Layered and segmented packing system for offshore thermal production well and using method of layered and segmented packing system

Abstract

The invention discloses a layered and segmented packing system for an offshore thermal production well and a using method of the layered and segmented packing system, and solves the technical problems that setting and unsetting operation of a packer is complex, and operation time efficiency is affected. The packing system comprises an upper connector, a central pipe and a lower connector, the central pipe is composed of a setting section and a supporting section, the outer diameter of the setting section is larger than that of the supporting section, a setting conical surface is arranged at the lower end of the setting section, the packing system further comprises a setting rubber barrel, a setting mechanism and a deblocking mechanism, the setting rubber barrel is movably arranged at the upper end of the supporting section in a sleeving mode, and the setting rubber barrel is sleeved with the supporting section. The setting mechanism is used for pushing the setting rubber barrel to move upwards to the setting conical surface so that the setting rubber barrel and a shaft can be set, the unsetting mechanism is used for pushing the setting rubber barrel to move downwards and loosen the setting rubber barrel, and after a worker lifts an oil well pipe column, the setting rubber barrel can move downwards and unset. Automatic setting and unsetting of the packing system can be achieved, a service tool does not need to be put down, operation is more convenient and faster, and the operation time efficiency can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field development, and in particular relates to a layered and segmented isolation system for an offshore thermal recovery well and a use method thereof. Background Art

[0002] The development of marine oil and gas resources is the hot spot and focus of the current development of the world's marine economy. Marine oil and gas resources not only have large reserves, but modern science and technology have already possessed tremendous capabilities for their development. The marine oil and gas industry has developed into an emerging, high-value-added leading industry in the marine economy.

[0003] With the large-scale application of thermal recovery of offshore heavy oil, the reservoir types have gradually expanded from single sand bodies to thin interlayers and thick layers, and the distribution of reservoir interlayers is complex and heterogeneous. In addition, after multiple rounds of steam injection in the early stage of development, there are common problems such as uneven steam absorption between layers and poor utilization, and even steam channeling, which affects the effect of thermal recovery.

[0004] At present, the use of layered / segmented injection and production technology can improve the steam injection profile and effectively increase the steam sweep volume and the degree of utilization of the oil layer. However, the injection and production method of offshore thermal wells is mainly based on the integration of high-temperature electric pumps and jet pumps. At the same time, combined with the special production requirements of the sea, it is necessary to put downhole safety control tools. Therefore, the offshore layered / segmented injection and production technology needs to be based on the onshore oil field technology and experience, combined with the special working conditions and requirements of the sea, to carry out targeted research and research.

[0005] The injection and production tubing in the related technology usually has a sealing system, which is usually mechanically sealed and unsealed, that is, the staff needs to lower the service tool to realize the sealing and unsealing control of the sealing system. There are problems such as complicated operation and affecting the timeliness of operation, which need to be improved. Summary of the invention

[0006] In order to solve all or part of the above problems, the purpose of the present invention is to provide a layered and segmented isolation system for offshore thermal recovery wells and a method of using the same. The isolation system can be automatically sealed and unsealed without the need to lower service tools, making the operation more convenient and effectively improving the operation time efficiency.

[0007] In a first aspect, the present invention provides a stratified and segmented isolation system for an offshore thermal recovery well, comprising:

[0008] An upper joint, used for connecting with an external component;

[0009] The center pipe is composed of a setting section and a supporting section, the top end of the setting section is connected to the upper joint, the supporting section is coaxially connected to the bottom end of the setting section, the outer diameter of the setting section is larger than the outer diameter of the supporting section, and the lower end of the setting section is provided with a setting cone surface;

[0010] A lower joint connected to the bottom end of the support section and used for connecting with an external component;

[0011] A sealing rubber cylinder is movably sleeved at the upper end of the supporting section;

[0012] A setting mechanism, used for pushing the setting rubber cylinder to move upward to the setting cone surface, so that the setting rubber cylinder and the wellbore are set;

[0013] The unsealing mechanism is used to push the sealing rubber cylinder downward and loosen the sealing rubber cylinder. When the staff lifts the oil well tubing, the sealing rubber cylinder can move downward relative to the oil well tubing and be unsealed under the action of the friction between its own outer wall and the inner wall of the wellbore.

[0014] Optionally, the setting cone surface is transitionally connected to the top end of the support section via a guiding slope, so that the setting rubber cylinder can smoothly move onto the setting cone surface under the guidance of the guiding slope.

[0015] Optionally, the setting mechanism comprises:

[0016] A support cylinder sleeve, which is sleeved at the lower end of the support section, the bottom end of the support cylinder sleeve is connected to the lower joint, and an annular accommodating cavity is formed between the inner side wall of the support cylinder sleeve and the outer side wall of the support section;

[0017] A piston part, vertically slidably connected in the accommodating chamber;

[0018] An expansion agent is filled in the accommodating cavity, and after the expansion agent is heated and expanded, it can push the piston part to move upward, so that the piston part pushes the setting rubber cylinder onto the setting cone surface.

[0019] Optionally, the supporting cylinder sleeve is provided with an injection hole communicating with the accommodating chamber, and a sealing plug is threadedly connected to the injection hole.

[0020] Optionally, the unblocking mechanism includes:

[0021] A thrust sleeve, a movable sleeve arranged on the setting section and located above the setting cone surface;

[0022] An adjusting ring, movably sleeved on the setting section and connected to the top end of the thrust sleeve;

[0023] A shearing ring is arranged on the setting section and is used to prevent the adjusting ring from moving downward. The shearing ring is made of a soluble material and can be dissolved in the well fluid.

