A permanently expandable open hole packer

Abstract

The application provides a permanent expansion type open hole packer, which comprises an outer cylinder and an inner cylinder sleeved together, the outer cylinder has an inner cavity, and the inner cylinder is provided with a first channel; a piston cavity is arranged between the outer cylinder and the inner cylinder, the piston cavity is provided with a first piston, a liquid inlet hole is arranged on the outer wall of the inner cylinder and communicates with the first channel and the piston cavity, and a rubber sleeve is arranged on the outer cylinder at the end of the piston away from the liquid inlet hole and communicates with the inner cavity. Wherein, the first piston is provided with a liquid injection channel capable of communicating the rubber sleeve and the liquid inlet hole, the first piston can move in the piston cavity under the action of fluid pressure in the first channel, so that the first piston can move from a first position of cutting off the communication between the rubber sleeve and the liquid inlet hole to a second position of keeping the rubber sleeve and the liquid inlet hole unobstructed, so that the fluid in the first channel flows into the rubber sleeve, and the rubber sleeve is set.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oilfield development, in particular to a permanent expansion type open hole packer. BACKGROUND

[0002] In the process of oil exploitation, open hole staged fracturing technology is one of the commonly used technologies. This technology can improve the single well production, and is one of the effective processes to realize the single well production. In the open hole staged fracturing process, the packer is one of the most commonly used downhole devices, which is mainly divided into compression type open hole packer and expansion type packer.

[0003] Compared with the compression type open hole packer, the expansion type packer has greater expansion ratio, longer sealing section and stronger adaptability to irregular wellbore, and has greater advantages in open hole layering. In order to avoid the expansion of the packer in advance and realize effective interlayer separation, the liquid injection valve must realize the opening and closing function. At the same time, it is also necessary to prevent the secondary expansion of the rubber tube, so as to ensure the sealing performance and reliability of the packer. SUMMARY

[0004] In view of the above technical problems, the present application aims to provide a permanent expansion type open hole packer. The permanent expansion type open hole packer of the present application can avoid the early expansion of the packer, realize effective interlayer separation, and prevent the secondary expansion of the rubber tube.

[0005] According to the present application, a permanent expansion type open hole packer is provided, comprising: an outer cylinder and an inner cylinder sleeved together, the outer cylinder having an inner cavity, and the inner cylinder defining a first channel for fluid flow; a piston cavity is arranged between the outer cylinder and the inner cylinder, the piston cavity is provided with a first piston, a liquid inlet hole is arranged on the outer wall of the inner cylinder and communicates with the first channel and the piston cavity, and a rubber tube is arranged on the outer cylinder away from the liquid inlet hole and communicates with the inner cavity.

[0006] Wherein, the first piston is provided with a liquid injection channel capable of communicating the inner cavity of the rubber tube and the liquid inlet hole, and the first piston is capable of moving in the piston cavity under the action of the fluid pressure in the first channel, so that the first piston can move from the first position of cutting off the communication between the inner cavity of the rubber tube and the liquid inlet hole to the second position of keeping the rubber tube and the liquid inlet hole unobstructed, so that the fluid in the first channel flows into the inner cavity of the rubber tube, and the rubber tube is set.

[0007] In a preferred embodiment, the liquid injection channel is configured in a substantially "L" shape, which has a liquid inlet section arranged axially along the outer cylinder and a liquid outlet section arranged radially along the outer cylinder, and the liquid inlet section and the liquid outlet section can communicate with the liquid inlet hole and the inner cavity of the rubber tube, respectively.

[0008] In a preferred embodiment, a first step is arranged on the inner wall of the piston cavity, which divides the piston cavity into a small-diameter cavity with a smaller diameter and a large-diameter cavity with a larger diameter, and the diameter of the small-diameter cavity is equal to the diameter of the first piston.

[0009] The first step is arranged at a position such that when the first piston is in the first position, the liquid inlet section and the liquid outlet section of the liquid channel are both located in the small-diameter cavity, and when the first piston is in the second position, the liquid inlet section and the liquid outlet section of the liquid channel are located in the small-diameter cavity and the large-diameter cavity of the piston cavity, respectively.

[0010] In a preferred embodiment, the permanent expandable open hole packer further comprises a pressure relief assembly, which can release the fluid pressure in the first channel acting on the first piston after the rubber sleeve is set, so that the first piston moves from the second position to the direction close to the first position.

[0011] In a preferred embodiment, the pressure relief assembly comprises a second piston arranged in the piston cavity, and a pressure relief hole penetrating through the outer cylinder to communicate the piston cavity and the space outside the outer cylinder.

