Ultrahigh-temperature CO2-resistant energized fracturing double-slip soluble bridge plug and fracturing method

Abstract

The invention belongs to the technical field of oil and gas field downhole tools, and particularly relates to an ultrahigh-temperature CO2-resistant energized fracturing double-slip soluble bridge plug and a fracturing method. The double-slip soluble bridge plug comprises a central pipe, the outer side of the central pipe is sequentially and coaxially sleeved with an upper anchoring assembly, a rubber sleeve assembly, a lower anchoring assembly and a guide shoe which abut against one another in the axial direction from top to bottom, and the upper anchoring assembly and the lower anchoring assembly are connected with the central pipe through setting shear pins. The guide shoe is fixedly connected with the central pipe, and tungsten carbide coatings are arranged on the surfaces of the central pipe, the upper anchoring assembly, the rubber sleeve assembly, the lower anchoring assembly and the guide shoe. The method can be suitable for a harsh stratum environment.

Description

Technical Field

[0001] The invention belongs to the technical field of downhole tools in oil and gas fields, and in particular relates to a double-slip soluble bridge plug for ultra-high temperature resistant CO2 energized fracturing and a fracturing method. Background Art

[0002] At present, soluble bridge plugs have been widely used for formation isolation in the process of oil and gas well operation. Using bridge plugs for formation isolation can effectively achieve staged fracturing. With the increase of drilling depth of oil and gas wells, the requirements for soluble bridge plugs are getting higher and higher. Taking shale oil and gas wells in some areas as an example, during the operation, the tight oil reservoir is as high as 6000-8000m, and the depth of some blocks is even more than 8000m. There are reservoir characteristics such as ultra-high temperature of 150℃-200℃ and high pressure of 70-100MPa of formation fracture pressure.

[0003] Due to the dense formation and extremely high fracture pressure, after the bridge plug is used to isolate the layer section, before the formal fracturing, the formation needs to be pre-treated by a complex fracturing process such as pre-injection of carbon dioxide, etc., especially in horizontal wells, which requires the bridge plug to be anchored up and down. In this environment, higher requirements are placed on the bridge plug, which is required to have characteristics such as resistance to ultra-high temperature, acid corrosion, bidirectional high pressure resistance and solubility. Before the formal fracturing, the formation needs to be pre-treated by a complex fracturing process such as pre-injection of carbon dioxide, etc., especially in horizontal wells, which requires the bridge plug to be anchored up and down. In this environment, higher requirements are placed on the bridge plug, which is required to have characteristics such as resistance to ultra-high temperature, acid corrosion, bidirectional high pressure resistance and solubility.

[0004] Chinese patent document CN112620055A discloses a hydrochloric acid resistant soluble bridge plug and its preparation method and application. The preparation method includes the following steps: preparing a soluble bridge plug, performing micro-arc oxidation treatment on the surface of the soluble bridge plug; coating the surface of the soluble bridge plug treated with micro-arc oxidation with hydrochloric acid resistant paint; filling the gap between the slip seat and the slip teeth in the soluble bridge plug with epoxy glue, and solidifying the epoxy glue. This application performs micro-arc oxidation treatment on the surface of the soluble bridge plug to form a micro-arc oxidation layer on its surface, and then seals the micropores formed after micro-arc oxidation by coating hydrochloric acid resistant paint, and fills the gap between the slip seat and the slip teeth with epoxy resin, so that the application has hydrochloric acid resistance and can meet the needs of oil fracturing construction.

[0005] Chinese patent document CN111484579A discloses a high-temperature soluble bridge plug and its preparation method. The preparation method includes the following steps: 1) taking butadiene and maleic anhydride, adding an anti-gelling agent, adding diisocyanatobutyronitrile dissolved in DMF as an initiator, adding KH570 as a coupling agent, and using DMF as a solvent; heating in a constant temperature oil bath under nitrogen protection, and fully reflux reaction at 140-180°C; 2) centrifugally washing the solid-liquid mixture after the above reaction, vacuum drying, and the obtained light yellow solid is the raw material for the high-temperature soluble bridge plug; the obtained raw material is thermoformed into a high-temperature soluble bridge plug using a mold. The invention makes full use of the copolymer synthesized from maleic anhydride and butadiene, which has the characteristics of high temperature resistance, pressure resistance, and water solubility, and finally degrades into water and carbon dioxide, reducing the backflow process, and is a biodegradable and environmentally friendly material. This high-temperature soluble bridge plug can be used in the development of unconventional gas reservoirs such as shale gas. The liquid in the well makes the high-temperature soluble bridge plug dissolve by itself, without the need for wellbore drilling and grinding operations and backflow treatment, and the full-bore production of the wellbore can be realized. This patent uses high-molecular organic matter as the base material of the bridge plug, which has acid and high temperature resistance, but its strength is lower than that of the magnesium alloy currently used in the market, especially in high temperature environments, where the strength decreases rapidly, so it is currently rarely used in the market and is still in the experimental stage. Summary of the invention

[0006] In view of the technical problems mentioned above, the present invention aims to provide a double-slip soluble bridge plug, which can be applied to harsh formation environments.

