Self-sealing packer, using method thereof and oil-water well anti-corrosion pipe column

Abstract

The invention discloses a self-sealing packer, a using method thereof and an oil-water well anti-corrosion tubular column, the self-sealing packer comprises an expanding screen pipe, the expanding screen pipe comprises an expanding section with screen holes, and the inner diameter of the expanding section is larger than the inner diameter of an oil pipe and smaller than the inner diameter of a casing pipe; the sealing structure is arranged outside the expanding section in a sleeving manner; the expansion structure is arranged between the expanding section and the sealing structure; after oil and water in the oil pipe enter the expanding section, the pressure is increased to extrude the expansion structure to expand outwards, the oil and water can flow into the expansion structure from the sieve holes and enable the expansion structure to expand, and the sealing structure can expand outwards under the action of expansion extrusion and expansion extrusion of the expansion structure. The oil casing annulus soft sealing device has a larger deformation sealing space, soft sealing is conducted on the oil casing annulus, the annulus can be sealed without deadly, the oil casing annulus can be effectively packed during setting, the sealing effect is not affected by casing corrosion, deformation, vertical wriggling of a pipe column and the like, the situation that normal unsealing cannot be achieved due to scaling, corrosion and other reasons is avoided, and the sealing effect is good. Therefore, the problem that overhaul is needed due to well jamming is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield development, in particular to a self-sealing packer and a use method thereof and an anti-corrosion pipe column for oil and water wells. Background Art

[0002] The anti-corrosion technology of oil and water well pipes includes two aspects: one is the packer, and the other is the corrosion inhibitor protection liquid added to the oil casing annulus. The packer is generally composed of an expansion packer or a compression packer. When the expansion packer and the compression packer are seated, the compression packer pushes the rubber to achieve sealing, so the expansion rate is low and the sealing pressure is large. When these two types of packers are used, they are often accompanied by wellbore scaling, corrosion, wellbore deformation, etc., which can easily cause the packer to be unable to be unsealed and removed normally, and then the pipe string is stuck in the well, requiring major repairs.

[0003] According to the sealing method of the packer, the packer can be divided into self-sealing type, compression type, expansion type and combination type. The self-sealing type achieves sealing by the interference fit between the packer and the inner diameter of the casing and the working pressure difference; the compression type achieves sealing by compressing the seal by axial force to enlarge the outer diameter of the seal; the expansion type achieves sealing by radial force and the hydraulic pressure of the inner cavity of the seal to enlarge the outer diameter of the packer; the combination type achieves sealing by any combination of the three types. The self-sealing packer is suitable for oil and water wells, but the existing expansion type self-sealing packer has a single seat seal form, and the expansion coefficient of the self-expanding rubber is relatively small. In the case of scaling and corrosion in the oil and water wells, there is still a problem that the seal cannot be released normally, causing the pipe string to be stuck in the well. Summary of the invention

[0004] The purpose of the present invention is to provide a self-sealing packer and a method of using the same, and an anti-corrosion tubing string for oil and water wells, so as to solve the problem that the existing self-sealing packers cannot be normally unsealed and removed due to scaling, corrosion, deformation and other problems in the oil and water wells, thereby causing the tubing string to be stuck in the well and requiring major repairs.

[0005] The above-mentioned purpose of the present invention can be achieved by adopting the following technical solutions:

[0006] The present invention provides a self-sealing packer, comprising: an expanded diameter screen pipe, comprising an expanded diameter section provided with screen holes, the inner diameter of the expanded diameter section being larger than the inner diameter of the oil pipe and smaller than the inner diameter of the casing; a sealing structure, which is sleeved outside the expanded diameter section; and an expansion structure, which is arranged between the expanded diameter section and the sealing structure; wherein, after the oil and water in the oil pipe enter the expanded diameter section, the pressure increases and the expansion structure is squeezed to expand outward, and the oil and water can flow from the screen holes into the expansion structure and expand the expansion structure, and the sealing structure can expand outward under the action of the expansion extrusion and expansion extrusion of the expansion structure.

[0007] In an embodiment of the present invention, the self-sealing packer further comprises a righting protection frame, which is sleeved outside the expanded diameter screen pipe, and the sealing structure and the expansion structure are located inside the righting protection frame, and the righting protection frame can shrink inwards and expand outwards by utilizing its own elasticity.