[0012] Wherein, a first gap is formed between the second piston and the first piston, which communicates with the liquid inlet hole, and the second piston can move in the piston cavity under the action of the fluid pressure in the first channel, so that the second piston has a third position to cut off the communication between the pressure relief hole and the liquid inlet hole, and a fourth position to keep the communication between the pressure relief hole and the liquid inlet hole.

[0013] In a preferred embodiment, the first piston and the second piston are fixed in the piston cavity by a first shear pin and a second shear pin, respectively, and the shear force of the second shear pin is greater than that of the first shear pin.

[0014] In a preferred embodiment, a first snap spring is further arranged on the first piston, which can fix the first piston at a fifth position to cut off the communication between the liquid inlet hole and the setting hole after the rubber sleeve is set.

[0015] In a preferred embodiment, a second gap is arranged between the second piston and the side wall of the piston cavity, and an elastic member is arranged in the gap, the second piston and the side wall of the piston cavity are connected through the elastic member, and the elastic member can push the second piston to move to a sixth position to cut off the communication between the pressure relief hole and the liquid inlet hole when the first piston is in the fifth position.

[0016] In a preferred embodiment, the permanent expandable open hole packer further comprises a second snap spring capable of fixing the first piston at the sixth position.

[0017] In a preferred embodiment, a balance hole is further provided on the outer wall of the outer cylinder, which communicates the second gap and the space outside the outer cylinder.

[0018] In a preferred embodiment, a stepped portion is further provided on the outer wall of the inner cylinder at the side of the first piston away from the liquid inlet hole. BRIEF DESCRIPTION OF DRAWINGS

[0019] The present application will be described below with reference to the accompanying drawings.

[0020] Figure 1 A schematic view of a permanent expandable open hole packer according to an embodiment of the present application is shown.

[0021] Figure 2 For Figure 1 A schematic view of a permanent expandable open hole packer according to an embodiment of the present application is shown.

[0022] In the present application, all the drawings are schematic drawings and are only used to illustrate the principles of the present application, and are not drawn according to the actual proportions. DETAILED DESCRIPTION

[0023] The present application will be described below with reference to the accompanying drawings. In this text, the terms "left side" and "right side" respectively refer to the side close to the upper joint and the side away from the upper joint.

[0024] The working process of the permanent expandable open hole packer 100 according to the present application will be described below.

[0025] Figure 1 A permanent expandable open hole packer 100 according to an embodiment of the present application is shown. As Figure 1 shown, the permanent expandable open hole packer 100 comprises an outer sleeve 10, an upper joint 12 is provided at a first end 11 of the outer sleeve 10. Meanwhile, an inner cavity 15 is defined in the outer sleeve 10, an inner sleeve 20 is provided in the inner cavity 15, and a first passage 25 for the flow of downhole fluid is defined in the inner sleeve 20.

[0026] As Figure 1 shown, a piston cavity 30 is provided between the outer sleeve 10 and the inner sleeve 20 in the radial direction, a first piston 35 is provided in the piston cavity 30, and the first piston 35 is capable of moving axially in the piston cavity 30 under the action of an external force.

[0027] Meanwhile, a pressure relief assembly 1 is also arranged in the piston cavity 30. The pressure relief assembly 1 comprises a second piston 38 arranged in the piston cavity 30. The second piston 38 and the first piston 35 are axially spaced apart by a first gap 36. A liquid inlet hole 32 is also arranged on the inner wall of the inner cylinder 20, which is in communication with the first gap 36.

[0028] As shown in Figure 1 At least one first shear pin 351 and at least one second shear pin 381 are also arranged on the inner wall of the outer cylinder 10. The first piston 35 and the second piston 38 are fixed on the outer cylinder by the first shear pin 351 and the second shear pin 381 respectively.

[0029] In the present application, a liquid injection channel 16 is also arranged in the first piston 38. The liquid injection channel 16 is configured in a substantially "L" shape, so that the liquid injection channel 16 has a liquid inlet section 161 arranged axially along the outer cylinder 10 and a liquid outlet section 162 arranged radially along the outer cylinder 10. The liquid inlet section 161 is located on the side of the first piston 35 close to the liquid inlet hole 32.

[0030] Meanwhile, a first step 18 is also arranged on the inner wall of the piston cavity 30. The first step 18 divides the piston cavity 30 into a small-diameter cavity 181 with a smaller diameter and a large-diameter cavity 182 with a larger diameter. The diameter of the small-diameter cavity 181 is equal to the outer diameter of the first piston 35.

[0031] In addition, a rubber sleeve (not shown) is arranged on the outer cylinder at the end of the piston away from the liquid inlet hole, and the inner cavity of the rubber sleeve is in communication with the large-diameter cavity 182 of the piston cavity 30.