[0024] A butterfly spring is arranged on the setting section and is used to push the adjusting ring to move downward;

[0025] The elastic force of the butterfly spring and the expansion force of the expansion agent are set as follows:

[0026] When the expansion agent expands due to heat, the expansion force of the expansion agent is greater than the elastic force of the butterfly spring, and the setting rubber cylinder can move to the setting cone surface under the push of the piston part;

[0027] When the shear ring is dissolved, the expansion force of the expansion agent is greater than the elastic force of the butterfly spring, the thrust sleeve cannot push the setting rubber cylinder to move downward, and the setting rubber cylinder remains in the setting position;

[0028] When the expansion agent cools and contracts, the elastic force of the butterfly spring is greater than the expansion force of the expansion agent, and the setting rubber cylinder can move downward under the action of the thrust sleeve to loosen the setting rubber cylinder.

[0029] Optionally, the unblocking mechanism further includes:

[0030] A limiting ring, which is fixedly sleeved on the setting section and is used to prevent the thrust sleeve from moving upward. An annular installation cavity is formed between the adjusting ring, the thrust sleeve and the limiting ring. The shear ring is arranged in the installation cavity, and the top end of the shear ring abuts against the adjusting ring, and the bottom end abuts against the limiting ring.

[0031] The dissolution channel is arranged on the adjusting ring and communicated with the mounting cavity.

[0032] Optionally, the isolation system further comprises two righting mechanisms, one of which is coaxially connected to the top end of the upper joint, and the other is coaxially connected to the bottom end of the lower joint, to ensure that the isolation system is centered in the wellbore.

[0033] Optionally, each of the righting mechanisms comprises:

[0034] The first joint is arranged vertically, and the top end of the first joint can be threadedly connected to the lower joint;

[0035] A support tube, coaxially connected to the bottom end of the first joint;

[0036] A second joint, coaxially connected to the bottom end of the support tube, and the bottom end of the second joint can be threadedly connected to the upper joint;

[0037] There are two protective rings, one of which is fixedly sleeved at the upper end of the support tube, and the other is fixedly sleeved at the lower end of the support tube. The two protective rings are respectively provided with an annular limiting edge at one end close to each other, and an annular limiting groove is formed between the inner side wall of the limiting edge and the outer side wall of the support tube;

[0038] A plurality of straightening blocks are respectively arranged between the two protection rings, the plurality of straightening blocks are arranged at equal intervals along the circumference of the support tube, the two ends of the plurality of straightening blocks are respectively movably arranged in the corresponding limit grooves, and the straightening blocks can move along the radial direction of the support tube, the straightening blocks are made of soluble materials, and the straightening blocks can be dissolved in the well fluid;

[0039] There are multiple elastic leaf springs, which are respectively arranged on the support tube. The multiple elastic leaf springs are arranged one-to-one correspondingly to the multiple straightening blocks, and the elastic leaf springs are used to push the corresponding straightening blocks to move radially along the support tube and make the straightening blocks tightly abut against the inner wall of the wellbore.

[0040] In a second aspect, the present invention provides a method for using a sealing system, comprising the following steps:

[0041] S1, connecting the isolation system to the oil well string, and then lowering the oil well string into the wellbore;

[0042] S2, controlling the sealing rubber cylinder to move upward to the sealing cone surface through the sealing mechanism, so that the sealing rubber cylinder is sealed with the wellbore;

[0043] S3, the packing rubber tube is controlled to move downward by the unsealing mechanism to loosen the packing rubber tube, and then the oil well pipe string is lifted up to make the packing rubber tube move downward relative to the oil well pipe string and realize unsealing.

[0044] Optionally, in S1, a high-temperature downhole safety valve, a high-temperature annulus safety packer, a tubing centralizer, a top packer, two injection valves, and an optical fiber monitoring mechanism are sequentially connected to the oil well tubing string;

[0045] At the same time, one of the righting mechanisms is connected to the top of the upper joint, and the other righting mechanism is connected to the bottom of the lower joint to form an isolation system, and then the isolation system is connected to the oil well pipe string, and the isolation system is located between the two injection valves;

[0046] Subsequently, the oil well tubular is lowered into the wellbore. At this time, the multiple straightening blocks on the two straightening mechanisms are respectively in close contact with the inner wall of the wellbore to straighten the oil well tubular and ensure that the oil well tubular is centered in the wellbore.

[0047] Optionally, in S2, hot steam is introduced into the oil well tubing, the expansion agent expands due to the heat and pushes the piston part to move upward, and then the piston part pushes the sealing rubber tube onto the sealing cone surface to seal the sealing rubber tube with the well wall, thereby realizing layered segmentation of the wellbore.

[0048] Optionally, in S3, when the shear ring is completely dissolved in the well fluid, the adjusting ring pushes the thrust sleeve downward under the action of the butterfly spring, and then the thrust sleeve pushes the sealing rubber tube downward to loosen the sealing rubber tube. Subsequently, the oil well tubing is lifted up, and the sealing rubber tube moves downward relative to the oil well tubing under the action of the friction between its own outer wall and the inner wall of the wellbore to achieve unsealing.

[0049] Optionally, in S3, when the shear ring is completely dissolved in the well fluid, the straightening block is also completely dissolved in the well fluid to ensure that the staff can smoothly lift the oil well tubing string.

