles equal in size. Next, the fat-soluble and water-soluble powder components of the drag reducing agent are stirred in a given weight ratio by any suitable means to prepare the ready-to-use drag reducing agent.

Embodiment 2

[0045] The fat-soluble powder component of the drag reducing agent is prepared as follows.

[0046] A 250 ml jacketed three-necked flask is placed on a Heidolph magnetic stirrer, and a circulation thermostat is connected to the flask jacket through silicone hoses.

[0047] A fluoroplastic-coated magnetic stirrer is placed into the flask. Then, 69.3 g of distilled water in a measuring glass are added to the flask, whereupon the magnetic drive of the stirrer is switched on, with the stirrer rotation speed being 800 rpm. While stirring, a rubber septum is placed into the neck of the flask, and a 250 mm veterinary needle is inserted through the septum, to which a nitrogen bottle from a reducer with a pressure of 0.01 MPa is connected through a silicone hose.

[0048] 55 g of isobutyl methacrylate are added to the flask in the process of constant stirring and nitrogen supply. Then, 3 g of sodium lauryl sulfate are added into the flask. Next, everything is stirred for about 15 minutes until sodium lauryl sulfate dissolves. Then, 0.23 g of monosubstituted potassium phosphate and 0.18 g of disubstituted potassium phosphate are added to the reaction mass. Then, stirring and nitrogen purging are performed for half an hour to remove the residual oxygen in the reaction mass.

[0049] After the nitrogen purging, 0.2 g of ammonium persulphate (a source of radicals) is added to the reaction mass.

[0050] After adding the source of radicals, the circulation thermostat is switched on for the circulation of a heat-transfer medium in the jacket of the reaction flask. A thermocouple is placed into the reaction mass to measure a reaction temperature. The reaction temperature is maintained at 151 C.

[0051] After the reaction mass reaches the above-indicated temperature, a prepared solution of 0.1 g of Mohr's salt (serving as an initiating agent) in 40 g of distilled water with 0.01 mol/l of sulfuric acid is added to the flask. The rate of adding the initiating agent solution is about 8 g/h.

[0052] The stirring and nitrogen purging are continuously performed during the reaction time.

[0053] After the reaction, the prepared latex solution is dried in a laboratory spray dryer at a temperature of 1105 C., after which 1.17 g of anti-agglomeration agentzinc stearateis added to the dry product.

[0054] Then, 0.59 g of propanol and 0.59 g of polypropylene glycol are added to the prepared powder, and everything is stirred until smooth.

[0055] The water-soluble powder component of the drag reducing agent is prepared as follows.

[0056] As noted earlier, a commercial high molecular weight polyacridamide powder may be used as the water-soluble powder component. For example, it is possible to use one of the following: Kemira: Superfloc A-130 or Superfloc C-498, SNF: Flopam AN934 or Flopam FO 4190.

[0057] If required, the particles of the water-soluble powder component and/or the fat-soluble powder component may be grinded to make the particles equal in size. Next, the fat-soluble and water-soluble powder components of the drag reducing agent are stirred in a given weight ratio by any suitable means to prepare the ready-to-use drag reducing agent.

Embodiment 3

[0058] In this embodiment, the other version of the fat-soluble powder component is used compared to those from embodiments 1 and 2.

[0059] A 250 ml jacketed three-necked flask is placed on a Heidolph magnetic stirrer, and a circulation thermostat is connected to the flask jacket through silicone hoses.

[0060] A fluoroplastic-coated magnetic stirrer is placed into the flask. Then, 69.3 g of distilled water in a measuring glass are added to the flask, whereupon the magnetic drive of the stirrer is switched on, with the stirrer rotation speed being 800 rpm. While stirring, a rubber septum is placed into the neck of the flask, and a 250 mm veterinary needle is inserted through the septum, to which a nitrogen bottle from a reducer with a pressure of 0.01 MPa is connected through a silicone hose.

[0061] 55 g of butyl methacrylate are added to the flask in the process of constant stirring and nitrogen supply. Then, 5 g of sodium lauryl sulfate and 2.7 g of neonol 9-12 are added to the flask. Next, everything is stirred for about 15 minutes until sodium lauryl sulfate dissolves. Then, 0.23 g of monosubstituted potassium phosphate and 0.18 g of disubstituted potassium phosphate are added to the reaction mass. Then, stirring and nitrogen purging are performed for half an hour to remove the residual oxygen in the reaction mass.