[0032] As shown in Figure 1 When the permanent expansion type open hole packer 100 is in the initial state, the liquid inlet section 161 and the liquid outlet section 162 of the liquid injection channel 16 are both located in the small-diameter cavity 181. At this time, since the diameter of the small-diameter cavity 181 is equal to the diameter of the first piston 35, the inner wall of the small-diameter cavity 181 can cover the liquid outlet section 162 of the liquid injection channel 16, preventing the fluid in the liquid injection channel 16 from flowing out of the liquid outlet section 162. At this time, the first piston 35 is located at a first position that can cut off the communication between the rubber sleeve and the liquid inlet hole 32.

[0033] As shown in Figure 1As shown, a pressure relief hole 19 is also arranged on the outer wall of the outer cylinder 10 corresponding to the second piston 38. When the permanent expansion type open hole packer 100 is in the initial state, the two ends of the second piston 38 are respectively located on the two sides of the pressure relief hole 19 in the axial direction, so that the second piston 38 can cut off the communication between the liquid inlet hole 32 and the pressure relief hole 19. At this time, the second piston 38 is located at a third position which cuts off the communication between the pressure relief hole 19 and the liquid inlet hole 32.

[0034] As described above, when the permanent expansion type open hole packer 100 is in the initial state, the first piston 35 can cut off the communication between the setting hole 16 and the inner cavity of the rubber sleeve and the liquid inlet hole 32, thereby preventing the rubber sleeve from being set too early.

[0035] When the high-pressure fluid injected into the first channel 25, the high-pressure fluid in the first channel 25 will first flow into the first gap 36, thereby applying a force to the first piston 35 and the second piston 38 in a direction away from the liquid inlet hole 32.

[0036] Figure 2 For Figure 1 As shown, the permanent expansion type open hole packer 100 is in the liquid injection and setting state. As shown, Figure 2 In the present application, the shearing force of the second shear pin 381 is set to be greater than the shearing force of the first shear pin 351. Thus, when the high-pressure fluid in the first channel 25 flows into the first gap 36, the first shear pin 351 will be cut off first. Then, under the push of the high-pressure fluid, the first piston 35 will move away from the liquid inlet hole 32 until the liquid injection channel 16 of the liquid injection channel 16 passes through the first step portion 18 to reach the large-diameter cavity 182 of the piston cavity 30.

[0037] At this time, since the diameter of the large-diameter cavity 182 is greater than the diameter of the first piston 35, the piston cavity 30 can no longer close the liquid injection channel 16. Then, the high-pressure fluid in the first channel 25 can enter the rubber sleeve through the liquid inlet hole 32, the liquid injection channel 16 and the large-diameter cavity 182 in sequence, thereby supporting the rubber sleeve to expand and complete the setting. At this time, the first piston 35 is located at a second position which keeps the rubber sleeve and the liquid inlet hole 32 in communication.

[0038] As shown, Figure 2 As shown, a second step portion 26 is also arranged on the outer wall of the inner cylinder 20 corresponding to the first piston 35. When the first piston 35 moves to the second position, it can form a connection with the second step portion 26, so that the first piston 35 can no longer continue to move to the right.

[0039] When the rubber sleeve is completely set, the volume of the rubber sleeve no longer increases, and the high-pressure fluid in the first channel 25 cannot continue to enter the rubber sleeve after reaching the first gap 36. Subsequently, the pressure in the first gap 36 continues to rise until the pressure shears the second shear pin 381.

[0040] When the second shear pin 381 is sheared, the second piston 38 is driven by the fluid pressure in the first gap 36 to move to the left until the entire second piston 38 moves to the left side of the pressure relief hole 19. At this time, the pressure relief hole 19 and the liquid inlet hole 32 are connected, and the second piston 38 reaches the fourth position at which the liquid inlet hole 32 and the pressure relief hole 19 are kept connected.

[0041] When the liquid inlet hole 32 and the pressure relief hole 19 are connected, the high-pressure fluid in the first channel 25 can pass through the liquid inlet hole 32 and the pressure relief hole 19 in sequence to reach the space outside the outer sleeve 10. At this time, the pressure in the first gap 36 rapidly decreases until the pressures on the left and right sides of the second piston 38 are balanced.

[0042] With the decrease of the pressure in the first gap 36, the pressure on the right side of the first piston 35 is higher than that on the left side, and under the action of the pressure difference, the first piston 35 moves to the left again until the liquid discharge section 162 of the liquid inlet channel 16 enters the small-diameter cavity 181 of the piston cavity 30. At this time, the first piston 35 cuts off the connection between the liquid inlet hole 32 and the setting hole 16 again, and the first piston 35 moves to the fifth position at which the connection between the liquid inlet hole 32 and the setting hole 16 is cut off again.

