Paraffin removing and inhibiting agent for oil well shaft and preparation process of paraffin removing and inhibiting agent

Abstract

The invention relates to the technical field of oil well paraffin removal and prevention, and discloses a paraffin removal and prevention agent for an oil well shaft and a preparation process. The paraffin remover and inhibitor for the oil well shaft comprises the following components in parts by weight: 10-25 parts of a compound surfactant, 15-30 parts of a mutual solvent, 5-10 parts of a stabilizer, 1-10 parts of a novel wax crystal improver, 0.2-0.5 part of a rapid penetrant, 0.5-1.5 parts of alkali and 25-70 parts of water, the novel wax crystal improver has a structure similar to that of paraffin, and wax crystals can be dissolved in the novel wax crystal improver, so that the wax crystals are not easy to gather and deposit on a pipe wall, and the dissolution rate of the wax crystals is further improved; sodium sulfonate in the structure has strong polarity and hydrophilicity, can adjust the crystallinity of paraffin inhibitor molecules, has a synergistic effect with asphalt, colloid and the like in crude oil, reduces the surface tension of water, has a good wetting effect, and improves the low-temperature fluidity of the crude oil.

Description

Technical Field

[0001] The invention relates to the technical field of oil well wax removal and prevention, in particular to a wax removal and prevention agent for oil well bores and a preparation process. Background Art

[0002] The wax in crude oil usually exists in liquid form under formation conditions. During the production and development process, with the decrease in temperature and pressure and the continuous escape of light components in crude oil, the crude oil's ability to dissolve wax is reduced. Wax precipitates and deposits in the form of crystals and is adsorbed on the oil well pipe wall, around the well wall and in the production casing, causing blockage of oil and gas migration channels and damage to the reservoir. Severe wax deposition in oil wells leads to increased crude oil viscosity, decreased oil and gas production, and may even cause production suspension. Therefore, oil well wax cleaning and prevention is an important technical measure to ensure the normal production of waxy crude oil. Oil well wax cleaning and prevention has become an important part of oil well management and a necessary measure to maintain normal crude oil extraction and transportation.

[0003] At present, the commonly used oil well wax removal and prevention technologies in my country mainly include mechanical wax removal technology, thermal wax removal and prevention technology, surface energy wax prevention technology, magnetic wax prevention technology, microbial wax removal and prevention technology and chemical agent wax removal and prevention technology. In comparison, chemical wax removal and prevention technology has the advantages of simple dosing method, good wax removal and prevention effect and wide application range, and is currently the most commonly used wax removal and prevention method. Chemical wax removers are mainly divided into water-based wax removers, oil-based wax removers and emulsion wax removers. Among them, oil-based wax removers mostly use benzene and xylene as organic solvents, which are highly toxic and easily diluted by crude oil. They have a low flash point and are more harmful to operators. Emulsion wax removers must have stable preparation and storage conditions, and must be demulsified immediately after reaching the bottom of the well, otherwise they will not play a role in wax removal and prevention, and the conditions for preparation and storage are harsh. Water-based wax removers can overcome the above-mentioned shortcomings of oil-based wax removers and emulsion wax removers, and have no odor, no pollution, and are environmentally friendly and safe during use, but they have the problems of low wax removal efficiency and poor wax prevention effect.

[0004] The invention synthesizes a novel wax crystal modifier having a structure similar to that of paraffin molecules and a hydrophilic group, utilizes the structural characteristics of the hydrophilic and lipophilic groups of the compounded surfactant, uniformly disperses the novel wax crystal modifier in water, and then compounded with a mutual solvent, a stabilizer, a rapid penetrant, an alkali, etc. to form an environmentally friendly and pollution-free water-based wax removing and preventing agent, avoids the use of harmful solvents such as xylene, has a strong wax removing effect, a fast wax dissolving speed, and further improves the low-temperature fluidity of crude oil. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art, provide a wax removal and prevention agent for oil well bore and a preparation process, solve the problem of poor wax removal and prevention effect in the prior art, and further improve the low-temperature fluidity of crude oil.

