CN117511524A - Rice granule type temporary plugging agent and preparation method thereof - Google Patents

Abstract

The rice grain type temporary plugging agent and its preparation method disclosed by the invention belong to the technical field of natural gas fracturing temporary plugging agents and are composed of the following components: polyvinyl alcohol 50%-75%, polycaprolactone 20%-40%, water-soluble 15%-35% starch, 1%-5% plasticizer, 5%-10% reinforcing agent, the sum of the above mass percentages is 100%. The rice-grained temporary plugging agent provided by the present invention solves the problems of large fracturing liquid loss and limited artificial fracture reforming due to imperfect temporary plugging and steering technology during the fracturing and reforming process of coal and rock gas reservoirs, and thereby It improves the effect of coal and rock gas fracturing and achieves the purpose of increasing production. The preparation method of the rice-grained temporary plugging agent provided by the present invention specifically designs the particle shape and parameters of the temporary plugging agent according to the characteristics of the coal and rock gas reservoir, which effectively improves the blocking adaptability of the temporary plugging agent to the coal and rock reservoir. .

Description

Rice grain type temporary plugging agent and preparation method thereof

Technical field

The invention belongs to the technical field of natural gas fracturing temporary plugging agents, and specifically relates to a rice-type temporary plugging agent. The invention also relates to a preparation method of the rice-type temporary plugging agent.

Background technique

In recent years, with the development of the national economy, the demand for natural gas has gradually increased, and coal and rock gas has received attention as an unconventional gas source. With the improvement of domestic fracturing technology, it has become possible to tap the potential of coal and rock gas reservoirs. my country's coal and rock gas reserves are relatively abundant, which is expected to help increase natural gas production and ensure national energy security. Coal and rock gas reservoirs have relatively developed natural fractures, with fracture widths of about 2-5 mm, high reservoir permeability, and strong core adsorption capacity. Therefore, during the fracturing stimulation process, it is easy to cause problems such as large fracturing fluid loss and limited artificial fracture reconstruction. It is necessary to use temporary plugging and diversion technology to improve the reservoir fracturing stimulation effect to achieve the purpose of increasing production.

At present, the existing temporary plugging and diversion technology is mainly applied to shale gas and tight oil and gas, while the related technologies and material products for coal and rock gas reservoir stimulation are not yet mature. The use of existing gel temporary plugging agent products will cause damage to the reservoir, and the use of solid particle temporary plugging agent products cannot match the characteristics of coal and rock gas reservoirs.

Contents of the invention

The first purpose of the present invention is to provide a rice-type temporary plugging agent, which solves the problem of large fracturing liquid loss due to imperfect temporary plugging and diverting technology during fracturing reformation of coal and rock gas reservoirs, and limitations in artificial fracture reformation. The problem.

The second object of the present invention is to provide a preparation method of rice grain type temporary plugging agent.

The first technical solution adopted by the present invention is a rice grain type temporary plugging agent, which is composed of the following components: polyvinyl alcohol 50%-75%, polycaprolactone 20%-40%, water-soluble starch 15%-35% %, plasticizer 1%-5%, reinforcing agent 5%-10%, the sum of the above mass percentages is 100%.

The invention is also characterized by:

The molecular weight of polyvinyl alcohol is 1500-3000, and the alcoholysis degree is 85%-100%.

The molecular weight of polycaprolactone is 500-2000.

The water-soluble starch is selected from one or more types of tapioca starch, corn starch or sweet potato starch.

The plasticizer is selected from one or both of dioctyl sebacate and dioctyl oxalate.

The enhancer is selected from one or more of potassium chloride, sodium chloride or calcium chloride.

The second technical solution adopted by the present invention is a preparation method of rice grain type temporary plugging agent, which specifically includes the following steps:

Step 1. Weigh the following components respectively according to mass percentage:

Polyvinyl alcohol 50%-75%, polycaprolactone 15%-40%, water-soluble starch 15%-35%, plasticizer 1%-5%, reinforcing agent 5%-15%, total mass percentage is 100%.

Step 2. Pretreatment: Mix the raw materials and crush them in a pulverizer, screen them, and collect the screened materials for later use.

Step 3. Add the pretreated raw materials into the reaction kettle, stir the reaction and then cool to room temperature.

Step 4. Add the material obtained in step 3 to the extruder for secondary melting, and use an underwater pelletizer to pellet the molten material;

Step 5: Filter and dry the particles obtained in Step 4 to obtain the rice-type temporary plugging agent.

In the stirring reaction in step 3, the stirring speed is 30-100r/min, the reaction temperature is 120-180°C, and the reaction time is 0.5-3h.

The temperature of the water in step 4 is 0-10°C.

The beneficial effects of the present invention are:

The rice-type temporary plugging agent of the present invention solves the problems of large fracturing liquid loss and limited artificial fracture reconstruction due to imperfect temporary plugging and steering technology, thereby improving the effect of coal and rock gas fracturing reconstruction and increasing production. Purpose.