[0043] As shown in Figure 2 A first snap spring 355 is further arranged on the first piston 35. The first snap spring 355 can be, for example, a snap spring. The first snap spring 355 can fix the first piston 35 at the fifth position after the first piston 35 reaches the fifth position, preventing the first piston 35 from continuing to move axially.

[0044] As shown in Figure 2 A second gap 384 is further arranged between the second piston 38 and the side wall of the piston cavity 30. An elastic member 386, which can be, for example, a spring, is arranged in the second gap 384, and the second piston 38 and the side wall of the piston cavity 30 are connected through the elastic member 386. The elastic member 386 is arranged in a compressed state when the second piston 38 reaches the fourth position.

[0045] When the first piston 35 reaches the fifth position, the communication between the liquid inlet hole 32 and the setting hole 16 is cut off, and the fluid in the first channel 25 can be normally discharged through the pressure relief hole 19, so that the fluid pressure on both sides of the second piston 38 is balanced, and the second piston 38 is subjected to the elastic force of the elastic member 386. At this time, the elastic member 386 pushes the second piston 38 to move to the right until the second piston 38 reaches the sixth position to cut off the communication between the pressure relief hole 19 and the liquid inlet hole 32 again.

[0046] Similarly, the second snap spring 385 is arranged on the second piston 38. The first snap spring 385 can fix the first piston at the sixth position after the second piston 38 reaches the sixth position, so as to prevent the second piston 38 from continuing to move in the axial direction.

[0047] At this time, with the first piston 35 and the second piston 38 being fixed again, the communication between the piston cavity 30, the rubber sleeve and the pressure relief hole 19 is cut off at the same time, so that the rubber sleeve can be prevented from being inflated and set again, and the whole setting process of the permanent expansion type open hole packer 100 is completed.

[0048] As shown in the preferred embodiment, Figure 2 The balance hole 40 is arranged on the outer wall of the outer cylinder 10 to communicate the second gap 384 and the space outside the outer cylinder 10. The balance hole 40 can ensure the pressure balance between the second gap 384 and the space outside the outer cylinder 10, prevent the formation of local high pressure in the second gap 384 when the second piston 38 moves, and hinder the normal movement of the second piston 38.

[0049] The working process of the permanent expansion type open hole packer 100 according to the present application is briefly described as follows.

[0050] The permanent expansion type open hole packer 100 according to the present application is used to connect between downhole pipes and is lowered into an oil well together with the pipes. When the open hole is needed to be isolated during the open hole staged fracturing operation, high-pressure fluid is first injected into the well, and then the fluid enters the first gap 36 of the piston cavity 30 through the downhole pipe, the first channel 25 and the liquid inlet hole 32 in sequence.

[0051] When the fluid enters the first gap 36, the first shear pin 351 is first sheared, and the first piston 35 is pushed to move from the first position at which the rubber sleeve and the liquid inlet hole 32 are cut off to the second position at which the rubber sleeve and the liquid inlet hole 32 are kept in communication. Then, the high-pressure fluid enters the rubber sleeve to support the rubber sleeve to be set.

[0052] When the rubber sleeve is set, the high pressure fluid in the first gap 36 can no longer enter the rubber sleeve. At this time, the liquid pressure in the first gap 36 continues to rise until the high pressure fluid cuts off the second shear pin 381, pushes the second piston 38 to move leftward until the second piston 38 reaches a fourth position where the pressure relief hole 19 and the liquid inlet hole 32 are communicated. Then, the fluid in the piston cavity 30 is discharged from the pressure relief hole 19, so that the pressure in the first gap 36 is reduced.

[0053] With the reduction of the pressure in the first gap 36, the pressure on the right side of the first piston 35 is higher than that on the left side. At this time, under the action of the pressure difference, the first piston 35 moves leftward again until the first piston 35 reaches a fifth position where the set hole 16 and the liquid inlet hole 32 are cut off from each other, and then the first snap spring 351 fixes the first piston 35 at the fifth position.

[0054] When the first piston 35 is fixed, with the normal discharge of the fluid in the piston cavity 30 from the pressure relief hole 19, the pressure on both sides of the second piston 38 is balanced.

[0055] When the pressure on both sides of the second piston 38 is balanced, the elastic member 386 pushes the second piston to move rightward until the second snap spring 385 fixes the second piston 38. At this time, the second piston 38 is at a sixth position where the pressure relief hole 19 and the liquid inlet hole 32 are cut off from each other.

