A kind of corrosion inhibitor for acid fracturing and preparation method thereof

Abstract

The present invention belongs to the technical field of tertiary oil recovery, and in particular to a corrosion inhibitor for acid fracturing and a preparation method thereof. The preparation method is as follows: (hydroxymethyl) triphenylphosphonium chloride, N, N-dimethylformamide, and a catalyst are sequentially added to an autoclave, the reactor is purged with nitrogen, vacuumized, heated at the same time, ethylene oxide is passed, the temperature is raised and the reaction is kept warm, the reaction pressure gradually decreases, and when the pressure no longer decreases, the reaction is stopped, and the reaction is cooled to less than 60 ° C; propylene oxide is passed, the temperature is raised and the reaction is kept warm, the reaction pressure gradually decreases, and when the pressure no longer decreases, the reaction is stopped, and the reaction is cooled to less than 60 ° C, pH7-8 is adjusted with hydrochloric acid, and N, N-dimethylformamide is distilled off under reduced pressure to obtain a product corrosion inhibitor. The present invention has the advantages of wide adaptability to temperature and good sustained release effect.

Description

Technical Field

[0001] The invention belongs to the technical field of tertiary oil recovery, and particularly relates to a corrosion inhibitor for acid fracturing and a preparation method thereof. Background Art

[0002] At present, as the production of oil and gas gradually decreases during oil and gas exploration, mining will also face a more severe environment. Oil well acid fracturing is one of the main measures for stabilizing and increasing production in various oil fields in my country. During oil field acid fracturing, the acid fracturing fluid is injected into the formation through the oil well pipe string. The acid fracturing fluid reacts with the limestone and other components in the formation to produce soluble substances. At the same time, under the action of high pressure, the pores of the formation are enlarged. When the soluble substances are discharged from the formation with the acid, the permeability of the oil-producing layer is increased, thereby achieving the purpose of increasing production.

[0003] Commonly used acidizing agents are hydrochloric acid with a mass fraction of 15% or 20%, or soil acid mixed with 12% hydrochloric acid and 3% hydrofluoric acid. Both acids are inorganic strong acids that can dissolve formation rock minerals and pore blockages. At the same time, acidizing technology will also cause serious corrosion to metal pipelines and equipment, and pose a potential threat to the formation. With the increase of well depth and temperature, corrosion will become more serious. In order to prevent acid fracturing fluid from corroding oil pipes, casings and metal equipment, adding corrosion inhibitors to acid fracturing fluid is a necessary anti-corrosion measure.

[0004] At present, the oil well acidizing corrosion inhibitors used at home and abroad mainly include organic amines, imidazolines, compound pyridines, etc. Among them, organic amines are highly toxic, imidazolines have high preparation costs, and compound pyridines have complex production processes. Therefore, the products currently used have certain limitations. Summary of the invention

[0005] The present invention aims at the deficiencies of the prior art and provides a corrosion inhibitor for acid fracturing and a preparation method thereof. The present invention has the advantages of wide adaptability to temperature and good slow-release effect.

[0006] One of the purposes of the present invention is to disclose a corrosion inhibitor for acid fracturing, wherein the molecular structure of the corrosion inhibitor for acid fracturing is as follows:

[0007]

[0008] Where: m is a natural number between 2 and 5;

[0009] n is a natural number from 5 to 20.

[0010] Another object of the present invention is to disclose a method for preparing the above-mentioned corrosion inhibitor for acid fracturing, and the specific steps of the preparation method are as follows:

[0011] (1) Add (hydroxymethyl)triphenylphosphonium chloride, N,N-dimethylformamide (DMF), and a catalyst to a high-pressure reactor in sequence, purge the reactor with nitrogen, evacuate the reactor, and raise the temperature at the same time. When the temperature reaches 80° C., stop evacuating the reactor, introduce ethylene oxide, raise the temperature to 120-140° C., and keep the temperature for reaction. The reaction pressure gradually decreases. When the pressure no longer decreases, stop the reaction and cool the reactor to below 60° C.;

[0012] (2) Propylene oxide is introduced, the temperature is raised to 150-180° C. and the temperature is kept for reaction, and the reaction pressure gradually decreases. When the pressure no longer decreases, the reaction is stopped, the temperature is cooled to below 60° C., the pH is adjusted to 7-8 with hydrochloric acid, and N,N-dimethylformamide (DMF) is distilled off under reduced pressure to obtain a corrosion inhibitor product.

