Metal swellable packer

Abstract

The present application belongs to the technical field of downhole tools, and particularly relates to a metal swelling packer. The metal swelling packer is used for sealing a downhole annulus, and comprises a mandrel and a sealing element arranged outside the mandrel. The sealing element is configured to be capable of swelling in a salt solution environment. The metal swelling packer further comprises anti-burst mechanisms fixedly arranged outside the mandrel. Two anti-burst mechanisms are respectively arranged at two ends of the sealing element. The anti-burst mechanisms are configured to have a size smaller than that of the downhole annulus in an initial state. In a setting process, the outer diameter of the anti-burst mechanisms is expanded to the size of the downhole annulus, so as to limit the swelling direction of the sealing element. The present application can make the sealing element concentrate on radial swelling, and ensure the sealing effect.

Description

Technical Field

[0001] This invention belongs to the field of downhole tool technology, specifically, it relates to a metal swelling packer. Background Technology

[0002] Packers are commonly used tools in oil drilling and completion. Their function is to achieve sealing and isolation of the annulus of the casing or the annulus between the casing and the wellbore.

[0003] Existing packer sealing elements are mainly made of rubber or special metals, achieving annular sealing through physical methods such as mechanical compression or hydraulic expansion. For example, compression packers use mechanical or hydraulic pressure to axially compress the rubber sleeve, causing radial expansion and thus achieving annular sealing. Chinese patent document CN104005729A discloses a metal expansion packer that uses conical sleeve compression to cause plastic deformation of the metal ring, leading to radial expansion of the rubber element and achieving annular sealing. Hydraulic expansion packers achieve annular sealing by injecting fluid into the rubber sleeve, causing volume expansion. Oil / water self-expanding rubber packers achieve annular sealing by absorbing liquid and expanding in volume. These packers rely on the good elasticity and extensibility of rubber to achieve annular sealing. However, rubber and other elastomers suffer from performance degradation under harsh conditions such as high temperature, high pressure, and high salinity, failing to meet the requirements for long-term downhole applications at high temperature and high pressure (>200℃ / 70MPa). Once a packer fails, it may lead to the cessation or failure of oil and gas well construction or production, causing significant losses.

[0004] Chinese patent documents CN111527333A and CN111630247A propose a packer technology based on a metal swelling material. This metal undergoes a chemical hydration reaction with salt water to produce water-insoluble oxides or hydroxides, and the volume of the product is significantly increased compared to the original metal. This product can then be used as a sealing element in a packer to achieve annular sealing. Because it is a metallic material, its sealing effect is less affected by temperature, and the packer structure is simple.

[0005] However, since this packer achieves metal swelling through a chemical reaction, ensuring that the metal expands primarily radially and not axially is crucial for achieving high-pressure packing. Currently, end rings are mainly used to restrict the initial axial displacement of the metal. To ensure good packer insertion performance, the outer diameter of the packer metal elements and end rings must be smaller than the inner diameter of the wellbore. However, relying solely on end rings with fixed outer diameters cannot effectively guarantee that the reaction products will not expand axially, thus significantly affecting the annular packing effect of the packer. Summary of the Invention

[0006] In view of the technical problems mentioned above, the present invention aims to provide a metal swelling packer that, while having good insertion performance, can also effectively limit the expansion direction of the sealing element during the expansion process, thereby improving the sealing effect of the packer.

[0007] According to the present invention, a metal swelling packer is provided for sealing a downhole annulus, comprising a mandrel and a sealing element disposed outside the mandrel, the sealing element being configured to expand in a brine solution environment. The metal swelling packer further includes anti-outburst mechanisms fixedly disposed outside the mandrel, two of the anti-outburst mechanisms being respectively disposed at both ends of the sealing element, wherein the anti-outburst mechanisms are configured such that, in an initial state, the size of the anti-outburst mechanism is smaller than the size of the downhole annulus; during setting, the outer diameter of the anti-outburst mechanism expands to the size of the downhole annulus to limit the expansion direction of the sealing element.