The preparation method of the rice-grained temporary plugging agent of the present invention specifically designs the particle shape and parameters of the temporary plugging agent according to the characteristics of the coal and gas reservoir, which effectively improves the plugging adaptability of the temporary plugging agent to the coal and rock reservoir.

Detailed ways

The present invention will be described in detail below with reference to specific embodiments.

The rice-type temporary plugging agent of the invention is composed of the following components: polyvinyl alcohol 50%-75%, polycaprolactone 20%-40%, water-soluble starch 15%-35%, and plasticizer 1%-5%. , enhancer 5%-10%, the sum of the above mass percentages is 100%. The rice-grained temporary plugging agent of the present invention solves the problem of large fracturing liquid loss and limited artificial fracture reconstruction due to imperfect temporary plugging and steering technology during the fracturing and reforming process of coal and rock gas reservoirs, thereby improving the efficiency of The effect of coal and rock gas fracturing has achieved the goal of increasing production.

The molecular weight of polyvinyl alcohol in the present invention is 1500-3000, and the alcoholysis degree is 85%-100%.

The molecular weight of polycaprolactone is 500-2000.

The water-soluble starch is selected from one or more types of tapioca starch, corn starch or sweet potato starch.

The plasticizer is selected from one or both of dioctyl sebacate and dioctyl oxalate.

The enhancer is selected from one or more of potassium chloride, sodium chloride or calcium chloride.

The preparation method of the rice-type temporary plugging agent of the present invention specifically designs the particle shape and parameters of the temporary plugging agent according to the characteristics of the coal and gas reservoir, which effectively improves the blocking adaptability of the temporary plugging agent to the coal and rock reservoir. Specifically, Proceed as follows:

Step 1. Weigh the following components respectively according to mass percentage:

Polyvinyl alcohol 50%-75%, polycaprolactone 15%-40%, water-soluble starch 15%-35%, plasticizer 1%-5%, reinforcing agent 5%-15%, total mass percentage is 100%;

Step 2. Pretreatment: Mix the raw materials and crush them in a pulverizer, then screen them with a 4-mesh screen, and collect the screened materials for later use;

Step 3. Add the pretreated raw materials into the reaction kettle, stir at a stirring speed of 30-100r/min, react at a temperature of 120-180°C for 0.5-3h, and then cool to room temperature;

Step 4. Add the material obtained in step 3 to the extruder for secondary melting. Use an underwater pelletizer to cut the molten material into pellets. The temperature of the water is 0-10°C. Adjust the parameters according to the cutting size to control the particle size. The long axis length is 1-5mm, the tip diameter is <1mm, and the aspect ratio is 1.2:1~3:1;

Step 5: Filter and dry the particles obtained in Step 4 to obtain the rice-type temporary plugging agent.

Example 1

The preparation method of the rice-type temporary plugging agent provided in this embodiment is specifically implemented according to the following steps:

Step 1. Weigh the following components respectively according to mass percentage:

Polyvinyl alcohol 50%, polycaprolactone 20%, tapioca starch 15%, dioctyl sebacate 5%, potassium chloride 10%, the sum of the total mass percentages is 100%;

Among them, the molecular weight of polyvinyl alcohol is 1500, the alcoholysis degree is 85%, and the molecular weight of polycaprolactone is 500;

Step 2. Pretreatment: Mix all the raw materials in step 1 and grind them through a pulverizer, then screen them with a 4-mesh screen, and collect the screened materials for later use;

Step 3. Add the pretreated raw materials into the reaction kettle, stir at a rotation speed of 30r/min, the reaction temperature is 120°C, and cool to room temperature after 0.5h of reaction;

Step 4. Add the material obtained in step 3 to the extruder for secondary melting, and put the molten material into an underwater pelletizer with a water temperature of 0°C for pelletizing;

Adjust the parameters according to the particle size, control the particle size to have a long axis length of 4mm, a tip diameter of <1mm, and an aspect ratio of 3:1;

Step 5: Filter and dry the particles obtained in Step 4 to obtain the rice-type temporary plugging agent sample 1.

Example 2

The preparation method of the rice-type temporary plugging agent provided in this embodiment is specifically implemented according to the following steps:

Step 1. Weigh the following components respectively according to mass percentage:

Polyvinyl alcohol 60%, polycaprolactone 15%, corn starch and sweet potato starch 15%, dioctyl sebacate and dioctyl oxalate 5%, sodium chloride and potassium chloride 5%, total mass percentage The sum is 100%;

Among them, the molecular weight of polyvinyl alcohol is 2500, the alcoholysis degree is 95%, and the molecular weight of polycaprolactone is 1500;

Step 2. Pretreatment: Mix all the raw materials in step 1 and grind them through a pulverizer, then screen them with a 4-mesh screen, and collect the screened materials for later use;

Step 3. Add the pretreated raw materials into the reaction kettle, stir at a rotation speed of 70r/min, the reaction temperature is 150°C, and cool to room temperature after 2 hours of reaction;

Step 4. Add the material obtained in step 3 to the extruder for secondary melting, and put the molten material into an underwater pelletizer with a water temperature of 5°C for pelletizing;

Adjust the parameters according to the particle size, control the particle size to have a long axis length of 5mm, a tip diameter of <1mm, and an aspect ratio of 2:1;

Step 5: Filter and dry the particles obtained in Step 4 to obtain the rice-type temporary plugging agent sample 2.