[0056] When the second piston 38 is at the sixth position where the communication between the pressure relief hole 19 and the liquid inlet hole 32 is cut off, the setting process of the whole permanent-expandable open hole packer 100 is completed.

[0057] Finally, it should be noted that the above only describes the preferred embodiments of the present application and does not constitute any limitation on the present application. Although the present application is 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 replacements to some technical features. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A permanent expansion-type naked-eye occluder (100), comprising: An outer cylinder (10) and an inner cylinder (20) are fitted together, the outer cylinder having an inner cavity (15) and the inner cylinder having a first channel (25) for fluid flow defined therein; A piston chamber (30) is provided between the outer cylinder and the inner cylinder, and a first piston (35) is provided in the piston chamber. An inlet hole (32) communicating with the first channel and the piston chamber is provided on the outer wall of the inner cylinder. A rubber sleeve communicating with the inner cavity is disposed on the outer cylinder at the end of the first piston away from the liquid inlet. The first piston is provided with a liquid injection channel (16) that connects the inner cavity of the rubber sleeve and the liquid inlet. The first piston can move within the piston cavity under the action of fluid pressure in the first channel, thereby enabling the first piston to move from a first position that cuts off the connection between the rubber sleeve and the liquid inlet to a second position that keeps the rubber sleeve and the liquid inlet unobstructed, so that the fluid in the first channel flows into the rubber sleeve, achieving rubber sleeve setting and sealing. The permanent expansion type open-eye packer (100) also includes a pressure relief assembly (1), which includes a second piston (38) disposed in the piston chamber and a pressure relief hole (19) penetrating the outer cylinder to connect the piston chamber and the outer space of the outer cylinder. A first gap (36) communicating with the inlet hole is formed between the second piston and the first piston. The second piston can move in the piston chamber under the action of fluid pressure in the first channel, so that the second piston has a third position that cuts off the communication between the pressure relief hole and the inlet hole and a fourth position that keeps the inlet hole and the pressure relief hole connected. The pressure relief assembly can relieve the fluid pressure in the first channel on the first piston after the rubber sleeve is set, so that the first piston moves from the second position toward the direction closer to the first position. The first piston and the second piston are fixed in the piston chamber by a first shear pin (351) and a second shear pin (381), respectively. The shearing force of the second shear pin is set to be greater than the shearing force of the first shear pin.

2. The permanent expansion-type naked-eye occluder (100) according to claim 1, characterized in that, The liquid injection channel is roughly "L" shaped, having an inlet section (161) arranged axially along the outer cylinder and a drain section (162) arranged radially along the outer cylinder. The inlet section and the drain section can communicate with the inlet hole (32) and the inner cavity of the rubber tube, respectively.

3. The permanent expansion type naked-eye occluder (100) according to claim 2, characterized in that, A first step (18) is provided on the inner wall of the piston chamber, which divides the piston chamber into a small-diameter chamber (181) with a smaller diameter and a large-diameter chamber (182) with a larger diameter. The diameter of the small-diameter chamber is set to be equal to the outer diameter of the first piston. The position of the first step is configured such that when the first piston is in the first position, the inlet section and the outlet section of the injection channel are simultaneously located in the small-diameter cavity, and when the first piston is in the second position, the inlet section and the outlet section of the injection channel are respectively located in the small-diameter cavity and the large-diameter cavity of the piston cavity.

4. The permanent expansion-type naked-eye occluder (100) according to any one of claims 1-3, characterized in that, A first retaining ring (355) is also provided on the first piston, which can fix the first piston in a fifth position after the rubber sleeve is set, cutting off the communication between the liquid inlet and the setting hole.

5. The permanent expansion-type naked-eye occluder (100) according to claim 4, characterized in that, A second gap (384) is provided between the second piston and the side wall of the piston chamber, and an elastic element (386) is provided in the second gap. The second piston and the side wall of the piston chamber are connected by the elastic element. The elastic element can push the second piston to a sixth position, which cuts off the connection between the pressure relief hole and the liquid inlet hole, when the first piston is in the fifth position.

6. The permanent expansion-type naked-eye occluder (100) according to claim 5, characterized in that, It also includes a second retaining ring (385) which is capable of fixing the second piston in the sixth position.

7. The permanent expansion type naked eye packer (100) according to claim 5, wherein a balance hole (40) communicating with the second gap and the outer space of the outer cylinder is further provided on the outer wall of the outer cylinder.

8. The permanent expansion type open-eye occluder according to claim 5, characterized in that, A second step (26) is also provided on the outer wall of the inner cylinder on the side of the first piston away from the liquid inlet.

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