Ceramic blanking plug

Abstract

The invention relates to the technical field of under-pressure operation in the petroleum and natural gas industry, and particularly discloses a high-temperature-resistant ceramic plug which comprises an upper connector, a lower connector and a high-temperature-resistant ceramic plug, the upper connector is connected with the lower connector, the high-temperature-resistant ceramic plug is connected between the upper connector and the lower connector in a sealed mode, and the high-temperature-resistant ceramic plug is sunken towards the direction of the lower connector. The maximum inner diameter phi a of the sunken area in the horizontal direction is larger than the inner diameter phi b of the upper connector and smaller than the inner diameter phi c of the lower connector, when the internal and external pressure difference of the sunken portion of the high-temperature-resistant ceramic plug is larger than a threshold value, the lower portion of the sunken portion cracks to form fragments capable of passing through the lower connector, and a residual portion with a fracture is formed on the upper portion of the sunken portion. And the threshold value is set according to the working pressure and temperature of the oil gas pipe at the joint during working. The blanking plug can form a high-temperature-resistant and high-pressure-resistant structure, residual ceramic after crushing can conveniently pass through the blanking plug, and the existing oil-gas-water well under-pressure operation is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of pressure operation in the petroleum and natural gas industry, in particular to a ceramic plug. Background Art

[0002] Pressurized operation is a controlled and forced operation of lifting and lowering the tubing in the wellbore with the help of a pressurized operation machine to overcome the upward force, friction force and downward force caused by the pressure in the well and the weight of the tubing under the pressure of the wellhead of oil, gas and water wells. It can operate and produce at the same time without suppressing the well or releasing the blowout. It can effectively protect the oil and gas layers, maintain the formation energy, shorten the operation cycle, reduce pollutant emissions and stabilize the single well production. It is a green, environmentally friendly, clean and low-carbon technology that is vigorously promoted. It has become one of the key technologies necessary for the large-scale and efficient development of shale gas and tight oil and gas in my country and for tapping the potential and increasing the efficiency of old wells.

[0003] In the construction of pressure operation, in order to prevent the wellbore fluid from overflowing, it is necessary to use the working gate blowout preventer and the working annular blowout preventer to seal the annulus between the tubing and the casing; the plugging tool inside the tubing can seal the inside of the tubing, shield and isolate the internal pressure of the tubing, and prevent the wellbore fluid from entering the tubing. The ceramic plug is a plugging tool inside the tubing, which should be built with a high-temperature resistant ceramic plug. The high-temperature resistant ceramic plug should be able to withstand the pressure from the bottom of the well to isolate the high pressure at the bottom of the well. When the oil, gas and water wells are produced after the well is completed under pressure, the high-temperature resistant ceramic plug will be broken by the top pressure and penetrate the oil, gas and water channels.

[0004] At present, the ceramic plugs used in pressurized operations have been found to have certain limitations. (1) The upper and lower joints of the ceramic plug are a single O-ring seal structure, and its high-temperature and high-pressure sealing capability is generally less than 70MPa. (2) The O-ring seal between the high-temperature resistant ceramic plug and the upper and lower joints and other metal parts has a high-temperature and high-pressure sealing capability that is generally less than 70MPa. (3) The inner diameter of the metal parts of the existing ceramic plugs is smaller than the inner diameter of the oil pipe. At the same time, the inner diameter of the residual ceramic after the high-temperature resistant ceramic plug is broken is smaller than the inner diameter of the plug. This superposition effect causes the inner diameter of the ceramic plug to be significantly smaller than the inner diameter of the oil pipe after the high-temperature ceramic plug is broken. The production flow channel is small, which is easy to cause blockage and affect oil and gas production and the passage of other downhole operation tools such as subsequent wire / cable operations. Summary of the invention

[0005] The object of the present invention is to provide a ceramic plug which can form a structure resistant to high temperature and high pressure and facilitate the passage of residual ceramics after crushing, thereby facilitating pressurized operations in existing oil, gas and water wells.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A ceramic plug comprises an upper joint, a lower joint and a high-temperature resistant ceramic plug, wherein the upper joint is connected to the lower joint, the high-temperature resistant ceramic plug is sealed and connected between the upper joint and the lower joint, the high-temperature resistant ceramic plug forms a depression toward the lower joint, the horizontal maximum inner diameter φa of the depression is greater than the inner diameter φb of the upper joint and smaller than the inner diameter φc of the lower joint, when the pressure difference between the inside and outside of the depression of the high-temperature resistant ceramic plug is greater than a threshold value, the lower part of the depression will rupture to form fragments that can pass through the lower joint, and the upper part of the depression will form a residual part with a fracture, and the threshold value is set according to the working pressure and temperature of the oil and gas pipe at the connection during operation.