[0006] To achieve the above object, the technical solution adopted by the present invention is: A wax removing and preventing agent for oil well bore, comprising the following components in parts by weight: 10-25 parts of a composite surfactant, 15-30 parts of a mutual solvent, 5-10 parts of a stabilizer, 1-10 parts of a new wax crystal improver, 0.2-0.5 parts of a fast penetrant, 0.5-1.5 parts of an alkali, and 25-70 parts of water.

[0007] The preparation process of the novel wax crystal modifier comprises the following steps: (1) Add 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt aqueous solution, tetrafluoroboric acid and tetrahydrofuran into a reaction flask, mix well, add epoxidized soybean oil, and perform reflux reaction at a speed of 150-300 r / min. After the reaction is completed, add sodium bicarbonate aqueous solution to adjust the pH of the system to neutral, extract with ethyl acetate and water, concentrate the organic phase, and dry it to obtain sodium olefin sulfonate modified soybean oil.

[0008] (2) Nitrogen is introduced into a reaction flask equipped with a reflux condenser, styrene and ethanol aqueous solution are added, and after uniform dispersion, sodium olefin sulfonate modified soybean oil is added, the temperature is raised to 45-55°C, and the mixture is stirred to dissolve. An initiator, azobisisobutyronitrile, is added, and the mixture is stirred to react. After the reaction is completed, the mixture is cooled and filtered, washed with ethanol, and dried to obtain a novel wax crystal modifier.

[0009] Furthermore, in the step (1), the sodium salt solution of 3-allyloxy-2-hydroxy-1-propanesulfonic acid is 6-15 parts, the tetrafluoroboric acid is 0.8-1.3 parts, and the epoxy soybean oil is 100 parts by weight.

[0010] Furthermore, in step (1), the reflux reaction temperature is 65-75° C. and the reflux reaction time is 3-8 h.

[0011] Furthermore, in the step (2), by weight, styrene is 100 parts, sodium olefin sulfonate-modified soybean oil is 15-70 parts, and azobisisobutyronitrile is 1-1.5 parts.

[0012] Furthermore, in step (2), the reaction temperature is 70-85° C. and the reaction time is 5-8 h.

[0013] Furthermore, the preparation process of the compound surfactant is carried out according to the following steps: add 30-60 parts by weight of alkylphenol polyoxyethylene polyoxypropylene ether, 25-40 parts of sodium lauryl sulfate and 10-20 parts of limonene into a reaction flask, stir evenly, add 5-10 parts of alkyl polyglycoside, mix at 50-70°C for 2-4h, and obtain a compound surfactant.

[0014] Furthermore, the mutual solvent is any one of isopropanol, ethylene glycol monobutyl ether, and diethylene glycol ethyl ether.

[0015] Furthermore, the stabilizer is ethylene glycol; and the rapid penetrating agent is 5-sodium sulfoisophthalate.

[0016] Furthermore, the alkali is any one of sodium hydroxide, sodium orthosilicate, sodium phosphate, and sodium hexametaphosphate.

[0017] Furthermore, the preparation process is carried out according to the following steps: adding a compound surfactant, a mutual solvent, an alkali and water into a reaction bottle, stirring for 10-20 minutes at a temperature of 20-35°C and a rotation speed of 300-500r / min, and after uniform dispersion, adding a stabilizer and a rapid penetrant, continuing to stir for 5-15 minutes, and then adding a new wax crystal improver, stirring and mixing, to obtain a wax removing and preventing agent for oil well bores.

[0018] By adopting the above technical solution, the beneficial effects of the present invention are: When preparing the wax removing and preventing agent for oil well bore, the present invention prepares alkylphenol polyoxyethylene polyoxypropylene ether, sodium lauryl sulfate, limonene and alkyl glycoside according to a certain ratio to obtain a composite surfactant; then, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt aqueous solution and epoxy soybean oil are subjected to an epoxy ring-opening reaction under the catalysis of tetrafluoroboric acid to obtain sodium olefin sulfonate modified soybean oil; then, the sodium olefin sulfonate modified soybean oil and styrene initiate polymerization to obtain a novel wax crystal improver; and finally, the wax removing and preventing agent is uniformly mixed with a mutual solvent, a stabilizer, a rapid penetrant and an alkaline substance to obtain the wax removing and preventing agent for oil well bore.

