A thermal well sand prevention steam injection and fishing integrated completion string

Abstract

The present invention discloses a thermal recovery well sand prevention steam injection and salvage integrated completion string, comprising a casing, an upper hanger, a sand prevention steam injection string, a salvage device, a bottom packer and a sand trap pocket; a plurality of the sand prevention steam injection strings are installed in the casing through the upper hanger and the bottom packer, a sand trap pocket is provided at the bottom of the casing, a salvage device is provided between two adjacent sand prevention steam injection strings, and a plurality of the salvage devices are located between the upper hanger and the bottom packer. The present invention can extend the effective period of sand prevention in the oil well during the sand prevention production process, can adjust the steam injection amount of different oil layers during the steam injection process, and facilitates the screen string to be lifted out of the ground when the screen is damaged or requires subsequent operations.

Description

Technical Field

[0001] The invention relates to the technical field of oil well completion tools, and in particular to a sand prevention and steam injection integrated completion string suitable for heavy oil thermal recovery wells. Background Art

[0002] The reservoirs of Liaohe Oilfield are mostly loose sandstone heavy oil reservoirs, and the main production method is steam stimulation, which accounts for more than 75% of the total heavy oil production. Most oil wells have sand production problems during the production process, so necessary sand prevention measures must be taken, mainly screen sand prevention.

[0003] An important sand control construction process among the screen pipe sand control measures is to suspend the screen pipe string with a hanger for sand control, which is widely used in early sand control oil wells or secondary sand control oil wells. The formation sand enters the screen casing annulus with the formation production fluid, and the coarser formation sand fills the screen casing annulus to form a stable sand bridge; a small amount of finer formation sand enters the screen pipe with the production fluid, and a part of it settles in the screen pipe, that is, accumulates in the sand settling pipe at the bottom of the screen pipe. Due to the small diameter of the screen pipe, after a period of production, the lower part of the screen pipe is filled with finer formation sand, resulting in a smaller flow section and a decrease in liquid production capacity. When the screen pipe is buried by sand for a long time, it is necessary to remove the sand control string to clean the sand or perform well washing and sand flushing operations, so its effective period of sand control is relatively short.

[0004] The existing sand control and steam injection are two sets of pipes. First, the sand control operation is carried out, and the screen pipe is lowered for oil and gas production. When the steam injection operation is needed, the steam injection pipe column is lowered. Figure 1 As shown in the figure, the steam injection measure is basically general steam injection, that is, a steam injection string is lowered into the well to inject steam generally, without considering the interlayer differences of the oil layer. Therefore, in heavy oil layers with large reservoir heterogeneity, especially thick heavy oil layers, due to the differences in absorption capacity of different layers, the steam injection amount of different layers varies greatly, resulting in poor steam injection effect of the entire oil well. Summary of the invention

[0005] The purpose of the present invention is to provide an integrated completion string for sand prevention, steam injection and salvage of thermal recovery wells, which can extend the effective period of sand prevention in the oil well during the sand prevention production process, adjust the steam injection amount of oil layers in different layers during the steam injection process, and facilitate the lifting of the screen pipe string out of the ground when the screen pipe is damaged or subsequent operations are required.

[0006] To achieve the above-mentioned purpose, the present application proposes an integrated completion string for sand prevention, steam injection and salvage in thermal recovery wells, comprising casing, an upper hanger, a sand prevention, steam injection string, a salvage device, a bottom packer and a sand trap bag; a plurality of the sand prevention, steam injection strings are installed in the casing through the upper hanger and the bottom packer, a sand trap bag is provided at the bottom of the casing, a salvage device is provided between two adjacent sand prevention, steam injection strings, and a plurality of the salvage devices are located between the upper hanger and the bottom packer.

[0007] Furthermore, the sand control steam injection string includes a sand control functional string located outside and a steam injection functional string located inside.

[0008] Furthermore, the sand control functional pipe column is a slotted screen pipe or a perforated pipe coated filter screen pipe.

