CN117264620A - Oilfield fracturing high-temperature-resistant degradable temporary plugging agent and preparation method thereof - Google Patents

Abstract

The invention discloses an oilfield fracturing high-temperature-resistant degradable temporary plugging agent which is prepared from the following raw materials in parts by weight: 70-80 parts of polyglycolide, 20-30 parts of carbon dioxide copolymer, 5-15 parts of poly (butylene adipate/terephthalate), 10-20 parts of starch, 1-4 parts of plasticizer, 3-8 parts of compatilizer, 1-10 parts of lubricant, 1-3 parts of heat stabilizer and 0.5-4 parts of nucleating agent. The invention also discloses a preparation method of the oilfield fracturing high-temperature-resistant degradable temporary plugging agent. The invention adopts the oil field fracturing high-temperature-resistant degradable temporary plugging agent, and solves the problems of poor plugging effect, such as poor strength, poor toughness, poor thermal stability under high temperature conditions, difficult maintenance of stable bearing strength and the like of the temporary plugging agent in the prior art.

Description

A high temperature resistant degradable temporary plugging agent for oilfield fracturing and its preparation method

Technical field

The invention relates to the technical field of oil and gas well temporary plugging and fracturing exploration and development, and in particular to a high temperature resistant degradable temporary plugging agent for oil field fracturing and a preparation method thereof.

Background technique

As we all know, oil and gas resources such as oil and natural gas are produced through wells (oil wells or gas wells, sometimes collectively referred to as "pit wells") containing porous and permeable underground layers. However, in recent years, with the continuous exploitation of oil and gas fields, the quality of reservoirs has declined year by year. For this reason, relevant oil and gas developers have mostly adopted reservoir fracturing to improve the permeability of underground reservoirs, so as to continue to effectively extract these resources. Exploitation of oil and gas resources from underground reservoirs. In order to replace the traditional multi-layer general fracturing technology to a certain extent, more and more scientific researchers have begun to study temporary plugging and diverting fracturing technology for the purpose of fracture diversion.

In recent years, more than 95% of the temporary plugging materials (temporary hole plugging) used in horizontal wells in major oil fields are conventional temporary plugging balls. Currently, the commonly used temporary plugging balls are generally made of wax, rubber, non-degradable plastics, alloys and biodegradable materials. Made of degradable materials, these temporary plugging balls have the following main technical problems in the temporary plugging process of perforation blastholes: Temporary plugging balls made of rubber or non-degradable plastics are often difficult to dissolve in practical applications and are easy to get stuck. In the blast hole, it affects the later flowback and oil and gas production; the wax ball can dissolve under certain temperature conditions, but its compressive strength is low and the sealing is unstable, especially when the formation rupture pressure is high, it cannot Pressure-bearing achieves effective temporary blocking of steering; the temporary blocking ball made of alloy (such as magnesium alloy) has high rigidity and strength, but it needs to be dissolved at a higher ion concentration, and has residue after dissolution, which is easy to cause damage to the underground The reservoir causes pollution; most of the temporary plugging balls made of degradable temporary plugging materials have poor strength and toughness, poor thermal stability under high temperature conditions, and are easy to lose strength quickly, making it difficult to maintain a stable pressure-bearing effect. The temporary plugging ball setting effect is sensitive to the construction displacement and the number of blastholes in the wellbore, so the plugging effect is not ideal.

The existing temporary plugging balls cannot have the ideal strength and toughness under high temperature conditions, have poor temperature resistance, and are difficult to maintain stable pressure-bearing strength. In view of the above technical problems, there is an urgent need to develop a degradable temporary seam plugging agent that is both rigid and flexible under high temperature conditions from aspects such as materials and structures.

Contents of the invention

The purpose of the present invention is to provide a high-temperature-resistant and degradable temporary plugging agent for oilfield fracturing, which solves the problem that the existing temporary plugging agents have poor strength, poor toughness, poor thermal stability under high temperature conditions, and difficulty in maintaining stable pressure-bearing strength. The problem of poor blocking effect. Another object of the present invention is to provide a method for preparing a high temperature resistant degradable temporary plugging agent for oilfield fracturing.

