Split type soluble bridge plug and stratum packing process

Abstract

The invention belongs to the technical field of oil and gas exploitation, and particularly relates to a split type soluble bridge plug and a stratum packing process. The split type soluble bridge plug comprises an anchor and a sealer, and after the anchor is anchored on the inner wall of an underground casing pipe, the sealer is coaxially inserted into the anchor in a sealed mode and is sealed with the underground casing pipe. The packer can complete stratum packing under the casing deformation working condition.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas exploitation, and in particular relates to a split soluble bridge plug and a formation isolation process. Background Art

[0002] At present, soluble bridge plugs have been widely used for formation isolation in the process of oil and gas well operation. The use of soluble bridge plugs for formation isolation can effectively achieve staged fracturing. With the increase in the drilling depth of oil and gas wells, the requirements for soluble bridge plugs are getting higher and higher. In some areas, the tight oil reservoir is as high as 6000-8000m, and the depth of some blocks is even above 8000m. There are reservoir characteristics such as ultra-high temperature of 150℃-200℃ and high pressure of 70-100MPa. Due to the dense formation and extremely high fracture pressure, the casing is very easy to deform, and the deformation size is relatively large. Some wellbores are affected by wellbore fracturing or block pressure, and even by the regional formation geology, and the deformation size is greater than 20%.

[0003] Conventional soluble bridge plugs are affected by their materials and structures. Soluble magnesium alloy materials that bear high pressure need to be added with other alloy materials with strong compressive resistance, and the proportion of magnesium components needs to be reduced, which restricts their ductility. The elongation performance itself cannot be as good as that of high-component (magnesium>90%) magnesium alloy materials. The support ring and protection ring that protect the soluble rubber rubber cylinder need a larger outer diameter support, which is extremely incompatible with the passing performance of casing-change well construction.

[0004] Conventional soluble bridge plugs require that the cone and slips be greatly expanded in structure, but the structure changes greatly, and it is difficult to control the angle structure of the cone and slips and the structure of the casing engagement. The slips may not be fully expanded, thus affecting the engagement and anchoring performance of the slip teeth, and may slip due to the high pressure during fracturing.

[0005] In view of the sleeve change working condition, the current basic method is to use large, medium, small or smaller diameter bridge plugs one by one until the bridge plug reaches its setting limit. This method of multiple bridge plug insertion increases the cost of soluble bridge plug tools, liquids, cycles and other ineffective costs. Secondly, although sometimes a small diameter conventional bridge plug passes and completes the setting, due to the structural limitations of the bridge plug itself, the setting is not tight and slippage often occurs during fracturing, resulting in ineffective operations. Summary of the invention

[0006] In view of the technical problems mentioned above, the present invention aims to provide a split soluble bridge plug, which can complete formation isolation under casing change conditions.

[0007] The present invention also proposes a formation isolation process, which uses the split soluble bridge plug proposed by the present invention to perform formation isolation.

[0008] According to the present invention, a split soluble bridge plug is provided, comprising an anchor and a sealer. After the anchor is anchored on the inner wall of a downhole casing, the sealer is coaxially sealed and inserted into the anchor and sealed with the downhole casing.

[0009] In a specific embodiment, the anchor includes a center tube, a cava and a guide shoe fixing seat which are coaxially arranged in sequence from top to bottom, the lower end of the cava is fixedly connected to the upper end of the guide shoe fixing seat, the lower end of the center tube is connected to the upper end of the cava through a conical surface, and when the center tube moves downward relative to the cava, the cava can be radially expanded through the conical surface, so that the cava is anchored to the inner wall of the downhole casing.

[0010] In a specific embodiment, a plurality of anchoring teeth are evenly arranged on the outer wall of the slip along the circumferential direction.

[0011] In a specific embodiment, at least four circles of anchoring teeth are provided on the outer wall of the slip.

[0012] In a specific embodiment, a primary sealing ring is coaxially arranged on the outer wall of the central tube through a conical surface, and the lower end surface of the primary sealing ring abuts against the upper end surface of the slip.

[0013] In a specific embodiment, ratchets are provided between contact surfaces of the slips and the central pipe.

[0014] In a specific embodiment, the sealer comprises:

[0015] Support frame;

[0016] A plurality of rubber sealing rings are coaxially arranged in sequence along the axial direction on the outer wall of the support frame;

[0017] A guide shoe is coaxially fixed at the lower end of the support frame, and the guide shoe is configured to be sealably inserted into the guide shoe fixing seat.