[0008] In an embodiment of the present invention, the oil pipe includes a lower oil pipe and an upper oil pipe, the upper oil pipe is connected to the lower oil pipe through the expanded diameter screen pipe, and the two ends of the straightening protection frame clamp and fix the two ends of the expansion structure to the lower oil pipe and the upper oil pipe.

[0009] In an embodiment of the present invention, the expanded diameter screen pipe further comprises two reducing sections, the inner diameter of the reducing section gradually decreases in an arc shape from the inner diameter of the expanded diameter section to the inner diameter of the oil pipe, and the two ends of the expanded diameter section are connected to the lower oil pipe and the upper oil pipe through the two reducing sections.

[0010] In an embodiment of the present invention, a plug is provided at the sieve hole, and the plug can be dissolved by the oil and water.

[0011] In an embodiment of the present invention, the dissolution time of the plug is greater than the time required for the self-sealing packer to be lowered to a preset position.

[0012] In an embodiment of the present invention, the plug is made of a soluble metal.

[0013] In an embodiment of the present invention, the sealing structure comprises a rubber water bag and an expansion rubber layer, wherein the expansion rubber layer is located between the rubber water bag and the expansion structure, and the expansion rubber layer can swell when it encounters water or oil.

[0014] In an embodiment of the present invention, the expansion material filled between the diameter-expanding section and the sealing structure forms the expansion structure, and the expansion material can swell when encountering water or oil.

[0015] The present invention also provides a method for using a self-sealing packer, which is the self-sealing packer mentioned above, and the method for using comprises the following steps: sealing: oil and water enter the expanded diameter section of the expanded diameter screen tube from the oil pipe and flow out from the screen hole into the expansion structure, and the sealing structure expands outwards to achieve sealing under the pressure difference between the expanded diameter section and the annulus of the casing and the squeezing effect of the expansion structure after it expands with oil and water; unsealing: lift the oil pipe and increase the axial pressure on the self-sealing packer to be greater than its axial sealing pressure, and the oil and water in the expansion structure flow back from the screen hole into the expanded diameter screen tube under the action of the axial pressure, causing the sealing structure to retract inwards to achieve unsealing.

[0016] In an embodiment of the present invention, before the seating step, the method of use further includes the following steps: lowering: plugging the sieve hole with a plug, and then lowering the self-sealing packer into the casing along with the oil pipe, and during the lowering process, the oil and water can enter the expanded diameter section from the oil pipe and dissolve the plug, until the self-sealing packer is lowered to a preset position and the plug is completely dissolved by the oil and water.

[0017] In an embodiment of the present invention, after the sealing step, the casing annulus includes a lower casing annulus located below the self-sealing packer and an upper casing annulus located above the self-sealing packer, and the use method further includes the following steps: well washing: well washing fluid flows from the oil pipe to the bottom of the well and enters the lower casing annulus, so that the pressure of the lower casing annulus is greater than the pressure of the lower casing annulus, until the pressure difference between the lower casing annulus and the lower casing annulus is greater than the preset pressure difference, and the well washing fluid in the lower casing annulus enters the upper casing annulus from the gap between the self-sealing packer and the casing and is discharged.

[0018] The present invention also provides an anti-corrosion tubing string for oil and water wells, comprising: an oil pipe, including an upper oil pipe and a lower oil pipe; at least one of the above-mentioned self-sealing sealers, connecting the upper oil pipe and the lower oil pipe; an upper anti-corrosion device, arranged outside the upper oil pipe, and the upper anti-corrosion device can slowly release a fixed corrosion inhibitor into the annulus between the upper oil pipe and the casing.

[0019] In an embodiment of the present invention, there are multiple self-sealing packers, the oil pipe also includes at least one middle oil pipe, the expanded diameter screen pipes of the multiple self-sealing packers are connected from top to bottom through at least one middle oil pipe, and the oil and water well anti-corrosion pipe string also includes at least one lower anti-corrosion device, which is arranged outside the middle oil pipe, and the lower anti-corrosion device can slowly release fixed corrosion inhibitor into the annulus between the middle oil pipe and the casing.