[0008] In a further solution, the downwardly depressed area of ​​the high temperature resistant ceramic plug is hemispherical.

[0009] In a further solution, the outer surface of the high temperature resistant ceramic plug hemisphere is provided with an annular groove in the latitude direction, and is provided with a plurality of longitudinal grooves evenly distributed along the spherical surface in the longitude direction.

[0010] In a further solution, a step is provided at the connection between the upper joint and the upper end surface of the high-temperature resistant ceramic plug, and the step is used to limit the upper end surface of the high-temperature resistant ceramic plug. The lower joint is limited by the side outer surface of the high-temperature resistant ceramic plug, and a first high-temperature resistant sealing ring is provided between the two.

[0011] In a further solution, the first high temperature resistant sealing ring is in a "V" shape, and the end of the lower joint connected to the high temperature resistant ceramic plug is in a wedge-shaped structure matching the side of the "V" shape.

[0012] In a further solution, the lower end of the upper joint and the upper end of the lower joint are connected by a first thread, and the first thread is sequentially connected to a support gasket and a second high-temperature resistant sealing ring near the lower end of the high-temperature resistant ceramic plug.

[0013] In a further embodiment, the difference between the latitude value of the annular groove and the latitude value of the upper end surface of the hemispherical shape is greater than 2° and less than 10°.

[0014] In a further embodiment, the maximum horizontal outer diameter of the spherical outer surface at the annular groove is smaller than the inner diameter at the outer lower joint.

[0015] In a further solution, outer surfaces of the upper joint and the lower joint are both provided with threads for connecting with a wrench.

[0016] In a further solution, the upper end of the upper joint and the lower end of the lower joint are both provided with a second thread for connection.

[0017] Beneficial effects of the present invention:

[0018] The ceramic plug of the present invention can effectively seal the pressure in the oil pipe during pressurized operation, greatly improving the high temperature and high pressure sealing performance of the ceramic plug. Therefore, during the downhole operation, the ceramic plug plays a good sealing role. After completing the oil pipe pressurized operation, the ceramic plug can rupture when the internal and external pressure difference reaches a threshold, forming a channel to allow oil and gas to pass through. The operation is simple, which further improves the efficiency of oil, gas and water well pressurized operations and other downhole operations.

[0019] The channel created after the ceramic plug in this case is ruptured can be the same as the inner diameter of the oil pipe, which is easy to form a large-diameter channel, avoiding the adverse effects of blockage on oil and gas production caused by the small-diameter channels formed after the rupture of ceramic pieces on the market. At the same time, it improves the passing capacity of tools such as steel wires and cables during other operations.

[0020] The ceramic plug of the present invention can make the temperature and pressure sealing ability of the wellbore reach 204°C and 105MPa;

[0021] The ceramic plug of the present invention can be widely used in oil, gas and water well pressure operation and other downhole operations. According to the principle of "conventional and unconventional natural gas development in parallel and orderly succession", the country is steadily promoting the continuous increase of conventional natural gas production, orderly accelerating the large-scale development of unconventional natural gas, and ensuring national energy security. There is a huge demand for pressure operation technology. The present invention provides assistance for the safety control of pressure operation and has broad prospects for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 is a cross-sectional schematic diagram of a ceramic plug in an embodiment of the present invention;

[0024] Figure 2 is a schematic diagram of a hemispherical high temperature resistant ceramic plug according to an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the exterior of a ceramic plug in an embodiment of the present invention;

[0026] In the figure: 1, upper joint; 11, step; 2, lower joint; 21, wedge-shaped structure; 3, high temperature resistant ceramic plug; 31, depression; 32, annular groove; 33, longitudinal groove; 4, first high temperature resistant sealing ring; 5, supporting gasket; 6, second high temperature resistant sealing ring; 7, tooth pattern; 8, first thread; 9, second thread. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] like Figure 1 As shown, a ceramic plug includes an upper joint 1, a lower joint 2 and a high-temperature resistant ceramic plug 3. The upper joint 1 is connected to the lower joint 2. The high-temperature resistant ceramic plug 3 is sealed and connected between the upper joint 1 and the lower joint 2. The high-temperature resistant ceramic plug 3 is recessed 31 toward the lower joint 2. The maximum inner diameter φa of the recess 31 of the high-temperature resistant ceramic plug 3 is greater than the inner diameter φb of the upper joint 1 and smaller than the inner diameter φc of the lower joint 2. When the internal and external pressure difference of the recess 31 of the high-temperature resistant ceramic plug 3 is greater than a threshold value, the lower part of the recess 31 will break to form fragments that can pass through the lower joint 2, and a residual part with a fracture will be formed on the upper part of the recess 31. The threshold value is set according to the working pressure and temperature of the oil and gas pipe at the connection during operation.