[0050] It can be seen from the above technical solutions that the offshore thermal recovery well stratified and segmented isolation system and its use method provided by the present invention have the following advantages:

[0051] The sealing system itself has a sealing mechanism and an unsealing mechanism, and adopts a thermal setting method, which can realize automatic sealing and unsealing control of the sealing rubber cylinder. There is no need to insert service tools, which makes the operation more convenient and effectively improves the operation time efficiency.

[0052] Other features and advantages of the present invention will be set forth in the description which follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0054] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of the present invention;

[0055] Figure 2 This is a schematic diagram of the structure of Example 1 of the present invention after the righting mechanism is removed;

[0056] Figure 3 Schematic diagram of the structure of the setting mechanism in Example 1 of the present invention;

[0057] Figure 4 This is a schematic diagram of the structure of the unsealing mechanism in Example 1 of the present invention;

[0058] Figure 5 Schematic diagram of the structure of the righting mechanism in Example 1 of the present invention;

[0059] Figure 6 It is a schematic diagram of the structure of the isolation system and the oil well tubing string in Example 2 of the present invention.

[0060] Description of reference numerals:

[0061] 1. Upper joint; 2. Center pipe; 21. Setting section; 22. Support section; 23. Setting cone; 24. Guide slope; 3. Lower joint; 4. Setting rubber cylinder; 41. Rubber cylinder body; 42. Upper shoulder guard; 43. Lower shoulder guard; 5. Setting mechanism; 51. Support cylinder sleeve; 52. Accommodating chamber; 53. Piston; 531. Piston ring; 532. Sealing packing; 533. Composite sealing ring; 534. Extrusion ring; 535. Inner pressure sleeve; 536. Outer Compression sleeve; 54, expansion agent; 55, injection hole; 56, sealing plug; 6, unsealing mechanism; 61, thrust sleeve; 62, limiting ring; 63, step groove; 64, adjustment ring; 65, installation cavity; 66, dissolving shear ring; 67, dissolving channel; 68, butterfly spring; 7, straightening mechanism; 71, first joint; 72, support tube; 73, second joint; 74, protection ring; 75, limiting edge; 76, limiting groove; 77, straightening block; 78, elastic leaf spring;

[0062] 100. Oil well tubing string; 200. Packing system; 300. High-temperature downhole safety valve; 400. High-temperature annulus safety packer; 500. Tubing centralizer; 600. Top packer; 700. Injection valve; 800. Fiber optic monitoring mechanism. DETAILED DESCRIPTION

[0063] To make the purpose, technical solution and advantages of the present invention more clear, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other arbitrarily without conflict.

[0064] Example 1

[0065] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 Embodiment 1 of the present invention is shown, which discloses a layered and segmented isolation system for offshore thermal recovery wells, including an upper joint 1, a central pipe 2 and a lower joint 3 which are threadedly connected in sequence from top to bottom, and a sealing rubber cylinder 4, a sealing mechanism 5 and an unsealing mechanism 6 are provided on the central pipe 2.

[0066] In one embodiment, Figure 1 , Figure 2 As shown, the center pipe 2 is composed of a setting section 21 and a support section 22. The support section 22 is coaxial and integrally connected to the bottom end of the setting section 21. The top end of the setting section 21 is threadedly connected to the upper joint 1, and the bottom end of the support section 22 is threadedly connected to the lower joint 3. The outer diameter of the setting section 21 is larger than the outer diameter of the support section 22. The lower end of the setting section 21 is integrally provided with a setting cone 23, and the outer diameter of the bottom end of the setting cone 23 is smaller than the outer diameter of the upper end thereof.

[0067] In one embodiment, Figure 1 , Figure 2 As shown, the setting rubber tube 4 is movably sleeved at the upper end of the support section 22, and the setting mechanism 5 is used to push the setting rubber tube 4 to move upward to the setting cone surface 23, so that the setting rubber tube 4 and the wellbore are set. The unsealing mechanism 6 is used to push the setting rubber tube 4 to move downward and loosen the setting rubber tube 4. When the staff lifts the oil well pipe string, the setting rubber tube 4 can move downward relative to the oil well pipe string under the action of the friction between its outer wall and the inner wall of the wellbore and realize unsealing.

[0068] It should be noted that the outer diameter of the sealing rubber tube 4 and the outer diameter of the sealing cone surface 23 are set according to the inner diameter of the wellbore. The specific parameters can be understood as follows: when the sealing rubber tube 4 is completely moved onto the sealing cone surface 23, the outer wall of the sealing rubber tube 4 can be tightly abutted against the inner wall of the wellbore to achieve the sealing of the sealing rubber tube 4 and the wellbore.

[0069] In one embodiment, Figure 1 , Figure 2 As shown, since the outer diameter of the lower end of the setting cone 23 is larger than the outer diameter of the support section 22, the setting cone 23 and the top of the support section 22 are transitionally connected via a guide slope 24, which is used to guide the expansion of the setting rubber cylinder 4, so that the setting rubber cylinder 4 can move smoothly to the setting cone 23 under the guidance of the guide slope 24, so as to improve the success rate of setting.

[0070] In one embodiment, Figure 2 , Figure 3 As shown, the setting mechanism 5 includes a support cylinder sleeve 51 sleeved at the lower end of the support section 22, the bottom end of the support cylinder sleeve 51 is threadedly connected to the lower joint 3, and an annular accommodating chamber 52 is formed between the inner side wall of the support cylinder sleeve 51 and the outer side wall of the support section 22, and a piston portion 53 is vertically slidably connected in the accommodating chamber 52, and the piston portion 53 is slidably sealed with the inner walls of both sides of the accommodating chamber 52. At the same time, the accommodating chamber 52 is filled with an expansion agent 54. When hot steam is passed into the central tube 2, the expansion agent 54 is heated and expanded to push the piston portion 53 to move upward, so that the piston portion 53 pushes the setting rubber cylinder 4 onto the setting cone surface 23.

