Temporary plugging ball with surface micro flow guide structure

Abstract

The invention discloses a temporary plugging ball with a surface micro flow guide structure, the outer surface of the temporary plugging ball is provided with the micro flow guide structure made of an elastic material, when the temporary plugging ball is set in a perforation hole, a micro flow guide channel can be formed between the micro flow guide structure and the wall surface of the perforation hole, and along with the increase of construction displacement, the micro flow guide channel is communicated with the wall surface of the perforation hole. When the internal and external pressure difference of the sleeve is increased, the micro flow guide structure can be controllably deformed, so that the micro flow guide channel is gradually shrunk until the micro flow guide channel is completely closed. The problem that a conventional temporary plugging ball is difficult to set due to the hole plugging water hammer effect can be solved, the adaptive capacity of the temporary plugging ball and a perforation hole is enhanced, and the setting stability and the operation success rate of the temporary plugging ball are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas exploitation, and particularly relates to a temporary plugging ball with a surface micro-diversion structure. BACKGROUND

[0002] Hydraulic fracturing technology is one of the core technologies for the development of unconventional oil and gas resources, and its basic principle is to form a fracture network in the formation by pumping fracturing fluid at high pressure to improve the oil and gas flow channel. In the multi-stage cluster fracturing process, temporary plugging ball technology is widely used to achieve flow distribution between fractures and directional modification of fracturing fluid.

[0003] The working mechanism of the temporary plugging ball is to achieve temporary plugging through the mechanical cooperation of the ball and the dominant liquid inlet perforation hole, forcing the subsequent fracturing fluid to divert to other perforation clusters or fractures that have not successfully initiated or have not fully expanded. In theory, when the diameter of the temporary plugging ball is slightly larger than the diameter of the perforation hole, the ball should be able to stably set in the hole to form an effective seal. However, the success rate of setting the temporary plugging ball is often low in actual application, and one of the main reasons is the complex fluid dynamics phenomenon - the plugging water hammer effect.

[0004] The physical mechanism of the plugging water hammer effect of the temporary plugging ball can be described as follows: when the high-speed flowing fracturing fluid carrying the temporary plugging ball reaches the perforation hole, the traditional smooth ball will instantaneously completely block the hole entrance. At this time, the high-speed fluid inside the hole continues to flow to the deep part of the fracture due to the inertia effect, and the complete plugging of the hole entrance leads to the inability of subsequent fluid to supplement. In this case, a local cavity is formed outside the casing of the plugging hole blocked by the temporary plugging ball. This unstable cavity will quickly collapse: the surrounding high-pressure fluid and possible fracture backflow liquid will quickly backflow, producing an instantaneous water hammer impact. This water hammer impact acts on the temporary plugging ball, and the resulting thrust force often exceeds the combined force of the gravity and static pressure of the temporary plugging ball, pushing the temporary plugging ball back to the wellbore from the plugging position. The temporary plugging ball pushed back will move to the hole again under the action of the wellbore fluid and try to set again. If the structure of the temporary plugging ball does not change, the above plugging water hammer effect will repeatedly occur, forming a "setting-out-positioning-repositioning-again setting-again positioning" cyclic bouncing phenomenon. The frequency of this phenomenon can reach 1-10 Hz, and the duration can last for several minutes to several tens of minutes, so that the conventional temporary plugging ball is always in a dynamic bouncing state and cannot stably stay in the hole to form a durable and reliable seal, seriously affecting the efficiency and effect of the temporary plugging fracturing operation.

[0005] In the prior art, researchers have proposed various optimization schemes for temporary plugging balls, mainly including: (a) material improvement scheme: increasing the density of the ball (using steel balls, ceramic balls, etc.) to improve gravity, or using degradable materials to avoid post-plugging problems. However, these schemes mainly solve the problems of static sealing and post-treatment, and have limited improvement on the water hammer effect during the dynamic setting process. (b) Structure strength improvement scheme: optimizing the internal structure of the ball (such as hollow design, composite materials, etc.) to improve impact resistance. However, this scheme still cannot avoid the water hammer problem caused by instantaneous complete plugging.