[0029] Its working principle or implementation method is that the upper joint 1 and the lower joint 2 are used to connect the ends of the oil and gas pipes respectively, and the high-temperature resistant ceramic plug 3 is used as a plugging piece to close the oil and gas pipes. Under the action of the sealed connection, leakage is prevented, so that pressure operation can be achieved. The concave structure of the high-temperature resistant ceramic plug 3 can improve the pressure bearing capacity, so that the pressure and temperature bearing capacity can reach 204°C and 105MPa. When 2-3MPa is pressurized from above the high-temperature resistant ceramic plug 3, the above-mentioned crushing occurs, and the lower fragments of the concave 31 are broken and washed away, and a residual with a fracture is formed on the upper part of the concave 31. Part, restore circulation, can obtain the inner diameter equal to or not much different from the oil pipe, and facilitate oil and gas to pass through the inner channel. Those skilled in the art should know that the specific thickness of the high-temperature resistant ceramic plug 3 can be obtained by referring to the existing ceramic plugging through a limited number of experiments. It can be different according to the need to withstand different high temperatures and high pressures at work. Those skilled in the art should be able to think of the above-mentioned inner diameter preferably being consistent with or not much different from the inner diameter of the oil pipe to be assembled. The residual part can allow oil, gas and water to pass through, and the inner diameter is not much different from the inner diameter of the oil pipe. It is a commonly used matching design method and will not be elaborated one by one.

[0030] According to the above working principle, some preferred embodiments or implementation structures are provided, and the downwardly recessed area 31 of the high temperature resistant ceramic plug 3 is in a hemispherical shape. This makes it easier to connect with the tubular upper and lower joints 2. Those skilled in the art should know that other structures that conform to the above principle should also be included in the scope of the present invention, such as a hemispherical shape, a U shape or an irregular curved surface shape.

[0031] like Figure 2As shown, the outer surface of the high temperature resistant ceramic plug 3 is provided with an annular groove 32 in the latitude direction and a plurality of longitudinal grooves 33 evenly distributed along the spherical surface in the longitude direction. This facilitates the formation of fractures along the predetermined longitudinal grooves 33 and annular grooves 32, so as to form regular circular fractures and fragments of controllable shapes. Such structures that facilitate fractures can also be various, such as intersecting longitudinal grooves 33 and transverse grooves, etc., which will not be described one by one.

[0032] A step 11 is provided at the connection between the upper joint 1 and the upper end surface of the high-temperature resistant ceramic plug 3, and the step 11 is used to limit the upper end surface of the high-temperature resistant ceramic plug 3. The lower joint 2 is limited by the side outer surface of the high-temperature resistant ceramic plug 3, and a sealed first high-temperature resistant sealing ring 4 is provided between the two.

[0033] The first high temperature resistant sealing ring 4 is in a "V" shape, and one end of the lower joint 2 connected to the high temperature resistant ceramic plug 3 is a wedge-shaped structure 21 that matches the side of the "V". The upper joint 1 is loaded with an inverted "V"-shaped first high temperature resistant sealing ring 4 and the lower joint 2. Under the elastic action of the "V"-shaped first high temperature resistant sealing ring 4, the convex surface of the high temperature resistant ceramic plug 3 will not directly contact the wedge-shaped mechanism of the lower joint 2; the V"-shaped first high temperature resistant sealing ring 4 has a stronger sealing ability, and at the same time, the pressure below the high temperature resistant ceramic plug 3 also has a sealing-assisting effect, further improving the sealing performance. The high temperature sealing pressure bearing capacity can reach 204°C and 105MPa, forming an isolation barrier, so that the fluid pressure below the high temperature resistant ceramic plug 3 is blocked and a seal is formed.

[0034] The lower end of the upper joint 1 is connected to the lower end of the upper joint 1 through a first thread 8, wherein the first thread 8 is preferably a short-pitch trapezoidal thread, so that the sealing performance is better, and the first thread 8 is connected to the support gasket 5 and the second high-temperature resistant sealing ring 6 in sequence near the lower end of the high-temperature resistant ceramic plug 3, and the support gasket 5 and the second high-temperature resistant sealing ring 6 can be supported in a groove opened on the first thread 8. In this way, the supporting force and sealing effect can be further improved to prevent leakage.