[0062] After the nitrogen purging, 0.2 g of ammonium persulphate (a source of radicals) is added to the reaction mass.

[0063] After adding the source of radicals, the circulation thermostat is switched on for the circulation of a heat-transfer medium in the jacket of the flask. A thermocouple is placed into the reaction mass to measure a reaction temperature. The reaction temperature is maintained at 151 C.

[0064] After the reaction mass reaches the above-indicated temperature, a prepared solution of 0.1 g of Mohr's salt (initiating agent) in 40 g of distilled water with 0.01 mol/l of sulfuric acid is added to the flask. The rate of adding the initiating agent solution is about 8 g/h.

[0065] The stirring and nitrogen purging are continuously performed during the reaction time.

[0066] After the reaction, the prepared latex solution is dried in a laboratory spray dryer at a temperature of 1105 C., after which 5.7 g of anti-agglomeration agentis zinc stearateare added to the dry product.

[0067] Then, 8.8 g of tridecyl amine and 8.8 g of tripentyl phosphate are added to the prepared powder, and everything is stirred until smooth.

[0068] The water-soluble powder component of the drag reducing agent is prepared as follows.

[0069] As noted earlier, a commercial high molecular weight polyacridamide powder may be used as the water-soluble component. For example, it is possible to use one of the following: Kemira: Superfloc A-130 or Superfloc C-498, SNF: Flopam AN934 or Flopam FO 4190.

[0070] If required, the particles of the water-soluble powder component and/or the fat-soluble powder component are grinded to make the particles equal in size. Next, the fat-soluble and water-soluble powder components of the drag reducing agent are stirred in a given weight ratio by any suitable means to prepare the ready-to-use drag reducing agent.

Embodiment 4

[0071] The fat-soluble powder component of the drag reducing agent is prepared as follows.

[0072] A 250 ml jacketed three-necked flask is placed on a Heidolph magnetic stirrer, and a circulation thermostat is connected to the flask jacket through silicone hoses.

[0073] A fluoroplastic-coated magnetic stirrer is placed into the flask. Then, 69.3 g of distilled water in a measuring glass are added to the flask, whereupon the magnetic drive of the stirrer is switched on, with the stirrer rotation speed being 800 rpm. While stirring, a rubber septum is placed into the neck of the flask, and a 250 mm veterinary needle is inserted through the septum, to which a nitrogen bottle from a reducer with a pressure of 0.01 MPa is connected through a silicone hose.

[0074] 55 g of 2-Ethylhexyl methacrylate and isobutyl methacrylate in equal proportion are added to the flask in the process of constant stirring and nitrogen supply. Then, 5.4 g of neonol 9-12 are added to the flask. Next, everything is stirred for about 15 minutes until sodium lauryl sulfate dissolves. Then, 0.23 g of monosubstituted potassium phosphate and 0.18 g of disubstituted potassium phosphate are added to the reaction mass. Then, stirring and nitrogen purging are performed for half an hour to remove the residual oxygen in the reaction mass.

[0075] After the nitrogen purging, 0.2 g of ammonium persulphate (a source of radicals) is added to the reaction mass.

[0076] After adding the source of radicals, the circulation thermostat is switched on for the circulation of a heat-transfer medium in the jacket of the reaction flask. A thermocouple is placed into the reaction mass to measure a reaction temperature. The reaction temperature is maintained at 151 C.

[0077] After the reaction mass reaches the above-indicated temperature, a prepared solution of 0.1 g of Mohr's salt (initiating agent) in 40 g of distilled water with 0.01 mol/l of sulfuric acid is added to the flask. The rate of adding the initiating agent solution is about 8 g/h.

[0078] The stirring and nitrogen purging are continuously performed during the reaction time.

[0079] After the reaction, the prepared latex solution is dried in a laboratory spray dryer at a temperature of 1105 C., after which 12.8 g of anti-agglomeration agenttalcumare added to the dry product.

[0080] Then, 6.1 g of decanol and 3 g of texanol are added to the prepared powder, and everything is stirred until smooth.