[0008] In one specific embodiment, the anti-protrusion mechanism includes: an anti-protrusion ring, the anti-protrusion ring including a fixed cylinder fixedly connected to the mandrel and a plurality of elastic ribs evenly distributed circumferentially along the fixed cylinder, with an opening groove between two adjacent elastic ribs; and a fixed sleeve, the fixed sleeve being sleeved on the outside of the elastic ribs for causing the elastic ribs to contract; wherein the fixed sleeve is configured to dissolve in a salt solution, and after the fixed sleeve dissolves, the elastic ribs expand radially.

[0009] In one specific embodiment, the elastic rib is disposed on the side of the fixed cylinder near the sealing element.

[0010] In one specific embodiment, the elastic rib tilts toward the sealing element when the setting is completed.

[0011] In one specific embodiment, the anti-protrusion mechanism includes at least two anti-protrusion rings, wherein the elastic ribs of the anti-protrusion rings are misaligned so that the opening slot is blocked by the elastic ribs.

[0012] In one specific embodiment, the anti-protrusion mechanism further includes an end ring sleeved on the mandrel, and the fixing cylinder is fixedly connected to the mandrel through the end ring.

[0013] In one specific embodiment, the end ring is connected to the mandrel via a threaded connection.

[0014] In one specific embodiment, the portion of the retaining sleeve furthest from the end ring is thinner than the portion closer to the end ring.

[0015] In one specific embodiment, the outer diameter of the fixing sleeve is the same everywhere, and the inner diameter of the fixing sleeve near the end ring is smaller than the inner diameter away from the end ring.

[0016] In one specific embodiment, the sealing element is made of any one or more metallic materials selected from magnesium, aluminum, and calcium.

[0017] Compared with the prior art, the advantages of this application are as follows.

[0018] The present invention can be provided with a fixed cylinder fixedly connected to the mandrel and an elastic rib provided at the end of the fixed cylinder. In the initial state, the elastic rib is restricted by the fixed cylinder and is in a contracted state. During the setting process, the fixed cylinder loses its restrictive function and the elastic rib expands radially, thereby restricting the expansion of the sealing element at both ends of the axial direction, so that the sealing element can concentrate on radial expansion and ensure the sealing effect. Attached Figure Description

[0019] The invention will now be described with reference to the accompanying drawings.

[0020] Figure 1 A schematic diagram of one embodiment of the metal swelling packer according to the present invention is shown;

[0021] Figure 2 A schematic diagram showing the disassembly of the anti-protrusion rings according to the present invention when they are used in combination is displayed;

[0022] Figure 3 A schematic diagram showing the shrinkage of the anti-protrusion ring according to the present invention is shown;

[0023] Figure 4 A schematic diagram of the setting of the metal swelling packer according to the present invention is shown.

[0024] In the diagram: 1. Mandrel; 2. End ring; 3. Anti-outburst ring; 31. Fixed cylinder; 32. Elastic rib; 33. Opening groove; 4. Sealing element; 5. Fixed sleeve; 6. Anti-outburst mechanism; 10. Wellbore; 100. Metal swelling packer.

[0025] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0026] The invention will now be described with reference to the accompanying drawings.

[0027] It should be noted that the directional terms or qualifiers such as "up" and "down" used in this application are all specific to the referenced [reference]. Figure 1 In this context, "axial" refers to the direction in which the axis of the mandrel points, i.e. Figure 1 The vertical direction is defined as "up" and the radial direction as "down". The radial direction refers to the direction perpendicular to the axial direction. These terms are not used to define the absolute position of the components involved, but can vary depending on the specific circumstances.

[0028] Figure 1 A schematic diagram of one embodiment of the metal swelling packer 100 according to the present invention is shown; Figure 2 This shows a schematic diagram of the disassembly of the anti-protrusion ring 3 according to the present invention when they are used in combination; Figure 3 A schematic diagram of the anti-protrusion ring 3 according to the present invention during retraction is shown; Figure 4 A schematic diagram of the setting of the metal swelling packer 100 according to the present invention is shown.