[0009] Furthermore, the sand control functional pipe column is alternately provided with sealing sections and sand control flow sections, and the inside and outside of the screen pipe in the sand control flow section are connected.

[0010] Furthermore, the steam injection functional pipe column includes an upper joint, a steam injection pipe column body, a flow hole and a thermal sensitive sealing ring. The top of the upper joint is connected to a screen tube coupling, and the lower part is connected to the steam injection pipe column body. A plurality of flow holes are arranged on the steam injection pipe column body. After the produced liquid flows into the sand control flow section, it enters the steam injection pipe column body through the flow holes.

[0011] Furthermore, a heat-sensitive sealing ring is arranged on the steam injection column body, and when the temperature reaches a certain value, the heat-sensitive sealing ring expands to seal the annular space where it is located.

[0012] Furthermore, a hole is drilled on the steam injection column body, and the steam injection flow valve is fixed in the through hole on the steam injection column body by means of a thread.

[0013] Furthermore, the steam injection flow valve includes a flow valve body, a steam injection hole, a spring and a circular baffle. The flow valve body is a cylinder with a radially arranged channel, the inner side of the channel is arranged in a cylindrical shape, and the outer side is arranged in a bell-mouth shape; a spring is installed in the channel, and the spring is provided with a circular baffle at one end of the bell-mouth. In the normal state of the spring, the circular baffle is at the outermost side of the bell-mouth, and several steam injection holes are arranged on the outside of the cylindrical channel.

[0014] Furthermore, an annular baffle is arranged outside each steam injection hole, and the annular baffle is connected to the overflow valve body by welding.

[0015] Furthermore, the annular baffle is set to be open at the corresponding steam injection hole, playing the role of a one-way valve, that is, the internal fluid of the steam injection hole breaks through the annular baffle and flows to the outside, while the external fluid cannot flow to the inside due to the action of the annular baffle.

[0016] Furthermore, the diameter of the circular baffle is smaller than the maximum diameter of the outer side of the trumpet-shaped channel, and larger than the diameter of the cylindrical channel.

[0017] Furthermore, the outer side of the bottom of the steam injection column body is connected to a flow centralizer through a thread, and the flow centralizer is configured in a gear shape to ensure that the upper and lower parts of the flow centralizer are connected, that is, the annulus between the steam injection function column and the sand control function column is connected up and down.

[0018] Furthermore, the salvage device includes an upper joint, a pin, a stop cap, a sliding locking block, a salvage cap and a lower joint. The upper joint is connected to the inner salvage cap through the pin, and an annular groove is provided on the outer side of the salvage cap to allow the sliding locking block to enter; a stop cap is provided on the outer side of the upper joint, and the lower part of the stop cap is connected to the lower joint through a thread, and the clamping platform on the inner side of the lower joint abuts against the bottom of the salvage cap.

[0019] As a further step, the upper part of the upper joint is a casing stepped buckle or an oblong buckle, which is used to connect the sand prevention steam injection pipe column located above;

[0020] As a further feature, a stop boss is provided inside the upper joint, which serves to limit the upward movement of the salvage cap during the salvage of the anti-sand steam injection pipe column.

[0021] As a further feature, a plurality of grooves are provided at the lower portion of the upper joint, which respectively serve to limit the sliding locking blocks.

[0022] As a further feature, the inner side of the blocking cap is configured to be a gradually shrinking trumpet shape, which cooperates with the sliding locking block to facilitate pushing the sliding locking block into the annular groove of the salvage cap.

[0023] As a further feature, the sliding locking blocks are distributed along the circumference, and a slope is arranged on the outer side to match the gradually shrinking trumpet shape on the inner side of the blocking cap.

[0024] As a further step, the upper hanger is arranged above the oil layer section, and the bottom packer is arranged below the oil layer section. During the production process, some finer formation sand enters the sand control steam injection pipe string, sinks downward in the annulus between the sand control functional pipe string and the steam injection functional pipe string, and finally falls into the sand settling pocket.