[0019] The new wax crystal modifier contains a long-chain branched structure of epoxidized soybean oil in its molecules, which acts as a eutectic in the anti-wax process and can be better adsorbed on the solid-liquid interface, thereby increasing the compatibility with the oil sample and playing a role of wetting reversal, thus strengthening the anti-wax effect. The sodium sulfonate in the structure of the new wax crystal modifier has strong polarity and hydrophilicity, and its strong polarity can change the polarity of the anti-wax agent molecules, and can adjust the crystallinity of the anti-wax agent molecules. At the same time, it plays a synergistic role with asphaltene, colloid, etc. in crude oil, thereby improving the anti-wax effect of the wax removal and prevention agent. Its hydrophilicity is reflected in the fact that sodium sulfonate, as a hydrophilic group, can greatly reduce the surface tension of water, and has a good wetting effect. It can also be adsorbed on the surface of wax crystals, so that the wax crystals form a polar surface that is not conducive to their continued growth, and the wax crystals can remain in a fine state. The synthesized new wax crystal modifier has a structure similar to paraffin. According to the principle of "like dissolves like", wax crystals can be dissolved in the wax removal and prevention agent, further increasing the dissolution rate of wax crystals.

[0020] The compound surfactant combines the advantages of wetting reversal of alkylphenol polyoxyethylene polyoxypropylene ether, sodium lauryl sulfate and alkyl polyglycoside, so that the wax surface is reversed from lipophilic to hydrophilic, and has a strong wetting and dispersing effect. It can be adsorbed on the surface of wax crystals to prevent the adsorption and deposition of non-polar wax crystals on the metal surface, weaken the adhesion between the wax block and the well wall, which is conducive to the shedding of wax and achieves the purpose of wax prevention. The limonene molecule contains double bonds and has good chemical stability at room temperature. It has a good dissolving effect on wax crystals on the surface of reservoir rocks and oil pipes. The penetration and dispersing properties of the compound surfactant help the wax removal and prevention agent penetrate into the gaps of loosely structured wax crystals, and at the same time reduce the interfacial tension between oil and wax. The surfactant molecules can penetrate the structure of the wax, weaken the binding force between wax molecules, and destroy the bonding force between individual wax molecules and the pipe wall, thereby causing the wax crystals to break up and disperse in the oil flow, flowing out of the oil well with the produced fluid, thereby playing a wax removal role.

[0021] The addition of mutual solvent solves the problem of poor mutual solubility between oil phase and water phase, making the solution system a uniform and stable whole, improving the permeability of water-based wax removal and prevention agent into waxy crude oil, enabling surfactant to better contact with wax in crude oil, and at the same time increasing the mutual solubility of oil including wax and water, dissolving wax crystals and thus improving the wax dissolution rate; the addition of alkali makes the asphaltene in oilfield wax easy to disperse in water, because the carboxyl, hydroxyl and other groups in the asphaltene can react with alkali to transform into sodium carboxyl and sodium hydroxyl, which improves the dispersion ability in water and forms numerous crystal nuclei, which are suspended in the oil flow in a dispersed form and carried away, thereby achieving the purpose of wax removal and prevention; the addition of penetrant can weaken the adhesion between wax molecules and pipe walls, which is beneficial to the shedding and removal of wax; the addition of stabilizer can lower the freezing point of the wax removal and prevention agent, thereby broadening the application range of the wax removal and prevention agent.

[0022] The wax removing and preventing agent prepared by the present invention dissolves the wax deposited on the pipe wall by means of a mutual solvent, is dispersed in crude oil under the action of a compound surfactant, and penetrates along the gaps in the wax and the gaps between the wax and the pipe wall of the oil well, so that the wax deposited on the surface of the pipe wall falls off from the surface of the pipe wall and is carried out of the oil well by the oil flow; the wax crystal improver changes the structure of the wax crystal, so that the wax crystal is not easy to aggregate and deposit on the pipe wall, and can effectively prevent the wax from forming in the oil well, thereby achieving the dual effects of wax removing and preventing wax, and further improving the low-temperature fluidity of the crude oil. DETAILED DESCRIPTION

[0023] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0024] 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt aqueous solution, CAS number is 52556-42-0.

[0025] Tetrafluoroboric acid, CAS number is 16872-11-0.

[0026] Epoxidized soybean oil, CAS number is 8013-07-8.