[0020] The characteristics and advantages of the present invention are:

[0021] The self-sealing packer and its use method and the anti-corrosion pipe column for oil and water wells of the present invention are connected to the oil pipe through the expanded diameter screen pipe. As oil and water flow into the oil pipe, the pressure in the oil pipe is greater than the pressure in the oil casing annulus. The present invention arranges an expanded diameter section with screen holes and an inner diameter greater than the oil pipe according to the Bernoulli equation, so that after oil and water flow from the oil pipe into the expanded diameter section, the flow rate decreases and the pressure increases, that is, the pressure difference between the expanded diameter section and the oil casing annulus is greater than the pressure difference between the oil pipe and the oil casing annulus, so that the expanded diameter section can squeeze the expansion structure to expand outward under the action of the internal and external pressure difference, and at the same time, oil and water can enter the expansion structure from the screen holes to expand the expansion structure, so that the sealing structure can be expanded and squeezed in the expansion and squeezing of the expansion structure. Under the dual action, it expands outward to achieve seating, thereby increasing the sealing pressure of the sealing structure and the sealing effect. When the axial pressure is greater than the axial sealing pressure of the sealing structure, the water in the expansion structure can flow back from the sieve hole to the expanded diameter section to shrink the sealing structure. Therefore, the self-sealing packer of the present invention has a larger deformation sealing space, and implements soft sealing on the oil casing annulus, which can achieve the effect of sealing the oil casing annulus without dying. On the one hand, the oil casing annulus can be effectively sealed during seating, and the sealing effect is not affected by casing corrosion, deformation, and up and down creep of the casing and the tubing. On the other hand, it will not be unable to be normally unsealed due to scaling, corrosion, etc., thereby avoiding the problem of well jamming and the need for overhaul. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0023] Figure 1 This is a diagram showing the use status of the self-sealing packer in the present invention.

[0024] Figure 2 It is a schematic diagram of oil and water flowing from the oil pipe into the expanded diameter section in the present invention.

[0025] Figure 3 It is a schematic structural diagram of the self-sealing packer of the present invention before use.

[0026] Figure 4 It is a schematic structural diagram of an anti-corrosion pipe string for oil and water wells in one embodiment of the present invention.

[0027] Figure 5 It is a schematic structural diagram of an anti-corrosion pipe string for oil and water wells in another embodiment of the present invention.

[0028] In the figure:

[0029] 1. Expanded diameter screen tube; 11. Expanded diameter section; 12. Reduced diameter section; 13. Screen hole; 2. Expansion structure; 3. Sealing structure; 4. Straightening protection frame; 5. Plug; 6. Oil pipe; 61. Upper oil pipe; 62. Lower oil pipe; 63. Middle oil pipe; 7. Upper anti-corrosion device; 8. Lower anti-corrosion device; 9. Casing; 91. Oil casing annulus; 92. Upper oil casing annulus; 93. Lower oil casing annulus; 10. Self-sealing packer; 10', self-sealing packer. DETAILED DESCRIPTION

[0030] 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.

[0031] Implementation Method 1

[0032] like Figure 1 As shown, the present invention provides a self-sealing packer 10, comprising: an expanded diameter screen 1, comprising an expanded diameter section 11 provided with a screen hole 13, the inner diameter D2 of the expanded diameter section 11 is larger than the inner diameter D1 of the oil pipe 6 and smaller than the inner diameter of the casing 9; a sealing structure 3, which is sleeved outside the expanded diameter section 11; an expansion structure 2, which is arranged between the expanded diameter section 11 and the sealing structure 3; wherein, after the oil and water in the oil pipe 6 enter the expanded diameter section 11, the pressure increases and the expansion structure 2 is squeezed to expand outward, and the oil and water can flow into the expansion structure 2 from the screen hole 13 and make the expansion structure 2 expand, and the sealing structure 3 can expand outward under the expansion extrusion of the expansion structure 2 and the expansion extrusion.

[0033] Combination Figure 2 As shown, according to the Bernoulli equation, when oil and water flow from the oil pipe 6 with a smaller inner diameter into the expanded diameter section 11 with a larger inner diameter, Among them, p1 is the pressure of oil and water at section J1 of the oil pipe 6; p2 is the pressure of oil and water at section J2 of the expanded diameter section 11; ρ is the density of oil and water; v1 is the flow rate of oil and water at section J1 of the oil pipe 6; v2 is the flow rate of oil and water at section J2 of the expanded diameter section 11; g is the acceleration of gravity; H1 is the depth of section J1; H2 is the depth of section J2; because the flow rates are the same, therefore, v1*A1=v2*A2; among them, A1 is the area of ​​section 1; A2 is the area of ​​section J2, from which it can be inferred that, Wherein, D1 is the inner diameter of the oil pipe 6; D2 is the inner diameter of the expanded diameter section 11. In addition, since H1 is the height difference between the sections J1 and J2, which can be ignored, it can be inferred that:

[0034]

[0035] It can be seen that after the oil and water enter the expanded diameter section 11 from the oil pipe 6, the flow rate decreases, but the pressure borne by the pipe wall of the expanded diameter section 11 is greater than the pressure borne by the pipe wall of the oil pipe 6, and the increased pressure is proportional to the square of the flow rate of the oil and water in the expanded diameter section 11; since the oil and water in the oil and water wells flow in the oil pipe 6, there will be a pressure head loss, so by increasing the internal and external pressure difference of the self-sealing seal 10, the sealing of the sealing structure 3 can be promoted.