[0025] As a further step, during the steam injection process, the pressure in the steam injection functional string increases; under the action of high-temperature hot steam, the thermal sealing ring expands to seal the annulus between the sand control functional string and the steam injection functional string.

[0026] Furthermore, during the steam injection process, the pressure in the steam injection functional column increases. In formations with good reservoir properties and easy steam injection, the pressure difference between the inside and outside of the steam injection flow valve is large, the spring is compressed, and the circular baffle moves with the spring until it reaches the bell mouth, blocking the flow channel and reducing the steam injection volume. In formations with poor reservoir properties and difficult steam injection, the pressure difference between the inside and outside of the steam injection flow valve is small, the spring is less compressed, the bell mouth is not completely blocked, and part of the steam enters the steam injection flow valve and is then injected into the formation.

[0027] As a further feature, the salvaging device is subjected to force by means of a sliding locking block during the lowering process.

[0028] As a further step, when the screen is damaged or other subsequent operations are required, the salvage tool is lowered; the salvage tool is then lifted up, and the salvage tool is stuck with the salvage cap; the salvage cap moves upward, and the pin is sheared; the salvage cap continues to move upward until it contacts the stop boss inside the upper joint; at this time, the sliding lock block just corresponds to the annular groove outside the salvage cap;

[0029] Continue to lift the salvage tool, the salvage cap and the upper joint move upward, the stop cap exerts a downward force on the sliding lock block, and the sliding lock block is pressed into the annular groove corresponding to the salvage cap;

[0030] After the sliding lock block enters the annular groove, the salvage tool, the upper joint, the salvage cap, the lower joint and the stop cap are disengaged, and the salvage tool lifts the upper joint, the salvage cap and the upper sand-proof steam injection pipe column out of the ground.

[0031] Compared with the prior art, the above technical scheme adopted by the present invention has the following advantages: the present invention can extend the effective period of sand control in the oil well during the sand control production process by optimizing the structural design of the pipe string; through the design of the steam injection functional pipe string, the steam injection amount of oil layers in different layers can be adjusted during the steam injection process, so as to achieve the purpose of effectively injecting steam into layers with good and poor physical properties of heterogeneous reservoirs; through the salvage device, when the sand control pipe string is damaged or other subsequent operations are required, it is more convenient to lift the pipe string out of the ground and safer to lower the pipe string. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the existing sand control injection and steam two sets of pipe strings;

[0033] Figure 2 This is a schematic diagram of the structure of the integrated completion string for sand prevention, steam injection and fishing in thermal recovery wells;

[0034] Figure 3 This is a schematic diagram of the structure of the sand prevention steam injection pipe column;

[0035] Figure 4 This is a schematic diagram of the steam injection overflow valve structure;

[0036] Figure 5 It is a schematic diagram of the structure of the overcurrent centralizer;

[0037] Figure 6 This is a schematic diagram of the salvage device structure;

[0038] Figure 7 Schematic diagram of the upper joint structure;

[0039] Figure 8 It is a schematic diagram of the sliding lock block structure;

[0040] Fig. 9 This is a schematic diagram of the salvage cap structure;

[0041] Fig.10This is a schematic diagram of the structure after the salvage device is disconnected;

[0042] Fig.11 This is a schematic diagram of extending the effective period of sand control of the pipe string of the present invention.