[0029] like Figure 1 As shown, the metal swelling packer 100 provided according to the present invention includes a mandrel 1, a sealing element 4, and anti-protrusion mechanisms 6. In this embodiment, the mandrel 1 is a long cylindrical shape. The sealing element 4 is also a long cylindrical shape and is sleeved on the outer wall of the mandrel 1. Two anti-protrusion mechanisms 6 are both sleeved on the outer wall of the mandrel 1 and are respectively disposed at the upper and lower ends of the sealing element 4.

[0030] Specifically, the sealing element 4 is made of metals such as magnesium, aluminum, and calcium, or an alloy formed by a combination of these metals. These metals and alloys undergo a metal hydration reaction in a salt solution environment to generate metal oxides or hydroxides. The volume of these products is significantly increased compared to the original metal or alloy, thus enabling a seal with adjacent interfaces. For example, the volume expansion rate of magnesium reacting with water to form magnesium hydroxide can reach 85%, while the volume expansion rate of aluminum reacting with water to form aluminum hydroxide can reach 160%. The specific structure of the sealing element 4 can be found in Chinese patent document CN111527333A.

[0031] The following example uses the setting of the wellbore 10. In this embodiment, the downhole annulus refers to the annular space between the wellbore 10 and the mandrel 1. In the initial state, the size of the anti-outburst mechanism 6 is smaller than the size of the downhole annulus. During the setting process, the outer diameter of the anti-outburst mechanism 6 expands to the size of the downhole annulus to limit the expansion direction of the sealing element 4.

[0032] In a preferred embodiment, in the initial state, as Figure 1 As shown, the outer diameter of the anti-outburst mechanism 6 is equal to the outer diameter of the sealing element 4. At this time, the metal swelling packer 100 has good insertion performance, which is conducive to the rapid insertion of the metal swelling packer 100 to the designed depth of the wellbore 10, after which setting begins. During the setting process, a salt solution is injected into the wellbore 10. The outer diameter of the anti-outburst mechanism 6 first expands and contacts the inner wall of the wellbore 10. The sealing element 4 also begins to gradually expand. Since the anti-outburst mechanism 6 has blocked both ends of the axial direction of the sealing element 4, limiting the axial expansion direction of the sealing element 4, the sealing element 4 can fully expand radially when expanding, thereby improving the sealing effect. When setting is completed, as Figure 4 As shown, the outer diameter of the anti-outburst mechanism 6 is equal to the outer diameter of the sealing element 4 and the inner diameter of the wellbore 10.

[0033] According to the present invention, the sealing element 4 is not limited to the cylindrical type provided by the present invention, and its specific shape is not a technical point of the present invention, and will not be described in detail here.

[0034] In one specific embodiment, the anti-protrusion mechanism 6 includes an anti-protrusion ring 3 and a fixing sleeve 5. Wherein, as... Figure 2 and Figure 3 As shown, the anti-surge ring 3 is made of elastic metal material and includes a fixed cylinder 31 and multiple elastic ribs 32. The fixed cylinder 31 is sleeved on the outside of the mandrel 1 and fixedly connected to the mandrel 1. The multiple elastic ribs 32 are evenly distributed circumferentially along the fixed cylinder 31 and are located at the ends of the fixed cylinder 31. An opening groove 33 is formed between two adjacent elastic ribs 32. In the absence of external force, the multiple elastic ribs 32 are in the shape of a conical disc with a certain angle. The fixed sleeve 5 is made of soluble material, and its outer diameter is equal to the outer diameter of the sealing element 4 in the initial state. It is sleeved on the outside of the elastic ribs 32 to provide radial constraint force for the elastic ribs 32, so that the elastic ribs 32 contract and fit against the sealing element 4. With this arrangement, when the fixed sleeve 5 is dissolved by the salt solution and loses its strength, the elastic ribs 32 lose their radial constraint force and expand radially to abut against the inner wall of the well casing 10, thereby constraining the axial expansion direction of the sealing element 4.

[0035] It is easy to understand that the soluble material used to make the fixing sleeve 5 is a common material in the field of downhole tool technology, and is not a key technical point of this invention, so it will not be described in detail here.