[0006] Through comprehensive analysis of the prior art, it can be found that most of the improvement schemes are based on the idea of static sealing, that is, assuming that the temporary plugging ball can be stably set and how to improve the sealing effect and service life after setting. However, in fact, the dynamic stability of the setting process itself is the key problem. SUMMARY

[0007] In view of the above problems, the present application aims to provide a temporary plugging ball with a surface micro-flow guiding structure.

[0008] The technical scheme of the present application is as follows: A temporary plugging ball with a surface micro-flow guiding structure, wherein the outer surface of the temporary plugging ball is provided with a micro-flow guiding structure made of an elastic material. When the temporary plugging ball is set in a perforation hole, the micro-flow guiding structure can form a micro-flow guiding channel with the wall surface of the perforation hole. As the construction discharge increases and the pressure difference between the inside and outside of the casing increases, the micro-flow guiding structure can undergo controllable deformation to gradually shrink the micro-flow guiding channel until it is completely closed.

[0009] Preferably, the micro-flow guiding structure is a concave structure, a convex structure, or a combination of concave and convex structures.

[0010] Preferably, the concave structure is any one or more of a groove, a concave hemisphere, a square pit, an annular groove, an arc-shaped groove, a grid-shaped concave point, and a honeycomb-shaped pit.

[0011] Preferably, the convex structure is any one or more of a prism, a convex hemisphere, a wave surface protrusion, a cylinder, a conical protrusion, a pyramid, an annular flange, an arc-shaped ridge, and a grid-shaped convex point.

[0012] Preferably, the micro-flow guiding structure is distributed on the outer surface of the temporary plugging ball in any of the following ways: (a) Regular lattice distribution, arranged in a square lattice, a hexagonal lattice, or a triangular lattice, with an adjacent structure spacing L satisfying 1mm≤L≤20mm; (b) Continuous linear distribution, continuously distributed along the meridians, latitudes, or spiral lines on the surface of the ball, with a line width W satisfying 0.5mm≤W≤10mm and a line spacing S satisfying 1mm≤S≤15mm. (c) Random distribution: randomly distributed on the surface of the sphere according to a predetermined probability density function, and the minimum distance between adjacent structures is not less than 1mm; (d) Partition combination distribution, the outer surface of the temporary plugging ball is divided into several regions, and different regions adopt different distribution modes or structural forms.

[0013] As a preferred, the temporary plugging ball is a hollow temporary plugging ball or a solid temporary plugging ball.

[0014] As a preferred, the characteristic size H of the micro-diversion structure satisfies 0.005D≤H≤0.15D, and D is the diameter of the temporary plugging ball.

[0015] As a preferred, the distribution density p of the micro-diversion structure satisfies 1 / cm²≤p≤20 / cm².

[0016] As a preferred, the elastic material is any one or more of thermoplastic polyurethane, hydrogenated nitrile rubber, silicone rubber, polylactic acid, polyglycolic acid, polyvinyl alcohol, and ethylene-propylene rubber.

[0017] As a preferred, the elastic modulus of the elastic material is greater than or equal to 0.01GPa and less than or equal to 10GPa, and the Poisson's ratio of the elastic material is greater than or equal to 0.2 and less than or equal to 0.49.