[0036] The self-sealing packer 10 of the present invention is connected to the oil pipe 6 through the expanded diameter screen tube 1. As the oil and water flow into the oil pipe 6, the pressure in the oil pipe 6 is greater than the oil casing annulus 91 (i.e. Figure 4 The present invention sets an expansion section 11 with a sieve hole 13 and an inner diameter greater than the oil pipe 6 according to the Bernoulli equation, so that after the oil and water flow from the oil pipe 6 into the expansion section 11, the flow rate decreases and the pressure increases, that is, the pressure difference between the expansion section 11 and the oil casing annulus 91 is greater than the pressure difference between the oil pipe 6 and the oil casing annulus 91, so that the expansion section 11 can squeeze the expansion structure 2 to expand outward under the action of the internal and external pressure difference, and at the same time, the oil and water can enter the expansion structure 2 from the sieve hole 13 to expand the expansion structure 2, so that the sealing structure 3 can expand outward under the dual action of the expansion extrusion and expansion extrusion of the expansion structure 2 to achieve the seat seal, thereby improving the sealing of the sealing structure 3 pressure, thereby improving the sealing effect, and when the oil pipe 6 is lifted up so that the axial pressure on the self-sealing packer 10 is greater than its axial sealing pressure, the water in the expansion structure 2 can flow back from the sieve hole 13 to the expanded diameter section 11 to shrink the sealing structure 3. Therefore, the self-sealing packer 10 of the present invention has a larger deformation sealing space, and a soft seal is implemented on the oil casing annulus 91, which can achieve the effect of sealing the oil casing annulus 91 without being dead. On the one hand, the oil casing annulus 91 can be effectively sealed during the sealing, and the sealing effect is not affected by the corrosion and deformation of the casing 9 and the up and down creep of the casing 9 and the oil pipe 6. On the other hand, it will not be unable to be normally unsealed due to scaling, corrosion and the like, thereby avoiding the problem of well jamming and the need for overhaul.

[0037] In addition, when washing an oil-water well, since formation water does not participate or rarely participates, positive well washing is generally adopted (i.e., the washing fluid flows into the wellhead tubing 6, passes through the casing annulus 91, and is discharged from the wellhead). After the self-sealing packer 10 is seated, the casing annulus 91 includes the lower casing annulus 93 located below the self-sealing packer 10 and the upper casing annulus 92 located above the self-sealing packer 10. Therefore, when washing the well, the casing annulus 91 at the wellhead is opened, and the washing fluid flows into the wellhead from the wellhead tubing 6. The fluid enters the well through the oil pipe 6 and reaches the bottom of the well, and then enters the lower casing annulus 93, so that the pressure of the lower casing annulus 93 is greater than the pressure of the upper casing annulus 92. Therefore, when the pressure difference between the lower casing annulus 93 and the upper casing annulus 92 increases to a preset pressure difference, the self-sealing packer 10 contracts, and the flushing fluid can flow from the gap between the self-sealing packer 10 and the casing 9 into the upper casing annulus 92, and then reach the wellhead, and then be discharged from the wellhead. After the well flushing is completed, the casing annulus 91 at the wellhead is closed.

[0038] Therefore, the present invention can not only meet the demand for tubing corrosion protection, but also solve the problem that the self-sealing packer 10 cannot be normally unsealed and removed due to scaling, corrosion, deformation, etc. of the casing 9 of the oil and water wells, which in turn causes the tubing to be stuck in the well and requires major repairs, and at the same time can meet the well washing requirements; it has a simple structure, low manufacturing cost, and is convenient for transportation and storage. It is suitable for soft isolation of the oil casing annulus 91 of oil and water wells. Combined with the protective liquid of the oil casing annulus 91, it not only meets the anti-corrosion demand in the pre-isolation casing 9 of the oil production well, but also meets the anti-corrosion demand in the isolation casing 9 of the water injection well.