[0081] The water-soluble powder component of the drag reducing agent is prepared as follows.

[0082] As noted earlier, a commercial high molecular weight polyacridamide powder may be used as the water-soluble powder component. For example, it is possible to use one of the following: Kemira: Superfloc A-130 or Superfloc C-498, SNF: Flopam AN934 or Flopam FO 4190.

[0083] If required, the particles of the water-soluble powder component and/or the fat-soluble powder component may be grinded to make the particles equal in size. Next, the fat-soluble and water-soluble powder components of the drag reducing agent are stirred in a given weight ratio by any suitable means to prepare the ready-to-use drag reducing agent.

Analysis of Dissolution Dynamics

[0084] To perform dissolution dynamics-aimed tests, water-in-oil emulsions with a different amount of reservoir water were prepared. The data of oil under test are given in Table 1 shown below.

TABLE-US-00001 TABLE 1 Physical and chemical properties of oil under test Parameter name Value Density at 20 C., kg/m.sup.3: 900-908 Oil freezing point, C. +2 Paraffin wt. % 5.4-6.7 Kinematic viscosity at 20 C., mm.sup.2/s 121 Mechanical impurities wt. % 0.0008-0.0100

[0085] The tests are based on measuring the viscosity of the water-in-oil emulsion at 60 C. (which is an oil transport temperature) over time using a Brookfield viscometer in a temperature-controlled cell. The viscosity growth indicates the dissolution of the drag reducing agent in the water-in-oil emulsion, thereby indicating its effectiveness.

[0086] Using a spatula, the drag reducing agent was added to the water-in-oil emulsion. Oil was stirred with the drag reducing agent using a magnetic stirrer. The data obtained are given in FIGS. 2-5 and in Tables 2-7 below.

[0087] In Tables 2-8, the total mass of all versions of the drag reducing agent is the same, that is, for example, the mass of the drag reducing agent based on pure polyacrylamide (PAM) is equal to the mass of the drag reducing agent prepared by stirring a PAM-based additive and an acrylate-based additive (ADRA).

[0088] FIGS. 1A and Table 2 show a version of the oil-in-water emulsion, in which oil droplets are in water at 25% water cut of the emulsion. The water cut of the oil-in-water emulsion below 25% is not considered, since practically, there are no oil-in-water emulsions with such a low water cut.

TABLE-US-00002 TABLE 2 Oil-in-water emulsion, 25% water cut (Dry) (Dry) PAM:ADRA PAM:ADRA PAM:ADRA PAM:ADRA PAM:ADRA PAM:ADRA PAM ADRA (4:1) (3:1) (2:1) (1:1) (1:2) (1:3) Oil temperature +60, C. Time, viscosity viscosity viscosity viscosity viscosity viscosity viscosity viscosity min mPas mPas mPas mPas mPas mPas mPas mPas 0 44.0 44.3 44.2 44.1 44.5 44.0 44.4 44.3 15 219 45 293 338 274 248 157 67 30 363 45 420 470 433 385 224 92 45 507 46 551 596 579 533 260 102 60 546 47 607 633 620 572 279 125 90 603 48 668 708 681 605 308 142

[0089] Table 2 shows that, in case of the oil-in-water emulsion with 25% water cut, the additive containing only the PAM component shows growth of the viscosity, and the drag reducing agent containing only the ADRA practically does not change the viscosity of the oil-in-water emulsion. This is probably due to the fact that the pure ADRA is not water-soluble, does not change its properties, for which reason changes in the properties of the oil droplets in water do not affect the total viscosity of the oil-in-water emulsion.

[0090] When adding the ADRA to PAM in a weight ratio of 3:1, more than 17% viscosity growth is observed in 90 minutes, which indicates the combination due to the use of the ADRA and PAM in the weight ratio of 3:1. This ratio provides the combination due to the maximal dissolution rate of the acrylate and polyacrylamide additives in the emulsion. Thus, in case of increase in the content of the acrylate additive up to 50%, its dissolution rate decreases due to the overdosing of the acrylate additive. The additional reduction of the PAM:ADRA ratio results in the decrease in the dissolution rate of the mixture in the emulsion due to the decrease in the content of polyacrylamide. The ratio 4:1 shows the decrease in the dissolution rate of the mixture due to the maximal dissolution rate of PAM in reservoir water. The ratio 2:1 shows the decrease in the dissolution rate due to the PAM deficiency.