[0013] In the present invention, preferably, based on 1 mole of (hydroxymethyl)triphenylphosphonium chloride, the amounts of ethylene oxide and propylene oxide are 2-5 mole parts and 5-20 mole parts, respectively.

[0014] In the present invention, preferably, the weight ratio of DMF to (hydroxymethyl)triphenylphosphonium chloride in step (1) is 10-20:1.

[0015] In the present invention, preferably, the catalyst in step (1) is one of potassium carbonate, sodium hydroxide, potassium hydroxide and calcium hydroxide, and the weight ratio of the catalyst to (hydroxymethyl)triphenylphosphonium chloride is 0.02-0.06:1.

[0016] The synthetic reaction equation of the corrosion inhibitor for acid fracturing of the present invention is as follows:

[0017]

[0018] The corrosion inhibitor for acid fracturing of the present invention is a quaternary phosphonium salt and an integrally embedded polyether composite surfactant, wherein the hydrophilic groups are quaternary phosphonium salt and polyoxyethylene ether, and the hydrophobic groups are benzene ring and polyoxypropylene ether. The quaternary phosphonium salt has a strong positive charge, which is greater than that of a quaternary ammonium salt, so the slow-release effect is better than that of a common quaternary ammonium salt, and the quaternary phosphonium salt can be adsorbed on the metal surface, adding a protective film to the metal to prevent hydrogen ions from approaching the metal surface, and the polyoxyethylene ether can increase the water solubility of the present invention; the three benzene rings are a dense hydrophobic protective layer, and the epoxypropylene ether belongs to a relatively long linear structure, so that it is difficult for the aqueous phase corrosive liquid to approach the metal surface.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0020] (1) Widely applicable, it has good sustained-release effect on hydrochloric acid and hydrofluoric acid from 60-180℃;

[0021] (2) The slow-release effect is good. The lowest static corrosion rates at normal pressure in 20wt% hydrochloric acid solution and 15wt% mud acid at 90℃ are 0.98g / (m 2 ·h)、1.5g / (m 2 ·h); the lowest dynamic corrosion rates at high temperature and high pressure in 20wt% hydrochloric acid solution and 15wt% earth acid solution at 180℃ were 11.8g / (m 2 ·h)、12.5g / (m 2 h). DETAILED DESCRIPTION

[0022] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without violating the spirit of the present invention.

[0023] The technical solution of the present invention is further described below in conjunction with specific embodiments:

[0024] Example 1

[0025] (1) 0.05 mol (hydroxymethyl) triphenylphosphonium chloride, 165 g DMF, and 0.68 g potassium carbonate were added to a high-pressure reactor in sequence, the reactor was purged with nitrogen, vacuumed, and the temperature was raised. When the temperature reached 80° C., vacuuming was stopped, 0.1 mol ethylene oxide was introduced, the temperature was raised to 120° C. and the reaction was kept warm. The reaction pressure gradually decreased. When the pressure no longer decreased, the reaction was stopped and the reactor was cooled to below 60° C.;

[0026] (2) 0.25 mol of propylene oxide was introduced, the temperature was raised to 150° C. and the reaction was kept at this temperature, and the reaction pressure gradually decreased. When the pressure no longer decreased, the reaction was stopped, the mixture was cooled to below 60° C., the pH was adjusted to 7-8 with hydrochloric acid, and DMF was distilled off under reduced pressure to obtain a corrosion inhibitor product.