[0039] Specifically, the expanded diameter section 11 is generally a tubular structure extending along the axial direction of the casing 9 in its initial state. The length of the sealing structure 3 is equal to or slightly less than the length of the expanded diameter section 11, so that after expansion, it has a sufficiently large sealing contact area with the inner wall of the casing 9. The oil pipe 6 includes an upper oil pipe 61 and a lower oil pipe 62. The two ends of the expanded diameter section 11 are connected to the upper oil pipe 61 and the lower oil pipe 62 through two reducing sections 12. The inner diameter of the reducing section 12 gradually shrinks from the inner diameter of the expanded diameter section 11 to the inner diameter of the oil pipe 6 in an arc shape, and has a stronger pressure bearing capacity, which is conducive to the expansion of the expanded diameter section 11 under the action of the internal and external pressure difference. The expanded diameter screen pipe 1 can be integrally formed with the upper oil pipe 61 and the lower oil pipe 62, or the two ends of the expanded diameter screen pipe 1 can be connected to the upper oil pipe 61 and the lower oil pipe 62 by setting an upper joint and a lower joint.

[0040] The sealing structure 3 includes a rubber water bag and an expansion rubber layer, and the expansion rubber layer is located between the rubber water bag and the expansion structure 2, thereby forming a double insurance sealing structure. The expansion rubber layer can swell when it encounters water or oil. When the self-sealing packer 10 is lowered to a preset position along with the oil pipe 6, oil and water flow from the oil pipe 6 into the expanded diameter section 11 and flow from the sieve hole 13 into the expansion structure 2 and the expansion rubber layer. The internal and external pressure difference of the self-sealing packer 10 provides power for the rubber water bag to expand outwards and seal. At the same time, the expansion structure 2 and the expansion rubber layer begin to absorb water and expand, thereby squeezing the rubber water bag to expand outwards, thereby improving the sealing performance of the rubber water bag.

[0041] The expansion material filled between the expanded diameter section 11 and the sealing structure 3 forms the expansion structure 2, and the expansion material can swell when it encounters water or oil. Specifically, the expansion material includes but is not limited to water-absorbing and swelling fibers. The sealing structure 3 is embedded in the outer wall surface of the expansion structure 2. The amount of the expansion material is determined according to the axial sealing pressure requirement of the self-sealing packer 10 and the expansion coefficient of the expansion material. For example, in the embodiment of the present invention, the axial sealing pressure requirement of the self-sealing packer 10 is 10MPa. When unsealing, the oil pipe 6 is lifted and the axial pressure on the self-sealing packer 10 exceeds 10MPa. The water in the expansion structure 2 is squeezed back into the expanded diameter screen pipe 1 and the sealing structure 3 retracts inward, thereby reducing the resistance when lifting the oil pipe 6 and effectively reducing the risk of well stuck.

[0042] like Figure 1 As shown, in an embodiment of the present invention, the self-sealing packer 10 further includes a righting protection frame 4, which is sleeved outside the expanded diameter screen pipe 1, and the sealing structure 3 and the expansion structure 2 are located inside the righting protection frame 4. The righting protection frame 4 can shrink inwardly and expand outwardly by utilizing its own elasticity.

[0043] The present invention provides a straightening protection frame 4, which can ensure that the oil pipe 6 is centered, so that the sealing structure 3 and the casing 9 are evenly stressed in the circumferential direction after the sealing, thereby improving the effectiveness and stability of the sealing structure 3 in isolating the oil casing annulus 91; on the other hand, when the self-sealing packer 10 is lowered with the oil pipe 6, it can effectively protect the sealing structure 3, avoiding the sealing structure 3 from being damaged by friction and unable to effectively seal; on the other hand, after the self-sealing packer 10 has been operating in the underground environment for a long time, when the straightening protection frame 4 is squeezed due to scaling or shrinkage deformation of the casing 9, the straightening protection frame 4 can adaptively shrink and squeeze the sealing structure 3 to shrink synchronously, so that the well will not be stuck when the oil pipe 6 is lifted. Specifically, the straightening protection frame 4 is generally a cage-shaped steel frame structure. After the straightening protection frame 4 is lowered into the casing 9 with the oil pipe 6, it can adapt to the inner diameter of the casing 9 by using its own elasticity, so that the straightening protection frame 4 and the casing 9 are in sliding contact, so that the oil pipe 6 can be straightened and located in the middle of the casing 9.