[0091] If the PAM-to-ADRA ratio of is 1:1, 1:2, 1:3, no viscosity growth observed, lower values in the right most columns of Table 2 are associated with the decrease of the PAM content in the additive.

[0092] FIG. 1B and Table 3 show a version of the water-in-oil emulsion, in which water droplets are in oil at 25% water cut of the emulsion. Usually, such an emulsion is formed in oil pipelines, so this version is most favorable in terms of reducing the cost of transporting the emulsion.

TABLE-US-00003 TABLE 3 Water-in-oil emulsion, 25% water cut (Dry) (Dry) PAM:ADRA PAM:ADRA PAM ADRA (3:1) (1:1) Oil temperature +60, C. Time, viscosity, viscosity, viscosity, viscosity, min mPas mPas mPas mPas 0 292.7 294.0 293.6 292.2 15 293 321 312 331 30 293 335 317 348 45 293 354 320 359 60 293 359 327 366 90 293 365 336 378 PAM:ADRA PAM:ADRA PAM:ADRA PAM:ADRA (1:2) (1:3) (1:4) (1:5) Oil temperature +60, C. Time, viscosity, viscosity, viscosity, viscosity, min mPas mPas mPas mPas 0 293.1 291.9 292.1 292.6 15 384 356 339 324 30 397 367 351 337 45 403 378 363 355 60 416 394 371 360 90 432 402 385 369

[0093] Table 3 shows that, in case of the water-in-oil emulsion with 25% water cut, the drag reducing agent containing only the ADRA component shows the viscosity growth, and the drag reducing agent containing only PAM does not change the viscosity of the emulsion. This is probably due to the fact that pure PAM is not oil-soluble, does not change its properties, for which reason changes in the properties of the water droplets in oil do not affect the total viscosity of the water-in-oil emulsion.

[0094] When adding PAM to the ADRA in a weight ratio from 1:3 to 1:1, from 3.5% viscosity growth in the weight ratio of 1:1 to more than 18% viscosity growth in the weight ratio of 1:2 is observed in 90 minutes, in which cases the viscosity almost reaches the values of the pure ADRA in a weight ratio of 1:5, which indicates the combination due to the use of PAM and the ADRA in a weight ratio from 1:1 to 1:4. The ratio of PAM-to-ADRA ratio of 1:2 provides the combination due to the maximal dissolution rate of the acrylate and polyacrylamide additives. Thus, the increase in the content of the acrylate additive up to the ratio of 1:4 results in the maximal dissolution rate of the acrylate additive. The additional increase in the content of the acrylate additive results in the decrease in the dissolution rate of the mixture in the emulsion. When the content of the acrylate additive is reduced to a weight ratio of 1:1, the prepared mixture is not sufficient to provide maximal dissolution rate, which indicates the acrylate additive deficiency.

[0095] If the ratio of PAM-to-ADRA ratio is 3:1, no viscosity growth observed, loss in values is associated with the decrease of the ADRA content in the additive.

[0096] At least the part of the data from Table 3 is visualized in FIG. 2 for illustrative purposes.

[0097] Table 4 shows a version of the oil-in-water emulsion, in which oil droplets are in water at 50% water cut of the emulsion.

TABLE-US-00004 TABLE 4 Oil-in-water emulsion, 50% water cut (Dry) (Dry) PAM:ADRA PAM:ADRA PAM:ADRA PAM:ADRA PAM:ADRA PAM:ADRA PAM ADRA (4:1) (3:1) (2:1) (1:1) (1:2) (1:3) Oil temperature +60, C. Time, viscosity viscosity viscosity viscosity viscosity viscosity viscosity viscosity min mPas mPas mPas mPas mPas mPas mPas mPas 0 69.0 70.3 68.2 70.0 71.5 68.7 70.4 69.3 15 244 70 309 353 297 267 177 84 30 388 70 442 493 454 408 246 99 45 532 71 576 614 592 556 270 125 60 573 71 620 659 645 599 292 131 90 622 71 687 721 699 628 325 149

[0098] Table 4 shows that, in case of the oil-in-water emulsion with 50% water cut, the drag reducing agent containing only the PAM component shows the viscosity growth, and the drag reducing agent containing only the ADRA practically does not change the viscosity of the oil-in-water emulsion. This is probably due to the fact that the pure ADRA is not water-soluble, does not change its properties, for which reason changes in the properties of the oil droplets in water do not affect the total viscosity of the oil-in-water emulsion.