[0007] The present invention also proposes a fracturing method, which uses the ultra-high temperature acid-resistant soluble bridge plug proposed by the present invention to perform sealing fracturing.

[0008] According to the present invention, a double-slip soluble bridge plug is provided, comprising a center tube, on the outer side of the center tube, an upper anchor assembly, a rubber cartridge assembly, a lower anchor assembly and a guide shoe are coaxially sleeved in sequence from top to bottom and axially abut against each other, the upper anchor assembly and the lower anchor assembly are connected to the center tube by sealing shear pins, the guide shoe is fixedly connected to the center tube, and a tungsten carbide coating is provided on the surfaces of the center tube, the upper anchor assembly, the rubber cartridge assembly, the lower anchor assembly and the guide shoe.

[0009] In a preferred embodiment, a plasma arc driven by direct current is used as a heat source to heat the material containing tungsten carbide as the main body to a molten or semi-molten state, and is sprayed on the surface of the central tube, the upper anchor assembly, the rubber sleeve assembly, the lower anchor assembly and the guide shoe to form a tungsten carbide coating. In the material containing tungsten carbide as the main body, the content of tungsten carbide is more than 95%.

[0010] In a preferred embodiment, an acid-resistant resin shatterable protective film is provided on the outer side of the tungsten carbide coating of the upper anchor assembly and the lower anchor assembly.

[0011] In a preferred embodiment, the dissolved acid-resistant resin liquid is sprayed onto the upper anchor assembly and the lower anchor assembly by a spray gun.

[0012] In a preferred embodiment, the upper anchoring assembly includes an upper cava and an upper cone which are coaxially sleeved on the center tube and adapted to each other, the upper end of the upper cava is axially abutted against the center tube, the upper cone is connected to the center tube via a sealing shear pin, and the lower end of the upper cone is axially abutted against the rubber cartridge assembly, and the lower anchoring assembly includes a lower cone and a lower cava which are coaxially sleeved on the center tube and adapted to each other, the lower end of the lower cava is axially abutted against the center tube, the lower cone is connected to the center tube via a sealing shear pin, and the upper end of the lower cone is axially abutted against the rubber cartridge assembly.

[0013] In a preferred embodiment, at least four rows of lower anchor teeth are provided on the outer wall of the lower slip, and the lower anchor teeth are made of high-strength ceramic particles.

[0014] In a preferred embodiment, at least two rows of upper anchoring teeth are provided on the outer wall of the upper slip, and the upper anchoring teeth are made of high-strength ceramic particles.

[0015] In a preferred embodiment, the rubber cylinder assembly includes an upper metal support ring, a rubber cylinder and a lower metal support ring coaxially arranged on the center tube from top to bottom, the upper end of the upper metal support ring is axially abutted against the upper anchor assembly, and the lower end of the lower metal support ring is axially abutted against the lower anchor assembly.

[0016] In a preferred embodiment, a protective ring is provided between the upper metal support ring and the rubber cylinder, and between the lower metal support ring and the rubber cylinder.

[0017] According to the present invention, a fracturing method is also provided, which uses the double slip soluble bridge plug provided by the present invention to perform sealing, comprising the following steps:

[0018] Step A: Within 48 hours before the double slip soluble bridge plug is lowered into the oil and gas well, use a well clearing gauge of the corresponding size or larger than the oil and gas well to clear the well or simulate pumping;

[0019] Step B: Send the double slip soluble bridge plug into the well through the adapter, and control the vertical section running speed at 50-70 m / min and the horizontal section running speed at 35-40 m / min;

[0020] Step C: After the double slip soluble bridge plug is put into place, it is set. Fracturing operation is carried out within 12 to 18 hours after the double slip soluble bridge plug is set. If the time of fracturing operation is delayed, 1 to 1.5 times the volume of wellbore water can be pumped in to reduce the chloride concentration in the wellbore;

[0021] Step D: Put the fracturing ball in 30 minutes before fracturing, with a speed of 3 to 4 m 3 / min pumping displacement will pump the fracturing ball into place. When the pumping liquid volume difference is 10m 3 When the casing capacity is reached, the pumping displacement is increased from 3 to 4 m 3 / min down to 1.5~2m 3 / min, fracturing after the ball is seated.