[0044] The two ends of the expansion structure 2 are clamped and fixed on the lower oil pipe 62 and the upper oil pipe 61 by the two ends of the centralizing protection frame 4, and the expansion structure 2 is restricted to expand and contract only in the radial direction, and the oil and water can be prevented from leaking from the gap between the expansion structure 2 and the expanded diameter screen pipe 1 to the oil casing annulus 91. Specifically, the two ends of the expansion structure 2 extend to the lower oil pipe 62 and the upper oil pipe 61 through the two reducing sections 12.

[0045] like Figure 3 As shown, in an embodiment of the present invention, a plug 5 is provided at the sieve hole 13, and the plug 5 can be dissolved by oil and water. The sieve hole 13 is blocked in advance by the plug 5, so as to prevent oil and water from flowing into the expansion structure 2 from the sieve hole 13 in advance and causing the expansion structure 2 to expand in advance, which is beneficial to reduce the resistance generated when the self-sealing packer 10 is lowered with the oil pipe 6. Specifically, the number of sieve holes 13 is preferably multiple, and the multiple sieve holes 13 are evenly distributed along the circumference and radial direction of the expansion section 11. The material of the plug 5 can be a soluble metal, including a magnesium-aluminum alloy that can be dissolved by water. The material of the plug 5 can also include other soluble metals or other materials that can be dissolved by water and / or oil in the prior art.

[0046] In order to ensure that the expansion structure 2 does not expand before being lowered to the preset position, in an embodiment of the present invention, the dissolution time of the plug 5 is controlled to be greater than the time required for the self-sealing packer 10 to be lowered to the preset position. Specifically, the dissolution time of the plug 5 is controlled by controlling the material, size, shape, etc. of the plug 5. For example, the larger the cross-sectional area of ​​the plug 5, the longer the dissolution time; the longer the length of the plug 5 in the expanded diameter section 11, the longer the dissolution time.

[0047] Implementation Method 2

[0048] The present invention also provides a method for using the self-sealing packer 10. The self-sealing packer 10 in this embodiment is the same as the self-sealing packer 10 in the first embodiment. The method for using the self-sealing packer 10 includes the following steps:

[0049] Sealing: Oil and water enter the expanded diameter section 11 of the expanded diameter screen 1 from the oil pipe 6 and flow out from the screen hole 13 to the expansion structure 2. The sealing structure 3 expands outwards to achieve sealing under the pressure difference between the expanded diameter section 11 and the oil casing annulus 91 and the squeezing effect of the expansion structure 2 after it expands with oil and water. Specifically, since the expansion structure 2 and the sealing structure 3 are arranged in the expanded diameter section 11, in the initial state, the sealing structure 3 has a first expanded outer diameter that is larger than the outer diameter of the oil pipe 6 and smaller than the inner diameter of the casing 9; and then in the use state, the sealing structure 3 forms a second expanded outer diameter equal to the inner diameter of the casing 9 under the dual effects of the internal and external pressure difference of the expanded diameter section 11 and the expansion of the expansion structure 2 when it expands with water, thereby achieving sealing. After sealing, the oil casing annulus 91 includes a lower oil casing annulus 93 located below the self-sealing packer 10 and an upper oil casing annulus 92 located above the self-sealing packer 10.

[0050] Unsealing: lift the oil pipe 6 and increase the axial pressure on the self-sealing packer 10 to a level greater than its axial sealing pressure, so that the oil and water in the expansion structure 2 flow back from the sieve hole 13 to the expanded diameter screen pipe 1 under the action of the axial pressure, and the sealing structure 3 retracts inward to achieve unsealing.

[0051] In an embodiment of the present invention, before the sealing step, the method of use further includes the following steps: lowering: using the plug 5 to block the sieve hole 13, and then lowering the self-sealing packer 10 into the casing 9 along with the oil pipe 6, and during the lowering process, oil and water can enter the expanded diameter section 11 from the oil pipe 6 and dissolve the plug 5, until the self-sealing packer 10 is lowered to the preset position and the plug 5 is completely dissolved by the oil and water.