[0099] When adding the ADRA to PAM in a weight ratio of 3:1, more than 15% viscosity growth is observed in 90 minutes, which indicates the combination due to the use of the ADRA and PAM in the weight ratio of 3:1. This ratio provides the combination due to the maximal dissolution rate of the acrylate and polyacrylamide additives in the emulsion. Thus, in case of increase in the content of the acrylate additive up to 50%, the dissolution rate decreases due to the overdosing of the acrylate additive. The additional reduction of the PAM-to-ADRA ratio results in the decrease in the dissolution rate of the mixture in the emulsion due to the decrease in the content of polyacrylamide. The ratio of 4:1 shows the decrease in the dissolution rate of the mixture due to the maximal dissolution rate of PAM in reservoir water. The ratio of 2:1 shows the decrease in the dissolution rate due to the PAM deficiency.

[0100] If the ratio of PAM-to-ADRA ratio is 1:1, 1:2, or 1:3, no viscosity growth observed, lower values in the right most columns of Table 4 are associated with the decrease of the PAM content in the additive.

[0101] Table 5 shows a version of the water-in-oil emulsion, in which water droplets are in oil at 50% water cut of the emulsion.

TABLE-US-00005 TABLE 5 Water-in-oil emulsion, 50% water cut (Dry) (Dry) PAM:ADRA PAM:ADRA PAM ADRA (3:1) (1:1) Oil temperature +60, C. Time, viscosity, viscosity, viscosity, viscosity, min mPas mPas mPas mPas 0 452.5 453.0 454.2 453.4 15 453 481 470 494 30 453 493 475 506 45 453 504 477 517 60 453 509 482 527 90 453 515 484 535 PAM:ADRA PAM:ADRA PAM:ADRA PAM:ADRA (1:2) (1:3) (1:4) (1:5) Oil temperature +60, C. Time, viscosity, viscosity, viscosity, viscosity, min mPas mPas mPas mPas 0 452.7 453.3 453.5 453.7 15 547 511 497 482 30 572 534 512 492 45 589 547 524 506 60 592 562 531 511 90 609 571 539 516

[0102] Table 5 shows that, in case of the water-in-oil emulsion with 50% water cut, the drag reducing agent containing only the ADRA component shows the viscosity growth, and the drag reducing agent containing only PAM does not change the viscosity of the emulsion. This is probably due to the fact that pure PAM is not oil-soluble, does not change its properties, for which reason changes in the properties of the water droplets in oil do not affect the total viscosity of the water-in-oil emulsion.

[0103] When adding PAM to the ADRA in a weight ratio from 1:4 to 1:1, from up to 4% viscosity growth in the weight ratio of 1:1 to more than 18% viscosity growth in the weight ratio of 1:2 is observed in 90 minutes, in which cases the viscosity almost reaches 5% in the weight ratio of 1:4, which indicates the combination due to the use of PAM and the ADRA in the weight ratio from 1:1 to 1:4. The ratio of PAM-to-ADRA ratio of 1:2 provides the combination due to the maximal dissolution rate of the acrylate and polyacrylamide additives. Thus, the increase in the content of the acrylate additive up to the weight ratio of 1:4 results in the maximal dissolution rate of the acrylate additive. The additional increase in the content of the acrylate additive results in the decrease in the dissolution rate of the mixture in the emulsion. When the content of the acrylate additive is reduced to the weight ratio of 1:1, the prepared mixture is not sufficient to provide maximal dissolution rate, which indicates the acrylate additive deficiency.

[0104] If the ratio of PAM-to-ADRA ratio is 3:1, no viscosity growth observed, loss in values is associated with the decrease of the ADRA content in the additive.

[0105] At least the part of the data from Table 5 is visualized in FIG. 3 for illustrative purposes.

