EA030206B1 - Method for removing asphalt-resin-paraffin deposits - Google Patents

Abstract

The invention is related to petroleum and gas industry and can be used for removal of asphalt-resin-paraffin deposits. The objective of the invention is enhancement of efficiency of the asphalt-resin-paraffin deposits removal method by decreasing power consumption and expense of the chemical reagent. Said objective is attained by provision of a method for removal of asphalt-resin-paraffin deposits, comprising descending a heating cable to a zone of possible paraffin formation, connection of the heating cable to an adjustable power source, and feeding a chemical dissolving reagent through a hydraulic channel to the well using a metering pump, wherein temperature over entire length of the heating cable is maintained at the paraffin melting point throughout the well depth, and the solvent used comprises mixture of stable gas condensate and light gas oil in the amount of 200 g per ton of oil produced with the following proportion of components, wt.%: stable gas condensate - 75, light gas oil - 25.

Description

The invention relates to the oil and gas industry and can be used when removing asphalt, resin and paraffin formations. The objective of the invention is to increase the efficiency of the method of removing asphalt-resin-paraffin deposits by reducing the energy consumed and the consumption of chemical reagent. The task is solved by the fact that in the method of removing asphalt-resin-paraffin deposits, including the descent into the zone of possible paraffin formation of the heating cable, connecting the heating cable to an adjustable power source and supplying a chemical reagent-solvent through a hydraulic channel into the well with a dosing pump, the temperature throughout the working part heating cable is maintained at the level of the melting point of paraffin throughout the entire depth of the well, and as a solvent at change the mixture of stable gas condensate and light gas oil in the amount of 200 g per 1 ton of oil produced in the following ratio of components, wt.%: stable gas condensate - 75, light gas oil - 25.

030206

The invention relates to the oil and gas industry and can be used when removing asphalt, resin and paraffin formations.

There is a method of dewaxing wells by pumping hot oil to the complete elimination of paraffin deposits, followed by replacing the gaseous medium to the dynamic level of the well [1].

The disadvantages of this method are the low efficiency and the long duration of the elimination of deaf asphalt-resin-paraffin plugs.

A known method of removing paraffin deposits in tubing of oil wells, which consists in obtaining a solvent based on condensed light hydrocarbons, entering them into the tubing of the well and circulating while running "on" a deep well pump [2].

The disadvantage of this method is its low efficiency as a result of the inability to provide long-term and reliable protection of the well from new deposits.

The closest to the invention to the technical essence and the achieved result is a method of removing asphalt-resin-paraffin deposits (ARPD), including the descent into the zone of possible paraffin formation of the heating cable with heating elements, connecting the heating elements of the cable to an adjustable power source and supplying a chemical reagent through the hydraulic channel to the well or the help of the dosing pump, or without it by gravity due to hydrostatic pressure below the point of the beginning of the crystal tion parafinogidratov [3].

The disadvantages of the known technical solutions are low removal efficiency asphalt, resin and paraffin deposits and high power consumption, as well as the use of a special device for the implementation of the proposed method.

The objective of the invention is to increase the efficiency of the method of removing asphalt-resin-paraffin deposits by reducing the energy consumed and the consumption of chemical reagent.

The task is solved by the fact that in the method of removing asphalt-resin-paraffin deposits, including the descent into the zone of possible paraffin formation of the heating cable, connecting the heating cable to an adjustable power source and supplying the chemical solvent to the solvent through the hydraulic channel into the well with a dosing pump, the temperature along the entire length of the heating cable support at the level of the melting point of paraffin throughout the depth of the well, and as a solvent at enyayut mixture was stable gas condensate and light gas oil in an amount of 200 g per 1 ton of oil produced in the following ratio, wt.%:

Stable gas condensate 75

Light gas oil 25

According to the invention, hydrocarbon solvents are used as a solvent: stable gas condensate according to TU 51-05751745-09-97 and light gas oil according to TU-0251-001-78158825-2013.

In the known method, the amount of deposits of paraffin decreases, however, this consumes a significant amount of energy, despite the fact that they use a cable with at least two heating elements.

In the proposed method of removing asphalt-resin-paraffin deposits, simultaneously with the thermal effect of the heater, which does not have a special heating control system, a mixture of stable gas condensate and light gas oil is pumped into the well.

Injecting a mixture of stable gas condensate and light gas oil into the annulus reduces the deposits of paraffin deposits, reduces the viscosity of the products produced. The components of stable gas condensate and light gas oil penetrate into the crystalline sticky mass of sediments, promote the separation of particles from each other and, in the form of a non-adhesive film, keep them in oil, preventing the deposition of paraffin and asphalt-tar substances on the tubing walls.

As a result of reducing the hydraulic resistance in the tubing, reducing the viscosity of the produced oil and energy consumption, the efficiency of the proposed method for removing paraffin-resin deposits increases.

The method of removing asphalt, resin and paraffin deposits is as follows.

