CN116218049A - Vulcanized latex and application thereof in pressure difference activated plugging agent - Google Patents

Abstract

The invention provides vulcanized latex prepared from the following raw materials in parts by weight: 100 parts of natural latex, 0.1-6 parts of vulcanizing agent, 0.2-8 parts of activating agent, 0.1-3 parts of anti-aging agent, 0.5-1.5 parts of accelerator, 0.01-1 part of stabilizer, 0.01-2 parts of water-soluble polymer and 0.01-5 parts of thickener. The vulcanized latex has good stability and fluidity, is suitable for being used as a main agent of a plugging agent, is assisted with an activating agent, a terminating agent and a suspending agent, and can be used for preparing a high-strength high-toughness high-temperature-resistant pressure difference activated sealing agent. And the high-temperature environment in the pit is favorable for further vulcanization, the crosslinking density is improved, and the performance of the sealant is further improved, so that the prepared sealant can realize long-term and stable plugging of the leakage.

Description

A vulcanized latex and its use in a pressure-differential activated plugging agent

Technical Field

The invention belongs to the field of plugging agents for oil and gas field development, and in particular relates to a vulcanized latex and application thereof in a pressure difference activated plugging agent.

Background Art

Since the 20th century, the proportion of oil and gas in the world's energy structure has gradually increased. It has replaced coal and become the king of energy, and occupies an extremely important position in the national economy. In the field of oil and gas field development, when it is necessary to carry out plugging operations in the wellbore, mechanical tools such as bridge plugs and packers or cement plugs are usually used for plugging. When using mechanical tools, it is necessary to use tools such as tubing, continuous tubing, and cables to lower the mechanical plugging tools to the designated position, and then make the mechanical plugging tools sit under the action of external force. After the operation is completed, if necessary, the mechanical tools can be pulled out through tools such as tubing, continuous tubing, and cables. This construction process is not only cumbersome, but also difficult to pull out when there are complex situations such as sand plugging in the wellbore and casing deformation, which complicates the accident. When using cement plugs for plugging operations, after the cement is pumped to the designated position, the cement is solidified to form a solid for plugging. The disadvantage of this method is that the hydraulic viscosity is generally greater than 100mPa.s, and if the plugging cement needs to be removed in the future, it can only be removed by mechanical grinding to break the cement, or by using explosives to blast the cement, etc. The process is complicated, and in the process of removing the cement, it is easy to cause damage to the downhole casing. In recent years, the use of new pressure-differential activated sealants with short repair cycles and easy operation has become a new trend in oil and gas field plugging.

The concept of differential pressure activated sealing is inspired by the "wound blood coagulation" behavior. It can achieve the plugging of the leaking place and complete the sealing repair through the liquid-solid conversion reaction activated only under the pressure difference at the leaking point. Compared with the traditional sealing repair strategy, the differential pressure activated sealant has good fluidity, strong adaptability to complex underground pipelines, and is easy to transport. In addition, the differential pressure activated sealant also has good stability, does not react during the transmission process, and is not affected by the transmission time, ambient temperature and pressure, which is convenient for fixed-point plugging. In order to achieve fixed-point differential pressure activated sealing, the sealant must have the ability of controlled aggregation, that is, it can be transformed from fluid to solid through differential pressure activation at the leaking place, so as to achieve the plugging of the leaking place. Usually, the differential pressure activated sealant is mostly prepared with latex as the main agent, and then added with activator, terminator and suspending agent. The addition of activator makes the latex particles coagulate, and the addition of terminator can adjust the degree of coagulation, so that the latex will not flocculate into blocks under normal pressure, and the addition of suspending agent ensures the stability of the sealant under normal conditions. When the sealant is injected into the well, the pressure difference at the leaking part of the pipeline will activate the coagulation of latex, causing the latex at the leaking part to flocculate into blocks and adapt to the shape of the leaking part to achieve a tight seal. However, most of the current pressure difference activated sealants use raw rubber latex. Although it can seal the leaking part, the strength of the raw rubber is poor. Coupled with the high temperature environment in the well, the plugging agent is prone to aging and failure.

Therefore, how to improve the main agent of the plugging agent so that it can not only ensure stability and fluidity, but also make the plugging agent have high strength and toughness, and maintain stable performance in high temperature environment still needs further exploration.

Summary of the invention

The invention aims to provide a vulcanized latex with excellent mechanical properties and use thereof in a plugging agent for plugging leakage in a wellbore of an oil and gas field development.

