Organic diverting acid plug removal liquid system and preparation method thereof

Abstract

The invention provides an organic diverting acid blocking removal liquid system and a preparation method, aiming at solving the problem that the existing diverting acid only depends on a diverting agent to delay the reaction speed of acid rocks and cannot meet the requirement of blocking removal of a deep part of a reservoir, and the organic diverting acid blocking removal liquid system and the preparation method thereof are designed aiming at a specific diverting agent to design a solid organic acid with a specific molecular structure. The solid organic acid has good compatibility with the diverting agent, not only can greatly delay the acid rock reaction speed, but also can greatly increase the viscosity of the unblocking liquid system when the acid rock reaction is about to be finished, so that the purpose of diverting the acid liquid is achieved. When the concentration of the solid organic acid is 30%, the acid rock reaction time of the system can reach 280 min, the steering time occurs after the acid rock reaction lasts for 250 min, the system has deep plug removal steering capacity, the purpose of deep uniform plug removal of an oil and gas reservoir is achieved, the corrosion rate of marble can reach 88% through final conversion according to a corrosion rate measuring method, and the system can be applied to deep plug removal of the oil and gas reservoir. The requirement on the corrosion capability of the unblocking liquid is met.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas extraction, and specifically relates to an organic diversion acid unblocking fluid system. Background Technology

[0002] Acidizing is a fundamental production enhancement measure in oil and gas reservoir development. It involves using acid to dissolve acid-soluble minerals or blockages in the reservoir, thereby increasing the reservoir's permeability and ultimately boosting well productivity. However, two typical engineering problems exist during acidizing: first, the effective acidizing distance is relatively short; conventional hydrochloric acid has an acidizing radius of only about half a meter, making it difficult to penetrate contaminated formations and even more difficult to connect to distant low-permeability oil and gas areas; second, following the principle of least resistance, the acid often flows towards high-permeability areas that we don't want to acidize, leaving low-permeability areas untreated, leading to acidizing failure or minimal effectiveness.

[0003] Currently, the most common method for directing acid flow to low-permeability areas is through diversion acid systems that rely on viscosity changes. These systems increase viscosity through upstream acid-rock reactions, preventing unreacted, low-viscosity acid from seeping into lower-permeability areas and thus improving permeability. However, extending the effective range of the acid flow is primarily achieved through the slowing properties of diverting agents, which have very limited acidification distance. Therefore, achieving both diversion and deep acidification is a crucial engineering problem that needs to be solved. This invention proposes a diversion acid system based on solid organic acids. This system possesses extremely long slowing capabilities and excellent diversion effects, effectively addressing the goal of deep diversion acidification. Summary of the Invention

[0004] To address the aforementioned problems in the existing technology, this invention provides an organic diverting acid unblocking fluid system that can effectively solve the problems of short acidification distance and small unblocking radius in existing diverting acids.

[0005] To achieve the above objectives, the technical solution adopted by the present invention to solve its technical problem is as follows:

[0006] An organic deblocking acid unblocking fluid system consists of solid organic acid, acid deblocking agent, corrosion inhibitor, iron ion stabilizer, drainage aid and water.

[0007] Furthermore, an organic deblocking acid unblocking fluid system comprises 10-30% solid organic acid, 5-7% acid deblocking agent, 1.5-2.5% corrosion inhibitor, 1% iron ion stabilizer, 1% drainage aid, and the balance being water.

[0008] Furthermore, solid organic acids have the following general structural formula:

[0009]

[0010] In the formula: n is the number of repeating units, n≥1.

[0011] Furthermore, the acid diverting agent has the following general structural formula:

[0012]

[0013] In the formula: R is a carbon chain with 18 carbon atoms.

[0014] Furthermore, the corrosion inhibitor is composed of quaternary ammonium salt surfactant, triethylene glycol, OP-10 emulsifier, and formic acid.

[0015] Furthermore, the iron ion stabilizer is composed of isoascorbic acid and ethylenediaminetetraacetic acid.

[0016] Furthermore, the corrosion inhibitor consists of 40% heterocyclic quaternary ammonium salt surfactant, 50% triethylene glycol, 8% OP-10 emulsifier, and 2% formic acid.

[0017] Furthermore, the iron ion stabilizer consists of 50% ascorbic acid and 50% ethylenediaminetetraacetic acid.

[0018] Furthermore, the drainage aid is composed of one or more of dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, and octadecyltrimethylammonium chloride, combined with 40% water.