Example 3

The preparation method of the rice-type temporary plugging agent provided in this embodiment is specifically implemented according to the following steps:

Step 1. Weigh the following components respectively according to mass percentage:

Polyvinyl alcohol 70%, polycaprolactone 10%, sweet potato starch 10%, dioctyl sebacate 5%, calcium chloride 5%, the sum of the total mass percentages is 100%;

Among them, the molecular weight of polyvinyl alcohol is 3000, the alcoholysis degree is 100%, and the molecular weight of polycaprolactone is 2000;

Step 2. Pretreatment: Mix all the raw materials in step 1 and grind them through a pulverizer, then screen them with a 4-mesh screen, and collect the screened materials for later use;

Step 3. Add the pretreated raw materials into the reaction kettle, stir at a rotation speed of 100r/min, the reaction temperature is 180°C, and cool to room temperature after 3 hours of reaction;

Step 4. Add the material obtained in step 3 to the extruder for secondary melting, and put the molten material into an underwater pelletizer with a water temperature of 10°C for pelletizing;

Adjust the parameters according to the particle size, control the particle size to have a long axis length of 3mm, a tip diameter of <1mm, and an aspect ratio of 1.5:1;

Step 5: Filter and dry the particles obtained in Step 4 to obtain the rice-type temporary plugging agent sample 3.

Comparative example 1

No temporary plugging agent is used.

Comparative example 2

Use 1-3mm cylindrical universal particle temporary plugging agent.

A 3mm simulated crack and a displacement device were used to conduct temporary plugging tests on the above samples. The simulated coal rock crack plugging effect is as follows:

It can be seen that compared with Comparative Example 1, the rice-grained temporary plugging agent of the present invention has obvious blocking effect; compared with Comparative Example 2, compared with the general-purpose temporary plugging agent, the rice-grained temporary plugging agent of the present invention has better performance for The particle shape and parameters of the temporary plugging agent are designed specifically to effectively match the cracks according to different fracture sizes. After entering the reservoir fractures, they can adapt themselves to form effective plugging, which effectively improves the sealing effect of the temporary plugging agent on the coal and rock reservoirs. Block adaptability.

Claims (9)

1. The rice grain type temporary plugging agent is characterized by comprising the following components: 50-75% of polyvinyl alcohol, 20-40% of polycaprolactone, 15-35% of water-soluble starch, 1-5% of plasticizer and 5-10% of reinforcing agent, wherein the sum of the mass percentages is 100%.

2. The rice grain type temporary plugging agent according to claim 1, wherein the molecular weight of the polyvinyl alcohol is 1500-3000 and the alcoholysis degree is 85% -100%.

3. The rice grain-type temporary plugging agent according to claim 1, wherein said polycaprolactone has a molecular weight of 500-2000.

4. The rice grain type temporary plugging agent according to claim 1, wherein the water-soluble starch is selected from one or more of tapioca starch, corn starch and sweet potato starch.

5. The rice granule type temporary plugging agent according to claim 1, wherein the plasticizer is selected from one or two of dioctyl sebacate or dioctyl oxalate.

6. The rice grain type temporary plugging agent according to claim 1, wherein said reinforcing agent is one or more selected from potassium chloride, sodium chloride and calcium chloride.

7. The method for preparing a rice grain type temporary plugging agent according to any one of claims 1 to 6, wherein the method is specifically implemented according to the following steps:

step 1, respectively weighing the following components in percentage by mass:

50-75% of polyvinyl alcohol, 15-40% of polycaprolactone, 15-35% of water-soluble starch, 1-5% of plasticizer, 5-15% of reinforcing agent and 100% of total mass percent;

step 2, pretreatment: mixing the raw materials, crushing by a crusher, screening by a screen, and collecting the screened materials for later use;

step 3, adding all the pretreated raw materials into a reaction kettle, stirring and reacting, and cooling to room temperature;

step 4, adding the materials obtained in the step 3 into an extruder for secondary melting, and granulating the materials in a molten state by using an underwater granulator;

and 5, filtering and drying the particles obtained in the step 4 to obtain the rice-grain temporary plugging agent.

8. The method for preparing a rice granule temporary plugging agent according to claim 7, wherein the stirring rotation speed in the stirring reaction in the step 3 is 30-100r/min, the reaction temperature is 120-180 ℃, and the reaction time is 0.5-3h.

9. The method for preparing a rice granule temporary plugging agent according to claim 7, wherein the temperature of the water in step 4 is 0-10 ℃.