[0035] like Figure 2 As shown, the difference between the latitude value of the annular groove 32 and the latitude value of the upper end surface of the hemispherical shape is greater than 2° and less than 10°. In this way, after the high-temperature resistant ceramic plug 3 is crushed, the fracture has a certain safe distance from the upper end surface, and the lower part has a certain crushing interval, so that the production flow channel meets the requirements after crushing.

[0036] The maximum horizontal outer diameter of the spherical outer surface at the annular groove 32 is smaller than the inner diameter at the outer lower joint 2. This can solve the problem that the inner diameter of the high-temperature resistant ceramic plug 3 is small after being broken, the production flow channel is limited, the production is easily affected, and other working tools such as steel wires and cables are difficult to pass through.

[0037] like Figure 3As shown, the outer surfaces of the upper joint 1 and the lower joint 2 are both provided with threads 7 for connecting with a wrench. This facilitates assembly and tightening with hydraulic pliers for gas well pressure operation, and prevents the pliers threads 7 from biting the body during the process of making and breaking the pliers.

[0038] The upper end of the upper joint 1 and the lower end of the lower joint 2 are both provided with a second thread 9 for connection.

[0039] The second high temperature resistant sealing ring 6 is an O-ring made of high temperature resistant FFKM perfluororubber material, and the supporting gasket ring 5 is made of high temperature resistant PEEK polyetheretherketone material, which has strong high temperature sealing ability, so that the high temperature resistance and pressure resistance values ​​of the connection between the two and the upper joint and the lower joint are 204°C and 105MPa respectively, which meets the requirements.

[0040] The preferred operation steps during implementation or installation may be: one end of the upper joint 1 is processed with a female thread matching the oil pipe for connection with the matching oil pipe; the other end is processed with a short pitch trapezoidal female thread for connection with the lower joint 2; one end of the lower joint 2 is processed with a male thread matching the oil pipe for connection with the matching oil pipe; the other end is processed with a short pitch trapezoidal male thread for connection with the short pitch trapezoidal female thread of the upper joint 1. During installation, ensure that the upper end face of the high-temperature resistant ceramic plug 3 rests on the step 11 of the upper joint 1, and fits tightly with the upper end face of the high-temperature resistant ceramic plug 3; the outer side of the lower joint 2 is processed with a joint stop, which is used to connect with the terminal end of the upper joint 1. The height of the stop matches the high-temperature resistant ceramic plug 3, ensuring that after the upper joint 1 and the lower joint 2 are assembled, there is an appropriate gap between the wedge-shaped end structure and the high-temperature resistant ceramic plug 3 and no direct contact; an inverted "V"-shaped first high-temperature resistant sealing ring 4 and the lower joint 2 are installed in the upper joint 1. Under the elastic action of the "V"-shaped first high-temperature resistant sealing ring 4, the convex surface of the high-temperature resistant ceramic plug 3 will not directly contact the wedge-shaped structure 21; the inverted "V"-shaped first high-temperature resistant sealing ring 4 has good sealing ability, and at the same time, the pressure below the high-temperature resistant ceramic plug 3 also has a sealing-aiding effect, which further improves the sealing performance and forms an isolation barrier, so that the fluid pressure below the high-temperature resistant ceramic plug 3 is blocked.

[0041] In the process of well completion under pressure, in order to prevent the wellbore fluid from blowing out, referring to the existing construction equipment, it is necessary to use a gate blowout preventer or annular blowout preventer to seal the annulus between the tubing and the casing. The inside of the tubing needs to be sealed with the above-mentioned ceramic plug to prevent the wellbore pressure from entering the tubing. The ceramic plug is a widely used internal plugging tool, and the example of the tubing under pressure is used for description.

[0042] Before the oil pipe enters the well, a ceramic plug needs to be placed at the bottom of the pipe string to block the high pressure in the wellbore, and then the fixed slips and the floating slips are used to overcome the upward force, friction and the combined force caused by the gravity of the pipe string generated by the wellbore pressure, and the oil pipe is continuously lowered. During the process of lowering the oil pipe, the wellbore pressure acts on the convex surface of the high temperature resistant ceramic plug 3;

[0043] When the completion string is lowered to the predetermined position, the tubing hanger is connected, and the tubing hanger is lowered by the pressure-operated machine, and the tubing hanger is seated into the casing spool, and the top screw is pushed into place; the sealing of the tubing hanger is tested, and after the test is qualified, the upper part of the tubing hanger is short-circuited. The above steps are further refined with reference to the existing plug installation process.

[0044] Under the action of pressure, the high-temperature resistant ceramic plug 3 squeezes the inverted V-shaped sealing ring, which plays a good role in assisting sealing, so that its temperature and pressure resistance can reach 204°C and above 105MPa respectively, forming an isolation barrier, so that the fluid pressure below the high-temperature resistant ceramic plug 3 is blocked, playing a blocking role.