[0027] Example 2

[0028] (1) 0.05 mol (hydroxymethyl) triphenylphosphonium chloride, 178 g DMF, and 0.98 g potassium carbonate were added to a high-pressure reactor in sequence, the reactor was purged with nitrogen, vacuumed, and the temperature was raised at the same time. When the temperature reached 80° C., vacuuming was stopped, 0.1 mol ethylene oxide was introduced, the temperature was raised to 120° C. and the reaction was kept warm. The reaction pressure gradually decreased. When the pressure no longer decreased, the reaction was stopped and the reactor was cooled to below 60° C.;

[0029] (2) 0.35 mol of propylene oxide was introduced, the temperature was raised to 150° C. and the reaction was kept at this temperature, and the reaction pressure gradually decreased. When the pressure no longer decreased, the reaction was stopped, the mixture was cooled to below 60° C., the pH was adjusted to 7-8 with hydrochloric acid, and DMF was distilled off under reduced pressure to obtain a corrosion inhibitor product.

[0030] Example 3

[0031] (1) 0.05 mol (hydroxymethyl) triphenylphosphonium chloride, 195 g DMF, and 0.33 g sodium hydroxide were added to a high-pressure reactor in sequence, the reactor was purged with nitrogen, vacuumed, and the temperature was raised. When the temperature reached 80° C., vacuuming was stopped, 0.15 mol ethylene oxide was introduced, the temperature was raised to 125° C. and the reaction was kept warm. The reaction pressure gradually decreased. When the pressure no longer decreased, the reaction was stopped and the reactor was cooled to below 60° C.;

[0032] (2) 0.45 mol of propylene oxide was introduced, the temperature was raised to 160° C. and the reaction was kept warm, and the reaction pressure gradually decreased. When the pressure no longer decreased, the reaction was stopped, the temperature was cooled to below 60° C., the pH was adjusted to 7-8 with hydrochloric acid, and DMF was distilled off under reduced pressure to obtain the product corrosion inhibitor.

[0033] Example 4

[0034] (1) 0.05 mol (hydroxymethyl) triphenylphosphonium chloride, 223 g DMF, and 0.45 g sodium hydroxide were added to a high-pressure reactor in sequence, the reactor was purged with nitrogen, vacuumed, and the temperature was raised. When the temperature reached 80° C., vacuuming was stopped, 0.15 mol ethylene oxide was introduced, the temperature was raised to 125° C. and the reaction was kept warm. The reaction pressure gradually decreased. When the pressure no longer decreased, the reaction was stopped and the reactor was cooled to below 60° C.;

[0035] (2) 0.5 mol of propylene oxide was introduced, the temperature was raised to 165° C. and the reaction was kept at this temperature, and the reaction pressure gradually decreased. When the pressure no longer decreased, the reaction was stopped, the temperature was cooled to below 60° C., the pH was adjusted to 7-8 with hydrochloric acid, and the DMF was distilled off under reduced pressure to obtain the product corrosion inhibitor.

[0036] Example 5

[0037] (1) 0.05 mol (hydroxymethyl) triphenylphosphonium chloride, 258 g DMF, and 0.63 g calcium hydroxide were added to a high-pressure reactor in sequence, the reactor was purged with nitrogen, vacuumed, and the temperature was raised. When the temperature reached 80° C., vacuuming was stopped, 0.2 mol ethylene oxide was introduced, the temperature was raised to 130° C. and the reaction was kept warm. The reaction pressure gradually decreased. When the pressure no longer decreased, the reaction was stopped and the reactor was cooled to below 60° C.;

[0038] (2) 0.6 mol of propylene oxide was introduced, the temperature was raised to 165° C. and the reaction was kept at this temperature, and the reaction pressure gradually decreased. When the pressure no longer decreased, the reaction was stopped, the temperature was cooled to below 60° C., the pH was adjusted to 7-8 with hydrochloric acid, and the DMF was distilled off under reduced pressure to obtain the product corrosion inhibitor.