[0019] Furthermore, an organic reversible acid unblocking solution system and its preparation method are characterized in that the organic reversible acid unblocking solution system is prepared by the following steps: according to the requirements of the reversible acid for the concentration of the main acid to be prepared, the mass of the solid organic acid, reversible agent, corrosion inhibitor, iron ion stabilizer, drainage aid and tap water to be used are calculated and weighed according to the proportion of the main acid and the proportion of each additive; the solid organic acid is dissolved in water and stirred thoroughly to ensure complete dissolution; then, the reversible agent is quickly added to the organic acid solution under stirring conditions, and stirring is continued for 5 minutes; the iron ion stabilizer and drainage aid are added and thoroughly mixed; finally, the corrosion inhibitor is added to the solution and stirring is continued for 10 minutes to ensure thorough mixing.

[0020] The present invention provides an acid diverting agent and a method for preparing a temperature-resistant diverting acid system, which has the following beneficial effects:

[0021] (1) The organic decontamination acid system provided by the present invention can significantly extend the decontamination time, make the effective distance of the acid liquid longer, and make the decontamination radius larger;

[0022] (2) The organic decontamination acid unblocking liquid system provided by the present invention has good compatibility, especially the decontamination agent and solid organic acid have good compatibility, which can give full play to their respective advantages. Attached Figure Description

[0023] Figure 1 Example 1: Viscosity and pH changes over reaction time.

[0024] Figure 2 Example 2: Viscosity and pH changes over reaction time.

[0025] Figure 3 Example 3: Viscosity and pH changes over reaction time.

[0026] Figure 4 Molecular structures of solid organic acids and acid-liquid diverting agents in Examples 1-3. Detailed Implementation

[0027] The principles and features of the present invention are described below with reference to the accompanying drawings. The embodiments given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0028] Example 1

[0029] The formulation consists of 10% solid organic acid, 5% acid diverting agent, 1.5% corrosion inhibitor, 1% iron ion stabilizer, and 1% drainage aid. 10g of solid organic acid is dissolved in 81.5g of water and stirred thoroughly until fully dissolved. Then, 5g of acid diverting agent is quickly added under stirring, and stirring continues for 5 minutes. Next, 1.5g of corrosion inhibitor, 1g of iron ion stabilizer, and 1g of drainage aid are added and thoroughly mixed. Finally, the corrosion inhibitor is added to the solution, and stirring continues for 10 minutes to ensure thorough mixing, thus obtaining the organic acid diverting agent unblocking solution system. Referring to the People's Republic of China Petroleum and Natural Gas Industry Standard SY / T 5886-2012 "Evaluation Method for Slow-Rate Acid Performance", an excess of marble particles (20 mesh) was added to the unblocking fluid system under stirring conditions. The system was heated to 90℃, and the pH and viscosity were measured at 30 min, 60 min, 90 min, 120 min, 140 min, 160 min, 180 min, 200 min, 220 min, 230 min, 240 min, 250 min, and 260 min of acid-rock reaction, and curves were plotted. The time when the pH value approached neutral and tended to stabilize was recorded as the complete acid-rock reaction time, and the reaction time corresponding to the significant increase in viscosity was recorded as the switching time. The results showed that the complete acid-rock reaction time was 180 min, and the significant increase in viscosity occurred at 140 min, that is, the switching time occurred after 140 min of acid-rock reaction. According to the dissolution rate determination method, the final dissolution rate of the marble particles was calculated to be 28%.

[0030] Example 2

[0031] The formulation consists of 20% solid organic acid, 6% acid diverting agent, 2.0% corrosion inhibitor, 1% iron ion stabilizer, and 1% drainage aid. 20g of solid organic acid is dissolved in 70g of water and stirred thoroughly until fully dissolved. Then, 6g of acid diverting agent is quickly added under stirring and stirred for 5 minutes. Next, 2g of corrosion inhibitor, 1g of iron ion stabilizer, and 1g of drainage aid are added and thoroughly mixed. Finally, the corrosion inhibitor is added to the solution and stirred for 10 minutes to ensure thorough mixing, thus obtaining the organic diverting acid unblocking solution system. Referring to the People's Republic of China Petroleum and Natural Gas Industry Standard SY / T 5886-2012 "Evaluation Method for Slow-Rate Acid Performance", an excess of marble particles (20 mesh) was added to the unblocking fluid system under stirring conditions. The system was heated to 90℃, and the pH and viscosity were measured at 30 min, 60 min, 90 min, 120 min, 140 min, 160 min, 180 min, 200 min, 220 min, 230 min, 240 min, 250 min, and 260 min of acid-rock reaction, and curves were plotted. The time when the pH value approached neutral and tended to stabilize was recorded as the complete acid-rock reaction time, and the reaction time corresponding to the significant increase in viscosity was recorded as the switching time. The results showed that the complete acid-rock reaction time was 240 min, and the significant increase in viscosity occurred at 200 min, that is, the switching time occurred after 200 min of acid-rock reaction. According to the dissolution rate determination method, the final dissolution rate of the marble particles was calculated to be 57%.

