Rope knot temporary plugging agent for fracturing as well as preparation method and application of rope knot temporary plugging agent

Abstract

The invention belongs to the field of temporary plugging agents for petroleum exploration and development fractured reservoir transformation, and particularly relates to a knotted temporary plugging agent for fracturing and a preparation method and application thereof. At the temperature of 60-80 DEG C, two tassel-shaped wings are wrapped around a ball knot of the rope knot temporary plugging agent by adopting a water-soluble high-viscosity coating solution, a spherical self-made rope knot is formed after rubbing and winding, and the surface of the rope knot is uniformly coated with the coating solution at the moment to form a transparent or faint yellow wrapping layer; and rolling the spherical knots adhered with the water-soluble high-viscosity coating solution in dry quartz sand or ceramsite for 10-20 seconds, so that a layer of quartz sand or ceramsite is adhered to the outer layers of the spherical knots, and the light yellow spherical modified knot temporary plugging agent for fracturing is obtained after the spherical knots are completely cooled and solidified. The rope knot temporary plugging agent is good in degradation performance, the rope knot can be released when the rope knot temporary plugging agent is transported to a hole, the rope knot is restored to the original shape, and subsequent degradation of the rope knot is not affected.

Description

Technical Field

[0001] The invention belongs to the field of temporary plugging agents for petroleum exploration and development fracturing reservoir reconstruction, and specifically relates to a knotted temporary plugging agent for fracturing, and a preparation method and application thereof. Background Art

[0002] The reservoir has high in-situ stress and a large difference in biaxial stress, poor compressibility, and great difficulty in effective transformation. Temporary plugging and fracturing can achieve full opening of multiple clusters in the horizontal well section in sequence, achieve effective transformation of multiple clusters in large sections, and meet the technical requirements for increasing production and efficiency. Temporary plugging agents are classified into granules, powders, fibers, and temporary plugging balls according to their appearance. Their advantages are that they are biodegradable, highly pressure-bearing, do not harm the reservoir, and can control the temporary plugging time. When perforating and plugging holes at the horizontal well staged fracturing construction site, the temporary plugging agent is usually allowed to enter the manifold skid by controlling the primary and secondary plug valves.

[0003] In actual on-site construction, temporary plugging balls are usually used to plug blastholes. However, due to the large amount of sand and high displacement during fracturing, the regular round temporary plugging balls designed for blastholes are constantly impacted and dropped by the sand-carrying fluid, and the expected effect cannot be achieved. The existing knot temporary plugging balls have poor sedimentation effect in the fracturing pre-fluid due to their low density, and are easy to stay or remain between the primary plug valve and the secondary plug valve, thereby affecting the temporary plugging effect. At the same time, during the temporary plugging fracturing process within the segment, the number of holes in a single cluster is usually 24 to 48 holes, and the number of knot temporary plugging balls added at a time is 12 to 24. If a large number of knot temporary plugging balls are added, the probability of mutual entanglement during migration will increase, which will significantly reduce the sealing effect of the knot temporary plugging balls.

[0004] CN113637466A discloses a high temperature resistant and degradable knot-type temporary plugging agent and its preparation method and application, but it only provides a preparation method of the knot temporary plugging agent, but does not take into account that the two wings of the knot will be entangled with each other in the manifold when added on site under actual working conditions, affecting the construction process. CN113445979A discloses a knot temporary plugging ball for staged fracturing of oil and gas fields. The invention patent proposes to use an outer shell to wrap the body of the knot temporary plugging ball, but it is confirmed through indoor experiments and field tests that the density of this temporary plugging agent is not large, the suspension is poor, it is difficult to degrade in the later stage of fracturing, the residue is large, and it will cause a certain degree of damage to the formation. CN115612468A discloses a knot temporary plugging ball and its preparation method and application. The knot temporary plugging ball uses a water-soluble encapsulation shell layer to wrap the knot ball, but it only provides a preparation method, simulates the downhole fracturing process, and does not explain the success rate of on-site addition under actual working conditions. Summary of the invention