[0039] Example 6

[0040] (1) 0.05 mol (hydroxymethyl) triphenylphosphonium chloride, 278 g DMF, and 0.7 g calcium hydroxide were added to a high-pressure reactor in sequence, the reactor was purged with nitrogen, vacuumed, and the temperature was raised. When the temperature reached 80° C., vacuuming was stopped, 0.2 mol ethylene oxide was introduced, the temperature was raised to 130° C. and the reaction was kept warm. The reaction pressure gradually decreased. When the pressure no longer decreased, the reaction was stopped and the reactor was cooled to below 60° C.;

[0041] (2) 0.7 mol of propylene oxide was introduced, the temperature was raised to 170° C. and the reaction was kept warm, and the reaction pressure gradually decreased. When the pressure no longer decreased, the reaction was stopped, the temperature was cooled to below 60° C., the pH was adjusted to 7-8 with hydrochloric acid, and DMF was distilled off under reduced pressure to obtain the product corrosion inhibitor.

[0042] Example 7

[0043] (1) 0.05 mol (hydroxymethyl) triphenylphosphonium chloride, 292 g DMF, and 0.81 g potassium hydroxide were added to a high-pressure reactor in sequence, the reactor was purged with nitrogen, vacuumed, and the temperature was raised. When the temperature reached 80° C., vacuuming was stopped, 0.2 mol ethylene oxide was introduced, the temperature was raised to 135° C. and the reaction was kept warm. The reaction pressure gradually decreased. When the pressure no longer decreased, the reaction was stopped and the reactor was cooled to below 60° C.;

[0044] (2) 0.8 mol of propylene oxide was introduced, the temperature was raised to 170° C. and the reaction was kept warm, and the reaction pressure gradually decreased. When the pressure no longer decreased, the reaction was stopped, the temperature was cooled to below 60° C., the pH was adjusted to 7-8 with hydrochloric acid, and DMF was distilled off under reduced pressure to obtain the product corrosion inhibitor.

[0045] Example 8

[0046] (1) 0.05 mol (hydroxymethyl) triphenylphosphonium chloride, 303 g DMF, and 0.89 g potassium hydroxide were added to a high-pressure reactor in sequence, the reactor was purged with nitrogen, vacuumed, and the temperature was raised. When the temperature reached 80° C., vacuuming was stopped, 0.25 mol ethylene oxide was introduced, the temperature was raised to 140° C. and the reaction was kept warm. The reaction pressure gradually decreased. When the pressure no longer decreased, the reaction was stopped and the reactor was cooled to below 60° C.;

[0047] (2) 0.9 mol of propylene oxide was introduced, the temperature was raised to 180° C. and the reaction was kept warm, and the reaction pressure gradually decreased. When the pressure no longer decreased, the reaction was stopped, the temperature was cooled to below 60° C., the pH was adjusted to 7-8 with hydrochloric acid, and DMF was distilled off under reduced pressure to obtain the product corrosion inhibitor.

[0048] Example 9

[0049] (1) 0.05 mol (hydroxymethyl) triphenylphosphonium chloride, 328 g DMF, and 0.98 g potassium hydroxide were added to a high-pressure reactor in sequence, the reactor was purged with nitrogen, vacuumed, and the temperature was raised. When the temperature reached 80° C., vacuuming was stopped, 0.25 mol ethylene oxide was introduced, the temperature was raised to 140° C. and the reaction was kept warm. The reaction pressure gradually decreased. When the pressure no longer decreased, the reaction was stopped and the reactor was cooled to below 60° C.;

[0050] (2) 1 mol of propylene oxide is introduced, the temperature is raised to 180° C. and the temperature is kept for reaction, the reaction pressure gradually decreases, and when the pressure no longer decreases, the reaction is stopped, the temperature is cooled to below 60° C., the pH is adjusted to 7-8 with hydrochloric acid, and DMF is distilled off under reduced pressure to obtain the product corrosion inhibitor.

[0051] Example 10 Corrosion Rate Test

[0052] The static corrosion rate at normal pressure and the dynamic corrosion rate at high temperature and high pressure were determined according to the method in SY / T 5405-2019 "Performance Test Method and Evaluation Method of Corrosion Inhibitors for Acidification". The test temperature of the static corrosion rate at normal pressure was 60°C and 90°C. The specific parameters are shown in Table 1. The test temperature of the dynamic corrosion rate at high temperature and high pressure was 100°C and 180°C. The specific parameters are shown in Table 2. The test results are shown in Table 3.