In the tubing of an oil well, the heating cable is lowered. Conduct a thermal effect on the flow of downhole products, in which the temperature of the liquid is maintained at the level of the melting point of paraffin. The cable is powered from the surface using regulated voltage sources. The cable descent depth should provide effective prevention of paraffin deposits, therefore, the cable descent depth should be chosen according to the maximum ARPD depth.

At the same time produce a mixture of stable gas condensate and light gas oil in the well. A mixture of stable gas condensate and light gas oil is prepared by simply mixing the components with a mechanical stirrer for 1 hour at room temperature until a homogeneous mass is formed. The physico-chemical characteristics of the prepared composition are as follows: density (at 20 ° C) 810 kg / m ³ ; dynamic viscosity (at 20 ° С) 0.93 mPa-s.

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The prepared mixture of stable gas condensate and light gas oil from the tank through the dosing pump is pumped into the annulus.

The flow rate of the injected mixture of stable gas condensate and light gas oil is 200 g per 1 ton of produced oil.

The proposed method was subjected to laboratory tests by the method of "cold rod". Metal tubes were lowered into the oil and cooled. After exposure of the rods in the oil, the mass of deposited on the surface of asphalt-resin-paraffin substances was determined.

To determine the optimal ratio of solvent components, metal rods were dipped into oil with the addition of various concentrations of stable gas condensate and light gas oil, respectively, 100: 0; 75:25; 50:50; 25:75; 0: 100 wt.%, Simultaneously passing a hot coolant through the rods at a temperature of 40 ° C (Table 1) and kept for 4 hours. Experiments were performed at various concentrations of a mixture of stable gas condensate and light gas oil in oil (0.005-0.050%). The results of the experiments showed that the highest dissolution efficiency is obtained by adding, regardless of its concentration in the oil, a mixture consisting of 75% of stable gas condensate and 25% of light gas oil.

To determine the effectiveness of the proposed method in the following experiments, metal rods were lowered into the oil with the addition of a mixture of stable gas condensate and light gas oil at a ratio of 75:25 wt.% At various concentrations, while simultaneously passing a hot heat carrier through them. In further experiments, the temperature of the coolant was raised below and above the melting point of paraffin over the entire depth of the well and the experiments were repeated. The physicochemical parameters of the oil used in the experiments are shown in Table. 2

Table 1

No of experience Initial weight of sediment, g The concentration of condensate in the mixture,% of mass. The concentration of light gas oil in the mixture,% of the mass. The concentration of solvent in oil,% of the mass. The ultimate weight of sediment, g The degree of dissolution of paraffin,% one 4,824 100 - 0,005 3,304 31.5 4,923 75 25 0,005 3.136 36.3 5.112 50 50 0,005 3,384 33.8 4.856 25 75 0,005 3,389 30.2 5,054 - 100 0,005 3,684 27.1 2 4,894 100 - 0,010 3.157 35.5 5,006 75 25 0,010 2,763 44.8 4,952 50 50 0,010 3,031 38,8 4,912 25 75 0,010 3.281 33.2 5.121 - 100 0,010 3,631 29.1 3 4,825 100 - 0.020 2,881 40.3 5,096 75 25 0.020 2.523 50.5 5.142 50 50 0.020 2,977 42.1 4,952 25 75 0.020 3,105 37.3 4,914 - 100 0.020 3,342 32.0 four 5.085 100 - 0.030 2,939 42.2 4,899 75 25 0.030 2.356 51.9 4,902 50 50 0.030 2,721 44.5 5.121 25 75 0.030 3,129 38.9 4,898 - 100 0.030 3.228 34.1 five 4,907 100 - 0.040 2,782 43.3 5,050 75 25 0.040 2,374 53.0 5.141 50 50 0.040 2,796 45.6 4,859 25 75 0.040 2,906 40.2 4,997 - 100 0.040 3.218 35.6 6 5.088 100 - 0.050 2,824 44.5 4,982 75 25 0.050 2.302 53,8 5,105 50 50 0.050 2,746 46.2 5,029 25 75 0.050 2,957 41.2 4,852 - 100 0.050 3,057 37.0

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table 2

Indicator oil Density of oil, g / cm ³ at 20 ° С 0.849 Dynamic viscosity, MPa * s 20 ^and C 93.74 30 ° С 50.36 40 ^ 0 28.60 50 ° C 19.14 60 ° C 10.66 70 ° C 5.84 80 ^and C 2.93 Paraffin content,% weight 21.60 Resin content,% weight 19.35 Asphaltenes content,% weight 1.75 The formation temperature of the first paraffin crystals, ° C +57,5 Paraffin melting point +45.0

After the exposure time expired, the rods were removed from the solvent with oil and weighed. The efficiency of dissolving paraffin is determined by changing the mass of paraffin as follows:

E = 100 - (MdsPO + rast * 1 00) / MasPO,%, where M _ARPD is the initial mass of ARPD on the rod;

M _ARPD + _rast - the mass remaining on the rod after aging in oil with the addition of a solvent and the use of coolant.

