阅读说明：本技术 一种自生酸体系及其应用 (Self-generated acid system and application thereof ) 是由 张�雄 李新勇 房好青 赵兵 罗攀登 耿宇迪 李春月 黄燕飞 李永寿 方裕燕 安 于 2020-05-21 设计创作，主要内容包括：本发明提供了一种自生酸体系及其应用。所述自生酸体系包括酯、均相剂和水,其还可以包括铁离子稳定剂。(The invention provides an acid generating system and application thereof. The self-generating acid system includes an ester, a homogenizing agent, and water, which may also include a ferric ion stabilizer.)

1. An acid generating system includes an ester, a homogenizing agent, and water.

2. The autogenous acid system of claim 1 wherein the ester comprises at least one of ethyl formate, methyl acetate, methyl acrylate, ethyl lactate, and diethyl oxalate.

3. The autogenous acid system of claim 1 or 2, wherein the homogenizing agent comprises at least one of methanol, ethanol, acetone, DMF, SDS, SDBS, tween 80, span 80, xanthan gum, and guar gum.

4. The authigenic acid system according to any of claims 1 to 3, further comprising an iron ion stabilizer.

5. The authigenic acid system of claim 4, wherein the iron ion stabilizer comprises at least one of ethylenediaminetetraacetic acid and sodium salts thereof, citric acid and sodium salts thereof, isoascorbic acid and sodium salts thereof, and nitrilotriacetic acid and sodium salts thereof.

6. The autogenous acid system according to any one of claims 1 to 5, characterized in that the ester content is 32.9 to 60% based on 100% of the total mass of the autogenous acid system.

7. The authigenic acid system according to any of claims 1-6, wherein the homogeneous agent is present in an amount of 4% to 15.5% based on 100% of the total weight of the authigenic acid system.

8. The authigenic acid system according to any of claims 1 to 7, wherein the water content is 28% to 60% based on 100% of the total weight of the authigenic acid system.

9. The authigenic acid system according to any of claims 4-8, wherein the iron ion stabilizer is present in an amount of 0.2% to 1% based on 100% of the total weight of the authigenic acid system.

10. Use of the autogenous acid system according to any one of claims 1 to 9 in oil well development.

Technical Field

The invention relates to an acid generating system, in particular to application of the acid generating system in oil well development.

Background

Along with the continuous deepening of oil well exploration and development in recent years, the high-temperature (more than or equal to 120 ℃) wells and mines are more and more. The development difficulty of the reservoir stratum with deep burial, high temperature and low permeability is large. If the acidizing fluid is directly injected by acid fracturing according to the conventional method, the reaction speed is high due to high temperature and high initial acid fluid concentration, and the acid fluid is quickly consumed by the ore rock near the injection well pipe and cannot deeply penetrate. While autogenous acid is a latent acid that does not exhibit acidity or exhibits weak acidity at the surface but gradually produces acid at formation temperatures. It produces acid liquor through chemical reaction to acidify the rock. The acid generation time is relatively long, so that the corrosion rate to the rock is slowed down, a longer and farther place can be reached, and the acidification distance of the acid liquor is effectively increased. Meanwhile, the corrosion effect on the underground pipe column can be reduced.