[0027] Example 1 (1) Add 1.2 g of 40% aqueous solution of 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, 0.12 g of tetrafluoroboric acid and 60 mL of tetrahydrofuran into a reaction flask, mix well, add 10 g of epoxidized soybean oil, reflux for 5 h at a speed of 200 r / min and a temperature of 70 °C. After the reaction is completed, add 15% aqueous sodium bicarbonate solution, adjust the pH of the system to neutral, extract with ethyl acetate and water, concentrate the organic phase, and dry to obtain sodium olefin sulfonate modified soybean oil.

[0028] (2) Nitrogen was introduced into a reaction flask equipped with a reflux condenser, 20 g of styrene and 260 mL of 80% by volume ethanol aqueous solution were added, and after uniform dispersion, 7 g of sodium olefin sulfonate-modified soybean oil was added, the temperature was raised to 50 °C, and the mixture was stirred to dissolve. 0.22 g of initiator azobisisobutyronitrile was added, and the mixture was reacted at 75 °C for 7 h, cooled and filtered, washed with ethanol, and dried to obtain a new wax crystal modifier.

[0029] (3) Add 15 g of alkylphenol polyoxyethylene polyoxypropylene ether, 10 g of sodium lauryl sulfate and 5 g of limonene into a reaction flask, stir evenly, then add 2.7 g of alkyl glycoside, and mix at 60°C for 3 h to obtain a composite surfactant.

[0030] (4) Add 10 g of a composite surfactant, 25 g of diethylene glycol ethyl ether, 1 g of sodium hydroxide and 58 g of water into a reaction bottle, stir at 25 °C and 400 r / min for 15 min, and after uniform dispersion, add 6 g of ethylene glycol and 0.4 g of 5-sodium sulfonate of isophthalic acid, continue stirring for 10 min, then add 1 g of a new wax crystal modifier, stir and mix well to obtain a wax remover and preventer for oil wellbore.

[0031] Example 2 (1) Add 15 g of 40% by mass 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt aqueous solution, 1.3 g of tetrafluoroboric acid and 800 mL of tetrahydrofuran into a reaction flask, mix well, add 100 g of epoxidized soybean oil, reflux at a speed of 150 r / min and a temperature of 65 ° C for 8 h. After the reaction is completed, add 20% by mass sodium bicarbonate aqueous solution, adjust the pH of the system to neutral, extract with ethyl acetate and water, concentrate the organic phase, and dry to obtain sodium olefin sulfonate modified soybean oil.

[0032] (2) Nitrogen was introduced into a reaction flask equipped with a reflux condenser, 5 g of styrene and 75 mL of 80% by volume ethanol aqueous solution were added, and after uniform dispersion, 3.5 g of sodium olefin sulfonate-modified soybean oil was added, the temperature was raised to 45 °C, and the mixture was stirred to dissolve. 0.075 g of initiator azobisisobutyronitrile was added, and the mixture was reacted at 70 °C for 8 h, cooled and filtered, washed with ethanol, and dried to obtain a new wax crystal modifier.

[0033] (3) Add 3 g of alkylphenol polyoxyethylene polyoxypropylene ether, 2 g of sodium lauryl sulfate and 1 g of limonene into a reaction flask, stir evenly, then add 0.5 g of alkyl glycoside, and mix at 50°C for 4 h to obtain a composite surfactant.

[0034] (4) Add 14 g of a composite surfactant, 30 g of isopropanol, 1.5 g of sodium phosphate and 41 g of water into a reaction bottle, stir at 20 °C and 300 r / min for 20 min, and after uniform dispersion, add 10 g of ethylene glycol and 0.5 g of 5-sodium sulfonate of isophthalic acid, continue stirring for 15 min, then add 3 g of a new wax crystal modifier, stir and mix well to obtain a wax remover and preventer for oil wellbore.

[0035] Example 3 (1) Add 3 g of 40% aqueous solution of 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, 0.4 g of tetrafluoroboric acid and 250 mL of tetrahydrofuran into a reaction flask, mix well, add 50 g of epoxidized soybean oil, reflux for 3 h at a speed of 300 r / min and a temperature of 75 °C. After the reaction is completed, add 10% aqueous sodium bicarbonate solution, adjust the pH of the system to neutral, extract with ethyl acetate and water, concentrate the organic phase, and dry to obtain sodium olefin sulfonate modified soybean oil.