[0005] In order to meet the needs of on-site construction and effectively improve the temporary plugging efficiency of temporary plugging agents, the present invention aims at the limitations of existing temporary plugging agents during on-site construction and provides a preparation method of a novel modified knot temporary plugging agent for fracturing. The modified knot temporary plugging agent can effectively prevent the mutual entanglement of knots in the manifold, increase the knot density, accelerate the knot settlement, and improve the success rate of on-site addition.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A method for preparing a knot temporary plugging agent for fracturing comprises the following steps:

[0008] At 60-80℃, a water-soluble high-viscosity coating solution is used to wrap the tassel-shaped wings around the ball knot of the knot temporary plugging agent, and a spherical homemade knot is formed after rubbing and winding. At this time, the coating solution has been evenly coated on the surface of the knot to form a transparent or light yellow wrapping layer. Then the spherical knot adhered with the water-soluble high-viscosity coating solution is rolled in dry quartz sand or ceramsite for 10-20 seconds, so that another layer of quartz sand or ceramsite is adhered to the outer layer of the spherical knot. After complete cooling and solidification, a light yellow spherical modified knot temporary plugging agent for fracturing is obtained. The knot temporary plugging agent has good degradation performance. When it moves to the hole, it can release the knot and restore it to its original shape without affecting the subsequent degradation of the knot.

[0009] The spherical homemade knot is made of one or more silk threads of polylactic acid, polyglycolic acid, polyvinyl alcohol, polybutylene succinate, polyadipate, and polybutylene terephthalate. The diameter of the ball part of the knot is 15-22mm, which can meet the needs of different actual downhole fracturing conditions.

[0010] The preparation method of the coating solution is as follows: by weight, 30-50 parts of polyethylene glycol are melted into a fluid state at 60-80°C for 10-30 minutes, and then 50-70 parts of a water-soluble substance are added and stirred for 3-5 minutes to form a transparent viscous coating solution.

[0011] The polyethylene glycol may be one or a combination of two of any types with a molecular weight greater than 400.

[0012] The water-soluble substance includes multiple components of the following: calculated by weight, 0.2-1 parts of polyacrylamide, 10-30 parts of organic starch, 40-50 parts of bone glue, 0.2-1 parts of guar gum, and 10-20 parts of water.

[0013] The particle size of the quartz sand or ceramsite can be any one of 20-40 mesh, 30-50 mesh, 40-70 mesh, and 70-140 mesh.

[0014] A knot temporary plugging agent for fracturing is prepared by the above method.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. Effectively improve the density of the knot temporary plugging agent, making the density of the knot temporary plugging agent from 0.9-1.0g / cm 3 Improved to 1.8-1.9g / cm 3； ; The sedimentation time is shortened from floating without sinking to rapid sinking within 3-4s.

[0017] 2. Indoor tests have shown that the knot can be restored to its original state within 10 minutes of stirring at 500r / min, and the water-soluble outer layer has been completely dissolved in the water without any residue, which can greatly reduce the damage to the bottom layer. And the degradation rate of the knot temporary plugging agent can reach 100% within 10 days of dissolution at 60-90℃.

[0018] 3. This new type of knot temporary plugging agent has been successfully applied on site. After the temporary plugging agent is in place, the pressure rises by 3-5MPa; for the same displacement construction, the pressure rises by 3-10MPa before and after temporary plugging. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a flow chart for the preparation of a new type of modified knot temporary plugging agent for fracturing. DETAILED DESCRIPTION

[0020] The present invention is described in detail below in conjunction with specific drawings and examples. The examples described below are only preferred embodiments of the present invention. It should be noted that the following description is only for the purpose of explaining the present invention and is not intended to limit the present invention in any form. Any simple modification, equivalent changes and modifications made to the embodiments according to the technical essence of the present invention are within the scope of the technical solution of the present invention. In the following examples, the materials, reagents, etc. used are obtained from commercial sources unless otherwise specified.