[0018] The beneficial effects of the present application are: (a) The present application can eliminate water hammer effect: through the design of micro-diversion structure, the instantaneous complete plugging at the initial setting can be avoided, and the pressure impact and bouncing phenomenon can be eliminated; (b) The present application can realize gradual sealing: through the design of pressure-responsive elastic structure, smooth transition from liquid permeability to sealing can be realized; (c) The present application can improve the adaptability of the temporary plugging ball: through the diversified surface structure design, it can adapt to different shapes and sizes of perforation holes; (d) The present application can optimize the comprehensive performance: while solving the setting problem, good pressure-bearing capacity, durability and economy are maintained. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 Schematic diagram of continuous line type distribution surface concave micro-diversion structure temporary plugging ball; Figure 2 Schematic diagram of temporary plugging ball with regular lattice distribution surface concave micro flow guiding structure; Figure 3 Schematic diagram of temporary plugging ball with regular lattice distribution surface convex micro flow guiding structure; Figure 4 Schematic diagram of temporary plugging ball with regular lattice distribution surface long strip convex micro flow guiding structure; Figure 5 Schematic diagram of temporary plugging ball with irregular continuous line type distribution surface concave micro flow guiding structure; Figure 6 Schematic diagram of temporary plugging ball with surface multiple type composite structure random lattice distribution convex micro flow guiding structure; Figure 7 Schematic diagram of temporary plugging ball with regular lattice distribution surface ring groove micro flow guiding structure; Figure 8 Schematic diagram of temporary plugging ball with multiple micro flow guiding structure types on surface; Figure 9 Schematic diagram of temporary plugging ball hole setting state with continuous line type distribution surface concave micro flow guiding structure; Figure 10 Schematic diagram of temporary plugging ball hole setting section with continuous line type distribution surface concave micro flow guiding structure; Figure 11 Schematic diagram of temporary plugging ball hole setting state with regular lattice distribution surface long strip convex micro flow guiding structure; Figure 12 Schematic diagram of temporary plugging ball hole setting section with regular lattice distribution surface long strip convex micro flow guiding structure; Figure 13 Schematic diagram of temporary plugging ball hole setting state with regular lattice distribution surface ring groove micro flow guiding structure; Figure 14 Schematic diagram of ordinary temporary plugging ball hole setting experiment result; Figure 15 Schematic diagram of temporary plugging ball hole setting experiment result with regular lattice distribution surface ring flange micro flow guiding structure. DETAILED DESCRIPTION

[0021] The application will be further described below in conjunction with the drawings and examples. It should be noted that the examples in the present application and the technical features in the examples can be combined with each other without conflict. It should be pointed out that all the technical and scientific terms used in the present application have the same meaning as that generally understood by the ordinary skilled in the art to which the present application belongs, unless otherwise specified. The "including" or "containing" and similar words used in the present application mean that the elements or objects before the words cover the elements or objects listed after the words and their equivalents, without excluding other elements or objects.

[0022] AsFigure 1 As shown, the application provides a temporary plugging ball with a surface micro-flow guiding structure, the outer surface of the temporary plugging ball is provided with a micro-flow guiding structure made of elastic material, when the temporary plugging ball is set in the perforation hole, the micro-flow guiding structure can form a micro-flow guiding channel between the perforation hole wall surface, as the construction displacement increases, the pressure difference between the inside and outside of the casing increases, the micro-flow guiding structure can be deformed controllably to make the micro-flow guiding channel gradually shrink until completely closed.

[0023] In the application, by setting the micro-flow guiding structure made of elastic material on the outer surface of the temporary plugging ball, the micro-flow guiding structure can form a micro-flow guiding channel between the perforation hole wall surface in the initial setting stage, effectively slow down the pressure sudden change inside and outside the plugging area, prevent the cavity formation and subsequent cavitation collapse impact caused by instantaneous complete plugging, thereby avoiding the temporary plugging ball bouncing off phenomenon caused by water hammer effect. As the construction displacement increases, the pressure difference between the inside and outside of the casing increases, the micro-flow guiding structure made of elastic material is deformed controllably to make the micro-flow guiding channel gradually shrink until completely closed, realizing the smooth transition from the micro-flow guiding state to the sealing state.

[0024] In one specific embodiment, the equivalent size δ of the micro-flow guiding channel satisfies 0.1mm≤δ≤5.0mm.

[0025] In one specific embodiment, the micro-flow guiding structure is a concave structure, a convex structure or a concave-convex combined structure.

[0026] Optionally, the concave structure is any one or more of a groove, a concave hemisphere, a square pit, an annular groove, an arc-shaped groove, a grid-shaped concave point and a honeycomb-shaped pit.

[0027] Optionally, the convex structure is any one or more of a prism, a convex hemisphere, a wave curved surface convex, a cylinder, a conical convex, a pyramid, an annular flange, an arc-shaped ridge and a grid-shaped convex point.

[0028] In one specific embodiment, the micro-flow guiding structure is distributed on the outer surface of the temporary plugging ball in the following any one way: (a) regular lattice distribution, arranged in a square lattice, a hexagonal lattice or a triangular lattice, the distance L between adjacent structures satisfies 1mm≤L≤20mm; (b) continuous line distribution, continuously distributed along the meridian line, the parallel line or the spiral line on the surface of the ball, the line width W satisfies 0.5mm≤W≤10mm, and the line spacing S satisfies 1mm≤S≤15mm; (c) random distribution: randomly distributed on the surface of the ball according to a preset probability density function, the minimum distance between adjacent structures is not less than 1mm; (d) a zoned distribution, the outer surface of the ball is divided into several zones, and different distribution modes or structural forms are used in different zones.