[0036] (2) Nitrogen was introduced into a reaction flask equipped with a reflux condenser, 40 g of styrene and 400 mL of 80% by volume ethanol aqueous solution were added, and after uniform dispersion, 6 g of sodium olefin sulfonate-modified soybean oil was added, the temperature was raised to 55°C, and the mixture was stirred to dissolve. 0.6 g of initiator azobisisobutyronitrile was added, and the mixture was reacted at 85°C for 5 h, cooled and filtered, washed with ethanol, and dried to obtain a new wax crystal modifier.

[0037] (3) Add 15 g of alkylphenol polyoxyethylene polyoxypropylene ether, 12.5 g of sodium lauryl sulfate and 5 g of limonene into a reaction flask, stir evenly, then add 2.5 g of alkyl glycoside, and mix at 70°C for 2 h to obtain a composite surfactant.

[0038] (4) Add 18 g of a composite surfactant, 15 g of ethylene glycol monobutyl ether, 0.5 g of sodium orthosilicate and 56 g of water into a reaction bottle, stir at 35 °C and 500 r / min for 10 min, and after uniform dispersion, add 5 g of ethylene glycol and 0.2 g of 5-sodium sulfonate of isophthalic acid, continue stirring for 5 min, then add 6 g of a new wax crystal modifier, stir and mix well to obtain a wax remover and preventer for oil well bore.

[0039] Example 4 (1) Add 3.6 g of 40% aqueous solution of 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, 0.4 g of tetrafluoroboric acid and 300 mL of tetrahydrofuran into a reaction flask, mix well, add 40 g of epoxidized soybean oil, reflux for 6 h at a speed of 280 r / min and a temperature of 70 °C. After the reaction is completed, add 20% aqueous sodium bicarbonate solution, adjust the pH of the system to neutral, extract with ethyl acetate and water, concentrate the organic phase, and dry to obtain sodium olefin sulfonate modified soybean oil.

[0040] (2) Nitrogen was introduced into a reaction flask equipped with a reflux condenser, 25 g of styrene and 325 mL of 80% by volume ethanol aqueous solution were added, and after uniform dispersion, 15 g of sodium olefin sulfonate-modified soybean oil was added, the temperature was raised to 50°C, and the mixture was stirred to dissolve. 0.325 g of initiator azobisisobutyronitrile was added, and the mixture was reacted at 80°C for 6 h, cooled and filtered, washed with ethanol, and dried to obtain a new wax crystal modifier.

[0041] (3) Add 4.5 g of alkylphenol polyoxyethylene polyoxypropylene ether, 3.5 g of sodium lauryl sulfate and 2 g of limonene into a reaction flask, stir evenly, then add 0.9 g of alkyl glycoside, and mix at 55 °C for 4 h to obtain a composite surfactant.

[0042] (4) Add 22 g of a composite surfactant, 20 g of isopropanol, 1.2 g of sodium hexametaphosphate and 40 g of water into a reaction bottle, stir at 30 °C and 420 r / min for 20 min, and after uniform dispersion, add 8 g of ethylene glycol and 0.3 g of 5-sodium sulfonate of isophthalic acid, continue stirring for 8 min, then add 8 g of a new wax crystal modifier, stir and mix well to obtain a wax remover and preventer for oil wellbore.

[0043] Example 5 (1) Add 2.8 g of 40% aqueous solution of 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, 0.18 g of tetrafluoroboric acid and 132 mL of tetrahydrofuran into a reaction flask, mix well, add 20 g of epoxidized soybean oil, reflux for 6 h at a speed of 240 r / min and a temperature of 70 °C. After the reaction is completed, add 15% aqueous sodium bicarbonate solution, adjust the pH of the system to neutral, extract with ethyl acetate and water, concentrate the organic phase, and dry to obtain sodium olefin sulfonate modified soybean oil.

[0044] (2) Nitrogen was introduced into a reaction flask equipped with a reflux condenser, 80 g of styrene and 960 mL of 80% by volume ethanol aqueous solution were added, and after uniform dispersion, 40 g of sodium olefin sulfonate modified soybean oil was added, the temperature was raised to 50 °C, and the mixture was stirred to dissolve, and 0.96 g of initiator azobisisobutyronitrile was added. After reacting at 75 °C for 7 h, the mixture was cooled and filtered, washed with ethanol, and dried to obtain a new wax crystal modifier.