[0018] In a specific embodiment, a plurality of circles of one-way locking rings are provided between the support frame and the guide shoe, and the one-way locking rings are configured to be adaptable to the inner wall of the anchor.

[0019] In a specific embodiment, the support skeleton and the rubber sealing ring are made of soluble rubber, and the support skeleton and the rubber sealing ring can expand radially in response to axial pressure, thereby enhancing sealing.

[0020] According to the present invention, a formation isolation process is also provided, using the split soluble bridge plug provided by the present invention, an anchor is put into the well and anchored on the inner wall of the downhole casing, and then a sealer is pumped into the well, the lower part of the sealer is inserted into the anchor, the anchor is sealed, and the upper part of the sealer is sealed with the downhole casing.

[0021] Compared with the prior art, the advantages of the present application are as follows.

[0022] The present invention includes an anchor and a sealer. During the working process, the anchor is first set and released at the target position using a pumping tool according to a conventional process. The slip of the anchor is anchored on the casing through anchoring teeth, and the primary sealing ring plays a preliminary sealing role with the casing wall. At this time, the perforating tool can be used to complete the perforation operation of multiple clusters. After the pumping and perforating tools are pulled out, the sealer is pumped into the position of the anchor before the fracturing begins. The pumping pressure pushes the sealer into the anchor and completes the locking. Under a certain displacement and liquid pressure, the sealer is axially compressed, thereby expanding radially to complete the isolation.

[0023] Due to structural limitations, conventional bridge plugs need to consider both sealing and anchoring performance, and the slips cannot expand significantly in the radial direction, so they cannot be firmly anchored with the downhole casing. The present invention sets the anchor and the sealer separately, and can set the anchor with longer slips and more slip anchoring teeth without considering sealing, so as to obtain a larger radial expansion size. Under this setting, the outer diameter of the anchor can be made smaller than that of the conventional bridge plug for cased wells, and its passing performance in cased wells is more advantageous.

[0024] At the same time, the sealer is made of soluble rubber and has a multi-stage rubber sealing ring, which has better compression performance and excellent passing performance in the sleeve variable section.

[0025] The two-stage split soluble bridge plug provided by the present invention can complete the setting, isolation and sealing pressure-bearing operations under certain formation temperature and 70MPa high-pressure working pressure difference conditions when the casing is relatively serious, avoiding the cased wells that cause repeated changes of tools and multiple pumping and running of soluble bridge plugs due to the inability to determine the size of conventional soluble bridge plugs at one time, thereby wasting the pumping and running of soluble bridge plug tools, liquids, cycles and other ineffective costs. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0027] Figure 1 A schematic diagram showing an embodiment of an anchor of a split-type soluble bridge plug according to the present invention;

[0028] Figure 2 A schematic diagram showing an embodiment of a sealer of a split soluble bridge plug according to the present invention is shown.

[0029] In the figure:

[0030] 1. Center pipe; 2. Conical surface; 3. Primary sealing ring; 4. Anchoring tooth; 5. Slip; 6. Locking fixture; 7. Guide shoe fixture; 71. Large diameter part; 72. Small diameter part; 8. Guide shoe; 9. One-way locking ring; 10. Rubber sealing ring; 11. Support frame; 111. Skeleton short section; 12. End sealing ring; 13. Conical ring; 14. Column ring; 100. Split soluble bridge plug; 101. Anchor; 102. Seal.

[0031] 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

[0032] The present invention will be described below with reference to the accompanying drawings.

[0033] It should be noted that, in the present application, the direction of the split soluble bridge plug 100 according to the present invention approaching the wellhead after entering the well is described as "up", "front" or similar terms, that is, Figure 1 The direction away from the wellhead is described as "down", "back" or similar terms, i.e. Figure 1 on the left side.

[0034] Figure 1 The structure of the anchor 101 of the split soluble bridge plug 100 according to the present invention is shown. Figure 2 The structure of the sealer 102 of the split soluble bridge plug 100 according to the present invention is shown.

[0035] like Figure 1 and Figure 2 As shown, the split soluble bridge plug 100 includes an anchor 101 and a sealer 102. After the anchor 101 is anchored on the inner wall of a downhole casing (not shown in the figure), the sealer 102 is coaxially sealed and inserted into the anchor 101 and sealed with the downhole casing.