The current literature reports that the authigenic acid type is primarily the formation of mineral acids such as HCl or HF. 2012 patents (application numbers 201210169268.9 and 201210457973.9) propose a method for mixing two solutions of an agent A and an agent B to obtain an authigenic acid, and the basic principle of the method is that formaldehyde or polyformaldehyde reacts with ammonium chloride to generate hydrochloric acid and then carbonate rock is corroded. Subsequently, the research on the self-generated acid system by Panbaofeng in 2014, Wangyang in 2016, Jia brightness in 2017 and the like finds that the self-generated acid system has better effect when being used in oil fields, but the self-generated acid has lower application temperature, 10% hydrochloric acid is generated at 70 ℃, and even a large amount of acid is generated at room temperature, so the situation of delaying acid generation is poor. Liu has authorized others to add chloroacetate to this system to provide some delay and achieve an effective erosion rate of 72%. 2015 Chen Dajun et al compound hydrochloric acid generated by hydrolyzing organic substituted carboxylate with formic acid to obtain self-generated acid, and the corrosion rate of rock at 100 ℃ is above 70%. In 2018, the effective corrosion rate of an authigenic acid system formed by compounding chlorinated organic matters capable of being decomposed into hydrochloric acid and HF can reach more than 40%. However, these systems produce primarily mineral acid to attack the rock, whereas mineral acid systems react quickly and are generally only suitable for low temperature (T <80 ℃) formations. In addition, most of the organic acid systems reported at present adopt chlorine-containing organic matters, and the chlorine-containing organic matters have the defects of high toxicity, environmental pollution and the like. Moreover, most inorganic self-generated acid systems are unstable in mixing time and can only be constructed in a way of instant use and preparation on site; or the method of alternately injecting two or more solvents into the stratum is adopted, which brings great inconvenience to construction and engineering operation and increases construction difficulty, and inorganic acid also has serious corrosion to the pipeline. Therefore, the development of the self-generated acid system suitable for the high-temperature (T is more than 100 ℃) stratum is more convenient for field construction and has important practical significance.

Disclosure of Invention

One aspect of the present invention provides an autogenous acid system that includes an ester, a homogenizing agent, and water.

In a specific embodiment, the ester comprises at least one of ethyl formate, methyl acetate, methyl acrylate, ethyl lactate, and diethyl oxalate.

In a specific embodiment, the homogenizing agent comprises at least one of methanol, ethanol, acetone, Dimethylformamide (DMF), SDS, sodium dodecylbenzene sulfonate (SDBS), tween 80, span 80, xanthan gum, and guar gum.

In practical application, the iron content in the rock varies due to different regions, and precipitation is easily caused under the condition of high iron content, so that an iron ion stabilizer can be added to avoid iron precipitation; if the iron content is low, the iron ion stabilizer may not be added.

Thus, in one embodiment, the self-generating acid system further comprises an iron ion stabilizer.

In a specific embodiment, the iron ion stabilizer comprises at least one of ethylenediaminetetraacetic acid and its sodium salt, citric acid and its sodium salt, isoascorbic acid and its sodium salt, and nitrilotriacetic acid and its sodium salt.

In one embodiment, the ester is present in an amount of 32.9% to 60% based on 100% of the total mass of the free acid system.

In one embodiment, the content of the homogeneous agent is 4% to 15.5% based on 100% by mass of the total amount of the self-generating acid system.

In one embodiment, the water is present in an amount of 28% to 60% based on 100% of the total mass of the self-generating acid system.

In one embodiment, the iron ion stabilizer is present in an amount of 0.2% to 1% based on 100% by mass of the total free acid system.

The second aspect of the invention provides the use of the autogenous acid system according to any one of the first aspect of the invention in oil well development.

The invention has the advantages of

The self-generated acid system does not generate organic chlorine, so the self-generated acid system is non-toxic, and has small corrosivity and low damage to equipment such as underground pipelines. The method comprises the following specific steps:

1) the self-acid-generating system obviously generates acid at a temperature of more than 130 ℃, the acid generation is slow, and the acid generation time is more than 6 hours; the reaction is slow below 120 ℃, for example, the content of generated acid is low within 3 hours; at high temperature (>120 ℃), the acid generation rate of the system is obviously accelerated, so that the method is suitable for corrosion of high-temperature formation carbonate at 140-;

2) the acid rock reaction capacity is at least equal to 15% hydrochloric acid;

3) the corrosion to the pipeline is low, and the acid-rock corrosion retarding effect is good;

4) the acid generating system is a homogeneous self-generating acid solution;

5) the disposable injection mode can be adopted, and great convenience is provided for oilfield site construction.