The present invention provides a vulcanized latex, which is prepared from the following raw materials in parts by weight:

100 parts of natural rubber latex, 0.1-6 parts of vulcanizing agent, 0.2-8 parts of activating agent, 0.1-3 parts of antioxidant, 0.5-1.5 parts of accelerator, 0.01-1 part of stabilizer, 0.01-2 parts of water-soluble polymer, and 0.01-5 parts of thickener.

Furthermore, the above-mentioned vulcanizing agent is sulfur and/or thiuram;

The activator is a combination of zinc oxide and stearic acid;

The antioxidant is antioxidant 4010 and/or antioxidant 4020;

The accelerator is a combination of one or more of accelerator CZ, accelerator TMTD, accelerator M, and accelerator DM, preferably accelerator CZ;

The stabilizer is a laurate;

The water-soluble polymer is polyacrylamide, polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl alcohol or polyethylene glycol;

The thickener is casein and/or peregrin O.

Furthermore, the weight proportion of the sulfur is 1 to 3 parts, or the weight proportion of the thiuram is 0.1 to 3 parts;

The weight portion of the zinc oxide is 0.1 to 5 parts, and the weight portion of the stearic acid is 0.1 to 3 parts;

The weight portion of the antioxidant 4010 is 0.1 to 3 parts, or the weight portion of the antioxidant 4020 is 0.1 to 3 parts;

The weight proportion of the water-soluble polymer is 0.01 to 2 parts;

The weight proportion of the casein is 0.01 to 1 part, or the weight proportion of the peregal O is 0.5 to 5 parts.

Furthermore, the above-mentioned vulcanized latex is made from the following raw materials in parts by weight:

100 parts of natural rubber latex, 0.13 parts of sulfur, 0.2 parts of zinc oxide, 1.5 parts of stearic acid, 1 part of antioxidant 4010, 0.8 parts of accelerator CZ, 0.5 parts of polyvinyl alcohol, 0.13 parts of potassium laurate, and 0.5-5 parts of peregal O.

The present invention also provides a method for preparing the above-mentioned vulcanized latex, comprising the following steps:

(1) Dispersing the vulcanizing agent, antioxidant, stabilizer, accelerator, and zinc oxide into water to prepare corresponding dispersions;

(2) Preheating the natural rubber latex emulsion to 60-80° C., adding the dispersion of step (1), the water-soluble polymer, the thickener and stearic acid, and reacting at 60-80° C. for 0.5-1.5 h.

Furthermore, the vulcanizing agent in the above step (1) is sulfur, and the concentration of the vulcanizing agent dispersion is 45-55wt%; the antioxidant is antioxidant 4010, and the concentration of the antioxidant dispersion is 45-55wt%; the concentration of the stabilizer dispersion is 5-15wt%; the accelerator is accelerator CZ, and the concentration of the accelerator dispersion is 45-55wt%; the concentration of the zinc oxide dispersion is 35-45wt%;

The mass fraction of the natural rubber latex emulsion in step (2) is 55-65wt%.

Furthermore, the concentration of the vulcanizing agent dispersion is 50wt%, the concentration of the antioxidant dispersion is 50wt%, the concentration of the stabilizer dispersion is 10wt%, the concentration of the accelerator dispersion is 50wt%, and the concentration of the zinc oxide dispersion is 40wt%;

The mass fraction of the natural rubber latex emulsion in step (2) is 60wt%.

Furthermore, the above step (2) is: preheating the natural rubber latex to 70° C., adding the dispersion of step (1) as well as the thickener and stearic acid, and reacting at 70° C. for 1 hour.

The present invention also provides the use of the above-mentioned vulcanized latex in a plugging agent; preferably, the plugging agent is a plugging agent used for plugging leakage in wellbore of oil and gas field development; more preferably, it is a pressure difference activated plugging agent.

The present invention also provides a plugging agent, which is prepared by using the above-mentioned vulcanized latex as a main agent and adding auxiliary agents;

The auxiliary agent includes any one or more of an activator, a terminator, a suspending agent, and a stabilizer;

Preferably, the activator comprises magnesium chloride, the terminator comprises OP-10, and the stabilizer comprises peregal O.

Beneficial effects of the present invention: The present invention provides a vulcanized latex prepared from a specific raw material composition, which has good stability and fluidity, is suitable for use as a main agent of a plugging agent, and is supplemented with an activator, a terminator and a suspending agent to prepare a high-strength, high-toughness and high-temperature resistant pressure-differential activated sealant. The high-temperature environment underground is conducive to further vulcanization, increasing the cross-linking density, and further improving the performance of the sealant, so that the prepared sealant can achieve long-term and stable plugging of the leakage point.