[0071] In this embodiment, materials such as n-octane, n-heptane, nonane, and petroleum ether with stable performance and a boiling range of 90 to 150°C are selected as the expansion agent 54. Tests have shown that the expansion agent 54 can generate a sealing load of not less than 23.74 MPa at the sealing temperature. When heated to 350°C, the expansion agent 54 can generate a sealing load of 31.84 MPa.

[0072] In one embodiment, Figure 2 , Figure 3As shown, the support cylinder sleeve 51 is provided with an injection hole 55 connected to the accommodating chamber 52, and the injection hole 55 is threadedly connected with a sealing plug 56, that is, the staff can inject the expansion agent 54 into the accommodating chamber 52 through the injection hole 55, so as to facilitate the staff's filling operation of the expansion agent 54.

[0073] In one embodiment, Figure 2 , Figure 3 As shown, the piston portion 53 includes a piston ring 531, and sealing packings 532 are respectively embedded at the lower ends of the inner wall and the outer wall of the piston ring 531, and the sealing packings 532 are tightly abutted against the corresponding inner wall of the accommodating chamber 52 to achieve the first seal between the piston ring 531 and the accommodating chamber 52.

[0074] In one embodiment, Figure 2 , Figure 3 As shown, the inner wall and the outer wall of the piston ring 531 are respectively provided with a composite sealing ring 533, which is located above the corresponding sealing packing 532, and the composite sealing ring 533 is tightly abutted against the corresponding inner wall of the accommodating chamber 52 to achieve a second seal between the piston ring 531 and the accommodating chamber 52.

[0075] In one embodiment, Figure 2 , Figure 3 As shown, the inner and outer walls of the piston ring 531 are respectively threadedly connected with an extrusion ring 534, and the extrusion ring 534 is tightly abutted against the corresponding inner wall of the accommodating cavity 52. ​​At the same time, the extrusion ring 534 is located above the corresponding composite sealing ring 533 and abuts against the composite sealing ring 533 to achieve compression and limiting of the composite sealing ring 533.

[0076] In one embodiment, Figure 2 , Figure 3 As shown, the upper end of the piston ring 531 has an internal thread and a thread, and the upper end of the piston ring 531 is threadedly connected with an inner pressure sleeve 535 and an outer pressure sleeve 536, which serve as an actuator for pushing the setting rubber cylinder 4 to move. At the same time, the inner pressure sleeve 535 and the outer pressure sleeve 536 are respectively tightly abutted against the corresponding inner walls of the accommodating chamber 52, and the inner pressure sleeve 535 is used to push the setting rubber cylinder 4 to move upward.

[0077] In this embodiment, the composite sealing ring 533 is composed of a fluororubber high-temperature packing + two flexible graphite + four modified polytetrafluoroethylene rings + three flexible graphite. The overall temperature resistance is 350°C and the pressure resistance is 21MPa. It effectively improves the sealing effect between the piston ring 531 and the accommodating cavity 52, and prevents the leakage of the expansion agent 54 under high and low temperature conditions, so as to meet the high and low temperature sealing expansion capacity of multiple rounds of steam injection.

[0078] In one embodiment, Figure 2 , Figure 4As shown, the unsealing mechanism 6 includes a thrust sleeve 61 movably sleeved on the setting section 21, the thrust sleeve 61 is located above the setting cone surface 23, and is used to push the setting rubber cylinder 4 to move downward. A limit ring 62 is integrally formed on the setting section 21, the limit ring 62 is located above the setting cone surface 23, and the inner side wall of the thrust sleeve 61 is provided with a step groove 63 that matches the limit ring 62 to achieve the limit of the thrust sleeve 61 in the vertical upward direction.

[0079] When the sealing rubber tube 4 moves completely to the sealing cone surface 23 and the top end of the sealing rubber tube 4 abuts against the thrust sleeve 61, the limit ring 62 abuts against the bottom of the step groove 63. At this time, the thrust sleeve 61 can prevent the sealing rubber tube 4 from moving upward, so that the sealing rubber tube 4 can expand further under the pushing action of the piston part 53 and abut against the inner wall of the wellbore more tightly to ensure the sealing effect.

[0080] In one embodiment, Figure 2 , Figure 4 As shown, an adjusting ring 64 is movably provided on the sealing section 21, and the bottom end of the adjusting ring 64 is sleeved on the top end of the thrust sleeve 61 and is threadedly connected to the thrust sleeve 61. The cross-section of the adjusting ring 64 is L-shaped, and an annular installation cavity 65 is formed between the adjusting ring 64, the thrust sleeve 61 and the limiting ring 62.

[0081] In one embodiment, Figure 2 , Figure 4 As shown, a shear ring 66 is provided in the installation cavity 65, the top of the shear ring 66 abuts against the inner wall of the top side of the adjustment ring 64, the bottom of the shear ring 66 abuts against the limit ring 62, and the shear ring 66 can prevent the adjustment ring 64 from moving downward. The shear ring 66 is made of a soluble material and can be dissolved in the well fluid. At the same time, the adjustment ring 64 is provided with a dissolving channel 67 connected to the installation cavity 65.