[0021] Example 1

[0022] Three kinds of silk threads, polylactic acid, polybutylene succinate and polybutylene adipate / terephthalate, were used to wrap into a knot with a diameter of 18 mm. 30 parts of polyethylene glycol 400 and polyethylene glycol 8000 with a mass ratio of 1:1 were melted into a fluid state at 60°C for 30 minutes, and then 0.8 parts of polyacrylamide, 10 parts of organic starch, 0.2 parts of guar gum and 4 parts of paraffin were added to form a coating solution, so that the tassel-shaped wings were wrapped around the ball knot of the homemade knot temporary plugging agent to form a ball knot, and then the outer layer was wrapped with quartz sand particles with a particle size of 70-140 mesh. The density of the knot temporary plugging agent obtained is 1.95g / cm 3. Indoor experiments have shown that the knot can be restored to its original state after stirring for 8 minutes at 500r / min, and the degradation rate can reach 100% after dissolving for 8 days at 70℃. The temporary plugging agent prepared was used in the multi-stage fracturing construction of a horizontal well in Jilin Oilfield. The settling time was 3.0s, and the pressure rose by 4.2MPa after the knot temporary plugging agent was in place; at the same displacement construction, the pressure rose by 6.5MPa before and after temporary plugging, indicating that the temporary plugging agent has played an effective role and met the needs of reservoir fracturing transformation.

[0023] Example 2

[0024] Three kinds of silk threads, polylactic acid, polybutylene succinate and polybutylene adipate / terephthalate, were used to wrap a knot with a diameter of 22 mm. 40 parts of polyethylene glycol 1000 and polyethylene glycol 4000 with a mass ratio of 1:2 were melted into a fluid state at 70°C for 20 minutes, and then 0.6 parts of polyacrylamide, 20 parts of organic starch, 20 parts of bone glue and 50 parts of water were added to form a coating solution. The tassel-shaped wings were wrapped around the ball knot of the homemade knot temporary plugging agent to form a ball knot, and then the outer layer was wrapped with ceramsite particles with a particle size of 40-70 mesh. The density of the knot temporary plugging agent obtained is 1.94 g / cm 3 . Indoor experiments have shown that the knot can be restored to its original state after stirring for 10 minutes at 500r / min, and the degradation rate can reach 100% after dissolving for 10 days at 90℃. The temporary plugging agent prepared was used in the multi-stage fracturing construction of a horizontal well in Jilin Oilfield. The settling time was 3.1s, and the pressure rose by 5.0MPa after the temporary plugging agent was in place; in the same displacement construction, the pressure rose by 10MPa before and after temporary plugging, indicating that the temporary plugging agent has played an effective role and met the needs of reservoir fracturing transformation.

[0025] Example 3

[0026] Three kinds of silk threads, polylactic acid, polybutylene succinate and polybutylene adipate / terephthalate, were used to wrap a knot with a diameter of 15 mm. 45 parts of polyethylene glycol 600 and polyethylene glycol 8000 with a mass ratio of 1:1.5 were melted into a fluid state at 80°C for 30 minutes, and then 1 part of polyacrylamide, 0.2 parts of guar gum, 20 parts of organic starch, 2 parts of paraffin wax, 25 parts of gelatin and 45 parts of water were added to form a coating solution. The tassel-shaped wings were wrapped around the ball knot of the homemade knot temporary plugging agent to form a ball knot, and then the outer layer was wrapped with quartz sand particles with a particle size of 30-50 mesh. The density of the knot temporary plugging agent obtained is 1.91 g / cm 3. Indoor experiments have shown that the knot can be restored to its original state after stirring for 7 minutes at 500r / min, and the degradation rate can reach 100% after dissolving for 7 days at 60℃. The temporary plugging agent prepared was used in the multi-stage fracturing construction of a horizontal well in Jilin Oilfield. The settling time was 3.2s, and the pressure rose by 3.3MPa after the temporary plugging agent was in place; in the same displacement construction, the pressure rose by 4.1MPa before and after temporary plugging, indicating that the temporary plugging agent has played an effective role and met the needs of reservoir fracturing transformation.