[0029] In the above embodiments, the adaptability of the ball to the perforation hole can be improved by different distribution modes, and when the application is used, different distribution modes are selected according to the specific perforation hole and the temporary plugging requirements.

[0030] The temporary plugging ball of the application mainly comprises a ball body and a surface micro-flow guiding structure provided on the ball body. The ball body provides basic geometric shape and mechanical strength, and the surface micro-flow guiding structure is responsible for functional fluid control. The design of the surface micro-flow guiding structure is based on the following principle: at the initial setting, a micro fluid channel is formed between the micro structure and the perforation hole wall, and the existence of these channels avoids the formation of a cavity outside the plugging area; as the wellbore pressure increases, the elastic micro structure deforms under the action of pressure difference, the channel gradually shrinks until it is completely closed, realizing the final complete sealing. Therefore, the temporary plugging ball can be a hollow temporary plugging ball or a solid temporary plugging ball.

[0031] In a specific embodiment, the characteristic dimension H (projection height or recess depth) of the micro-flow guiding structure satisfies 0.005D≤H≤0.15D, and D is the diameter of the ball body of the temporary plugging ball.

[0032] In a specific embodiment, the distribution density p of the micro-flow guiding structure satisfies 1 / cm²≤p≤20 / cm².

[0033] In a specific embodiment, the elastic material is any one or more of thermoplastic polyurethane, hydrogenated nitrile rubber, silicone rubber, polylactic acid, polyglycolic acid, polyvinyl alcohol, and ethylene-propylene rubber.

[0034] In a specific embodiment, the elastic modulus of the elastic material is greater than or equal to 0.01 GPa and less than or equal to 10 GPa, and the Poisson's ratio of the elastic material is greater than or equal to 0.2 and less than or equal to 0.49.

[0035] In a specific embodiment, the micro-flow guiding structure with geometric edges is rounded, which can reduce local stress concentration and improve structural durability. Optionally, the radius R of the rounding satisfies 0.1mm≤R≤5mm, In summary, compared with the existing temporary plugging ball technology, the temporary plugging ball of the application has the following advantages: (1) fundamentally eliminate water hammer effect, greatly improve the success rate of setting: the invention by designing controllable micro guide structure on the surface of the ball, avoid the instantaneous complete plugging in the initial setting stage. Formed millimeter level (0.1-5mm) guide channel allows fluid exchange, effectively prevent the formation of cavity behind the plugging area and its collapse caused by water hammer shock wave. This makes the temporary plugging ball can stay in the hole position after initial contact, significantly improve the first setting success rate.

[0036] (2) the invention uses elastic material to build micro guide structure has the pressure response characteristics. After the initial setting, as the displacement of the casing pressure gradually rises, the elastic microstructure deformation under the action of pressure difference, micro guide channel gradually shrink until completely closed, complete setting.

[0037] (3) enhance the adaptability of irregular hole, the design of surface micro guide structure (protrusions, recesses and their combination) breaks the form limit of traditional smooth ball. Diversified structure form (prism, convex hemisphere, groove, concave hemisphere (micro cavity), square pit, ring groove, etc.) and flexible adjustable distribution mode (regular lattice, continuous line, random, partition combination), improve the contact matching ability of temporary plugging ball and various shape, size (especially non ideal circular or exist damage) perforation hole, so as to realize effective setting in complex working conditions.

[0038] (4) optimize the reliability and durability of structure, the design of micro guide structure, its non smooth surface enhances the mechanical interaction force with the hole wall (compared with smooth surface), reduces the risk of being washed out by high speed fluid in the casing. Further, by rounding the edges of the microstructure, the stress concentration can be effectively reduced, and the strength of the microstructure can be improved.

[0039] The temporary plugging ball with surface micro guide structure described in the invention is illustrated as follows: As shown in Figure 1 , the surface of the temporary plugging ball is provided with concave micro guide grooves distributed in continuous line, which form a guide network along the meridian and latitude direction. The cross section shape of the groove can be designed as rectangle, semicircle or trapezoid according to the working condition, the line width W=0.5mm, the characteristic size H (depth)=0.5mm, and the micro guide channel is constructed by continuous distribution. The edge of the groove is rounded, and the radius R=0.2mm.