[0036] According to the present invention, the elastic rib 32 is disposed on the side of the fixed cylinder 31 near the sealing element 4, and the conical disc-shaped openings formed by the elastic ribs 32 of the two anti-protrusion rings 3 located at the upper and lower ends of the sealing element 4 are opposite each other, i.e. Figure 4 As shown, after the elastic rib 32 loses the radial constraint of the fixing sleeve 5, it tilts towards the sealing element 4. Under the action of the elastic rib 32, the sealing element 4 expands, and its cross-section is a trapezoid with a shorter outer side and a longer inner side. The direction closer to the center of the wellbore 10 is considered "inner," and the direction farther from the center of the wellbore 10 is considered "outer." This arrangement further directs the expansion volume of the sealing element 4 radially, which is beneficial for improving the sealing effect of the setting seal.

[0037] In a preferred embodiment, such as Figure 2 As shown, each anti-protrusion mechanism 6 includes at least two anti-protrusion rings 3, with the elastic ribs 32 of the anti-protrusion rings 3 misaligned, thereby blocking the opening groove 33. This arrangement further blocks the axial expansion direction of the sealing element 4, improving the sealing effect.

[0038] In a preferred embodiment, the anti-protrusion mechanism 6 further includes an end ring 2 sleeved on the mandrel 1, and a fixing cylinder 31 fixedly connected to the mandrel 1 via the end ring 2. Specifically, the outer diameter of the end ring 2 is equal to the outer diameter of the sealing element 4 in the initial state. The end ring 2 is sleeved on the mandrel 1 via a threaded connection, and the fixing cylinder 31 of the anti-protrusion ring 3 is disposed inside the end ring 2 via an insertion connection. A fixing sleeve 5 is sleeved on the outside of the elastic rib 32, and the fixing sleeve 5 abuts against the end face of the end ring 2.

[0039] According to the present invention, such as Figure 1 As shown, in a preferred embodiment, the portion of the fixing sleeve 5 furthest from the end ring 2 is thinner than the portion closer to the end ring 2. Specifically, the outer diameter of the fixing sleeve 5 is constant throughout, and the thickness difference is achieved by varying the inner diameter of the fixing sleeve 5. This arrangement ensures that, on the one hand, the thicker portion prevents the fixing sleeve 5 from failing during insertion, while the thinner portion allows the fixing sleeve 5 to dissolve quickly upon contact with the salt solution. On the other hand, during the stage where the elastic rib 32 is in contact with the inner wall of the fixing sleeve 5, the elastic rib 32 can be divided into a first segment, a second segment, and a third segment connected sequentially. The first segment is parallel or nearly parallel to the fixing cylinder 31, the second segment is parallel to... Figure 4 The inclined direction of the elastic rib 32 after contacting the well casing 10 is parallel or nearly parallel, and the third section is parallel to the fixed cylinder 31. Under this arrangement, the elastic rib 32... Figure 1 Become Figure 4 During the process, the changes in the first and second segments are small or constant, which helps to further control the expansion direction of the sealing element 4, ultimately allowing the sealing element 4 to form Figure 4 The shape shown.

[0040] In a preferred embodiment, to further ensure that the dissolution of the fixing sleeve 5 precedes the expansion of the sealing element 4, the dissolution time of the fixing sleeve 5 can be controlled by controlling the composition of the soluble material constituting the fixing sleeve 5. However, the method of controlling the dissolution rate by changing the composition of the soluble material is prior art and not a key feature of this invention, and will not be elaborated upon here.

[0041] According to the present invention, the specific working principle is as follows.

[0042] In the initial state, such as Figure 1 As shown, the outer diameter of the anti-outburst mechanism 6 is equal to the outer diameter of the sealing element 4. Specifically, the outer diameters of the end ring 2 and the fixing sleeve 5 are equal to the outer diameter of the sealing element 4. At this time, the metal swelling packer 100 has good running performance, which is conducive to the rapid running of the metal swelling packer 100 to the designed depth of the wellbore 10, after which setting begins.