[0106] Table 6 shows a version of the oil-in-water emulsion, in which oil droplets are in water at 75% water cut of the emulsion.

TABLE-US-00006 TABLE 6 Oil-in-water emulsion, 75% water cut (Dry) (Dry) PAM:ADRA PAM:ADRA PAM:ADRA PAM:ADRA PAM:ADRA PAM:ADRA PAM ADRA (4:1) (3:1) (2:1) (1:1) (1:2) (1:3) Oil temperature +60, C. Time, viscosity viscosity viscosity viscosity viscosity viscosity viscosity viscosity min mPas mPas mPas mPas mPas mPas mPas mPas 0 101.0 102.0 103.1 103.4 101.6 102.8 102.2 103.1 15 361 102 383 439 392 336 242 116 30 486 103 529 606 548 462 349 146 45 608 103 644 741 690 583 382 161 60 723 105 758 850 784 698 435 175 90 877 106 912 1004 947 812 489 188

[0107] Table 6 shows that, in case of the oil-in-water emulsion with 75% water cut, the drag reducing agent containing only the PAM component shows the viscosity growth, and the drag reducing agent containing only the ADRA practically does not change the viscosity of the oil-in-water emulsion. This is probably due to the fact that the pure ADRA is not water-soluble, does not change its properties, for which reason changes in the properties of the oil droplets in water do not affect the total viscosity of the oil-in-water emulsion.

[0108] When adding the ADRA to PAM in a weight ratio of 3:1, up to 15% viscosity growth is observed in 90 minutes, which indicates the combination due to the use of the ADRA and PAM in the weight ratio of 3:1. This ratio provides the combination due to the maximal dissolution rate of the acrylate and polyacrylamide additives in the emulsion. Thus, in case of increase in the content of the acrylate additive up to 50%, the dissolution rate decreases due to the overdosing of the acrylate additive. The additional reduction of the PAM-to-ADRA weight ratio results in the decrease in the dissolution rate of the mixture in the emulsion due to the decrease in the content of polyacrylamide. The weight ratio of 4:1 shows the decrease in the dissolution rate of the mixture due to the maximal dissolution rate of the PAM in reservoir water. The weight ratio of 2:1 shows the decrease in the dissolution rate due to the PAM deficiency.

[0109] If the ratio of PAM-to-ADRA weight ratio is 1:1, 1:2, or 1:3, no viscosity growth observed, lower values in the right most columns of Table 6 are associated with the decrease of the PAM content in the drag reducing agent.

[0110] Table 7 shows a version of the water-in-oil emulsion, in which water droplets are in oil at 75% water cut of the emulsion.

TABLE-US-00007 TABLE 7 Water-in-oil emulsion, 75% water cut (Dry) (Dry) PAM:ADRA PAM:ADRA PAM ADRA (3:1) (1:1) Oil temperature +60, C. Time, viscosity, viscosity, viscosity, viscosity, min mPas mPas mPas mPas 0 617.0 616.2 616.8 615.9 15 618 632 620 631 30 618 644 626 657 45 618 652 633 672 60 618 661 639 684 90 618 675 644 707 PAM:ADRA PAM:ADRA PAM:ADRA PAM:ADRA (1:2) (1:3) (1:4) (1:5) Oil temperature +60, C. Time, viscosity, viscosity, viscosity, viscosity, min mPas mPas mPas mPas 0 617.1 616.4 616.9 616.2 15 665 651 643 631 30 699 680 652 645 45 712 696 668 652 60 729 701 674 662 90 738 714 683 676

[0111] Table 7 shows that, in case of the water-in-oil emulsion with 50% water cut, the drag reducing agent containing only the ADRA component shows the viscosity growth, and the drag reducing agent containing only PAM does not change the viscosity of the emulsion. This is probably due to the fact that pure PAM is not oil-soluble, does not change its properties, for which reason changes in the properties of the water droplets in oil do not affect the total viscosity of the water-in-oil emulsion.