[0052] In an embodiment of the present invention, the method of use further comprises the following steps: Well washing: the well washing fluid flows from the oil pipe 6 to the bottom of the well and enters the lower casing annulus 93, so that the pressure of the lower casing annulus 93 is greater than the pressure of the lower casing annulus 93, until the pressure difference between the lower casing annulus 93 and the lower casing annulus 93 is greater than the preset pressure difference, and the well washing fluid in the lower casing annulus 93 enters the upper casing annulus 92 from the gap between the self-sealing packer 10 and the casing 9 and is discharged. Specifically, after the well washing is completed, the casing annulus 91 of the wellhead is closed.

[0053] Implementation Method 3

[0054] like Figure 4 As shown, the present invention also provides an anti-corrosion tubing string for oil and water wells, comprising: an oil pipe 6, including an upper oil pipe 61 and a lower oil pipe 62; at least one of the above-mentioned self-sealing packers 10, connecting the upper oil pipe 61 and the lower oil pipe 62; an upper anti-corrosion device 7, arranged outside the upper oil pipe 61, and the upper anti-corrosion device 7 can slowly release a fixed corrosion inhibitor into the annulus between the upper oil pipe 61 and the casing 9.

[0055] like Figure 5As shown, in the embodiment of the present invention, there are multiple self-sealing packers 10, the oil pipe 6 also includes at least one middle oil pipe 63, the expanded diameter screen pipes 1 of the multiple self-sealing packers 10 are connected from top to bottom through at least one middle oil pipe 63, the oil and water well anti-corrosion pipe string also includes at least one lower anti-corrosion device 8, the lower anti-corrosion device 8 is arranged outside the middle oil pipe 63, and the lower upper anti-corrosion device 7 can slowly release the fixed corrosion inhibitor into the annulus between the middle oil pipe 63 and the casing 9.

[0056] like Figure 4 As shown, in one embodiment of the present invention, a water recovery well has a well depth of 1470m, a perforation section depth of 1440m-1450m, and in the oil and water well anti-corrosion string, the upper anti-corrosion device 7 adopts a solid corrosion inhibitor device, and the oil pipe 6 is an N80 oil pipe 6. The oil and water well anti-corrosion string includes: an upper oil pipe 61 placed in the casing 9 from the wellhead, a solid corrosion inhibitor device installed on the upper oil pipe 61 and located at a depth of 650m, a self-sealing packer 10 connected to the upper oil pipe 61 at the upper end and sealed at a depth of 1400m, and a lower oil pipe 62 connected to the lower end of the self-sealing packer 10 and lowered to a depth of 1420m.

[0057] like Figure 5 As shown, in another embodiment of the present invention, a produced water return oil well has a well depth of 1470m and a perforation section of 1440-1450m. In the anti-corrosion pipe string, both the upper anti-corrosion device 7 and the lower anti-corrosion device 8 use solid corrosion inhibitor devices, and the oil pipe 6 is an N80 oil pipe 6. The oil and water well anti-corrosion pipe string includes: an upper oil pipe 61 placed in the casing 9 from the wellhead, a solid corrosion inhibitor device installed on the upper oil pipe 61 and located at a depth of 650m, a self-sealing packer 10 connected to the upper oil pipe 61 at the upper end and sealed at a depth of 1350m, a middle oil pipe 63 connected to the lower end of the self-sealing packer 10 at the upper end, another self-sealing packer 10' connected to the lower end of the middle oil pipe 63 at the upper end and sealed at a depth of 1400m, and a lower oil pipe 62 connected to the self-sealing packer 10' and lowered to a depth of 1420m.

[0058] The above are only several embodiments of the present invention. Those skilled in the art may make various changes or modifications to the embodiments of the present invention based on the contents disclosed in the application documents without departing from the spirit and scope of the present invention.

Claims

1. A self-sealing packer, characterized in that: include: An expanded diameter screen pipe, comprising an expanded diameter section provided with screen holes, wherein the inner diameter of the expanded diameter section is larger than the inner diameter of the oil pipe and smaller than the inner diameter of the casing; A sealing structure, sleeved outside the expanded diameter section; An expansion structure, disposed between the diameter expansion section and the sealing structure; Among them, after the oil and water in the oil pipe enter the expanded section, the pressure increases and squeezes the expansion structure to expand outward, and the oil and water can flow into the expansion structure from the sieve hole and expand the expansion structure, and the sealing structure can expand outward under the expansion extrusion and expansion extrusion of the expansion structure.

2. The self-sealing packer according to claim 1, characterized in that: The self-sealing packer also includes a centering protection frame, which is sleeved outside the expanded diameter screen pipe, and the sealing structure and the expansion structure are located inside the centering protection frame. The centering protection frame can shrink inwards and expand outwards by utilizing its own elasticity.