[0036] like Figure 1 As shown, the anchor 101 includes a center pipe 1, a cava 5 and a guide shoe fixing seat 7 which are coaxially arranged from top to bottom. The lower end of the cava 5 is fixedly connected to the upper end of the guide shoe fixing seat 7, and the lower end of the center pipe 1 is connected to the upper end of the cava 5 through a conical surface 2. When the center pipe 1 moves downward relative to the cava 5, the cava 5 can be radially expanded through the conical surface, so that the cava 5 is anchored to the inner wall of the downhole casing.

[0037] Specifically, the lower outer wall of the central tube 1 is set to be a conical surface 2, and the outer diameter of the conical surface 2 gradually decreases from top to bottom, the upper inner wall of the slip 5 is set to be a cone adapted to the conical surface 2, and the upper inner diameter of the slip 5 gradually decreases from the top. The inner wall of the slip 5 contacts the conical surface 2 of the central tube 1.

[0038] The well-entering tool of the anchor 101 includes a center rod (not shown in the figure) and a push tube (not shown in the figure). The well-entering tool is a prior art and is not the technical key point of the present invention.

[0039] The process of lowering the anchor 101 into the downhole casing (not shown in the figure) is as follows: on the ground, the center rod is coaxially inserted into the anchor 101, and fixedly connected to the guide shoe fixing seat 7 of the anchor 101 by shear pins or other means; the slip 5 is sleeved on the center rod from top to bottom, and fixedly connected to the upper end of the guide shoe fixing seat 7 by threaded connection; the center pipe 1 is sleeved on the center rod from top to bottom, and the conical surface 2 of the center pipe 1 is in contact with the inner wall of the slip 5; the push tube is sleeved on the center rod from top to bottom, and the lower end surface of the push tube is in contact with the upper end surface of the center pipe 1; finally, the push tube and the center rod carry the anchor 101 into the well.

[0040] After the anchor 101 is put into the well, the center rod of the well tool moves upward relative to the push tube of the well tool, so that the slips 5 move upward relative to the center pipe 1. The slips 5 expand radially under the action of the conical surface 2, so as to be anchored on the inner wall of the downhole casing.

[0041] In a specific embodiment, the central tube 1, slips 5 and guide shoe fixing seat 7 of the anchor 101 are made of soluble magnesium alloy material.

[0042] In a specific embodiment, a plurality of anchor teeth 4 are evenly arranged along the circumferential direction on the outer wall of the slip 5. Preferably, at least four circles of anchor teeth 4 are arranged along the axial direction on the outer wall of the slip 5. The anchor teeth 4 are all made of high-strength ceramic particles.

[0043] In a specific embodiment, the outer wall of the lower end of the guide shoe fixing seat 7 is configured to be tapered, and the outer diameter of the tapered portion gradually decreases from top to bottom.

[0044] The shoe guide fixing seat 7 includes a large diameter portion 71 and a small diameter portion 72. The outer diameter of the large diameter portion 71 is larger than the outer diameter of the small diameter portion 72. An external thread is provided on the outer wall of the small diameter portion 72. The cava 5 is fixedly connected to the small diameter portion 72 by a threaded connection. The lower end surface of the cava 5 abuts against the upper end surface of the large diameter portion 71 of the shoe guide fixing seat 7.

[0045] In a preferred embodiment, a locking fixing seat 6 is fixedly provided on the upper end of the small diameter portion 72 of the guide shoe fixing seat 7. The locking fixing seat 6 can be adapted to the one-way locking ring 9. The one-way locking ring 9 can only move downward relative to the locking fixing seat 6 and cannot move upward.

[0046] In a preferred embodiment, a primary sealing ring 3 is coaxially arranged on the outer wall of the central tube 1 through the conical surface 2, the inner wall of the primary sealing ring 3 is also set to be conical, and the cone angle of the inner wall of the primary sealing ring 3 is equal to the cone angle of the conical surface 2 of the central tube 1, and the lower end surface of the primary sealing ring 3 abuts against the upper end surface of the slip 5. In the process of the central tube 1 moving downward relative to the slip 5, the primary sealing ring 3 is also radially expanded by the conical surface 2 of the central tube 1, and the primary sealing ring 3 can be sealed with the downhole casing after radial expansion.

[0047] Furthermore, in a preferred embodiment, the inner wall of the upper end of the central tube 1 is configured to be conical.