[0022] Compared with the prior art, the advantages of the present application are as follows.

[0023] The present invention sprays a tungsten carbide coating mainly containing tungsten carbide as a soluble corrosion-inhibiting particle coating on the surface of a double-slip soluble bridge plug by spraying, and separately sprays an acid-resistant resin fracture-resistant protective film on the tungsten carbide coating of an anchoring component. The former can improve the acid resistance of the bridge plug, and the latter acid-resistant resin fracture-resistant protective film can protect the present invention from reacting with well fluid within 24 hours, so that the bridge plug can perform sealing operations in high temperature, high pressure and acidic environments. After 24 hours, the protective film falls off, and the bridge plug reacts quickly with the well fluid, thereby improving the working efficiency of the ultra-high temperature acid-resistant soluble bridge plug. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be described below with reference to the accompanying drawings.

[0025] Figure 1 A schematic diagram showing a first embodiment of a double slip soluble bridge plug according to the present invention is shown;

[0026] Figure 2 A schematic diagram showing a second embodiment of a double slip soluble bridge plug according to the present invention is shown;

[0027] Figure 3 A schematic diagram showing the connection between a first embodiment of a double slip soluble bridge plug according to the present invention and an adapter push cylinder is shown;

[0028] Figure 4 A schematic diagram showing the connection between a second embodiment of a double slip soluble bridge plug according to the present invention and an adapter push cylinder is shown;

[0029] Figure 5 The schematic diagram of the structure in which a tungsten carbide coating is arranged on the outer side of the central tube 1 is shown.

[0030] In the figure:

[0031] 1. Center tube; 101. Inner cavity; 2. Upper slip; 3. Upper anchoring tooth; 4. Upper cone; 5. Upper metal support ring; 6. Rubber cartridge; 7. Protective ring; 8. Lower metal support ring; 9. Lower cone; 10. Lower slip; 11. Lower anchoring tooth; 12. Guide shoe; 14. Adapter connecting rod; 141. Rod-shaped portion; 142. Connecting portion; 143. Connecting section; 144. Transition section; 15. Adapter push cylinder; 16. Dissolution channel; 161. First channel; 162. Second channel; 17. Shear pin; 18. Sealing shear pin; 20. Tungsten carbide coating; 61. Rubber cartridge assembly; 62. Upper anchoring assembly; 63. Lower anchoring assembly; 100. Double slip soluble bridge plug.

[0032] In the present application, all drawings are schematic drawings, which are only used to illustrate the principles of the present invention and are not drawn according to the actual scale. DETAILED DESCRIPTION

[0033] The present invention will be described below with reference to the accompanying drawings.

[0034] It should be noted that, in the present application, the direction close to the wellhead after the double-clava soluble bridge plug 100 according to the present invention enters the well is described as "top", "up", "front" or similar terms, and the direction away from the wellhead is described as "bottom", "down", "back" or similar terms.

[0035] Embodiment 1:

[0036] This embodiment provides a specific structure of a double-slip soluble bridge plug 100.

[0037] In this embodiment, if Figure 1 and Figure 5 As shown, the double-slip soluble bridge plug 100 includes a central tube 1, on the outer side of the central tube 1, an upper anchor assembly 62, a rubber cartridge assembly 61, a lower anchor assembly 63 and a guide shoe 12 are coaxially sleeved in sequence from top to bottom and axially abut against each other, the upper anchor assembly 62 and the lower anchor assembly 63 are connected to the central tube 1 through a sealing shear pin 18, the guide shoe 12 is fixedly connected to the central tube 1, and a tungsten carbide coating 20 is provided on the surfaces of the central tube 1, the upper anchor assembly 62, the rubber cartridge assembly 61, the lower anchor assembly 63 and the guide shoe 12.

[0038] In a specific embodiment, a plasma arc driven by direct current is used as a heat source to heat a material mainly containing tungsten carbide to a molten or semi-molten state, and is then sprayed on the surface of the central tube 1, the upper anchor assembly 62, the rubber cylinder assembly 61, the lower anchor assembly 63 and the guide shoe 12 to form a tungsten carbide coating 20.

[0039] In a preferred embodiment, an acid-resistant resin shatterable protective film is provided on the outer side of the tungsten carbide coating 20 of the upper anchor assembly 62 and the lower anchor assembly 63. In this embodiment, the dissolved acid-resistant resin liquid is sprayed on the upper anchor assembly 62 and the lower anchor assembly 63 by a spray gun, thereby forming the acid-resistant resin shatterable protective film. In order to ensure the bite ability and stability of the upper anchor assembly 62 and the lower anchor assembly 63, it is necessary to slow down the solubility speed of the upper anchor assembly 62 and the lower anchor assembly 63, so the acid-resistant resin shatterable protective film is provided on the upper anchor assembly 62 and the lower anchor assembly 63.