[0045] (3) Add 10 g of alkylphenol polyoxyethylene polyoxypropylene ether, 6 g of sodium lauryl sulfate and 3 g of limonene into a reaction flask, stir evenly, then add 1.2 g of alkyl polyglycoside, and mix at 55 °C for 4 h to obtain a composite surfactant.

[0046] (4) Add 25 g of a composite surfactant, 30 g of ethylene glycol monobutyl ether, 1.5 g of sodium phosphate and 33 g of water into a reaction bottle, stir at 30 °C and 350 r / min for 20 min, and after uniform dispersion, add 5 g of ethylene glycol and 0.4 g of sodium 5-sulfonate of isophthalic acid, continue stirring for 15 min, then add 10 g of a new wax crystal modifier, stir and mix well to obtain a wax remover and preventer for oil wellbore.

[0047] Comparative Example 1 10 g of the composite surfactant (prepared in Example 1), 25 g of diethylene glycol ethyl ether, 1 g of sodium hydroxide and 58 g of water were added to a reaction bottle, stirred at a temperature of 25° C. and a rotation speed of 400 r / min for 15 min, and after uniform dispersion, 6 g of ethylene glycol and 0.4 g of sodium 5-sulfonate of isophthalic acid were added, stirred and mixed to obtain a wax removing and preventing agent for oil well bores.

[0048] Comparative Example 2 25 g of diethylene glycol ethyl ether, 1 g of sodium hydroxide and 58 g of water were added to a reaction bottle, stirred at a temperature of 25°C and a rotation speed of 400 r / min for 15 min, and after uniform dispersion, 6 g of ethylene glycol and 0.4 g of sodium 5-sulfonate of isophthalic acid were added, and stirring was continued for 10 min. Then, 1 g of a new wax crystal improver (prepared in Example 1) was added, and the mixture was stirred to obtain a wax removing and preventing agent for oil well bores.

[0049] Wax dissolution rate test: refer to the standard SY / T6300-2009 "Technical conditions for wax removers and wax inhibitors for oil production" to conduct wax dissolution rate test. Add 15mL of synthetic wax remover and wax inhibitor for oil wellbore into the wax dissolution test device, and the water bath temperature is 45℃. After the solution is kept at a constant temperature, put the wax ball into the wax remover and wax inhibitor solution, and record the time t required for the wax ball to dissolve completely at different temperatures. The calculation formula for the wax dissolution rate V is: V=m / t, where V is the wax dissolution rate (g / min), m is the mass of the wax ball (g), and t is the time required for the wax ball to dissolve completely (min).

[0050] Wax prevention rate test: referring to the standard SY / T6300-2009 "Technical conditions for wax cleaners and wax inhibitors for oil production", the wax prevention rate of wax cleaners and wax inhibitors at different temperatures was tested using the circulating wax tube method. The wax prevention rate E is calculated as E=(m1-m0) / m1, where E is the wax prevention rate (%), m1 is the wax content of the oil sample without wax cleaner and wax inhibitor (g), and m0 is the wax content of the oil sample with wax cleaner and wax inhibitor (g).

[0051] Table 1 Wax dissolution rate and wax resistance test

[0052] It can be seen from the test results in the above table that with the increase of the content of the compound surfactant and the new wax crystal improver in the wax removing and preventing agent for oil well bore, the wax dissolving rate is significantly improved. At the same time, the temperature has a greater influence on the wax dissolving rate. At 30°C, the wax dissolving rate of the wax removing and preventing agent in Example 5 is 0.0801g / min. After the temperature is raised to 60°C, the wax dissolving rate reaches 0.1395g / min, indicating that the higher the temperature, the faster the movement of the molecules on the surface of the wax crystal. According to the principle of "like dissolves like", the wax crystal can be dissolved in the new wax crystal improver, and the compound surfactant has a solubilizing effect, which further improves the dissolution rate of the wax crystal.