[0082] In one embodiment, Figure 2 , Figure 4 As shown, a butterfly spring 68 is sleeved on the setting section 21, the top end of the butterfly spring 68 abuts against the upper joint 1, and the bottom end abuts against the adjusting ring 64, and the butterfly spring 68 is used to push the adjusting ring 64 to move downward.

[0083] In this embodiment, the elastic force of the butterfly spring 68 and the expansion force of the expansion agent 54 are set as follows: when the expansion agent 54 expands due to heat, the expansion force of the expansion agent 54 is greater than the elastic force of the butterfly spring 68. At this time, the sealing rubber tube 4 can move to the sealing cone surface 23 under the push of the piston portion 53, so that the sealing rubber tube 4 and the wellbore are sealed; when the shear ring 66 is dissolved, the expansion force of the expansion agent 54 is greater than the elastic force of the butterfly spring 68, and the thrust sleeve 61 cannot push the sealing rubber tube 4 to move downward, and the sealing rubber tube 4 remains in the sealing position; when the expansion agent 54 cools and shrinks, the elastic force of the butterfly spring 68 is greater than the expansion force of the expansion agent 54, and the sealing rubber tube 4 can move downward under the action of the thrust sleeve 61, so that the sealing rubber tube 4 is loosened.

[0084] In this embodiment, the shear ring 66 is used to limit the support of the adjustment ring 64 to prevent the butterfly spring 68 from releasing the unsealing force in advance, so as to ensure that the sealing rubber cylinder 4 can be set smoothly. The butterfly spring 68 is made of chromium-nickel-iron alloy Inconel718, which is assembled back to back and designed to release the elastic force of 15-20kN. The shear ring 66 is made of soluble magnesium alloy, and the outer protection is covered with a nylon protective sleeve. When steam is injected, the nylon sleeve melts first, and the soluble magnesium ring slowly dissolves in the chloride ion-containing well fluid. It has been verified by indoor tests that the soluble magnesium alloy dissolves completely in the chloride ion-containing well fluid in three days at room temperature.

[0085] In the isolation system of this embodiment, hot steam is introduced into the central pipe 2, and the expansion agent 54 expands due to the heat, and the piston part 53 pushes the sealing rubber tube to move upward until the sealing rubber tube moves to the setting cone surface 23 and completes the setting with the wellbore. As the heat injection temperature rises, the shear ring 66 gradually dissolves, and the adjustment ring 64 loses its limit, and the thrust sleeve 61 is driven to move downward under the action of the butterfly spring 68. At this time, the elastic force of the butterfly spring 68 is less than the expansion force of the expansion agent 54, and the elastic force of the butterfly spring 68 = the expansion force of the expansion agent 54 + the friction between the setting rubber tube 4 and the setting cone surface 23, so as to achieve force balance, that is, the thrust sleeve 61 cannot push the setting rubber tube 4 to move downward, and the setting rubber tube 4 and the wellbore maintain a stable setting state. After the heat injection is stopped, the wellbore temperature decreases, and the expansion force of the expansion agent 54 decreases. At this time, the elastic force of the butterfly spring 68 is greater than the expansion force of the expansion agent 54, and then the thrust sleeve 61 can push the setting rubber tube 4 to move downward and loosen the setting rubber tube 4. Finally, the oil well pipe string is lifted up. Since the friction force between the setting rubber tube 4 and the inner wall of the wellbore is greater than the friction force between the setting rubber tube 4 and the setting cone surface 23, the setting rubber tube 4 moves downward relative to the oil well pipe string, so that the setting rubber tube 4 is smoothly released.

[0086] In one embodiment, Figure 3 , Figure 4As shown, the setting rubber cylinder 4 is composed of a rubber cylinder body 41, an upper shoulder guard 42 and a lower shoulder guard 43. The rubber cylinder body 41 is movably sleeved on the support section 22, the upper shoulder guard 42 is fixed to the bottom end of the thrust sleeve 61, and the lower shoulder guard 43 is fixed to the top end of the internal pressure sleeve 535. In this embodiment, the rubber cylinder body 41 adopts a modified polytetrafluoroethylene rubber cylinder. The modified polytetrafluoroethylene rubber cylinder is determined by filling modification and orthogonal experimental method. The rubber cylinder component is 350°C, 21MPa, and the pressure difference is ≥5MPa. The upper shoulder guard 42 and the lower shoulder guard 43 are respectively made of brass, which play a role in protecting the upper and lower end surfaces of the rubber cylinder from hard damage after the rubber cylinder body 41 expands.

[0087] The layered and segmented isolation system for offshore thermal wells in this embodiment adopts a slip-free, thermal setting structure, which can realize automatic setting and unsealing without the need to run service tools, and has reliable performance, an overall temperature resistance of 350°C, and a pressure resistance of 21MPa, which can adapt to the high temperature and high pressure environment underground. At the same time, a composite sealing structure of graphite ring + modified polytetrafluoroethylene + high temperature resistant rubber ring is adopted, and the sealing performance is reliable. Not only that, when the setting rubber cylinder 4 is unsealed, as the setting rubber cylinder 4 contracts after cooling down, the setting rubber cylinder 4 is loosened under the elastic force of the butterfly spring 68, which can effectively avoid the problem of difficulty in lifting in the horizontal section or the high-angle well section, ensure the safety of the operation, and meet the harsh and strict offshore operation construction requirements.