[0040] According to the present invention, in a specific embodiment, the upper anchoring assembly 62 includes an upper cava 2 and an upper cone 4 coaxially sleeved on the center pipe 1 and adapted to each other, the upper end of the upper cava 2 is axially abutted against the center pipe 1, the upper cone 4 is connected to the center pipe 1 through a sealing shear pin 18, and the lower end of the upper cone 4 is axially abutted against the rubber cartridge assembly 61, and the lower anchoring assembly 63 includes a lower cone 9 and a lower cava 10 coaxially sleeved on the center pipe 1 and adapted to each other, the lower end of the lower cava 10 is axially abutted against the guide shoe 12, the lower cone 9 is connected to the center pipe 1 through a sealing shear pin 18, and the upper end of the lower cone 9 is axially abutted against the rubber cartridge assembly 61.

[0041] In a preferred embodiment, at least two rows of upper anchor teeth 3 are evenly distributed on the upper slip 2, and both the upper slip 2 and the upper anchor teeth 3 are made of high-strength ceramic particles. In this embodiment, the upper anchor teeth 3 use smaller high-strength ceramic particles, preferably with a size of 8×5mm or 9.5×7.5mm. Through this arrangement, the insoluble matter left in the well after dissolution is less than 1%, achieving the effect of facilitating the dissolution of the bridge plug.

[0042] In a preferred embodiment, at least four rows of lower anchor teeth 11 are evenly distributed on the lower slip 10, and both the lower slip 10 and the lower anchor teeth 11 are made of high-strength ceramic particles. In this embodiment, the lower anchor teeth 11 use smaller high-strength ceramic particles, preferably with a size of 8×5mm or 9.5×7.5mm. Through this arrangement, the insoluble matter left in the well after dissolution is less than 2%, achieving the effect of facilitating the dissolution of the bridge plug.

[0043] The rubber cylinder assembly 61 includes an upper metal support ring 5, a rubber cylinder 6 and a lower metal support ring 8 coaxially arranged on the central tube 1 from top to bottom. The upper end of the upper metal support ring 5 is axially abutted against the upper anchor assembly 62, and the lower end of the lower metal support ring 8 is axially abutted against the lower anchor assembly 63.

[0044] A protective ring 7 is provided between the upper metal support ring 5 and the rubber cylinder 6 , and between the lower metal support ring 8 and the rubber cylinder 6 .

[0045] Combination Figure 3As shown, the lower end of the adapter push tube 15 is axially abutted against the upper slip 2, and the adapter connecting rod 14 is fixedly connected to the center pipe 1 through the shear pin 17. When the double slip soluble bridge plug 100 needs to be set, the adapter connecting rod 14 moves upward relative to the adapter push tube 15, and the adapter connecting rod 14 drives the center pipe 1 and the guide shoe 12 to move upward relative to the adapter push tube 15 and the upper slip 2, so that the upper slip 2, the upper cone 4, the upper metal support ring 5, the rubber tube 6, the protective ring 7, the lower metal support ring 8, the lower cone 9, and the lower slip 10 are mutually axially compressed to achieve radial expansion, thereby achieving setting. After the setting is completed, the adapter connecting rod 14 continues to move upward relative to the adapter push tube 15 to cut the shear pin 17, thereby completing the release.

[0046] In another embodiment, the adapter connecting rod 14 can also be connected to the central tube by a threaded connection. In this arrangement, the purpose of controlling the loss of the hand is achieved by controlling the strength of the threaded connection.

[0047] In a specific embodiment, the bridge plug setting method is as follows.

[0048] Step 1: Within 48 hours before the double slip soluble bridge plug 100 is lowered, use a well clearing gauge of corresponding size or slightly larger size to clear the well or simulate pumping.

[0049] Step 2: After the double slip soluble bridge plug 100 is installed at the lower end of the adapter connecting rod 14, the double slip soluble bridge plug 100 is lowered to the fracturing to maintain a continuous operation as much as possible.

[0050] The process of connecting the double slip soluble bridge plug 100 with the adapter connecting rod 14 is as follows:

[0051] The adapter connecting rod 14 is inserted from the top of the double slip soluble bridge plug 100 and aligned with the hole of the shear pin 17 at the top of the double slip soluble bridge plug 100;

[0052] Align and tighten the holes on the adapter connecting rod 14 and the shear pins 17 of the double slip soluble bridge plug 100 with the dedicated shear pins 17;

[0053] Install the limit pin (not shown in the figure), and make sure the pin is installed in the limit slot (not shown in the figure);

[0054] Connect the conversion joint (not shown) until there is no gap between the adapter push cylinder 15 and the double slip soluble bridge plug 100;

[0055] Install no less than four M8 stop pins (not shown) of the conversion joint from the hole (not shown) of the adapter push tube 15.