Obviously, according to the above contents of the present invention, in accordance with common technical knowledge and customary means in the art, without departing from the above basic technical ideas of the present invention, other various forms of modification, replacement or change may be made.

The above contents of the present invention are further described in detail below through specific implementation methods in the form of embodiments. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples. All technologies realized based on the above contents of the present invention belong to the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows the mechanical properties of the vulcanized latex of the present invention. (a) Mechanical properties of natural latex and vulcanized latex with different vulcanization times, (b) Effect of vulcanization time on latex strength.

FIG. 2 is a comparison of mechanical properties of different accelerator vulcanization systems in the vulcanized latex screening process of the present invention.

3 is a curve showing the change of pipe wall pressure in a simulated plugging experiment of a plugging agent prepared from a vulcanized latex with CZ as the accelerator, a plugging agent prepared from unvulcanized NR, and a plugging agent prepared from a vulcanized latex with DOTG as the accelerator.

DETAILED DESCRIPTION

The raw materials and equipment used in the present invention are all known products, which are obtained by purchasing commercially available products.

The natural latex used in the embodiment of the present invention is natural high-ammonia concentrated latex (DRC≥30%, domestically produced in Dongfeng).

Example 1. Preparation of vulcanized latex of the present invention

According to the dosage in Table 1, stabilizer, zinc oxide activator, vulcanizer and antioxidant are ball-milled and stably dispersed in water to prepare a dispersion of corresponding concentration. A certain amount of natural rubber latex emulsion is added to a three-necked flask and preheated at 70°C, and then the prepared vulcanizer dispersion, thickener and stearic acid activator are added to the three-necked flask. The mixed emulsion is mechanically stirred at 70°C for 90 minutes and then cooled to obtain pre-vulcanized natural rubber latex.

Table 1 Natural rubber latex pre-vulcanization formula

Example 2, Preparation of vulcanized latex of the present invention

According to the dosage in Table 2, stabilizer, zinc oxide activator, vulcanizer and antioxidant are ball-milled and stably dispersed in water to prepare a dispersion of corresponding concentration. A certain amount of natural rubber latex emulsion is added to a three-necked flask and preheated at 70°C, and then water-soluble polymer, prepared vulcanizer dispersion and thickener are added to the three-necked flask. The mixed emulsion is mechanically stirred at 70°C for 1 hour and then cooled to obtain pre-vulcanized natural rubber latex.

Table 2 Natural rubber latex pre-vulcanization formula

Example 3, Preparation of vulcanized latex of the present invention

According to the dosage in Table 3, stabilizer, zinc oxide activator, vulcanizer and antioxidant are ball-milled and stably dispersed in water to prepare a dispersion of corresponding concentration. A certain amount of natural rubber latex emulsion is added to a three-necked flask and preheated at 60°C, and then water-soluble polymer, prepared vulcanizer dispersion and thickener are added to the three-necked flask. The mixed emulsion is mechanically stirred at 70°C for 1 hour and then cooled to obtain pre-vulcanized natural rubber latex.

Table 3 Natural rubber latex pre-vulcanization formula

Example 4, preparation of vulcanized latex of the present invention

According to the dosage in Table 4, stabilizer, zinc oxide activator, vulcanizer and antioxidant were ball-milled and stably dispersed in water to prepare a dispersion of corresponding concentration. A certain amount of natural rubber latex was added to a three-necked flask and preheated at 60°C, and then water-soluble polymer, prepared vulcanizer dispersion and thickener were added to the three-necked flask. The mixed emulsion was mechanically stirred at 60°C for 1 hour and then cooled to obtain pre-vulcanized natural rubber latex.

Table 4 Natural rubber latex pre-vulcanization formula

Example 5: Preparation of a plugging agent using the vulcanized latex of the present invention as the main agent of the plugging agent

According to the proportion in Table 5, a certain amount of the pre-vulcanized latex in Example 2 is added with a stabilizer under stirring in a high-speed stirrer, and an activator is added dropwise within 10 minutes at room temperature, and the stirring is suspended for 15 minutes to allow the rubber particles to continue to grow; then the stirring is turned on and a terminator is added to form a micron-sized small particle emulsion. The emulsion is a plugging agent with the pre-vulcanized latex of the present invention as the main agent.

Table 5 Pre-vulcanized natural latex plugging agent formula

Comparative Example 1, natural latex

The natural latex raw material used in Example 1 (natural high-ammonia concentrated latex (DRC ≥ 30%, domestically produced by Dongfeng)) is denoted as NR.