[0040] As shown in Figure 2 , the surface of the temporary plugging ball is provided with concave micro cavity structure distributed in regular lattice, and the micro cavity is in the shape of hemispherical shell. The curvature radius R of the micro cavity and the diameter D of the ball satisfy 0.01D≤R≤1D, the characteristic size H (depth)=0.5mm, and the distribution density ρ≈9 / cm².

[0041] As shown inFigure 3 As shown in the drawings, the surface of the temporary plugging ball is a regular lattice distributed convex half-sphere shell structure temporary plugging ball, which is complementary to Figure 2 the concave microcavity forming structure.

[0042] As shown in the drawings, the surface of the temporary plugging ball is a regular lattice distributed convex half-sphere shell structure temporary plugging ball, which is complementary to Figure 4 the concave microcavity forming structure.

[0043] As shown in the drawings, the surface of the temporary plugging ball is a regular lattice distributed convex half-sphere shell structure temporary plugging ball, which is complementary to Figure 5 the concave microcavity forming structure.

[0044] As shown in the drawings, the surface of the temporary plugging ball is a regular lattice distributed convex half-sphere shell structure temporary plugging ball, which is complementary to Figure 6 the concave microcavity forming structure.

[0045] As shown in the drawings, the surface of the temporary plugging ball is a regular lattice distributed convex half-sphere shell structure temporary plugging ball, which is complementary to Figure 7 the concave microcavity forming structure.

[0046] As shown in the drawings, the surface of the temporary plugging ball is a regular lattice distributed convex half-sphere shell structure temporary plugging ball, which is complementary to Figure 8 the concave microcavity forming structure.

[0047] As shown in the drawings, the surface of the temporary plugging ball is a regular lattice distributed convex half-sphere shell structure temporary plugging ball, which is complementary to the concave microcavity forming structure.

[0048] Embodiment 1 As shown in the drawings, the surface of the temporary plugging ball is a regular lattice distributed convex half-sphere shell structure temporary plugging ball, which is complementary to Figure 1 the concave microcavity forming structure. Figure 9 As shown in the drawings, the surface of the temporary plugging ball is a regular lattice distributed convex half-sphere shell structure temporary plugging ball, which is complementary to Figure 10As shown. In this embodiment, the sphere is a thermoplastic polyurethane (TPU) with an elastic modulus of 1 GPa and a diameter D = 20 mm.

[0049] When the temporary plugging ball is carried to the perforation orifice by the fracturing fluid, it first forms initial contact with the edge of the orifice: the continuous concave grooves distributed along the latitude and longitude lines on the surface of the ball adhere to the orifice wall, forming 3-4 annular interconnected micro-channels (equivalent size δ=0.5mm). At this time, the fracturing fluid outside the orifice can flow into the orifice through the grooves, and the high-speed fluid originally in the orifice can also flow back to the wellbore through the grooves, realizing dynamic exchange of fluid inside and outside the orifice, and completely avoiding the formation of cavities inside the orifice caused by the instantaneous plugging of traditional smooth balls.

[0050] As the fracturing fluid flow rate increases, the pressure inside the casing gradually rises. Under the pressure difference, the TPU material (elastic modulus 1 GPa) of the temporary plugging ball undergoes elastic deformation, and the sidewalls on both sides of the groove are slowly squeezed towards the center, gradually narrowing the groove cross-sectional width from 0.5 mm. During this process, the fluid flow rate through the channel gradually decreases with the cross-sectional contraction, but remains flowing to avoid sudden pressure changes. When the pressure rises to the design threshold, the outer TPU layer completely adheres to the orifice wall, the groove cross-sectional width shrinks to 0, and the micro-channel is completely closed. Because there is no cavity formation or cavitation collapse impact throughout the process, the temporary plugging ball remains stably in contact with the orifice wall without bouncing, achieving a smooth transition from micro-channeling to complete sealing.