[0056] In another embodiment, the adapter connecting rod 14 is connected to the central tube 1 by threaded connection, as follows:

[0057] The adapter connecting rod 14 is screwed to the central tube 1 through the thread;

[0058] Install the limit pin (not shown in the figure), and make sure the pin is installed in the limit slot (not shown in the figure);

[0059] Connect the conversion joint (not shown) until there is no gap between the adapter push cylinder 15 and the double slip soluble bridge plug 100;

[0060] Install no less than four M8 stop pins (not shown) of the conversion joint from the hole (not shown) of the adapter push tube 15.

[0061] Step 3: Under normal circumstances, the entry speed of the vertical section is controlled at 50-70m / min, and the maximum entry speed is 70m / min. Under normal circumstances, the entry speed of the horizontal section is controlled at 35-40m / min, and the maximum entry speed is 50m / min.

[0062] After the double slip soluble bridge plug 100 is lowered into place, it starts to be set. The power source for setting can be provided by a hydraulic setting tool equipped with a continuous tubing or a cable gunpowder setting tool.

[0063] The upper part of the adapter push tube 15 is threadedly connected to the outer sleeve of the setting tool (not shown in the figure), and the lower part is axially abutted against the upper slip 2. The top of the adapter connecting rod 14 is threadedly connected to the inner sleeve of the setting tool, and the lower part of the adapter connecting rod 14 is connected to the central pipe 1. During the setting process, the adapter connecting rod 14 and the setting tool remain relatively stationary, and the adapter push tube 15 pushes the upper slip 2 to produce relative displacement.

[0064] The sealing state is: when the initial force is relatively small, the upper metal support ring 5 and the lower metal support ring 8 of the double slip soluble bridge plug 100 are first forced to open, and the rubber cylinder 6 begins to be compressed.

[0065] As the thrust increases, the upper slip 2 and the lower slip 10 are gradually opened, the pins connecting the upper cone 4 and the lower cone 9 with the central tube 1 are sheared off, and the rubber cylinder 6 continues to be squeezed and enlarged.

[0066] As the thrust increases, the upper slip 2 and the lower slip 10 are fully opened. Under the extrusion pressure, the upper slip 2 and the lower slip 10 expand radially along the upper cone 4 and the lower cone 9 respectively, and are gradually pressed onto the wall of the sleeve (not shown in the figure), and the rubber cylinder 6 is compressed to completely seal the sleeve.

[0067] When the thrust gradually increases and reaches the breaking force of the shear pin 17 or the connecting thread connecting the adapter connecting rod 14 and the center pipe 1, the adapter connecting rod 14 is separated from the center pipe 1. At this time, the upper slip 2 and the lower slip 10 are completely bitten and locked on the casing, and the rubber cylinder 6 is squeezed into a surface shape and sealed with the casing, thereby realizing the external sealing of the double slip soluble bridge plug 100 and the casing.

[0068] Step 4: 30 minutes before fracturing, the soluble ball is placed on the ball seat inside the top of the double slip soluble bridge plug 100 to achieve the sealing between the double slip soluble bridge plug 100 and the inside of the casing. Pumping is required immediately after the ball is placed. When the pumping liquid volume difference is 10m 3 When the casing volume of the stuck fracturing layer is reached, the pumping displacement is increased from 3 to 4 m 3 / min down to 1.5~2m 3 / min, fracturing after the ball is seated; the three steps of ball dropping, pumping and fracturing are performed continuously.

[0069] In a preferred embodiment, the center pipe 1 and the guide shoe 12 are made of a soluble magnesium alloy. In this embodiment, the soluble magnesium alloy material includes magnesium, zinc, aluminum, nickel, and copper, and the mass percentage of each component is: magnesium>85%, zinc 2-5%, aluminum 2-4%, nickel 1-3%, and copper 1-3%. The soluble magnesium alloy material provided in this embodiment is combined with the structure of the double slip soluble bridge plug 100, so that the double slip soluble bridge plug 100 can withstand a pressure of up to 70MPa and a temperature range of 0℃~200℃, and can achieve pressure bearing, rapid dissolution, and complete dissolution 6-10 days after construction in a complex wellbore environment.

[0070] In a preferred embodiment, the soluble magnesium alloy material further comprises neodymium and / or cerium, wherein the mass percentage of neodymium is 0-2%, and the mass percentage of cerium is 0-2%.