[0048] According to the present invention, a ratchet (not shown in the figure) is provided between the contact surface of the cava 5 and the center tube 1. The ratchet enables the cava 5 to move upward only relative to the center tube 1. After the cava 5 is radially expanded and anchored by the center tube 1, the ratchet locks the cava 5 and the center tube 1 so that the two cannot be reset, thereby preventing the anchoring from loosening.

[0049] According to the present invention, the sealer 102 comprises a support frame 11 , a rubber sealing ring 10 and a guide shoe 8 .

[0050] A plurality of rubber sealing rings 10 are coaxially arranged in sequence along the axial direction on the outer wall of the support frame 11. A guide shoe 8 is coaxially fixed at the lower end of the support frame 11, and the guide shoe 8 is configured to be able to be sealed and plugged into the guide shoe fixing seat 7.

[0051] In a preferred embodiment, the support frame 11 and the rubber sealing ring 10 are made of soluble rubber, and the support frame 11 and the rubber sealing ring 10 can respond to axial pressure and expand radially, thereby enhancing sealing. The outer diameter of the guide shoe 8 is smaller than the outer diameter of the support frame 11, and the outer diameter of the support frame 11 is adapted to the inner diameter of the central tube 1.

[0052] During the anchoring process of the anchor 101, the central tube 1 moves downward relative to the slip 5, so after the anchor 101 is anchored on the inner wall of the downhole casing, the axial length of the anchor 101 is greatly shortened. Before the fracturing begins, the sealer 102 is pumped into the downhole, so that the guide shoe 8 of the sealer 102 is inserted into the guide shoe fixing seat 7. The guide shoe 8 is made of soluble rubber. After the guide shoe 8 is inserted into the guide shoe fixing seat 7, the inner cavity of the guide shoe fixing seat 7 can be sealed, and then the inner cavity of the anchor 101 can be sealed. Since the axial length of the anchor 101 is greatly shortened, after the guide shoe 8 is inserted into the guide shoe fixing seat 7, the lower length of the support frame 11 is located in the central tube 1, and the upper part of the support frame 11 is located above the central tube 1. The lower part of the support frame 11 is adapted to the central tube 1 to seal the inner cavity of the central tube 1. At the same time, the rubber sealing ring 10 on the support frame 11 can be adapted to the conical inner wall at the upper end of the central tube 1 to further seal the central tube 1. The upper part of the support frame 11 is matched with the inner wall of the downhole casing through the rubber sealing ring 10 to seal the downhole casing.

[0053] In a preferred embodiment, a plurality of one-way locking rings 9 are arranged between the support frame 11 and the guide shoe 8, and the one-way locking rings 9 are arranged to be adapted to the inner wall of the anchor 101. Under this arrangement, after the guide shoe 8 is inserted into the guide shoe fixing seat 7, the one-way locking ring 9 can contact the inner wall of the anchor 101, so that the sealer 102 can only move downward relative to the anchor 101, and cannot move upward, thereby preventing the seal from failing.

[0054] In a preferred embodiment, the supporting skeleton 11 includes a plurality of coaxially fixedly connected skeleton short sections 111 , and a rubber sealing ring 10 is coaxially arranged on each skeleton short section 111 .

[0055] In a preferred embodiment, an end sealing ring 12 is provided at the upper end of the support frame 11 , the outer diameter of the end sealing ring 12 is greater than the outer diameter of the rubber sealing ring 10 , and the axial length of the end sealing ring 12 is greater than the axial length of the rubber sealing ring 10 .

[0056] In a preferred embodiment, the rubber sealing ring 10 comprises a coaxially fixedly connected cone ring 13 and a column ring 14. The outer diameter of the cone ring 13 gradually decreases from top to bottom, and the end with the largest outer diameter of the cone ring 13 is equal to the outer diameter of the column ring 14, and the two are fixedly connected.

[0057] In a preferred embodiment, the outer diameter of the end sealing ring 12 gradually decreases from top to bottom.

[0058] According to the present invention, in a specific embodiment, a formation isolation process is provided, and the formation is isolated using the split soluble bridge plug 100 provided by the present invention. First, an anchor 101 is put into the well and anchored on the inner wall of the downhole casing, and then a sealer 102 is pumped into the well, and the lower part of the sealer 102 is inserted into the anchor 101 to seal the anchor 101, and the upper part of the sealer 102 is sealed with the downhole casing.