3. The self-sealing packer according to claim 2, characterized in that: The oil pipe comprises a lower oil pipe and an upper oil pipe, the upper oil pipe is connected to the lower oil pipe through the expanded diameter screen pipe, and the two ends of the straightening protection frame clamp and fix the two ends of the expansion structure to the lower oil pipe and the upper oil pipe.

4. The self-sealing packer according to claim 3, characterized in that: The expanded diameter screen pipe also includes two diameter reducing sections, the inner diameter of the diameter reducing section gradually decreases from the inner diameter of the expanded diameter section to the inner diameter of the oil pipe in an arc shape, and the two ends of the expanded diameter section are connected to the lower oil pipe and the upper oil pipe through the two diameter reducing sections.

5. The self-sealing packer according to claim 1, characterized in that: A plug is provided at the sieve hole, and the plug can be dissolved by the oil and water.

6. The self-sealing packer according to claim 5, characterized in that: The dissolution time of the plug is greater than the time required for the self-sealing packer to be lowered to a preset position.

7. The self-sealing packer according to claim 5, characterized in that: The material of the plug is soluble metal.

8. The self-sealing packer according to claim 1, characterized in that: The sealing structure comprises a rubber water bag and an expansion rubber layer, wherein the expansion rubber layer is located between the rubber water bag and the expansion structure, and the expansion rubber layer can swell when encountering water or oil.

9. The self-sealing packer according to claim 1, characterized in that: The expansion material filled between the expanded diameter section and the sealing structure forms the expansion structure, and the expansion material can swell when it meets water or oil.

10. A method for using a self-sealing packer, characterized in that: The self-sealing packer is the self-sealing packer according to any one of claims 1 to 9, and the method of use comprises the following steps: Sealing: Oil and water enter the expanded diameter section of the expanded diameter screen pipe from the oil pipe and flow out from the screen hole into the expansion structure. The sealing structure expands outwards to achieve sealing under the pressure difference between the expanded diameter section and the casing annulus and the squeezing effect of the expansion structure after it expands with oil and water; Unsealing: lift the oil pipe and increase the axial pressure on the self-sealing packer to a level greater than its axial sealing pressure. Under the action of the axial pressure, the oil and water in the expansion structure flow back from the sieve hole into the expanded diameter sieve pipe, causing the sealing structure to retract inwards to achieve unsealing.

11. The method for using the self-sealing packer according to claim 10, characterized in that: Prior to the sealing step, the method of use further comprises the following steps: Lowering: Use a plug to block the sieve hole, and then lower the self-sealing packer into the casing along with the oil pipe. During the lowering process, the oil and water can enter the expanded diameter section from the oil pipe and dissolve the plug, until the self-sealing packer is lowered to a preset position and the plug is completely dissolved by the oil and water.

12. The method for using the self-sealing packer according to claim 10, characterized in that: After the sealing step, the casing annulus includes a lower casing annulus located below the self-sealing packer and an upper casing annulus located above the self-sealing packer. The use method further includes the following steps: Well washing: the washing fluid flows from the oil pipe to the bottom of the well and enters the lower casing annulus, so that the pressure of the lower casing annulus is greater than the pressure of the lower casing annulus, until the pressure difference between the lower casing annulus and the lower casing annulus is greater than the preset pressure difference, and the washing fluid in the lower casing annulus enters the upper casing annulus from the gap between the self-sealing packer and the casing and is discharged.

13. An anti-corrosion pipe string for oil and water wells, characterized in that: include: Oil pipe, including upper oil pipe and lower oil pipe; At least one self-sealing packer according to any one of claims 1 to 9, connecting the upper tubing and the lower tubing; The upper anti-corrosion device is arranged outside the upper oil pipe, and the upper anti-corrosion device can slowly release the fixed corrosion inhibitor into the annulus between the upper oil pipe and the casing.

14. The anti-corrosion pipe string for oil and water wells according to claim 13, characterized in that: There are multiple self-sealing packers, and the oil pipe also includes at least one middle oil pipe. The expanded diameter screens of the multiple self-sealing packers are connected from top to bottom through at least one middle oil pipe. The oil and water well anti-corrosion pipe string also includes at least one lower anti-corrosion device, which is arranged outside the middle oil pipe. The lower anti-corrosion device can slowly release fixed corrosion inhibitor into the annulus between the middle oil pipe and the casing.

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