[0053] Temperature is the main factor affecting paraffin deposition. The higher the temperature, the less likely it is to precipitate wax and form wax crystals. However, when the temperature drops, wax crystals begin to precipitate from the crude oil. The test results in the above table show that even at a relatively low temperature of 30°C, the wax prevention rate of the prepared oil wellbore wax remover and paraffin inhibitor is above 60%, with the highest reaching 75.4%, showing a good wax prevention effect. This is because the new wax crystal modifier has a branched structure of long-chain epoxy soybean oil branches, which can be better adsorbed to the solid-liquid interface and play a role in wetting reversal. The more branches there are, the greater the proportion of non-polar segments in the polymer molecules, which plays a role of eutectic in the wax prevention process. , which increases its compatibility with oil samples and strengthens the anti-wax effect; at the same time, its structure contains sodium sulfonate groups with strong polarity. After copolymerization with styrene, the polar groups enter the molecular chain. The strong polarity can change the polarity of the anti-wax agent molecules and adjust the crystallinity of the anti-wax agent molecules. At the same time, it can synergize with asphaltene, colloids, etc. in crude oil, thereby enhancing the anti-wax effect of the anti-wax agent; sodium sulfonate, as a hydrophilic group, can greatly reduce the surface tension of water, and has a good wetting effect. It can also be adsorbed on the surface of wax crystals, so that the wax crystals form a polar surface that is not conducive to continued growth, so that they can remain in a fine state and achieve the purpose of wax removal.

[0054] Comparative Example 1 does not contain a wax remover and preventer for oil well bores, and its wax dissolving ability only relies on auxiliary agents such as mutual solvents, and the wax prevention effect is poor; Comparative Example 2 does not contain a composite surfactant, has no wetting reversal effect, and has poor wax dissolving performance.

[0055] Crude oil viscosity test: weigh 100g of crude oil, heat the crude oil until it is completely melted, add 0.5mL of the paraffin remover and paraffin inhibitor prepared in the embodiment and the comparative example respectively, stir thoroughly for 20min, seal the crude oil with the water-based paraffin remover and paraffin inhibitor added, heat at 80°C for 1h, draw 10mL with a syringe and add it to the sample holding tube, start the rotational viscometer, set the speed to 50r / min, record the viscosity value after the measured value displayed by the instrument is basically stable, measure 5 times and take the average value, and the measuring temperatures are 20°C, 30°C and 40°C respectively.

[0056] Table 2 Crude oil viscosity test

[0057] It can be seen from the test results in the above table that the lower the temperature, the higher the viscosity of the crude oil. The viscosity of the crude oil with the addition of the wax removal and prevention agent is much lower than the viscosity of the crude oil without the addition of the wax removal and prevention agent, and the difference between the two increases as the temperature continues to decrease; when the temperature is 20°C, the viscosity of the crude oil in Example 4 drops to 870.3mP·s, and the viscosity of the crude oil in Comparative Example 1 is 1961.2mP·s without the addition of the wax removal and prevention agent, indicating that the addition of the wax removal and prevention agent effectively reduces the viscosity of the crude oil. This is because the composite surfactant and the new wax crystal modifier in the wax removal and prevention agent have good penetration and dispersion properties, so that the wax removal and prevention agent penetrates into the gaps of the wax crystals in the loose structure to weaken the binding force between the wax molecules, hinder the formation of wax crystals and the growth of large wax blocks, weaken the binding force between the wax molecules, and thus reduce the viscosity of the crude oil; however, when the temperature is higher than the freezing point of the crude oil, the viscosity difference between the two decreases rapidly at 40°C, because at this time, the influence of temperature on the viscosity of the crude oil plays a major role; it can be seen that the wax removal and prevention agent prepared by the present invention has good wax removal and prevention performance, which improves the low-temperature fluidity of the crude oil.

[0058] Surface tension test: Test according to standard SY / T5370-2018 "Surface and interfacial tension determination method".