[0043] Explanation of the numbers in the figure: 1. casing; 2. upper hanger; 3. sand control steam injection string; 4. fishing device; 5. bottom packer; 6. sand trap;

[0044] 10. Sand control function column; 11. Sand control flow section; 12. Sealing section; 20. Steam injection function column; 21. Upper joint; 22. Steam injection column body; 23. Flow hole; 24. Thermosensitive sealing ring; 25. Steam injection flow valve; 26. Flow centralizer;

[0045] 251, flow valve body; 252, steam injection hole; 253, spring; 254, baffle; 255, bell mouth; 256, annular baffle;

[0046] 41. Upper joint; 42. Pin; 43. Stop cap; 44. Fixed locking block; 45. Salvage cap; 46. Lower joint. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application, that is, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0048] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0049] It should be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "includes..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0050] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0051] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] Example 1

[0053] The present embodiment provides an integrated completion string for sand prevention, steam injection and salvage of a thermal recovery well, comprising a casing, an upper hanger, a sand prevention, steam injection string, a salvaging device, a bottom packer and a sand trap bag; a plurality of the sand prevention, steam injection strings are installed in the casing through the upper hanger and the bottom packer, a sand trap bag is provided at the bottom of the casing, a salvaging device is provided between two adjacent sand prevention, steam injection strings, and a plurality of the salvaging devices are located between the upper hanger and the bottom packer.

[0054] The upper hanger is a commonly used tool in oil fields. The upper hanger is used to hang the sand prevention steam injection pipe string to fix it on the casing and seal the annulus.

[0055] The sand-proof steam injection pipe string has a sand-proof function during the production process and can adjust the steam injection amount at different layers during the steam injection process. The sand-proof steam injection pipe string is divided into two parts: an inner part and an outer part.

[0056] The outside is a sand control functional pipe string, that is, a commonly used screen pipe string, which can be a slotted screen pipe, a perforated pipe coated filter screen pipe and other screen pipes currently used in the sand control field.

[0057] The sand control functional pipe column is optimized into a sand control flow section and a sealing section, that is, in the sand control flow section, the inside and outside of the screen pipe can be connected, and it has the ability to prevent sand flow. The slit screen pipe is reflected by slits, and the perforated pipe coated filter screen pipe is reflected by through holes.

[0058] The interior is a steam injection functional pipe column, including an upper joint, a steam injection pipe column body, a flow hole, a thermal sealing ring, a steam injection flow valve, and a flow centralizer;

[0059] The upper part of the upper joint is connected to the screen tube coupling, and the lower part is connected to the steam injection pipe column body.

[0060] The steam injection pipe column body is provided with a flow hole, and the produced liquid flows into the steam injection pipe column body through the flow hole after flowing in from the sand control flow section.

[0061] A thermosensitive sealing ring is arranged on the main body of the steam injection pipe column. The thermosensitive sealing ring is a mature tool in the current oil field. Its material is thermosensitive resin, etc. Its function is to keep the sealing ring in its original state at normal temperature. When the temperature reaches a certain value, the sealing ring expands, sealing the annular space where it is located and can bear a certain pressure. When the temperature drops, the sealing ring returns to its original state.

[0062] A steam injection overflow valve is provided on the main body of the steam injection pipe column. The structure of the steam injection overflow valve is as follows: Figure 4 As shown, it includes a flow valve body, a steam injection hole, a spring, a circular baffle, a bell mouth, and an annular baffle; a hole is punched on the steam injection column body, and the steam injection flow valve is fixed in the through hole on the steam injection column body by a thread. The flow valve body is a cylinder, and a channel is radially arranged. The inside of the channel is arranged in a cylindrical shape, and the outside of the channel is arranged in a bell mouth shape. A spring is arranged in the channel, and a circular baffle is arranged at one end of the bell mouth of the spring. In the normal state of the spring, the circular baffle is at the outermost side of the bell mouth and cannot block the bell mouth. The diameter of the circular baffle is smaller than the maximum diameter of the outside of the bell mouth and larger than the diameter of the inner cylindrical channel. Several steam injection holes are arranged on the outside of the inner cylindrical channel, preferably 4. An annular baffle is arranged on the outside of the steam injection hole. The material of the annular baffle is required to have certain elasticity and hardness. The annular baffle is connected to the flow valve body by welding. The annular baffle is set to be open at the four steam injection holes, playing the role of a one-way valve, that is, the internal fluid of the steam injection hole can break through the annular baffle and flow to the outside, while the external fluid cannot flow to the inside due to the action of the annular baffle.