In order to achieve the above purpose, the present invention provides a high-temperature resistant degradable temporary plugging agent for oilfield fracturing, which is prepared from the following components and their weight parts of raw materials: 70-80 parts of polyglycolide, 20 parts of carbon dioxide copolymer -30 parts, polybutylene adipate/terephthalate 5-15 parts, starch 10-20 parts, plasticizer 2-6 parts, compatibilizer 5-10 parts, lubricant 1-10 parts, 1-3 parts of heat stabilizer and 0.5-4 parts of nucleating agent.

Preferably, the starch is corn starch, and the plasticizer is one or more of phthalate, subebate, epoxidized soybean oil, and epoxyacetyl linolenic acid methyl ester.

Preferably, the compatibilizer is one or more of polycarbonate, polymethylsiloxane, silicone resin, ethylene-vinyl acetate copolymer, and ethylene-propylene-diene monomer copolymer.

Preferably, the nucleating agent is one or more of sodium dibenzylidene sorbitol succinate, sodium glutarate, and sodium caproate.

Preferably, the lubricant is one of stearamide, butyl stearate, and glycerol trihydroxystearate.

Preferably, the heat stabilizer is a mixture of lead stearate and epoxy fatty acid ester.

A method for preparing a high-temperature resistant degradable temporary plugging agent for oilfield fracturing, including the following steps:

Step 1: Weigh each component raw material in parts by weight, and then dry the weighed polyglycolide, carbon dioxide copolymer, and polybutylene adipate/terephthalate at 100-130°C. and mix evenly to obtain a mixture;

Step 2: Add the mixture in step 1 to the mixer, then add starch and nucleating agent. After mixing evenly, add compatibilizer, plasticizer, heat stabilizer and lubricant in sequence, and mix thoroughly, that is Prepare premix;

Step 3: Granulate the prepared premix through a twin-screw extruder to prepare the degradable temporary plugging agent.

The advantages and positive effects of the high-temperature resistant degradable temporary plugging agent for oilfield fracturing and its preparation method according to the present invention are:

1. By adding carbon dioxide copolymer and starch to polyglycolide, the present invention improves the degradability of the temporary plugging agent, accelerates the degradation speed, and avoids affecting flowback and oil and gas production. Starch not only improves degradability but also improves The mechanical properties of the temporary plugging agent improve the strength of the temporary plugging agent, and there is no residue after degradation, which will not cause pollution to the underground reservoir.

2. Polybutylene adipate/terephthalate is added to the temporary plugging agent of the present invention. Under the action of the compatibilizer, it can have better compatibility with polyglycolide, thereby imparting the material system with It has a certain toughness and can appropriately reduce the impact of the rigidity of polyglycolic acid on the final material system. Temporary plugging agent particles with a certain degree of toughness can undergo appropriate deformation under the action of the underground formation, which is conducive to the mutual interaction between the temporary plugging agent particles. The stacking forms a relatively dense sealing layer, which is conducive to maintaining stable pressure-bearing strength.

3. The addition of a nucleating agent in the present invention is beneficial to improving the crystallization speed of polyglycolide and improving its crystallinity. The increased crystallinity is beneficial to improving the high temperature resistance of the material system. The thermal stabilizer and plasticizer are used in combination. It is beneficial to improve the thermal stability of the temporary plugging agent under high temperature conditions, so that the temporary plugging agent under high temperature conditions can maintain its own mechanical strength for a period of time, which can effectively prevent the rapid collapse of the plugging layer, and thus can Effectively ensure the smooth progress of temporary plugging and diverting fracturing construction.

The technical solution of the present invention will be described in further detail below through examples and comparative examples.

Detailed ways

The technical solutions of the present invention will be further described below through examples and comparative examples.

Unless otherwise defined, technical terms or scientific terms used in the present invention shall have the usual meaning understood by a person with ordinary skill in the field to which the present invention belongs.

Example 1

A high-temperature-resistant degradable temporary plugging agent for oilfield fracturing, prepared from the following components and raw materials in parts by weight: 70 parts of polyglycolide, 20 parts of carbon dioxide copolymer, polyadipic acid/terephthalic acid 5 parts of butylene glycol, 10 parts of starch, 2 parts of plasticizer, 4 parts of compatibilizer, 2 parts of lubricant, 1 part of heat stabilizer, and 1 part of nucleating agent.

The starch is corn starch and the plasticizer is phthalate. The compatibilizer is ethylene-propylene-diene monomer copolymer. The nucleating agent is sodium dibenzylidene sorbitol succinate. The lubricant is stearamide. The heat stabilizer is a mixture of lead stearate and epoxy fatty acid ester, and the mass ratio of lead stearate and epoxy fatty acid ester is 1:2.