[0032] Example 3

[0033] The formulation consists of 30% solid organic acid, 7% acid diverting agent, 1.5% corrosion inhibitor, 1% iron ion stabilizer, and 1% drainage aid. 30g of solid organic acid is dissolved in 59g of water and stirred thoroughly until fully dissolved. Then, 7g of acid diverting agent is quickly added under stirring and stirred for 5 minutes. Next, 2g of corrosion inhibitor, 1g of iron ion stabilizer, and 1g of drainage aid are added and thoroughly mixed. Finally, the corrosion inhibitor is added to the solution and stirred for 10 minutes to ensure thorough mixing, thus obtaining the organic acid diverting agent unblocking solution system. Referring to the People's Republic of China Petroleum and Natural Gas Industry Standard SY / T 5886-2012 "Evaluation Method for Slow-Rate Acid Performance", an excess of marble particles (20 mesh) was added to the unblocking fluid system under stirring conditions. The system was heated to 90℃, and the pH and viscosity were measured at 30 min, 60 min, 90 min, 120 min, 140 min, 160 min, 180 min, 200 min, 220 min, 230 min, 240 min, 250 min, and 260 min of acid-rock reaction, and curves were plotted. The time when the pH value approached neutral and tended to stabilize was recorded as the complete acid-rock reaction time, and the reaction time corresponding to the significant increase in viscosity was recorded as the switching time. The results showed that the complete acid-rock reaction time was 280 min, and the significant increase in viscosity occurred at 250 min, that is, the switching time occurred after 250 min of acid-rock reaction. According to the dissolution rate determination method, the final dissolution rate of the marble particles was calculated to be 88%.

Claims

1. An organic decongestant acid unblocking system and its preparation method, characterized in that, An organic decongestant acid unblocking system consists of solid organic acid, acid decongestant, corrosion inhibitor, iron ion stabilizer, drainage aid and water.

2. The organic decongestant acid unblocking system according to claim 1, characterized in that, An organic diverting acid unblocking system comprises 20-40% solid organic acid, 5-7% acid diverting agent, 1.5-2.5% corrosion inhibitor, 1% iron ion stabilizer, 1% drainage aid, and the balance being water.

3. The organic decongestant acid unblocking system according to claim 1, characterized in that, Solid organic acids have the following general structural formula: In the formula: n is the number of repeating units, n≥1.

4. The organic decongestant acid unblocking system according to claim 1, characterized in that, Acid diverting agents have the following general structural formula: In the formula: R is a carbon chain with 18 carbon atoms.

5. The organic decongestant acid unblocking system according to claim 1, characterized in that, The corrosion inhibitor is composed of quaternary ammonium salt surfactant, triethylene glycol, OP-10 emulsifier, and formic acid.

6. The organic decongestant acid unblocking system according to claim 1, characterized in that, The iron ion stabilizer is composed of isoascorbic acid and ethylenediaminetetraacetic acid.

7. The corrosion inhibitor according to claim 5 is composed of 40% heterocyclic quaternary ammonium salt surfactant, 50% triethylene glycol, 8% OP-10 emulsifier and 2% formic acid.

8. The iron ion stabilizer according to claim 6 is composed of 50% ascorbic acid and 50% ethylenediaminetetraacetic acid.

9. The drainage aid according to claim 7 is composed of one or more of dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, and octadecyltrimethylammonium chloride, and 40% water.

10. The organic decongestant acid unblocking system and its preparation method according to claim 1, characterized in that... This organic diversion acid unblocking system is prepared by the following steps: (1) Based on the requirements of the main acid concentration for the diverting acid to be prepared, calculate and weigh the mass of the solid organic acid, diverting agent, corrosion inhibitor, iron ion stabilizer, drainage aid and tap water used according to the proportion of the main acid and the proportion of each additive. (2) Dissolve the solid organic acid in water and stir it thoroughly to dissolve it completely. Then, under stirring conditions, quickly add the deflecting agent to the organic acid solution and continue stirring for 5 minutes. Then, add the iron ion stabilizer and the drainage aid and mix them thoroughly. Finally, add the corrosion inhibitor to the solution and continue stirring for 10 minutes to mix them thoroughly.

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