[0112] When adding PAM to the ADRA in a weight ratio from 1:4 to 1:1, from up to 5% viscosity growth in the weight ratio of 1:1 to more than 9% viscosity growth in the weight ratio of 1:2 is observed in 90 minutes, in which cases the viscosity almost reaches 1% in the weight ratio of 1:4, which indicates the combination due to the use of PAM and the ADRA in the weight ratio from 1:1 to 1:4. The ratio of PAM-to-ADRA weight ratio of 1:2 provides the combination due to the maximal dissolution rate of the acrylate and polyacrylamide additives. Thus, the increase in the content of the acrylate additive up to the weight ratio of 1:4 results in the maximal dissolution rate of the acrylate additive. The additional increase in the content of the acrylate additive results in the decrease in the dissolution rate of the mixture in the emulsion. When the content of the acrylate additive is reduced to the weight ratio of 1:1, the prepared mixture is not sufficient to provide maximal dissolution rate, which indicates the acrylate additive deficiency.

[0113] If the ratio of PAM-to-ADRA weight ratio is 3:1, no viscosity growth observed, loss in values is associated with the decrease of the ADRA content in the additive.

[0114] At least the part of the data from Table 7 is visualized in FIG. 4 for illustrative purposes.

[0115] As follows from the above data, it may be concluded that the drag reducing agent according to the invention provides the fast and effective reduction of the hydrodynamic drag of a turbulent flow of water-in-oil emulsions in pipelines and, as a result, provides ramp-up, and reduction in expenses for transporting a hydrocarbon liquid.

[0116] The lower limit of the water cut range in which the drag reducing agent shows its efficiency, was analyzed additionally. Table 8 below shows the viscosity of the drag reducing agent in the water-in-oil emulsion at 15% water cut.

TABLE-US-00008 TABLE 8 Water-in-oil emulsion, 15% water cut (Dry) (Dry) PAM:ADRA PAM:ADRA PAM:ADRA PAM:ADRA PAM ADRA (3:1) (1:1) (1:2) (1:3) Oil temperature +60, C. Time, viscosity, viscosity, viscosity, viscosity, viscosity, viscosity, min mPas mPas mPas mPas mPas mPas 0 104.3 103.8 104.1 104.2 104.0 104.1 15 104 122 109 112 124 123 30 104 157 115 133 158 157 45 104 164 122 136 162 164 60 104 176 129 141 177 175 90 104 188 134 143 187 188

[0117] Table 8 shows that at a low water cut the mixture of the two water-soluble and fat-soluble powder components is less effective than the pure ADRA.

[0118] As a result, it is preferable to use the drag reducing agent according to the invention in the water cut range from 15 to 75%.

[0119] FIG. 5 shows a flowchart of a method 500 for reducing the hydrodynamic drag of the water-in-oil emulsion according to the invention. As shown in FIG. 5, the method 500 includes steps S502-S510. In the steps S502 and S504, the fat-soluble and water-soluble powder components of the drag reducing agent are prepared, for example, in accordance with any of embodiments 1-4 discussed above. In the step S506, the components are stirred in a weight ratio of ranging from 1:2 to 1:4, preferably 1:3. In the next step S508, an amount of the drag reducing agent is calculated, which needs to be added to a pipeline through which the water-in-oil emulsion is pumped. The step S508 may be performed based on properties of the water-in-oil emulsion, such as a water content, an oil composition, an emulsion temperature, requirements for an additive content in oil, etc. After that, in the step S510, the calculated amount of the drag reducing agent is added to the pipeline by any suitable means, for example, a screw doser.

[0120] The invention is not limited to the embodiments described herein. Other embodiments of the invention staying within the essence and scope of the invention will be apparent to those skilled in the art based on the information set forth herein.

[0121] In the appended claims, the word comprise and its derivates does not exclude other elements or operations, and the indefinite article a or an does not exclude a plurality. Furthermore, the steps and/or stages of the method 500 can be performed in an order other than the one discussed above and shown in FIG. 5. For example, the step S504 may be performed before the step S502.

[0122] Although exemplary embodiments have been described in detail and shown in the accompanying drawings, it should be understood that such embodiments are illustrative only and are not used to limit the invention and that the invention should not be limited to the specific configurations and structures shown and described, as other various modifications may be apparent to the persons skilled in the relevant field.

[0123] The features mentioned in various dependent claims, as well as the implementations disclosed in various parts of the description, can be combined to achieve the advantageous effect, even if the possibility of such a combination is not disclosed explicitly.