[0063] A flow centralizer is arranged outside the bottom of the steam injection column body, and the flow centralizer is connected to the main gas column body through a thread. Figure 5 As shown, the flow centralizer is configured in a gear shape to ensure that the upper and lower parts of the flow centralizer can be connected, that is, the annulus between the steam injection function string and the sand control function string is connected up and down, so that the formation sand entering the string can settle downward.

[0064] The structure of the salvage device is as follows: Figure 6 As shown, it includes an upper joint, a pin, a stop cap, a sliding lock block, a salvage cap, and a lower joint.

[0065] The upper joint is as Figure 7 As shown, the upper part is a common casing stepped buckle or an oblong buckle, which is used to connect the sand-proof steam injection pipe column above. A stop boss is arranged inside the upper joint, which limits the upward movement of the salvage cap during the salvage of the sand-proof steam injection pipe column. The upper joint is connected to the salvage cap through a pin, and four grooves are arranged at the lower part of the upper joint, which can limit the four sliding lock blocks.

[0066] The stop cap is arranged outside the upper joint, and the lower part is connected to the lower joint by a thread. The inner side of the stop cap is arranged in a gradually shrinking trumpet shape, which cooperates with the sliding lock block, and its function is to facilitate pushing the sliding lock block into the annular groove of the salvage cap to avoid axial jamming of the sliding lock block.

[0067] The sliding lock block is as follows Figure 8 As shown, multiple, preferably four, are provided, distributed along the circumference, and a slope is provided on the outer side to match the gradually shrinking trumpet shape on the inner side of the blocking cap.

[0068] The lower joint has a limiting effect on the salvage cap, preventing the lower joint and the stop cap from moving upward relative to the upper joint.

[0069] The salvage cap is as Fig. 9 As shown, it is connected to the upper joint through a pin, and an annular groove is arranged on the outside of the salvage cap to allow the sliding lock block to enter.

[0070] During the lowering process, the above-mentioned salvage device is stressed by the sliding lock block, and the pin is not stressed and will not break. When it is necessary to lift the sand-proof steam injection pipe column, the salvage tool is lowered, the salvage cap of the salvage device is lifted up, the pin is cut off, the sliding lock block is no longer stressed, the salvage device is disconnected, and the salvage function device is disconnected. Fig.10 shown.

[0071] The length of the sand control steam injection pipe string is set according to the thickness of the oil layer section of each well, so that the length of the pipe string is greater than the thickness of the oil layer section to be sand controlled. A bottom packer is set at the bottom of the sand control steam injection pipe string. The bottom packer plays a sealing role and is a mature application tool in oil fields. The bottom packer needs to be set below the oil layer section.

[0072] The following is an introduction to the functions of each part:

[0073] 1) Extend the effective period of oil well sand control

[0074] Existing technology such as Fig.11 As shown in the left figure, the formation sand enters the screen annulus with the formation production fluid. The coarser formation sand fills the screen annulus, and a small amount of finer formation sand enters the screen pipe with the production fluid, part of which settles in the screen pipe and accumulates in the sand settling pipe at the bottom of the screen pipe. Since the sand settling pipe vertical well is small, after a period of production, the sand settling pipe is filled with finer formation sand, which then accumulates in the screen pipe, resulting in a smaller screen pipe flow section and a decrease in liquid production capacity. When the screen pipe is buried with a lot of sand, it is necessary to remove the sand control pipe column to clean the sand or perform well washing and sand flushing operations.

[0075] In the present invention, the length of the sand control steam injection pipe string is greater than the thickness of the oil layer section to be sand controlled, the upper hanger is arranged above the oil layer section, and the bottom packer is arranged below the oil layer section. During the production process, some finer formation sand enters the sand control steam injection pipe string, sinks downward in the annulus between the sand control function pipe string and the steam injection function pipe string, and finally falls into the sand settling pocket. Compared with the existing technology, the volume of the sand settling pocket is increased, the time to fill the sand settling pocket is extended, and the corresponding effective period of sand control is extended.