Comparative Example 2: Pre-vulcanized latex using accelerator DOTG

According to the dosage in Table 6, zinc oxide activator, vulcanizing agent and antioxidant were ball-milled and stably dispersed in water to prepare a dispersion of corresponding concentration. A certain amount of natural rubber latex emulsion was added to a three-necked flask and preheated at 70°C, and then the prepared vulcanizing agent dispersion was added to the three-necked flask. After the mixed emulsion was mechanically stirred at 70°C for 0.5 hours, a vulcanized natural rubber latex with poor stability was obtained.

Table 6 Natural rubber latex pre-vulcanization formula

Comparative Example 3: Preparation of a plugging agent using natural latex as the main agent

According to the proportion in Table 7, a certain amount of natural latex in Example 1 is added with a stabilizer under stirring in a high-speed stirrer, and an activator is added dropwise within 10 minutes at room temperature, and stirring is suspended for 15 minutes to allow the rubber particles to continue to grow; then stirring is turned on and a terminator is added to form a micron-sized small particle emulsion. This emulsion is a plugging agent with natural latex as the main agent of the plugging agent.

Table 7 Natural latex plugging agent formula

Comparative Example 4: Preparation of a plugging agent using Comparative Example 2 as the main agent of the plugging agent

According to the proportion in Table 8, a certain amount of the pre-vulcanized latex in Comparative Example 2 is added with a stabilizer under stirring in a high-speed stirrer, and an activator is added dropwise within 10 minutes at room temperature, and the stirring is suspended for 15 minutes to allow the rubber particles to continue to grow; then the stirring is turned on and a terminator is added to form a micron-sized small particle emulsion. The emulsion is a plugging agent with the pre-vulcanized latex of the present invention as the main agent.

Table 8 Pre-vulcanized natural latex plugging agent formula

The beneficial effects of the present invention are demonstrated by experimental examples below.

Experimental Example 1: Mechanical properties of the vulcanized latex of the present invention

The mechanical properties of the vulcanized latex were tested by uniaxial tensile test, and the results are shown in Figure 1. It can be seen that, relative to unvulcanized natural latex (NR), the tensile strength and elongation at break of the latex increased significantly after vulcanization (Figure 1a). The strength of the pre-vulcanized latex with a vulcanization time of 1 hour reached 13.2MPa, which is 5.5 times the strength of natural latex (2.2MPa); at the same time, its elongation at break reached 1088%, which was 138% higher than the elongation at break of natural latex (789%) (Figure 1b). It can be seen that, relative to the direct use of natural latex as the main sealing agent, the use of the pre-vulcanized rubber of the present invention can significantly improve the strength of the plugging agent without affecting the stability and fluidity of the latex, which is conducive to achieving more effective plugging.

The performance of vulcanized latex of different vulcanization accelerator systems was compared by tensile testing, and the results are shown in Figure 2. It can be seen that relative to the vulcanization system of accelerator DOTG (Comparative Example 2), the systems of accelerator TMTD (Example 3) and accelerator CZ (Example 1) all exhibit higher mechanical properties. In particular, the accelerator CZ system mentioned in Example 1 exhibits a fracture strength of nearly 30MPa, which is twice that of the accelerator DOTG system (nearly 15Mpa). It can be seen that, relative to other vulcanization systems, the vulcanization system provided by the present invention exhibits significant advantages in mechanical properties, which is conducive to achieving more durable and stable plugging.

Experimental Example 2: Performance of the plugging agent with the vulcanized latex of the present invention as the main agent

The process of blocking the plugging material at the leak can be monitored by simulating the plugging experiment, and then reflecting its sealing behavior to the pipeline breach. As a result, as shown in Figure 3, it can be seen that the plugging agent prepared by unsulfurized NR is destroyed by pressurized water flow after 60min, and it is impossible to play a plugging effect. And the plugging agent (Example 3) prepared by the vulcanization system formed by accelerator CZ of the present invention forms effective plugging after 100min, but the plugging agent prepared by the vulcanization system formed by accelerator DOTG (Comparative Example 2) shows a sealing speed and sealing effect that are not as good as the plugging agent prepared by the vulcanization system formed by accelerator CZ, illustrating that the vulcanized latex constructed by the present invention can form an effective solidification in the pipeline under pressure quickly, so as to achieve the plugging of the pipeline.

In summary, the present invention provides a vulcanized latex prepared from a specific raw material composition, which has good stability and fluidity, is suitable for use as the main agent of a plugging agent, and is supplemented with an activator, a terminator and a suspending agent to prepare a high-strength, high-toughness and high-temperature resistant pressure-differential activated sealant. The high-temperature environment downhole is conducive to further vulcanization, increasing the cross-linking density, and further improving the performance of the sealant, so that the prepared sealant can achieve long-term and stable plugging of the leakage point.