[0051] Example 2 use Figure 4 The temporary plugging ball, as shown, with a regular lattice distribution and a surface of elongated convex micro-guiding structure, seals the orifice. Its setting state is as follows: Figure 11 As shown, its setting section is as follows Figure 12 As shown. In this embodiment, the microfluidic structure material is hydrogenated nitrile butadiene rubber (HNBR), with an elastic modulus of 1 GPa, a Poisson's ratio of 0.42, a sphere diameter D = 20 mm, and a density of 1.1 g / cm³.

[0052] When the temporary plugging ball reaches the orifice, the elongated, convex micropillars with a regular lattice distribution on their surface make line contact with the orifice wall, and the gaps between the micropillars form multiple independent micro-channels. At this time, the fracturing fluid can flow bidirectionally inside and outside the orifice through the gaps, eliminating the pressure difference impact caused by the instantaneous plugging.

[0053] As the pressure inside the casing rises to the design threshold, the hydrogenated nitrile butadiene rubber (HNBR) material undergoes controlled deformation under axial pressure—the height of the micropillars gradually compresses, while the width of the micropillars gradually increases due to lateral expansion. The gap gradually narrows as the micropillars expand, and the fluid flow rate decreases synchronously, but the pressure inside and outside the orifice remains constant. When the pressure reaches the design threshold, the micropillars completely fill the gap, and their tops fit tightly against the orifice wall, completely closing the micro-channel. Throughout the process, the temporary plugging ball remains stably seated at the center of the orifice due to the absence of impact thrust caused by the cavity, preventing a "seat-ejection" cycle.

[0054] Example 3 use Figure 7 The temporary plugging ball, as shown, with a micro-flow guiding structure featuring a regular lattice distribution and annular grooves on its surface, seals the orifice. Its setting state is as follows: Figure 13 As shown. In this embodiment, the sphere is made of polylactic acid (PLA) material with an elastic modulus of 1 GPa, and the sphere diameter D = 20 mm.

[0055] When the temporary plugging ball contacts the orifice, the annular groove on its surface forms an annular channel with the edge of the orifice, constituting a flow guiding network. At this time, the fracturing fluid can flow through the gaps in the annular channel of the groove, quickly balancing the pressure inside and outside the orifice and preventing the formation of local cavities.

[0056] As the pressure inside the casing rises to the design threshold, the outer PLA material (elastic modulus 1 GPa) gradually deforms under the pressure difference—the wall of the annular groove expands towards the center (groove width shrinks from 0.5 mm to 0.2 mm). The equivalent dimension δ of the channel gradually decreases with deformation, the fluid throughput gradually decreases, and no impact load is generated. When the pressure reaches the design threshold, the annular groove is filled with the expanded PLA material, and the channel is completely closed. Due to the design of the micro-guided structure of the annular groove, regardless of the posture of the temporary plugging ball in contact with the orifice, at least two independent channels can be guaranteed to participate in fluid exchange, with no bouncing during the setting process and stable setting.

[0057] To further verify the advantages of the temporary plugging ball of the present invention, a setting test was conducted under the same working conditions (orifice diameter 15 mm, fracturing fluid flow rate 7.44 m³ / min, and temporary plugging ball diameter 20 mm) using a conventional smooth temporary plugging ball and the temporary plugging ball with surface micro-guiding structure described in the present invention. The comparison results are as follows: like Figure 14As shown in the diagram, the dynamic state of a conventional smooth temporary plugging ball during setting is illustrated in the experimental diagram: at the instant of initial contact between the plugging ball and the orifice (approximately 0.574 s), the orifice inlet is instantly and completely blocked due to the lack of a flow-guiding structure on the ball's surface. At this moment, the high-speed fracturing fluid flowing inside the orifice continues to propel into the depth of the fracture due to inertia, and the blocked inlet prevents fluid replenishment, rapidly forming a local cavity with a diameter of approximately 70 mm on the outer side of the area where the plugging ball and the orifice wall are in contact (observed at T=0.629 s). This cavity rapidly collapses at T=0.574 s, and the surrounding high-pressure fluid and fracture return fluid rush back at high speed, generating a water hammer impact force far exceeding the combined force of the plugging ball's own weight and static pressure, directly pushing the plugging ball back into the wellbore from the orifice position (T=0.789 s).