[0071] Embodiment 2:

[0072] In the prior art, if the bridge plug encounters resistance or gets stuck during the lowering process, and the bridge plug cannot be lifted up, the only option is to wait for the soluble bridge plug to slowly dissolve under the immersion of drilling fluid. Due to the limitation of the bridge plug structure in the prior art, before the bridge plug is released normally, the adapter connecting rod will seal the top of the bridge plug, and the drilling fluid cannot enter the interior of the bridge plug, which reduces the contact surface between the drilling fluid and the bridge plug, and the bridge plug dissolves slowly, which delays the construction time.

[0073] like Figure 1 and Figure 3 As shown, a double-slip soluble bridge plug 100 is shown, including a central pipe 1, an adapter rod 14 is arranged on the top of the central pipe 1, and a dissolution-aiding channel 16 is arranged on the adapter rod 14, and the dissolution-aiding channel 16 connects the space above the adapter rod 14 with the inner cavity 101 of the central pipe 1.

[0074] Under this setting of the present embodiment, in addition to the conventional bridge plug unblocking method in the prior art, the present embodiment can also use other methods for unblocking. When the soluble bridge plug encounters obstruction or gets stuck during entering the well, the dissolution channel 16 can be used for drilling fluid circulation to complete the circulation unblocking. If the drilling fluid circulation cannot complete the unblocking work, the solvent can be pumped downhole to mix the solvent with the drilling fluid in the well and enter the inner cavity 101 of the central pipe 1 through the dissolution channel 16. In this way, the contact area between the solvent and the drilling fluid and the double slip soluble bridge plug 100 can be increased, and the time for dissolving and unblocking can be shortened.

[0075] It is easy to understand that the double slip soluble bridge plug 100 is made of soluble material, which is a prior art and not the technical point of the present invention. A co-solvent is a material that can promote the dissolution of a soluble material, and the specific composition of this material is not the technical point of the present invention and will not be described here.

[0076] In a specific embodiment, the adapter connecting rod 14 includes a rod-shaped portion 141 and a connecting portion 142 which are coaxially fixed from top to bottom, the connecting portion 142 is connected to the central pipe 1, and the dissolution-aiding channel 16 is arranged on the connecting portion 142. During operation, the rod-shaped portion 141 is connected to a downhole tool for controlling the upper body or the lower body of the double slip soluble bridge plug 100.

[0077] In this embodiment, the outer diameter of the connecting portion 142 is greater than the outer diameter of the rod-shaped portion 141. In the actual working process, the central tube 1 is axially abutted against the adapter push tube 15, and the adapter connecting rod 14 is located inside the adapter push tube 15. Since the outer diameter of the connecting portion 142 is greater than the outer diameter of the rod-shaped portion 141, an annulus exists between the rod-shaped portion 141 and the adapter push tube 15, which facilitates the flow of liquid and enables the fluid to enter the inner cavity 101 of the central tube 1 through the dissolution-aiding channel 16.

[0078] Furthermore, in this embodiment, the inner wall of the connecting portion 142 contacts the outer wall of the central tube 1. That is, the connecting portion 142 is coaxially sleeved on the outside of the central tube 1. Figure 1 As shown, the connection portion 142 is fixedly connected to the central pipe 1 via a shear pin 17 .

[0079] In a specific embodiment, the connecting portion 142 is configured as a cylinder with one end closed and the other end open, the closed end of the connecting portion 142 is connected to the rod-shaped portion 141, and the open end of the connecting portion 142 is used to sleeve the central tube 1. Further, the connecting portion 142 includes a connecting section 143 and a transition section 144 that are coaxially fixedly connected, the transition section 144 is located between the rod-shaped portion 141 and the connecting section 143, and the transition section 144 is arranged at the upper end of the connecting section 143, that is, the transition section 144 is the closed end of the connecting portion 142. After the connecting portion 142 is sleeved on the central tube 1, the transition section 144 is located above the central tube 1, and the dissolution-aiding channel 16 is arranged on the transition section 144.

[0080] In this embodiment, a plurality of dissolution-assisting channels 16 are evenly arranged along the circumferential direction on the transition section 144. The central axis of the dissolution-assisting channel 16 is inclined to the central axis of the adapter connecting rod 14. Through this arrangement, the upper end of the dissolution-assisting channel 16 can be communicated with the annulus between the adapter connecting rod 14 and the adapter push cylinder 15, and the lower end of the dissolution-assisting channel 16 can be communicated with the inner cavity 101 of the central pipe 1.