For comparison, the proposed method with a known metal rod with ARPD was lowered into the oil with the addition of 0.050% hydrocarbon solvent FLEK-P017, while simultaneously passing through it the hot coolant (according to the prototype). The results of the experiments are shown in Table. 3

_ _ Table 3

No of experience Initial weight of sediment, g The concentration of solvent in oil,% of the mass. Temperature heating, The ultimate weight of sediment, g The degree of dissolution of paraffin,% one 4,923 0,005 40 3.136 36.3 2 5,006 0,010 40 2,763 44.8 3 5,096 0.020 40 2.523 50.5 four 4,899 0.030 40 2.356 51.9 five 5,050 0.040 40 2,374 53.0 6 4,982 0.050 40 2.302 53,8 7 5.021 0,050 (prototype) 40 3,936 21.6 eight 5.085 0,005 45 2.207 56,6 9 4,987 0,010 45 1,735 65.2 ten 5,102 0.020 45 0.561 89.0 eleven 5,022 0.030 45 0.537 89.3 12 4,889 0.040 45 0.513 89.5 13 4,905 0.050 45 0,491 90.0 14 5.115 0,050 (prototype) 45 3,642 28,8 15 5,009 0,005 50 1,928 61.5 sixteen 4,956 0,010 50 1.432 71.1 17 4,883 0.020 50 0,508 89.6 18 4,959 0.030 50 0.501 89.9 nineteen 5,001 0.040 50 0.485 90.3 20 5.086 0.050 50 0.458 91.0 21 5.083 0,050 (prototype) 50 3.416 32,8 22 4,843 0,005 60 1.535 68.3 23 5,066 0,010 60 1,180 76.7 24 4,911 0.020 60 0.437 91.1 25 5,105 0.030 60 0.408 92.0 26 4,995 0.040 60 0.385 92.3 27 4,892 0.050 60 0.338 93.1 28 5,107 0,050 (prototype) 60 3,059 40.1 29 5.087 0,005 70 1,450 71.5 thirty 4,851 0,010 70 0.883 81,8 31 4,923 0.020 70 0.399 91.9 32 5.111 0.030 70 0.399 92.2 33 5,009 0.040 70 0.376 92.5 34 4,906 0.050 70 0.334 93.2 35 5.021 0,050 (prototype) 70 2,752 45.2 36 4,995 0,005 80 1,209 75.8 37 5,099 0,010 80 0.908 82.2 38 4,917 0.020 80 0.369 92.5 39 4,851 0.030 80 0.330 93.2 40 4,900 0.040 80 0.294 94.0 41 5,100 0.050 80 0.265 94.8 42 5,031 0,050 (prototype) 80 2,561 49.1

It was established that with an increase in the temperature and concentration of the proposed mixture, the degree of dissolution also increases at a temperature of 80 ° C using a mixture of stable gas condensate.

sat and light gas oil 0.05 wt.%, it reaches 94.8%. As can be seen from the table. 3, when using a heater with a hydrocarbon solvent of 0.05% concentration (according to the prototype), 49.1% ARPD dissolves at 80 ° C. The addition of the proposed mixture of 0.02 wt.% Allows at a temperature of 45 ° C to increase the degree of dissolution to 89.0%. The application of the method should provide the temperature of heating the oil flow at the level of the melting point of paraffin. With further increase in temperature and solvent concentration above 0.02 wt.%, The growth rate of the degree of dissolution decreases. On the basis of the conducted studies, it was found that to increase the efficiency of ARPD removal, it is advisable to add the proposed solvent - a mixture of stable gas condensate and light gas oil in an amount of 0.02 wt.% And heat the cable to the level of paraffin melting temperature throughout the depth of the well. This will increase the degree of dissolution of paraffin wax up to 89.0%.

As a result of the study, it was found that adding a mixture of condensate and light gas oil while simultaneously heating the cable to the melting point of paraffin over the entire depth of the well contributes to increasing the degree of dissolving the sediment, reducing power consumption and improving the bottomhole treatment efficiency and increasing the productivity of the well.

Literature.

1. 8I 1234593, Е21В 37/06, 1986.

2. CI 2256064, Е21В 37/06, 2005.

3. CI 2273725, Е21В 37/06, Е21В 43/24, 2006.

Claims (1)

CLAIM Method for removing asphalt-resin-paraffin deposits, including lowering into the zone of possible asphalt-resin-paraffin formation of a heating cable, connecting the heating cable to an adjustable power source and supplying a chemical reagent-solvent through a hydraulic channel to the well using a dosing pump, characterized in that the temperature is maintained throughout at the level of the melting point of paraffin throughout the depth of the well, and as a solvent it is used A mixture of stable gas condensate and light gas oil in an amount of 200 g per 1 ton of oil produced in the following ratio, wt.%: stable gas condensate - 75, light gas oil - 25.