[0045] By positive pressurization, when the lower pressure exceeds 2-3MPa, the annular groove contacts with the wedge structure 21 of the lower joint 2 and produces a stress concentration effect; the upper pressure continues to increase, when it exceeds the lower pressure by about 10%, the high-temperature resistant ceramic plug 3 breaks into several fragments along the annular groove 32 and the longitudinal groove 33, and the remaining high-temperature resistant ceramic plug 3 forms a regular circular fracture, and the fracture aperture is basically the same as the inner diameter of the oil pipe. Finally, the overall inner diameter of the above-mentioned ceramic plug is basically consistent with the inner diameter of the oil pipe, forming a large-diameter oil, gas and water channel, which does not affect production and the passage of other operating tools in the later stage.

[0046] Those skilled in the art should be able to imagine that if the shape of the oil pipe changes, the shape of the above-mentioned ceramic plug can be adaptively changed accordingly.

[0047] It should be noted that the terms "first", "second" etc. in the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged in appropriate circumstances, so that the embodiments of the present application described here. In the present application, the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inside", "outside", "middle", "vertical", "horizontal", "lateral", "longitudinal" etc. are based on the orientation or positional relationship shown in the accompanying drawings.

[0048] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. 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 can be combined in any one or more embodiments or examples in a suitable manner.

[0049] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A ceramic plug, characterized in that: The invention comprises an upper joint (1), a lower joint (2) and a high temperature resistant ceramic plug (3), wherein the upper joint (1) is connected to the lower joint (2), the high temperature resistant ceramic plug (3) is sealed and connected between the upper joint (1) and the lower joint (2), the high temperature resistant ceramic plug (3) forms a depression (31) in the direction of the lower joint (2), the maximum inner diameter (φa) of the depression (31) in the horizontal direction is greater than the inner diameter (φb) of the upper joint (1) and smaller than the inner diameter (φc) of the lower joint (2), when the pressure difference between the inside and outside of the depression (31) of the high temperature resistant ceramic plug (3) is greater than a threshold value, the lower part of the depression (31) will break to form fragments that can pass through the lower joint (2), and the upper part of the depression (31) will form a residual part with a fracture, and the threshold value is set according to the working pressure and temperature of the oil and gas pipe at the connection point during operation.

2. A ceramic plug according to claim 1, characterized in that: The downwardly concave (31) area of ​​the high temperature resistant ceramic plug (3) is in a hemispherical shape.

3. A ceramic plug according to claim 2, characterized in that: The outer surface of the high-temperature resistant ceramic plug (3) is provided with an annular groove (32) in the latitude direction on the hemispherical outer surface, and with a plurality of longitudinal grooves (33) evenly distributed along the spherical surface in the longitude direction.

4. A ceramic plug according to claim 3, characterized in that: A step (11) is provided at the connection between the upper joint (1) and the upper end surface of the high-temperature resistant ceramic plug (3), and the step (11) is used to limit the upper end surface of the high-temperature resistant ceramic plug (3). The lower joint (2) is limited by the side outer surface of the high-temperature resistant ceramic plug (3), and a sealed first high-temperature resistant sealing ring (4) is provided between the two.

5. A ceramic plug according to claim 4, characterized in that: The first high temperature resistant sealing ring (4) is in a "V" shape, and one end of the lower joint (2) connected to the high temperature resistant ceramic plug (3) is in a wedge-shaped structure (21) that matches the side surface of the "V" shape.

6. A ceramic plug according to claim 4, characterized in that: The lower end of the upper joint (1) and the upper end of the lower joint (2) are connected via a first thread (8), and the first thread (8) is connected in sequence to a support washer (5) and a second high-temperature resistant sealing ring (6) near the lower end of the high-temperature resistant ceramic plug (3).

7. A ceramic plug according to claim 3, characterized in that: The difference between the latitude value at the annular groove (32) and the latitude value of the upper end surface of the hemispherical shape is greater than 2° and less than 10°.

8. A ceramic plug according to claim 7, characterized in that: The maximum horizontal outer diameter of the spherical outer surface at the annular groove (32) is smaller than the inner diameter at the outer lower joint (2).

9. A ceramic plug according to claim 1, characterized in that: The outer surfaces of the upper joint (1) and the lower joint (2) are both provided with thread patterns (7) for connecting with a wrench.

10. A ceramic plug according to any one of claims 1 to 9, characterized in that: The upper end of the upper joint (1) and the lower end of the lower joint (2) are both provided with a second thread (9) for connection.

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