[0088] In one embodiment, Figure 1 , Figure 5 As shown, the isolation system also includes two straightening mechanisms 7, one of which is coaxially connected to the top of the upper joint 1, and the other is coaxially connected to the bottom of the lower joint 3. The straightening effect of the two straightening mechanisms 7 can ensure that the isolation system is centered in the wellbore to prevent wear of the isolation system.

[0089] In one embodiment, Figure 1 , Figure 5 As shown, each straightening mechanism 7 includes a first joint 71, a support tube 72 and a second joint 73 which are threadedly connected in sequence from top to bottom. The top end of the first joint 71 can be threadedly connected to the lower joint 3, and the bottom end of the second joint 73 can be threadedly connected to the upper joint 1.

[0090] In one embodiment, Figure 1 , Figure 5 As shown, protective rings 74 are fixedly mounted at the upper and lower ends of the support tube 72, and the ends of the two protective rings 74 close to each other are integrally connected with an annular limiting edge 75, and an annular limiting groove 76 is formed between the inner wall of the limiting edge 75 and the outer wall of the support tube 72.

[0091] In one embodiment, Figure 1 , Figure 5As shown, a plurality of straightening blocks 77 are arranged between the two protective rings 74, and the plurality of straightening blocks 77 are arranged at equal intervals along the circumference of the support tube 72. At the same time, the two ends of the plurality of straightening blocks 77 are movably arranged in the corresponding limit grooves 76, and the straightening blocks 77 can move along the radial direction of the support tube 72, and make the middle position of the straightening blocks 77 tightly abut against the inner wall of the wellbore.

[0092] In one embodiment, Figure 1 , Figure 5 As shown, a plurality of elastic leaf springs 78 are arranged on the support tube 72, and the plurality of elastic leaf springs 78 are arranged one by one corresponding to the plurality of straightening blocks 77, and the elastic leaf springs 78 are used to push the corresponding straightening blocks 77 to move radially along the support tube 72 and make the straightening blocks 77 tightly abut against the inner wall of the wellbore.

[0093] In this embodiment, the maximum outer diameter of the straightening mechanism 7 is 118 mm, and the maximum outer diameter of the straightening mechanism 7 after the straightening block 77 is ablated is 105 mm. An elastic straightening structure is adopted, which can shrink when encountering resistance, and is suitable for the sand control section of a horizontal well with a diameter of 4.75″ in the reservoir of an offshore thermal recovery well. The elastic leaf spring 78 is made of high-temperature resistant spring steel, and serves as a power mechanism for the straightening mechanism 7 to radially support the straightening block 77, thereby ensuring the tight contact effect between the straightening block 77 and the inner wall of the wellbore, thereby ensuring the straightening effect.

[0094] In this embodiment, the straightening block 77 is made of polyglycolide soluble material, and the straightening block 77 can be dissolved in the well fluid during steam injection, reducing the load of unsealing and pulling out the oil well pipe string, ensuring that the oil well pipe string can be pulled out smoothly. At the same time, the ablation speed of the straightening block 77 is equal to the ablation speed of the shear ring 66, that is, after the shear ring 66 is ablated, the straightening block 77 is also completely ablated, so that the staff can pull out the oil well pipe string in the shortest time.

[0095] From the above process, it can be seen that the sealing system adopts a slip-free, thermal setting method, so that the setting rubber cylinder 4 can be automatically set and forced to release, without the need to put in service tools, making the operation more convenient and effectively improving the operation time. At the same time, the performance of the sealing system is reliable, with an overall temperature resistance of 350°C and a pressure resistance of 21MPa, meeting the harsh and strict use requirements at sea.

[0096] Example 2

[0097] like Figure 6 The embodiment 2 of the present invention is shown. In this embodiment, a method for using the isolation system 200 in the embodiment 1 is disclosed, including the following steps:

[0098] S1, one of the righting mechanisms 7 is connected to the top of the upper joint 1, and the other righting mechanism 7 is connected to the bottom of the lower joint 3 to form an isolation system 200, and then the isolation system 200 is connected to the oil well pipe string 100. At the same time, the high-temperature downhole safety valve 300, the high-temperature annular safety packer 400, the tubing righting device 500, the top packer 600, the two injection valves 700, and the optical fiber monitoring mechanism 800 are sequentially connected to the oil well pipe string 100, and the isolation system 200 is located between the two injection valves 700.

[0099] Subsequently, a pressure test and status check is conducted before going down the well, the surface pressure pipeline process is connected, the pressure of the accommodation chamber 52 is slowly increased to 35MPa, and the pressure is maintained for 15 minutes. The pressure drop is qualified if it is less than 1%. After the pressure test is completed, the expansion agent 54 is poured until the accommodation chamber 52 is full, and the sealing plug 56 is tightened. Check whether the sealing rubber cylinder 4, the nylon sleeve of the shear ring 66, and the polyglycolide degradable straightening block 77 are intact, and check whether the straightening block 77 is in normal contraction and rebound state. At the same time, the demodulator is debugged, and the monitoring optical cable is connected to the demodulator for debugging to ensure that the temperature and acoustic vibration signals of the optical fiber monitoring mechanism 800 are normal.

[0100] Next, the oil well tubular string 100 is lowered into the wellbore to the designed position. At this time, the multiple straightening blocks 77 on the two straightening mechanisms 7 are respectively in close contact with the inner wall of the wellbore to straighten the oil well tubular string 100, ensuring that the oil well tubular string 100 is centered in the wellbore to prevent the isolation system 200 from being scratched by the wellbore.