Detailed Description

The above-described aspects of the invention are explained in more detail below by means of preferred embodiments, but they are not intended to limit the invention.

The reagents in the examples of the present invention were all commercially available unless otherwise specified.

Example 1

Adding 60 mass percent of methyl acetate, 28 mass percent of water, 11 mass percent of methanol and 1 mass percent of ferric ion stabilizer EDTA disodium salt into a beaker, mixing and uniformly stirring to obtain a clear and transparent homogeneous solution system with water and ester mutually soluble, namely an authigenic acid system.

Pouring the self-generated acid system into a high-pressure reaction kettle container, sealing, heating to 120 ℃, taking out after 2 hours of reaction, and analyzing the content of the organic acid by an acid-base titration method, wherein the hydrolysis rate of the ester is 0.8%.

Example 2

Adding 30 mass percent of methyl acetate, 2.9 mass percent of ethyl formate, 50.7 mass percent of water, 9.8 mass percent of methanol, 5.7 mass percent of ethanol and 0.9 mass percent of ferric ion stabilizer trisodium citrate into a beaker, mixing and uniformly stirring to obtain a clear and transparent homogeneous solution system with mutual solubility of water and ester, namely a self-generated acid system.

Pouring the self-generated acid system into a high-pressure reaction kettle container, sealing, heating to 120 ℃, reacting for 2 hours, taking out, analyzing the content of the organic acid by an acid-base titration method, wherein the hydrolysis rate of the ester is 2.9%.

Example 3

Adding 35.8 mass percent of methyl acetate, 58 mass percent of water, 5.2 mass percent of SDBS and 1 mass percent of ferric ion stabilizer EDTA disodium salt into a beaker, mixing and uniformly stirring to obtain a clear and transparent homogeneous solution system with water and ester mutually soluble, namely an authigenic acid system.

Pouring the self-generated acid system into a high-pressure reaction kettle container, sealing, heating to 120 ℃, taking out after 2 hours of reaction, analyzing the content of the organic acid by an acid-base titration method, wherein the hydrolysis rate of the ester is 1.7%.

Example 4

Adding 33.3 mass percent of methyl acetate, 2.5 mass percent of ethyl formate, 51.5 mass percent of water, 6.5 mass percent of DMF, 5.2 mass percent of SDBS and 1 mass percent of ferric ion stabilizer EDTA disodium salt into a beaker, mixing and uniformly stirring to obtain a clear and transparent homogeneous solution system with mutual solubility of water and ester, namely an authigenic acid system.

Pouring the self-generated acid system into a high-pressure reaction kettle container, sealing, heating to 120 ℃, taking out after 2 hours of reaction, analyzing the content of the organic acid by an acid-base titration method, wherein the hydrolysis rate of the ester is 5.8%.

Example 5

Adding 34 mass percent of methyl acetate, 3.3 mass percent of ethyl formate, 51.3 mass percent of water, 11.1 mass percent of methanol and 0.3 mass percent of ferric ion stabilizer trisodium citrate into a beaker, mixing and uniformly stirring to obtain a clear and transparent homogeneous solution system with mutual solubility of water and ester, namely a self-generated acid system.

Pouring the self-generated acid system into a high-pressure reaction kettle container, sealing, heating to 130 ℃, taking out after reacting for 2 hours, and analyzing the content of the organic acid by an acid-base titration method, wherein the hydrolysis rate of the ester is 2.6%.

Example 6

Adding 37 mass percent of methyl acetate, 51.1 mass percent of water, 11.7 mass percent of acetone and 0.2 mass percent of ferric ion stabilizer trisodium citrate into a beaker, mixing and uniformly stirring to obtain a clear and transparent homogeneous solution system with water and ester mutually soluble, namely a self-generated acid system.

Pouring the self-generated acid system into a high-pressure reaction kettle container, sealing, heating to 130 ℃, taking out after reacting for 2 hours, and analyzing the content of the organic acid by an acid-base titration method, wherein the hydrolysis rate of the ester is 0.7%.