[0059] In a specific embodiment, the on-site construction process technology is to first seal the anchor 101 at the target position by using a cable soluble bridge plug or oil connection according to the conventional process. When the anchor 101 is anchored on the casing, the primary sealing ring 3 plays a preliminary sealing role with the casing wall. At this time, the multi-cluster perforating operation can continue to be completed normally. After the pumping and perforating tools are pulled out, the soluble sealer 102 is put in to replace the conventional soluble ball before the fracturing starts and is pumped into the anchor 101. Position, pumping pressure pushes the soluble sealer 102 into the anchor 101, and the guide shoe 8 of the sealer 102 is pressed into the locking seat 6 of the anchor 101, until the sealer 102 can no longer go down, the one-way locking ring 9 is locked with the locking seat 6, and can no longer move up, at which time the sealer 102 and the anchor 101 form an integral structure, part of the rubber sealing ring 10 of the sealer 102 enters the anchor 101, and part of the rubber sealing ring 100 is exposed outside the anchor 101. Under a certain displacement and liquid pressure, axial pressure can be generated on the sealer 102 to strengthen the seal of the sealer 102 on the downhole casing.

[0060] The anchor 101 provided by the present invention can be configured as a central tube 1 with a longer conical surface 2, a longer slip 5, and more anchor teeth 4, so that its outer diameter can be made smaller than the small-sized soluble bridge plug used in conventional cased wells, and its passing performance in cased wells is more advantageous. At the same time, the soluble sealer is made of soluble rubber, and it has a multi-stage soluble rubber sealing ring 10, which has better compression performance, so its passing performance in the casing change section is excellent.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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 split soluble bridge plug, characterized in that: It comprises an anchor (101) and a sealer (102). After the anchor (101) is anchored on the inner wall of a downhole casing, the sealer (102) is coaxially sealed and inserted into the anchor (101) and is sealed with the downhole casing.

2. The split soluble bridge plug according to claim 1, characterized in that: The anchor (101) comprises a center pipe (1), a slip (5) and a guide shoe fixing seat (7) which are coaxially arranged in sequence from top to bottom. The lower end of the slip (5) is fixedly connected to the upper end of the guide shoe fixing seat (7). The lower end of the center pipe (1) is connected to the upper end of the slip (5) via a conical surface. When the center pipe (1) moves downward relative to the slip (5), the slip (5) can be radially expanded via the conical surface, thereby anchoring the slip (5) to the inner wall of the downhole casing.

3. The split soluble bridge plug according to claim 2, characterized in that: A plurality of anchor teeth (4) are evenly arranged along the circumferential direction on the outer wall of the slip (5).

4. The split soluble bridge plug according to claim 3, characterized in that: At least four circles of anchoring teeth (4) are arranged on the outer wall of the slip (5).

5. The split soluble bridge plug according to claim 2, characterized in that: A primary sealing ring (3) is coaxially arranged on the outer wall of the central tube (1) via a conical surface, and the lower end surface of the primary sealing ring (3) abuts against the upper end surface of the slip (5).

6. The split soluble bridge plug according to claim 2, characterized in that: Ratchet teeth are arranged between the contact surfaces of the slips (5) and the central pipe (1).

7. The split soluble bridge plug according to any one of claims 2 to 6, characterized in that: The sealer (102) comprises: Support frame (11); A plurality of rubber sealing rings (10) are coaxially arranged in sequence along the axial direction on the outer wall of the support frame (11); A guide shoe (8) is coaxially fixed at the lower end of the support frame (11), and the guide shoe (8) is configured to be sealably inserted into the guide shoe fixing seat (7).

8. The split soluble bridge plug according to claim 7, characterized in that: A plurality of one-way locking rings (9) are also arranged between the support frame (11) and the guide shoe (8), and the one-way locking rings (9) are arranged to be compatible with the inner wall of the anchor (101).

9. The split soluble bridge plug according to claim 7, characterized in that: The support frame (11) and the rubber sealing ring (10) are made of soluble rubber, and the support frame (11) and the rubber sealing ring (10) can respond to axial pressure and expand radially, thereby enhancing sealing.

10. A formation isolation process, characterized in that: Using the split soluble bridge plug according to any one of claims 1 to 9, an anchor (101) is put into the well and anchored on the inner wall of the downhole casing, and then a sealer (102) is pumped into the well, the lower part of the sealer (102) is inserted into the anchor (101), the anchor (101) is sealed, and the upper part of the sealer (102) is sealed with the downhole casing.

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