[0101] S2, hot steam is injected into the oil well pipe string 100, the temperature of the isolation system 200 gradually increases, the expansion agent 54 expands due to the heat and pushes the piston part 53 to move upward, at this time, the piston part 53 pushes the setting rubber cylinder 4 to move upward to the setting cone surface 23. The isolation system 200 in this embodiment is set when the temperature reaches 200℃~260℃, and then, according to the temperature and acoustic vibration joint interpretation results obtained by the optical fiber monitoring mechanism 800, and the injection amount of each layer / segment is obtained, the sealing effect of the isolation system 200 can be verified by comparing with the design value.

[0102] After the sealing rubber cylinder 4 is set, the nylon sleeves of the straightening block 77 and the shear ring 66 are slowly hydrolyzed, and the shear ring 66 made of magnesium alloy is slowly dissolved in the chloride ion-containing production liquid. The elastic force of the butterfly spring 68 acts on the sealing rubber cylinder 4, and the elastic force of the butterfly spring 68, the expansion potential energy of the expansion agent 54, and the friction force inside and outside the sealing rubber cylinder 4 reach a mechanical balance, and the sealing rubber cylinder 4 still maintains a set and sealed state.

[0103] S3, after stopping the heat injection, wait for the wellbore to cool down slowly, test the temperature according to the optical fiber monitoring mechanism 800, and observe the temperature measurement results to show that the temperature of the isolation system 200 drops below the setting temperature. As the temperature continues to drop, the expansion potential energy of the expansion agent 54 decreases, and the elastic potential energy of the butterfly spring 68 overcomes the expansion potential energy and the friction of the setting rubber tube 4, so that the thrust sleeve 61 pushes the setting rubber tube 4 to move downward to loosen the setting rubber tube 4. Then, slowly lift the oil well tubular string 100, and the setting rubber tube 4 moves downward relative to the oil well tubular string 100, thereby realizing the unsealing of the setting rubber tube 4. Then slowly lift and lower the oil well tubular string 100 to ensure that the oil well tubular string 100 is alive, and then slowly pull out the oil well tubular string 100.

[0104] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in the present invention should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0105] In addition, the terms "first", "second", etc. 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. In the description of the present invention, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A stratified and segmented isolation system for offshore thermal wells, characterized in that: include: An upper connector (1) for connecting with an external component; The center pipe (2) is composed of a setting section (21) and a support section (22), wherein the top end of the setting section (21) is connected to the upper joint (1), and the support section (22) is coaxially connected to the bottom end of the setting section (21), the outer diameter of the setting section (21) is larger than the outer diameter of the support section (22), and the lower end of the setting section (21) is provided with a setting cone surface (23); A lower joint (3), connected to the bottom end of the support section (22) and used for connecting with an external component; A sealing rubber cylinder (4) is movably sleeved at the upper end of the support section (22); A setting mechanism (5) is used to push the setting rubber cylinder (4) to move upward to the setting cone surface (23) so that the setting rubber cylinder (4) is set with the wellbore; The unsealing mechanism (6) is used to push the sealing rubber cylinder (4) to move downward and loosen the sealing rubber cylinder (4). When the staff lifts up the oil well pipe string, the sealing rubber cylinder (4) can move downward relative to the oil well pipe string and achieve unsealing under the action of the friction force between its own outer wall and the inner wall of the wellbore.

2. The isolation system according to claim 1, characterized in that: The setting cone surface (23) is transitionally connected to the top end of the support section (22) via a guide slope (24), so that the setting rubber cylinder (4) can move smoothly onto the setting cone surface (23) under the guidance of the guide slope (24).

3. The isolation system according to claim 1, characterized in that: The setting mechanism (5) comprises: A support cylinder sleeve (51) is sleeved at the lower end of the support section (22), the bottom end of the support cylinder sleeve (51) is connected to the lower joint (3), and an annular accommodating cavity (52) is formed between the inner side wall of the support cylinder sleeve (51) and the outer side wall of the support section (22); A piston portion (53) vertically slidably connected in the accommodating chamber (52); An expansion agent (54) is filled in the accommodating cavity (52), and after the expansion agent (54) is heated and expanded, it can push the piston portion (53) to move upward, so that the piston portion (53) pushes the setting rubber cylinder (4) onto the setting cone surface (23).

4. The isolation system according to claim 3, characterized in that: The supporting cylinder sleeve (51) is provided with an injection hole (55) communicating with the accommodating chamber (52), and a sealing plug (56) is internally threadedly connected to the injection hole (55).

5. The isolation system according to claim 3, characterized in that: The unsealing mechanism (6) comprises: A thrust sleeve (61) is movably mounted on the setting section (21) and is located above the setting cone surface (23); An adjusting ring (64) is movably sleeved on the setting section (21) and connected to the top end of the thrust sleeve (61); A shearing ring (66) is arranged on the setting section (21) and is used to prevent the adjusting ring (64) from moving downward. The shearing ring (66) is made of a soluble material and can be dissolved in the well fluid. a butterfly spring (68), arranged on the setting section (21) and used for pushing the adjusting ring (64) to move downward; The elastic force of the butterfly spring (68) and the expansion force of the expansion agent (54) are set as follows: When the expansion agent (54) expands due to heat, the expansion force of the expansion agent (54) is greater than the elastic force of the butterfly spring (68), and the setting rubber cylinder (4) can move onto the setting cone surface (23) under the push of the piston part (53); When the shear ring (66) is dissolved, the expansion force of the expansion agent (54) is greater than the elastic force of the butterfly spring (68), and the thrust sleeve (61) cannot push the setting rubber cylinder (4) to move downward, and the setting rubber cylinder (4) remains in the setting position; When the expansion agent (54) cools and contracts, the elastic force of the butterfly spring (68) is greater than the expansion force of the expansion agent (54), and the setting rubber cylinder (4) can move downward under the action of the thrust sleeve (61) to loosen the setting rubber cylinder (4).