Claims (10)

1. The vulcanized latex is characterized by being prepared from the following raw materials in parts by weight:

100 parts of natural latex, 0.1-6 parts of vulcanizing agent, 0.2-8 parts of activating agent, 0.1-3 parts of anti-aging agent, 0.5-1.5 parts of accelerator, 0.01-1 part of stabilizer, 0.01-2 parts of water-soluble polymer and 0.01-5 parts of thickener.

2. The vulcanized latex according to claim 1, wherein said vulcanizing agent is sulfur and/or thiuram;

the activator is a combination of zinc oxide and stearic acid;

the anti-aging agent is anti-aging agent 4010 and/or anti-aging agent 4020;

the accelerator is one or a combination of more of accelerator CZ, accelerator TMTD, accelerator M and accelerator DM, preferably accelerator CZ;

the stabilizer is a lunar silicate;

the water-soluble polymer is polyacrylamide, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl alcohol or polyethylene glycol;

the thickener is casein and/or peregal O.

3. The vulcanized latex according to claim 2, wherein the weight part of the sulfur is 1 to 3 parts, or the weight part of the thiuram is 0.1 to 3 parts;

the weight part of the zinc oxide is 0.1-5 parts, and the weight part of the stearic acid is 0.1-3 parts;

0.1 to 3 parts by weight of the anti-aging agent 4010 or 0.1 to 3 parts by weight of the anti-aging agent 4020;

the weight part of the water-soluble polymer is 0.01-2 parts;

the casein is 0.01-1 weight part, or the peregal O is 0.5-5 weight part.

4. A vulcanised latex according to any of claims 1 to 3, characterised in that it is made up of the following raw materials in parts by weight:

100 parts of natural latex, 0.13 part of sulfur, 0.2 part of zinc oxide, 1.5 parts of stearic acid, 0.1 part of anti-aging agent 4011 part, 0.8 part of accelerator CZ, 0.5 part of polyvinyl alcohol, 0.13 part of potassium laurate and 0.5 to 5 parts of peregal O.

5. The method for producing a vulcanized latex as defined in any one of claims 2 to 4, comprising the steps of:

(1) Dispersing a vulcanizing agent, an anti-aging agent, a stabilizer, an accelerator and zinc oxide into water to prepare corresponding dispersion liquid;

(2) Preheating natural latex emulsion to 60-80 ℃, adding the dispersion liquid, the water-soluble polymer, the thickening agent and the stearic acid in the step (1), and reacting for 0.5-1.5 h at 60-80 ℃.

6. The method according to claim 5, wherein the vulcanizing agent in the step (1) is sulfur, and the concentration of the vulcanizing agent dispersion is 45-55wt%; the anti-aging agent is anti-aging agent 4010, and the concentration of the anti-aging agent dispersion liquid is 45-55wt%; the concentration of the stabilizer dispersion liquid is 5-15 wt%; the accelerator is accelerator CZ, and the concentration of accelerator dispersion liquid is 45-55wt%; the concentration of the zinc oxide dispersion liquid is 35-45 wt%;

the mass fraction of the natural latex emulsion in the step (2) is 55-65wt%.

7. The method of claim 6, wherein the vulcanizing agent dispersion has a concentration of 50wt%, the antioxidant dispersion has a concentration of 50wt%, the stabilizer dispersion has a concentration of 10wt%, the accelerator dispersion has a concentration of 50wt%, and the zinc oxide dispersion has a concentration of 40wt%;

the mass fraction of the natural latex emulsion in the step (2) is 60wt%. .

8. The method of claim 5, wherein step (2) comprises: the natural latex is preheated to 70 ℃, the dispersion liquid in the step (1), the thickening agent and stearic acid are added, and the reaction is carried out for 1h at 70 ℃.

9. Use of the vulcanized latex as defined in any one of claims 1-5 in a blocking agent; preferably, the plugging agent is a plugging agent for leak-off plugging in an oil and gas field development wellbore; more preferably a pressure differential activated plugging agent.

10. A plugging agent, which is characterized in that the plugging agent is prepared by taking the vulcanized latex as a main agent and adding an auxiliary agent;

the auxiliary agent comprises any one or more of an activating agent, a terminating agent, a suspending agent and a stabilizing agent;

preferably, the activator comprises magnesium chloride, the terminator comprises OP-10, and the stabilizer comprises peregal O.

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