[0076] 2) Improve steam injection effect

[0077] During the production process, the formation fluid carries the formation sand from the oil layer into the outer annulus of the sand control, steam injection and salvage integrated tubing string. Due to the sealing effect of the upper hanger and the bottom packer, large particles of formation sand accumulate in the outer annulus, and some small particles of formation sand enter the sand control functional tubing string and reach the annulus between the sand control functional tubing string and the steam injection functional tubing string.

[0078] The formation fluid passes through the flow holes and enters the interior of the pipe string, and is then pumped out of the ground by the oil pump. Some of the fine formation sand carried by the formation fluid settles in the annulus between the sand control function pipe string and the steam injection function pipe string. Due to the setting of the annular baffle in the steam injection flow valve, the formation sand cannot enter the steam injection flow valve, avoiding blocking its internal space and affecting the compression of the spring.

[0079] During the steam injection process, the pressure in the steam injection function string increases; under the action of high-temperature hot steam, the thermal sealing ring expands to seal the annulus between the sand control function string and the steam injection function string.

[0080] During the steam injection process, the pressure in the steam injection function column increases. In formations with good reservoir properties and easy steam injection, the pressure difference between the inside and outside of the steam injection flow valve is large, the spring is compressed, and the baffle moves with the spring until it reaches the bell mouth, blocking the flow channel and reducing the amount of steam injection. In formations with poor reservoir properties and difficult steam injection, the pressure difference between the inside and outside of the steam injection flow valve is small, the spring is less compressed, the bell mouth is not completely blocked, and part of the steam enters the steam injection flow valve and is then injected into the formation, ensuring that both good and poor physical properties in heterogeneous reservoirs can be effectively injected with steam, thereby improving the effect of steam injection.

[0081] 3) Pipe fishing function

[0082] The salvage device is used to make it easier to pull out the pipe string when the screen is damaged or other subsequent operations are required. After a period of production, the pipe string is difficult to pull out because the formation sand is pushed out of the pipe string and the sand control steam injection pipe string has a multi-layer structure and is heavy. When the screen is damaged or other subsequent operations are required, it is difficult to pull out the pipe string. The entire pipe string cannot be pulled out at one time.

[0083] For this purpose, salvage tools were lowered;

[0084] Lift the fishing tool upwards, and the fishing tool will clamp the fishing cap. The fishing cap moves upwards, and the pin is sheared. The fishing cap continues to move upwards until it contacts the boss inside the upper joint.

[0085] At this time, the sliding locking block just corresponds to the annular groove on the outer side of the salvage cap.

[0086] Continue to lift the salvage tool, the salvage cap and the upper joint move upward, and the stop cap exerts a downward force on the sliding lock block. Since the inner side of the stop cap is set in a gradually shrinking trumpet shape and corresponds to the outer inclined surface of the sliding lock block, the sliding lock block is pressed into the annular groove of the salvage cap.

[0087] The sliding lock block enters the annular groove, the salvage tool, the upper joint, the salvage cap, the lower joint and the stop cap are disengaged, and the salvage tool lifts the upper joint, the salvage cap and the upper pipe string out of the ground.

[0088] Re-insert the salvage tool and repeat the above steps until all the tubing is removed.

[0089] During the lowering process, the salvage device is stressed by the sliding lock block, and the pin is not stressed and will not break. When the sand-proof steam injection pipe string needs to be raised, the salvage tool is lowered, the salvage cap of the salvage device is lifted, the pin is cut off, the sliding lock block is no longer stressed, and the salvage device is disconnected, which improves the safety of the pipe string lowering.