A method for preparing a high-temperature resistant degradable temporary plugging agent for oilfield fracturing, including the following steps:

Step 1: Weigh each component raw material in parts by weight, then dry the weighed polyglycolide, carbon dioxide copolymer, and polybutylene adipate/terephthalate at 100°C and mix them. Homogenize to obtain a mixture;

Step 2: Add the mixture in step 1 to the mixer, then add starch and nucleating agent. After mixing evenly, add compatibilizer, plasticizer, heat stabilizer and lubricant in sequence, and mix thoroughly, that is Prepare premix;

Step 3: Pellet the prepared premix through a twin-screw extruder to prepare a degradable temporary plugging agent.

Example 2

A high-temperature-resistant degradable temporary plugging agent for oilfield fracturing, prepared from the following components and raw materials in parts by weight: 75 parts of polyglycolide, 25 parts of carbon dioxide copolymer, polyadipic acid/terephthalic acid 10 parts of butylene glycol, 15 parts of starch, 3 parts of plasticizer, 5 parts of compatibilizer, 4 parts of lubricant, 1.5 parts of heat stabilizer, and 2 parts of nucleating agent.

The starch is corn starch and the plasticizer is subebrate. The compatibilizer is silicone resin. The nucleating agent is sodium glutarate. The lubricant is butyl stearate. The heat stabilizer is a mixture of lead stearate and epoxy fatty acid ester, and the mass ratio of lead stearate and epoxy fatty acid ester is 1:2.

A method for preparing a high-temperature resistant degradable temporary plugging agent for oilfield fracturing, including the following steps:

Step 1: Weigh each component raw material in parts by weight, and then dry the weighed polyglycolide, carbon dioxide copolymer, and polybutylene adipate/terephthalate at 115°C and mix them. Homogenize to obtain a mixture;

Step 2: Add the mixture in step 1 to the mixer, then add starch and nucleating agent. After mixing evenly, add compatibilizer, plasticizer, heat stabilizer and lubricant in sequence, and mix thoroughly, that is Prepare premix;

Step 3: Pellet the prepared premix through a twin-screw extruder to prepare a degradable temporary plugging agent.

Example 3

A high-temperature-resistant and degradable temporary plugging agent for oilfield fracturing, prepared from the following components and raw materials in parts by weight: 80 parts of polyglycolide, 30 parts of carbon dioxide copolymer, polyadipic acid/terephthalic acid 15 parts of butylene glycol, 20 parts of starch, 4 parts of plasticizer, 6 parts of compatibilizer, 5 parts of lubricant, 3 parts of heat stabilizer, and 2.5 parts of nucleating agent.

The starch is corn starch, and the plasticizer is epoxy soybean oil and epoxy acetyl linoleate methyl ester. Compatibilizers are polycarbonate, polymethicone, and silicone resin. The nucleating agents are sodium dibenzylidene sorbitol succinate and sodium glutarate. The lubricant is glyceryl trihydroxystearate. The heat stabilizer is a mixture of lead stearate and epoxy fatty acid ester, and the mass ratio of lead stearate and epoxy fatty acid ester is 1:2.

A method for preparing a high-temperature resistant degradable temporary plugging agent for oilfield fracturing, including the following steps:

Step 1: Weigh each component raw material in parts by weight, then dry the weighed polyglycolide, carbon dioxide copolymer, and polybutylene adipate/terephthalate at 125°C and mix them. Homogenize to obtain a mixture;

Step 2: Add the mixture in step 1 to the mixer, then add starch and nucleating agent. After mixing evenly, add compatibilizer, plasticizer, heat stabilizer and lubricant in sequence, and mix thoroughly, that is Prepare premix;

Step 3: Pellet the prepared premix through a twin-screw extruder to prepare a degradable temporary plugging agent.

Comparative example 1

A high-temperature resistant and degradable temporary plugging agent for oilfield fracturing, which is prepared from the following components and raw materials in parts by weight: 70 parts of polyglycolide, 5 parts of polybutylene adipate/terephthalate, 2 parts plasticizer, 4 parts compatibilizer, 2 parts lubricant, 1 part heat stabilizer, 1 part nucleating agent.