[0053] Table 1 Conditions for determining static corrosion rate at normal pressure

[0054]

[0055] Table 2 High temperature and high pressure dynamic corrosion rate measurement conditions

[0056]

[0057] Table 3 Corrosion rate test results

[0058]

[0059] From Table 1-3 we can see that:

[0060] (1) The corrosion inhibitor for acid fracturing of the present invention (Examples 1-9) has a static corrosion rate of no more than 1.45 g / (m 2 h), the lowest is 0.94g / (m2 h);

[0061] (2) The corrosion inhibitor for acid fracturing of the present invention (Examples 1-9) has a static corrosion rate of less than 1.6 g / (m 2 h), the minimum is 0.98g / (m 2 h);

[0062] (3) The high temperature and high pressure dynamic corrosion rate of the acid fracturing corrosion inhibitor of the present invention (Examples 1-9) in a 15 wt% mud acid solution at 100°C is no more than 2.7 g / (m 2 h), the minimum is 1.4g / (m 2 h);

[0063] (4) The corrosion inhibitor for acid fracturing of the present invention (Examples 1-9) has a high temperature and high pressure dynamic corrosion rate of less than 20 g / (m 2 h), the minimum is 12.5g / (m 2 h).

[0064] The above is only a preferred embodiment of the present invention, and is not any formal or substantial limitation of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the method of the present invention, and these improvements and supplements are also considered as the protection scope of the present invention. Any technician familiar with this profession, without departing from the spirit and scope of the present invention, can make some changes, modifications and equivalent changes made by using the technical content disclosed above, which are equivalent embodiments of the present invention; at the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a corrosion inhibitor for acid fracturing, characterized in that: The specific steps of the preparation method are as follows: (1) adding (hydroxymethyl)triphenylphosphonium chloride, N,N-dimethylformamide, and a catalyst to a high-pressure reactor in sequence, purging the reactor with nitrogen, evacuating the reactor, and heating the reactor at the same time. When the temperature reaches 80° C., stopping evacuating the reactor, introducing ethylene oxide, heating the reactor to 120-140° C. and keeping the temperature for reaction, the reaction pressure gradually decreases, and when the pressure no longer decreases, stopping the reaction, and cooling the reactor to below 60° C., based on 1 mole part of (hydroxymethyl)triphenylphosphonium chloride, the amount of ethylene oxide used is 2-5 mole parts; the weight ratio of N,N-dimethylformamide to (hydroxymethyl)triphenylphosphonium chloride is 10-20:1; (2) introducing propylene oxide, raising the temperature to 150-180° C. and keeping the temperature to react, the reaction pressure gradually decreases, and when the pressure stops decreasing, stopping the reaction, cooling to below 60° C., adjusting the pH to 7-8 with hydrochloric acid, and distilling off N,N-dimethylformamide under reduced pressure to obtain a corrosion inhibitor product; based on 1 molar part of (hydroxymethyl)triphenylphosphonium chloride, the amount of propylene oxide used is 5-20 molar parts; The molecular structure of the corrosion inhibitor is as follows: Where: m is a natural number between 2 and 5; n is a natural number from 5 to 20.

2. The method for preparing a corrosion inhibitor for acid fracturing according to claim 1, characterized in that: The catalyst in step (1) is one of potassium carbonate, sodium hydroxide, potassium hydroxide and calcium hydroxide.

3. The method for preparing a corrosion inhibitor for acid fracturing according to claim 1 or 2, characterized in that: The weight ratio of the catalyst to (hydroxymethyl)triphenylphosphonium chloride is 0.02-0.06:

1.

4. A corrosion inhibitor for acid fracturing, characterized in that: The molecular structural formula of the acid fracturing corrosion inhibitor is as follows: Where: m is a natural number between 2 and 5; n is a natural number from 5 to 20.

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