[0059] Table 3 Surface tension test

[0060] It can be seen from the test results in the above table that with the increase of the content of the compound surfactant in the wax removal and prevention agent for oil well bores, its surface tension value gradually decreases. After the surfactant is adsorbed on the surface of the wax crystal, the directionally arranged adsorption layer is covered with hydrophilic groups such as sodium sulfate and sodium sulfonate, making the surface hydrophilic. The wax crystals precipitated from the crude oil are not easily adsorbed and deposited, thereby achieving the purpose of wax prevention; the compound surfactant has the effect of reducing surface tension and wetting reversal, can promote emulsification, reduce the tendency of wax deposition, and can well peel wax from the oil pipe, thereby increasing the wax dissolution rate; Comparative Example 2 does not contain a compound surfactant, its surface tension value is higher, and the wetting reversal effect is poor, which makes the wax dissolution effect poor.

[0061] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A wax remover and preventer for oil wells, characterized in that: The wax removing and preventing agent for oil well bore comprises the following components in parts by weight: 10-25 parts of compound surfactant, 15-30 parts of mutual solvent, 5-10 parts of stabilizer, 1-10 parts of new wax crystal improver, 0.2-0.5 parts of fast penetrant, 0.5-1.5 parts of alkali, and 25-70 parts of water; The preparation process of the novel wax crystal modifier is carried out according to the following steps: (1) Adding a sodium salt solution of 3-allyloxy-2-hydroxy-1-propanesulfonic acid, tetrafluoroboric acid and tetrahydrofuran into a reaction flask, mixing well, adding epoxidized soybean oil, and performing a reflux reaction at a speed of 150-300 r / min. After the reaction is completed, adding a sodium bicarbonate aqueous solution to adjust the pH of the system to neutral, extracting with ethyl acetate and water, concentrating the organic phase, and drying to obtain sodium olefin sulfonate modified soybean oil; (2) nitrogen is introduced into a reaction flask with a reflux condenser, styrene and ethanol aqueous solution are added, and after uniform dispersion, sodium olefin sulfonate modified soybean oil is added, the temperature is raised to 45-55° C., stirred to dissolve, azobisisobutyronitrile as an initiator is added, stirred to react, after the reaction is completed, cooled and filtered, washed with ethanol, and dried to obtain a novel wax crystal modifier; The preparation process of the compound surfactant is carried out according to the following steps: 30-60 parts by weight of alkylphenol polyoxyethylene polyoxypropylene ether, 25-40 parts by weight of sodium lauryl sulfate and 10-20 parts by weight of limonene are added to a reaction flask, and after uniform stirring, 5-10 parts of alkyl polyglycoside are added, and mixed at 50-70° C. for 2-4 hours to obtain a compound surfactant; The mutual solvent is any one of isopropanol, ethylene glycol monobutyl ether, and diethylene glycol ethyl ether; The stabilizer is ethylene glycol; the rapid penetrating agent is 5-sodium sulfoisophthalate.

2. The wax removing and preventing agent for oil well bore according to claim 1, characterized in that: In the step (1), by weight, the sodium salt solution of 3-allyloxy-2-hydroxy-1-propanesulfonic acid is 6-15 parts, the tetrafluoroboric acid is 0.8-1.3 parts, and the epoxy soybean oil is 100 parts.

3. The wax removing and preventing agent for oil well bore according to claim 1, characterized in that: In the step (1), the reflux reaction temperature is 65-75° C. and the reflux reaction time is 3-8 h.

4. The wax removing and preventing agent for oil well bore according to claim 1, characterized in that: In the step (2), by weight, styrene is 100 parts, sodium olefin sulfonate modified soybean oil is 15-70 parts, and azobisisobutyronitrile is 1-1.5 parts.

5. The wax removing and preventing agent for oil well bore according to claim 1, characterized in that: In the step (2), the reaction temperature is 70-85° C. and the reaction time is 5-8 h.

6. The wax removing and preventing agent for oil well bore according to claim 1, characterized in that: The alkali is any one of sodium hydroxide, sodium orthosilicate, sodium phosphate and sodium hexametaphosphate.

7. A process for preparing the wax removing and preventing agent for oil well bore as claimed in any one of claims 1 to 5, characterized in that: The preparation process is carried out according to the following steps: adding a compound surfactant, a mutual solvent, an alkali and water into a reaction bottle, stirring for 10-20 minutes at a temperature of 20-35°C and a rotation speed of 300-500r / min, adding a stabilizer and a rapid penetrant after being evenly dispersed, continuing to stir for 5-15 minutes, then adding a new wax crystal modifier, stirring and mixing, and obtaining a wax removing and preventing agent for oil well bores.

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