Plasticizers are phthalates. The compatibilizer is ethylene-propylene-diene monomer copolymer. The nucleating agent is sodium dibenzylidene sorbitol succinate. The lubricant is stearamide. The heat stabilizer is a mixture of lead stearate and epoxy fatty acid ester, and the mass ratio of lead stearate and epoxy fatty acid ester is 1:2.

A method for preparing a high-temperature resistant degradable temporary plugging agent for oilfield fracturing, including the following steps:

Step 1: Weigh each component raw material in parts by weight, and then dry the weighed polyglycolide and polybutylene adipate/terephthalate at 100°C, and mix them evenly to obtain a mixture. material;

Step 2: Add the mixture in step 1 to the mixer, and then add the nucleating agent. After mixing evenly, add the compatibilizer, plasticizer, heat stabilizer and lubricant in sequence, and mix thoroughly to obtain premix;

Step 3: Pellet the prepared premix through a twin-screw extruder to prepare a degradable temporary plugging agent.

Comparative example 2

A high-temperature-resistant degradable temporary plugging agent for oilfield fracturing, prepared from the following components and raw materials in parts by weight: 75 parts of polyglycolide, 25 parts of carbon dioxide copolymer, polyadipic acid/terephthalic acid 10 parts of butylene glycol, 3 parts of plasticizer, 5 parts of compatibilizer, 4 parts of lubricant, 1.5 parts of heat stabilizer, and 2 parts of nucleating agent.

The plasticizer is subebrate. The compatibilizer is silicone resin. The nucleating agent is sodium glutarate. The lubricant is butyl stearate. The heat stabilizer is a mixture of lead stearate and epoxy fatty acid ester, and the mass ratio of lead stearate and epoxy fatty acid ester is 1:2.

A method for preparing a high-temperature resistant degradable temporary plugging agent for oilfield fracturing, including the following steps:

Step 1: Weigh each component raw material in parts by weight, and then dry the weighed polyglycolide, carbon dioxide copolymer, and polybutylene adipate/terephthalate at 115°C and mix them. Homogenize to obtain a mixture;

Step 2: Add the mixture in step 1 to the mixer, and then add the nucleating agent. After mixing evenly, add the compatibilizer, plasticizer, heat stabilizer and lubricant in sequence, and mix thoroughly to obtain premix;

Step 3: Pellet the prepared premix through a twin-screw extruder to prepare a degradable temporary plugging agent.

Comparative example 3

A high-temperature-resistant and degradable temporary plugging agent for oilfield fracturing, prepared from the following components and raw materials in parts by weight: 80 parts of polyglycolide, 30 parts of carbon dioxide copolymer, polyadipic acid/terephthalic acid 15 parts of butylene glycol, 20 parts of starch, 4 parts of plasticizer, 6 parts of compatibilizer, 5 parts of lubricant, and 2.5 parts of nucleating agent.

The starch is corn starch, and the plasticizer is epoxy soybean oil and epoxy acetyl linoleate methyl ester. Compatibilizers are polycarbonate, polymethicone, and silicone resin. The nucleating agents are sodium dibenzylidene sorbitol succinate and sodium glutarate. The lubricant is glyceryl trihydroxystearate.

A method for preparing a high-temperature resistant degradable temporary plugging agent for oilfield fracturing, including the following steps:

Step 1: Weigh each component raw material in parts by weight, then dry the weighed polyglycolide, carbon dioxide copolymer, and polybutylene adipate/terephthalate at 125°C and mix them. Homogenize to obtain a mixture;

Step 2: Add the mixture in step 1 to the mixer, then add starch and nucleating agent. After mixing evenly, add compatibilizer, plasticizer, and lubricant in sequence, and mix thoroughly to prepare a premix. material;

Step 3: Pellet the prepared premix through a twin-screw extruder to prepare a degradable temporary plugging agent.

Performance tests were performed on Examples 1-3 and Comparative Examples 1-3 respectively, and the test results are shown in Table 1.