[0058] like Figure 15 As shown, during the setting process of the temporary plug ball with a regular dot-matrix distributed surface annular flange micro-guiding structure of the present invention, due to its unique surface micro-guiding structure, the fracturing fluid can flow through the channel gap formed between the temporary plug ball and the orifice at the moment of setting (T=0.820S), avoiding the generation of local cavities and making the setting stable. Subsequently, as the pressure inside the sleeve increases, complete sealing is achieved.

[0059] The comparison of the results shows that the temporary plugging ball with surface micro-flow guiding structure described in this invention can eliminate the water hammer effect from the source through the surface micro-flow guiding structure, and achieve a smooth transition from "initial micro-flow guiding - progressive sealing - stable pressure bearing". The setting stability, operation success rate and the improvement effect on fracturing are all significantly better than conventional products.

[0060] The above description is merely a representative embodiment of the present invention and is not intended to limit the present invention in any way. Any embodiment made by those skilled in the art without departing from the scope of the present invention and utilizing the disclosed technical content is an equivalent embodiment of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A temporary plugging ball with a surface micro-flow guiding structure, characterized in that, The outer surface of the temporary plugging ball is provided with a micro-flow guiding structure made of elastic material. When the temporary plugging ball is seated in the perforation hole, the micro-flow guiding structure can form a micro-flow guiding channel between itself and the wall of the perforation hole. As the construction discharge increases, the pressure difference between the inside and outside of the casing increases, and the micro-flow guiding structure can undergo controllable deformation to gradually shrink the micro-flow guiding channel until it is completely closed.

2. The temporary plugging ball with a surface micro-flow guiding structure according to claim 1, characterized in that, The micro-guide structure is a concave structure, a convex structure, or a combination of concave and convex structures.

3. The temporary plugging ball with a surface micro-flow guiding structure according to claim 2, characterized in that, The concave structure is any one or more of the following: groove, concave hemisphere, square pit, annular groove, arc groove, grid-like pit, and honeycomb pit.

4. The temporary plugging ball with a surface micro-flow guiding structure according to claim 2, characterized in that, The convex structure is any one or more of the following: prism, convex hemisphere, wavy surface protrusion, cylinder, conical protrusion, pyramid, annular flange, arc ridge, and grid-like protrusion.

5. The temporary plugging ball with a surface micro-flow guiding structure according to claim 1, characterized in that, The micro-guiding structure is distributed on the outer surface of the temporary clogging ball in any of the following ways: (a) Regular dot matrix distribution, arranged in square, hexagonal or triangular dot matrix, with the spacing L between adjacent structures satisfying 1mm≤L≤20mm; (b) Continuous linear distribution, continuously distributed along the meridians, parallels or spirals on the surface of the sphere, with line width W satisfying 0.5mm≤W≤10mm and line spacing S satisfying 1mm≤S≤15mm; (c) Random distribution: The structures are randomly distributed on the surface of the sphere according to a preset probability density function, and the minimum distance between adjacent structures is not less than 1 mm; (d) Zoned combination distribution: the outer surface of the temporary blocking ball is divided into several regions, and different regions adopt different distribution methods or structural forms.

6. The temporary plugging ball with a surface micro-flow guiding structure according to claim 1, characterized in that, The temporary blocking ball can be a hollow temporary blocking ball or a solid temporary blocking ball.

7. The temporary plugging ball with a surface micro-flow guiding structure according to claim 1, characterized in that, The characteristic dimension H of the micro-channel structure satisfies 0.005D≤H≤0.15D, where D is the diameter of the temporary blocking ball.

8. The temporary plugging ball with a surface micro-flow guiding structure according to claim 1, characterized in that, The distribution density ρ of the micro-guide structure satisfies 1 / cm² ≤ ρ ≤ 20 / cm².

9. The temporary plugging ball with a surface micro-flow guiding structure according to claim 1, characterized in that, The elastic material is any one or more of thermoplastic polyurethane, hydrogenated nitrile rubber, silicone rubber, polylactic acid, polyglycolic acid, polyvinyl alcohol, and ethylene propylene rubber.

10. The temporary plugging ball with a surface micro-flow guiding structure according to any one of claims 1-9, characterized in that, The elastic modulus of the elastic material is greater than or equal to 0.01 GPa and less than or equal to 10 GPa, and the Poisson's ratio of the elastic material is greater than or equal to 0.2 and less than or equal to 0.49.

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