Example 7

Adding 31.5% by mass of methyl acetate, 4.4% by mass of ethyl formate, 52.6% by mass of water, 11.3% by mass of methanol and 0.2% by mass of ferric ion stabilizer trisodium citrate into a beaker, mixing and uniformly stirring to obtain a clear and transparent homogeneous solution system with mutual solubility of water and ester, namely an authigenic acid system.

Pouring the self-generated acid system into a high-pressure reaction kettle container, sealing, heating to 130 ℃, taking out after 5 hours of reaction, and analyzing the content of the organic acid by an acid-base titration method, wherein the hydrolysis rate of the ester is 25.3%.

Example 8

Adding 33.3 mass percent of methyl acetate, 3.9 mass percent of ethyl formate, 51.0 mass percent of water and 11.8 mass percent of methanol into a beaker, mixing and uniformly stirring to obtain a clear and transparent homogeneous solution system with water and ester mutually soluble, namely an authigenic acid system.

Pouring the self-generated acid system into a high-pressure reaction kettle container, sealing, heating to 140 ℃, taking out after 5 hours of reaction, and analyzing the content of the organic acid by an acid-base titration method, wherein the hydrolysis rate of the ester is 29.3%.

Example 9

Adding methyl acetate with the mass content of 36.9%, 54.3% of water, 8.3% of methanol and 0.5% of ferric ion stabilizer EDTA disodium salt into a beaker, and stirring and mixing to obtain a water-ester-miscible self-generated acid solution, namely a self-generated acid system.

Pouring the self-generated acid system into an autoclave container, sealing, heating to 150 ℃, taking out after 7 hours of reaction, analyzing the content of the organic acid by an acid-base titration method, and obtaining the hydrolysis rate of the ester of 32.5 percent.

Example 10

Adding 35.3 mass percent of methyl acetate, 60 mass percent of water, 4 mass percent of SDS and 0.7 mass percent of ferric ion stabilizer EDTA disodium salt into a beaker, and stirring and mixing to obtain a water-ester-soluble authigenic acid solution, namely an authigenic acid system.

Pouring the self-generated acid system into an autoclave container, sealing, heating to 150 ℃, taking out after 5 hours of reaction, and analyzing the content of the organic acid by an acid-base titration method, wherein the hydrolysis rate of the ester is 62.8%.

Example 11

Methyl acetate and 4.8% ethyl formate in mass contents of 33%, 54% water and 8.2% methanol were added to a beaker, and stirred and mixed to obtain an authigenic acid system.

The autogenous acid system is poured into an autoclave container, 15 g of calcium carbonate powder is added into the autogenous acid system, the container is sealed and heated to 150 ℃, 7.18 g of calcium carbonate is remained after 6 hours of reaction, and the corrosion rate of the calcium carbonate powder is 63.5 percent. Wherein, the residual calcium carbonate powder is obtained by filtering and drying the calcium carbonate powder by using filter paper and then weighing the calcium carbonate powder by using balance, and the corrosion rate is the dissolved mass/theoretical dissolved mass.

Example 12

Methyl acetate with the mass content of 34.6%, 58.8% of water, 5.9% of SDS and 0.7% of disodium EDTA as an iron ion stabilizer are added into a beaker, and stirred and mixed to obtain a homogeneous self-generated acid system.

The self-generated acid system is poured into an autoclave container, 20 g of carbonate rock is added into the self-generated acid system, the self-generated acid system is sealed and heated to 150 ℃, the acid content in the system is analyzed to be 0.65mol/L after 12 hours of reaction, 1.8 g of carbonate rock is remained, and the rock corrosion rate is 91%. Wherein, the acid content is obtained by measuring NaOH standard solution; and drying the residual carbonatite rock, and weighing the dried carbonatite rock by using balance, wherein the corrosion rate is the dissolved mass/theoretical dissolved mass.