[0043] During the setting process, a salt solution is injected into the wellbore 10. The thinner portion of the fixing sleeve 5 dissolves first, losing its radial constraint on the elastic rib 32. This causes the elastic rib 32 to expand radially and contact the inner wall of the wellbore 10. Then, the sealing element 4 also begins to gradually expand. Since the elastic rib 32 has blocked both ends of the sealing element 4, restricting the axial expansion direction of the sealing element 4, the sealing element 4 can fully expand radially during expansion, thereby improving the sealing effect.

[0044] Upon completion of the setting process, the sealing element 4 expands to... Figure 4 The state shown is as follows. At this time, the elastic rib 32 is fully expanded, and its end near the wellbore 10 is pressed against the wellbore 10 by the sealing element 4. In this configuration, the elastic rib can also withstand axial pressure and support the metal swelling packer 100, thereby improving the pressure-bearing capacity of the metal swelling packer 100.

[0045] The metal swelling packer 100 of this invention solves the problems of temperature resistance and long-term sealing reliability of packers by using a special metal material to replace the rubber packer sealing element 4 in the prior art. Furthermore, this packer achieves setting through a chemical reaction, eliminating the need for mechanical and hydraulic setting operations. It features a simple structure, convenient operation, and multiple elastic ribs 32 working together, with minimal requirements on wellbore shape and clearance. This metal swelling packer 100 has good adaptability to field well conditions and can meet the annular sealing requirements of ultra-deep wells, geothermal wells, and hot dry rock wells.

[0046] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0047] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0048] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0049] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A metal swelling packer for sealing a downhole annulus, comprising a mandrel (1) and a sealing element (4) disposed outside the mandrel (1), the sealing element (4) being configured to expand in a brine solution environment, characterized in that, The metal swelling packer also includes anti-protrusion mechanisms (6) fixedly disposed outside the mandrel (1), with two anti-protrusion mechanisms (6) respectively disposed at both ends of the sealing element (4), wherein the anti-protrusion mechanisms (6) are configured such that... In the initial state, the size of the anti-outburst mechanism (6) is smaller than the size of the downhole annulus; During the setting process, the outer diameter of the anti-outburst mechanism (6) expands to the size of the downhole annulus to limit the expansion direction of the sealing element (4). The anti-protrusion mechanism (6) includes: an anti-protrusion ring (3), which includes a fixed cylinder (31) fixedly connected to the mandrel (1) and a plurality of elastic ribs (32) evenly distributed circumferentially along the fixed cylinder (31), with an opening groove (33) between two adjacent elastic ribs (32); a fixed sleeve (5), which is sleeved on the outside of the elastic ribs (32) to cause the elastic ribs (32) to contract; wherein, the fixed sleeve (5) is configured to dissolve in a salt solution, and after the fixed sleeve (5) dissolves, the elastic ribs (32) expand radially, and the anti-protrusion mechanism (6) includes at least two anti-protrusion rings (3), with the elastic ribs (32) of the anti-protrusion rings (3) being misaligned so that the opening groove (33) is blocked by the elastic ribs (32).

2. The metal swelling packer according to claim 1, characterized in that, The elastic rib (32) is disposed on the side of the fixed cylinder (31) near the sealing element (4).

3. The metal swelling packer according to claim 2, characterized in that, When the sealing is completed, the elastic rib (32) tilts toward the sealing element (4).

4. The metal swelling packer according to any one of claims 1 to 3, characterized in that, The anti-protrusion mechanism (6) also includes an end ring (2) sleeved on the mandrel (1), and the fixed cylinder (31) is fixedly connected to the mandrel (1) through the end ring (2).

5. The metal swelling packer according to claim 4, characterized in that, The end ring (2) is connected to the mandrel (1) by a threaded connection.

6. The metal swelling packer according to claim 4, characterized in that, The portion of the fixing sleeve (5) furthest from the end ring (2) is thinner than the portion closest to the end ring (2).

7. The metal swelling packer according to claim 6, characterized in that, The outer diameter of the fixing sleeve (5) is the same everywhere, and the inner diameter of the fixing sleeve (5) near the end ring (2) is smaller than the inner diameter of the part away from the end ring (2).

8. The metal swelling packer according to any one of claims 1 to 3, characterized in that, The sealing element (4) is made of one or more metallic materials selected from magnesium, aluminum, and calcium.

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