Table 1 test results

Example 1 Example 2 Example 3 Comparative example 1 Comparative example 2 Comparative example 3 100℃ pressure, MPa 73.4 72.6 70.4 62.9 55.4 36.4 120℃ pressure, MPa 71.2 701.1 68.3 58.4 52.1 32.3 150℃ pressure, MPa 68.6 68.4 66.2 56.3 50.4 30.4 Initial degradation time, hours 82 89 86 116 106 90 Complete degradation time, days 9 10 8 16 14.5 10

As shown in Table 1, compared with Examples 1-3, Comparative Example 1 does not add carbon dioxide copolymer and starch. The high temperature pressure and degradation time of Comparative Example 1 are worse than those of Examples 1-3. Comparative Example 2 is different from Examples 1-3. Compared with 1-3, no starch was added. The high temperature pressure and degradation time of Comparative Example 2 were worse than those of Embodiment 1-3 and Comparative Example 1. Compared with Embodiment 1-3, Comparative Example 3 did not add a heat stabilizer. The high temperature pressure bearing effect of Example 3 is worse than that of Example 1-3 and Comparative Example 1-2.

Table 1 shows that by adding carbon dioxide copolymer and starch to polyglycolide, the degradability of the temporary plugging agent is improved and the degradation speed is accelerated. The starch improves the degradability while also improving the mechanical properties of the temporary plugging agent and improving the temporary plugging agent. The strength of the blocking agent. Adding a nucleating agent to the temporary plugging agent will help improve the crystallization speed of polyglycolide and increase its crystallinity. Increased crystallinity will help improve the high temperature resistance of the material system. The use of heat stabilizers and plasticizers in combination It is beneficial to improve the thermal stability of the temporary plugging agent under high temperature conditions, so that the temporary plugging agent under high temperature conditions can maintain its own mechanical strength for a period of time, which can effectively prevent the rapid collapse of the plugging layer, and thus can Effectively ensure the smooth progress of temporary plugging and diverting fracturing construction.

Therefore, the present invention adopts the above-mentioned high-temperature resistant degradable temporary plugging agent for oilfield fracturing and its preparation method to solve the problem that the existing temporary plugging agent has poor strength, poor toughness, poor thermal stability under high temperature conditions, and difficulty in maintaining stable bearing capacity. Pressure strength and other problems of poor sealing effect.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: The technical solution of the present invention may be modified or equivalently substituted, but these modifications or equivalent substitutions cannot cause the modified technical solution to depart from the spirit and scope of the technical solution of the present invention.

Claims (7)

1. A high-temperature resistant and degradable temporary plugging agent for oilfield fracturing, which is characterized in that: it is prepared from the following components and their weight parts: 70-80 parts of polyglycolide, 20-30 parts of carbon dioxide copolymer , 5-15 parts of polybutylene adipate/terephthalate, 10-20 parts of starch, 1-4 parts of plasticizer, 3-8 parts of compatibilizer, 1-10 parts of lubricant, heat stabilizer 1-3 parts, nucleating agent 0.5-4 parts. 2. A kind of oil field fracturing high-temperature-resistant degradable temporary plugging agent according to claim 1, characterized in that: the starch is corn starch, and the plasticizer is phthalate, subebate, One or more of epoxidized soybean oil and epoxyacetyl linolenic acid methyl ester. 3. A kind of oil field fracturing high temperature resistant degradable temporary plugging agent according to claim 1, characterized in that: the compatibilizer is polycarbonate, polymethicone, silicone resin, ethylene-vinyl acetate One or more of copolymers and ethylene-propylene-diene monomer copolymers. 4. A kind of oilfield fracturing high temperature resistant degradable temporary plugging agent according to claim 1, characterized in that: the nucleating agent is sodium dibenzylsorbitol succinate, sodium glutarate, or sodium hexanoate. one or several kinds. 5. A kind of oil field fracturing high temperature resistant degradable temporary plugging agent according to claim 1, characterized in that: the lubricant is stearamide, butyl stearate, and glycerol trihydroxystearate. A sort of. 6. A high-temperature resistant degradable temporary plugging agent for oilfield fracturing according to claim 1, characterized in that: the heat stabilizer is a mixture of lead stearate and epoxy fatty acid ester. 7. A method for preparing a high temperature resistant degradable temporary plugging agent for oilfield fracturing according to any one of claims 1 to 6, characterized in that it includes the following steps: Step 1: Weigh each component raw material in parts by weight, and then dry the weighed polyglycolide, carbon dioxide copolymer, and polybutylene adipate/terephthalate at 100-130°C. and mix evenly to obtain a mixture; Step 2: Add the mixture in step 1 to the mixer, then add starch and nucleating agent. After mixing evenly, add compatibilizer, plasticizer, heat stabilizer and lubricant in sequence, and mix thoroughly, that is Prepare premix; Step 3: Granulate the prepared premix through a twin-screw extruder to prepare the degradable temporary plugging agent.