[0027] Example 4

[0028] Three kinds of silk threads, polylactic acid, polybutylene succinate and polybutylene adipate / terephthalate, were used to wrap a knot with a diameter of 20 mm. 35 parts of polyethylene glycol 400 and polyethylene glycol 1000 with a mass ratio of 1:1 were melted at 65°C for 15 minutes to form a fluid state, and then 0.6 parts of guar gum, 25 parts of organic starch, 2 parts of paraffin wax, 20 parts of gelatin and 50 parts of water were added to form a coating solution. The tassel-shaped wings were wrapped around the ball knot of the homemade knot temporary plugging agent to form a ball knot, and then the outer layer was wrapped with ceramsite particles with a particle size of 20-40 mesh. The density of the knot temporary plugging agent obtained is 1.87 g / cm 3 . Indoor experiments have shown that the knot can be restored to its original state after stirring for 9 minutes at 500r / min, and the degradation rate can reach 100% after dissolving for 9 days at 80℃. The temporary plugging agent prepared was used in the multi-stage fracturing construction of a horizontal well in Jilin Oilfield. The settling time was 3.8s, and the pressure rose by 4.6MPa after the temporary plugging agent was in place; in the same displacement construction, the pressure rose by 8.9MPa before and after temporary plugging, indicating that the temporary plugging agent has played an effective role and met the needs of reservoir fracturing transformation.

[0029] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing a knot temporary plugging agent for fracturing, characterized in that: The following steps are involved: At 60-80℃, a water-soluble high-viscosity coating solution is used to wrap the tassel-shaped two wings around the ball knot of the knot temporary plugging agent. After kneading and winding, a spherical homemade knot is formed. At this time, the coating solution has been evenly coated on the surface of the knot to form a transparent or light yellow wrapping layer. The spherical knot adhered with the water-soluble high-viscosity coating solution is rolled in dry quartz sand or expanded clay for 10-20 seconds, so that a layer of quartz sand or expanded clay is adhered to the outer layer of the spherical knot. After complete cooling and solidification, a light yellow spherical modified knot temporary plugging agent for fracturing is obtained.

2. The method for preparing the knot temporary plugging agent for fracturing according to claim 1, characterized in that: The spherical homemade knot is formed by winding one or more silk threads of polylactic acid, polyglycolic acid, polyvinyl alcohol, polybutylene succinate, polyadipate, and butylene terephthalate, and the diameter of the ball knot part of the knot is 15-22mm.

3. The method for preparing the knot temporary plugging agent for fracturing according to claim 1, characterized in that: The preparation method of the coating solution is as follows: by weight, 30-50 parts of polyethylene glycol are melted into a fluid state at 60-80°C for 10-30 minutes, and then 50-70 parts of a water-soluble substance are added and stirred for 3-5 minutes to form a transparent viscous coating solution.

4. The method for preparing the knot temporary plugging agent for fracturing according to claim 1, characterized in that: The polyethylene glycol may be one or a combination of two of any types having a molecular weight greater than 400.

5. The method for preparing the knot temporary plugging agent for fracturing according to claim 1, characterized in that:

5. The water-soluble substance includes multiple components of the following: calculated by weight, 0.2-1 parts of polyacrylamide, 10-30 parts of organic starch, 40-50 parts of gelatin, 0.2-1 parts of guar gum, and 10-20 parts of water.

6. The method for preparing the knot temporary plugging agent for fracturing according to claim 1, characterized in that: The particle size of the quartz sand or ceramsite can be any one of 20-40 mesh, 30-50 mesh, 40-70 mesh, and 70-140 mesh.

7. The knot temporary plugging agent for fracturing prepared by the method for preparing the knot temporary plugging agent for fracturing according to claim 1.

8. The method for preparing the knot temporary plugging agent for fracturing according to claim 1, characterized in that: The application characteristics of the rope knot temporary plugging agent for fracturing are: the rope knot is released when it moves to the hole to restore it to its original shape.

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