6. The isolation system according to claim 5, characterized in that: The unsealing mechanism (6) further comprises: A limiting ring (62) is fixedly sleeved on the setting section (21) and is used to prevent the thrust sleeve (61) from moving upward. An annular installation cavity (65) is formed between the adjusting ring (64), the thrust sleeve (61) and the limiting ring (62). The shear ring (66) is arranged in the installation cavity (65), and the top end of the shear ring (66) abuts against the adjusting ring (64) and the bottom end abuts against the limiting ring (62). The dissolution channel (67) is arranged on the adjustment ring (64) and communicates with the installation cavity (65).

7. The isolation system according to claim 1, characterized in that: The isolation system also includes two straightening mechanisms (7), one of which is coaxially connected to the top of the upper joint (1), and the other is coaxially connected to the bottom of the lower joint (3), so as to ensure that the isolation system is centered in the wellbore.

8. The isolation system according to claim 7, characterized in that: Each of the straightening mechanisms (7) comprises: A first joint (71) is arranged vertically and the top end of which can be threadedly connected to the lower joint (3); A support tube (72) coaxially connected to the bottom end of the first joint (71); A second joint (73) is coaxially connected to the bottom end of the support tube (72), and the bottom end of the second joint (73) can be threadedly connected to the upper joint (1); There are two protective rings (74), one of which is fixedly sleeved on the upper end of the support tube (72), and the other is fixedly sleeved on the lower end of the support tube (72). The two protective rings (74) are respectively provided with an annular limiting edge (75) at one end close to each other, and an annular limiting groove (76) is formed between the inner side wall of the limiting edge (75) and the outer side wall of the support tube (72); There are a plurality of straightening blocks (77) which are respectively arranged between the two protection rings (74); the straightening blocks (77) are arranged at equal intervals along the circumference of the support tube (72); both ends of the straightening blocks (77) are respectively movably arranged in the corresponding limiting grooves (76); and the straightening blocks (77) can move along the radial direction of the support tube (72); the straightening blocks (77) are made of soluble materials, and can be dissolved in well fluid; There are multiple elastic leaf springs (78) respectively arranged on the support tube (72). The multiple elastic leaf springs (78) are arranged in one-to-one correspondence with the multiple straightening blocks (77). The elastic leaf springs (78) are used to push the corresponding straightening blocks (77) to move radially along the support tube (72) and make the straightening blocks (77) tightly abut against the inner wall of the wellbore.

9. A method for using the isolation system according to any one of claims 1 to 8, characterized in that: The steps include: S1, connecting the isolation system to the oil well string, and then lowering the oil well string into the wellbore; S2, controlling the sealing rubber cylinder to move upward to the sealing cone surface (23) through the sealing mechanism (5), so that the sealing rubber cylinder (4) is sealed with the wellbore; S3, controlling the packing rubber tube to move downward through the unsealing mechanism (6) to loosen the packing rubber tube, and then lifting the oil well pipe string, so that the packing rubber tube moves downward relative to the oil well pipe string and unsealing is achieved.

10. The method for using the isolation system according to claim 9, characterized in that: In S1, a high-temperature downhole safety valve, a high-temperature annulus safety packer, a tubing centralizer, a top packer, two injection valves, and an optical fiber monitoring mechanism are sequentially connected to the oil well tubing string; At the same time, one of the righting mechanisms (7) is connected to the top of the upper joint (1), and the other righting mechanism (7) is connected to the bottom of the lower joint (3) to form an isolation system, and then the isolation system is connected to the oil well pipe string, and the isolation system is located between the two injection valves; Subsequently, the oil well pipe string is lowered into the wellbore. At this time, the plurality of straightening blocks (77) on the two straightening mechanisms (7) are respectively in close contact with the inner wall of the wellbore to straighten the oil well pipe string and ensure that the oil well pipe string is centered in the wellbore.

11. The method for using the isolation system according to claim 9, characterized in that: In S2, hot steam is introduced into the oil well pipe string, the expansion agent (54) expands due to the heat and pushes the piston part (53) to move upward, and then the piston part (53) pushes the sealing rubber cylinder (4) onto the sealing cone surface (23), so that the sealing rubber cylinder (4) is sealed with the well wall, thereby realizing the layered segmentation of the wellbore.

12. The method for using the isolation system according to claim 9, characterized in that: In S3, when the shear ring (66) is completely dissolved in the well fluid, the adjusting ring (64) pushes the thrust sleeve (61) downward under the action of the butterfly spring (68), and then the thrust sleeve (61) pushes the sealing rubber tube (4) downward and loosens the sealing rubber tube (4). Subsequently, the oil well pipe is lifted up, and the sealing rubber tube (4) moves downward relative to the oil well pipe under the action of the friction between its outer wall and the inner wall of the wellbore and is unsealed.

13. The method for using the isolation system according to claim 12, characterized in that: When the shear ring (66) is completely dissolved in the well fluid, the straightening block (77) is also completely dissolved in the well fluid to ensure that the staff can smoothly lift the oil well pipe string.

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