[0081] Embodiment three:

[0082] like Figure 2 and Figure 4 , which shows a schematic diagram of a second embodiment of the double slip soluble bridge plug 100. In this embodiment, the structure of the connecting portion 142 is different from that in the first embodiment, and the remaining structures can refer to the first embodiment. The difference is that in this embodiment, the outer wall of the connecting portion 142 contacts the inner wall of the central pipe 1, that is, the inner wall of the central pipe 1 contacts the outer wall of the connecting portion 142.

[0083] Specifically, the connecting portion 142 includes a connecting section 143 and a transition section 144 which are coaxially arranged, and the transition section 144 is located between the rod-shaped portion 141 and the connecting section 143. The upper portion of the connecting section 143 is arranged in a truncated cone shape, and the radius gradually decreases from top to bottom, and the radius of the upper end of the connecting section 143 is equal to the radius of the transition section 144. The radius of the transition section 144 is greater than the radius of the rod-shaped portion 141.

[0084] After the connecting portion 142 is fixedly connected to the central tube 1 , the transition section 144 is located above the central tube 1 , and the dissolution-aiding channel 16 is arranged on the transition section 144 and the connecting section 143 .

[0085] In a preferred embodiment, the dissolution-aiding channel 16 includes a first channel 161 and a second channel 162, the first channel 161 is located in the transition section 144, and the first channel 161 is perpendicular to the central axis of the adapter connecting rod 14, the second channel 162 is coaxially arranged in the connecting section 143, and the second channel 162 is connected to the first channel 161, and the connection point between the first channel 161 and the second channel 162 is located at the midpoint of the first channel 161.

[0086] Embodiment 4:

[0087] In one embodiment of the present invention, a method for removing obstruction from a bridge plug is provided. When the double-slip soluble bridge plug 100 provided by the present invention encounters obstruction or gets stuck during entering a well, a solvent is pumped into the well, so that the solvent enters the inner cavity of the central pipe 1 through the solvent-aiding channel 16, dissolving the double-slip soluble bridge plug 100, accelerating the dissolution rate of the double-slip soluble bridge plug 100, and completing the removal of obstruction.

[0088] Furthermore, if a protrusion occurs during the seating of the double slip soluble bridge plug 100, the following measures can be taken to achieve the purpose of cyclic dissolution, such as:

[0089] When the double slip soluble bridge plug 100 encounters an obstruction before reaching the predetermined position, liquid can be pumped from the surface into the well to flush the wellbore through the dissolution-aiding channel 16 until the obstruction point is passed;

[0090] When the double-slip soluble bridge plug 100 encounters resistance and is pulled up and stuck, it is determined whether the conditions for on-site sealing are met according to the process requirements. If the construction requirements are met, it is directly sealed. If the double-slip soluble bridge plug 100 needs to be processed, high-concentration brine or acid solution must be pumped into the dissolution-aiding channel 16 of the double-slip soluble bridge plug 100 to achieve drilling-free rapid dissolution of the double-slip soluble bridge plug 100.

[0091] In a preferred embodiment, the site is complicated and normal running cannot be guaranteed. After the double slip soluble bridge plug 100 is taken out and cleared, a smaller double slip soluble bridge plug 100 can be run in according to the wellbore conditions. If the double slip soluble bridge plug 100 is run in and encounters resistance, the cable is pulled up, the running speed is reduced, and the plug is run in again. If resistance is encountered again at the same position, the cable is pulled out, the well clearing gauge is run in and cleared, and if the double slip soluble bridge plug 100 is run in and encounters resistance, the cable is pulled up to the safe tension that the cable can withstand. If the double slip soluble bridge plug 100 cannot be lifted up and loosened, a high concentration (10-15%) potassium chloride aqueous solution or 5 ~15% hydrochloric acid, the potassium chloride aqueous solution or acid solution is transported to the interior of the double slip soluble bridge plug 100 through the dissolution-aiding channel 16, and the double slip soluble bridge plug 100 can be quickly dissolved. After the double slip soluble bridge plug 100 is dissolved or loosened, the pumping pipe string is pulled out for inspection; in the process of lowering the double slip soluble bridge plug 100, if the midway sealing occurs and the ignition is lost, high concentration potassium chloride or 5~15% hydrochloric acid can be pumped in to dissolve the double slip soluble bridge plug 100. After the dissolution is completed, the plug is tested, and the powder and debris produced by the dissolution are flushed into the lower part, and a new double slip soluble bridge plug 100 is pumped again.

[0092] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0093] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0094] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0095] Finally, it should be noted that the above is only a preferred embodiment of the present invention and does not constitute any limitation to the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the aforementioned embodiments or to replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A double slip soluble bridge plug, characterized in that: The invention comprises a central tube (1), on the outer side of the central tube (1), an upper anchor assembly (62), a rubber sleeve assembly (61), a lower anchor assembly (63) and a guide shoe (12) are coaxially sleeved in sequence from top to bottom and are axially abutted against each other; the upper anchor assembly (62) and the lower anchor assembly (63) are connected to the central tube (1) via a sealing shear nail (18); the guide shoe (12) is fixedly connected to the central tube (1); and a tungsten carbide coating (20) is provided on the surfaces of the central tube (1), the upper anchor assembly (62), the rubber sleeve assembly (61), the lower anchor assembly (63) and the guide shoe (12).

2. The double slip soluble bridge plug according to claim 1, characterized in that: A plasma arc driven by direct current is used as a heat source to heat a material mainly containing tungsten carbide to a molten or semi-molten state, and is then sprayed on the surfaces of the central tube (1), the upper anchor assembly (62), the rubber sleeve assembly (61), the lower anchor assembly (63) and the guide shoe (12), thereby forming a tungsten carbide coating (20).

3. The double slip soluble bridge plug according to claim 2, characterized in that: An acid-resistant resin breakable protective film is provided on the outside of the tungsten carbide coating (20) of the upper anchoring assembly (62) and the lower anchoring assembly (63).

4. The double slip soluble bridge plug according to claim 3, characterized in that: The dissolved acid-resistant resin liquid is sprayed onto the upper anchor assembly (62) and the lower anchor assembly (63) by a spray gun.

5. The double slip soluble bridge plug according to any one of claims 1 to 4, characterized in that: The upper anchoring assembly (62) comprises an upper slip (2) and an upper cone (4) which are coaxially sleeved on the center pipe (1) and adapted to each other, the upper end of the upper slip (2) is axially abutted against the center pipe (1), the upper cone (4) is connected to the center pipe (1) via a sealing shear pin (18), and the lower end of the upper cone (4) is axially abutted against the rubber cartridge assembly (61); the lower anchoring assembly (63) comprises a lower cone (9) and a lower slip (10) which are coaxially sleeved on the center pipe (1) and adapted to each other, the lower end of the lower slip (10) is axially abutted against the center pipe (1), the lower cone (9) is connected to the center pipe (1) via a sealing shear pin (18), and the upper end of the lower cone (9) is axially abutted against the rubber cartridge assembly (61).

6. The double slip soluble bridge plug according to claim 5, characterized in that: At least four rows of lower anchor teeth (11) are arranged on the outer wall of the lower slip (10), and the lower anchor teeth (11) are made of high-strength ceramic particles.

7. The double slip soluble bridge plug according to claim 5, characterized in that: At least two rows of upper anchor teeth (3) are arranged on the outer wall of the upper slip (2), and the upper anchor teeth (3) are made of high-strength ceramic particles.

8. The double slip soluble bridge plug according to claim 5, characterized in that: The rubber cylinder assembly (61) comprises an upper metal support ring (5), a rubber cylinder (6) and a lower metal support ring (8) which are coaxially arranged on the central tube (1) from top to bottom, the upper end of the upper metal support ring (5) is axially abutted against the upper anchor assembly (62), and the lower end of the lower metal support ring (8) is axially abutted against the lower anchor assembly (63).

9. The double slip soluble bridge plug according to claim 8, characterized in that: A protective ring (7) is provided between the upper metal support ring (5) and the rubber cylinder (6), and between the lower metal support ring (8) and the rubber cylinder (6).

10. A fracturing method, characterized in that: The double slip soluble bridge plug according to any one of claims 1 to 9 is used for setting, comprising the following steps: Step A: Within 48 hours before the double slip soluble bridge plug is lowered into the oil and gas well, use a well clearing gauge of the corresponding size or larger than the oil and gas well to clear the well or simulate pumping; Step B: Send the double slip soluble bridge plug into the well through the adapter, and control the vertical section running speed at 50-70 m / min and the horizontal section running speed at 35-40 m / min; Step C: After the double slip soluble bridge plug is put into place, it is set. Fracturing operation is carried out within 12 to 18 hours after the double slip soluble bridge plug is set. If the time of fracturing operation is delayed, 1 to 1.5 times the volume of wellbore water can be pumped in to reduce the chloride concentration in the wellbore; Step D: Put the fracturing ball in 30 minutes before fracturing, with a speed of 3 to 4 m 3 / min pumping displacement will pump the fracturing ball into place. When the pumping liquid volume difference is 10m 3 When the casing capacity is reached, the pumping displacement is increased from 3 to 4 m 3 / min down to 1.5~2m 3 / min, fracturing after the ball is seated.

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