[0090] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A thermal recovery well sand prevention steam injection and fishing integrated completion string, characterized in that: It comprises a casing, an upper hanger, a sand-proof steam injection pipe string, a salvaging device, a bottom packer and a sand trap pocket; a plurality of the sand-proof steam injection pipe strings are installed in the casing through the upper hanger and the bottom packer, a sand trap pocket is provided at the bottom of the casing, a salvaging device is provided between two adjacent sand-proof steam injection pipe strings, and a plurality of the salvaging devices are located between the upper hanger and the bottom packer; The sand control steam injection pipe string comprises a sand control functional pipe string located outside and a steam injection functional pipe string located inside; The steam injection functional pipe column comprises an upper joint, a steam injection pipe column body, a flow hole and a thermal-sensitive sealing ring. The top of the upper joint is connected to a screen tube coupling, and the bottom is connected to the steam injection pipe column body. A plurality of flow holes are arranged on the steam injection pipe column body. After the produced liquid flows in from the sand control flow section, it enters the steam injection pipe column body through the flow holes. A hole is drilled on the steam injection column body, and the steam injection flow valve is fixed in the through hole on the steam injection column body by means of a thread; The steam injection flow valve comprises a flow valve body, a steam injection hole, a spring and a circular baffle. The flow valve body is a cylinder with a radially arranged channel. The inner side of the channel is arranged in a cylindrical shape and the outer side is arranged in a bell-mouth shape. A spring is installed in the channel. The spring is provided with a circular baffle at one end of the bell-mouth. In a normal state of the spring, the circular baffle is located at the outermost side of the bell-mouth. A plurality of steam injection holes are arranged outside the cylindrical channel. During the steam injection process, the pressure in the steam injection function column increases. In formations with good reservoir properties and easy steam injection, the pressure difference between the inside and outside of the steam injection flow valve is large, the spring is fully compressed, and the circular baffle moves with the spring until it reaches the bell mouth, blocking the flow channel and reducing the steam injection volume. In formations with poor reservoir properties and difficult steam injection, the pressure difference between the inside and outside of the steam injection flow valve is small, the spring is partially compressed, the bell mouth is not completely blocked, and some steam enters the steam injection flow valve and is then injected into the formation. A heat-sensitive sealing ring is arranged on the steam injection column body, and when the temperature reaches a certain value, the heat-sensitive sealing ring expands to seal the annular space where it is located; An annular baffle is arranged outside each of the steam injection holes, and the annular baffle is connected to the overflow valve body by welding; The annular baffle is set in an open shape at the corresponding steam injection hole, and plays the role of a check valve, that is, the fluid inside the steam injection hole breaks through the annular baffle and flows to the outside, and the external fluid cannot flow to the inside due to the action of the annular baffle; The salvage device comprises an upper joint, a pin, a stopper cap, a sliding lock block, a salvage cap and a lower joint. The upper joint is connected to the salvage cap on the inner side through the pin. An annular groove is arranged on the outer side of the salvage cap to allow the sliding lock block to enter. A stopper cap is arranged on the outer side of the upper joint. The lower part of the stopper cap is connected to the lower joint through a thread. The clamping platform on the inner side of the lower joint abuts against the bottom of the salvage cap. The inner side of the stop cap is configured to be a gradually shrinking trumpet shape, which cooperates with the sliding lock block to facilitate pushing the sliding lock block into the annular groove of the salvage cap; When the screen is damaged or other follow-up operations are required, the salvage tool is lowered; the salvage tool is then lifted up, and the salvage tool is stuck with the salvage cap; the salvage cap moves upward, and the pin is sheared; the salvage cap continues to move upward until it contacts the stop boss inside the upper joint; at this time, the sliding lock block just corresponds to the annular groove on the outside of the salvage cap; Continue to lift the salvage tool, the salvage cap and the upper joint move upward, the stop cap exerts a downward force on the sliding lock block, and the sliding lock block is pressed into the annular groove corresponding to the salvage cap; After the sliding lock block enters the annular groove, the salvage tool, the upper joint, the salvage cap, the lower joint and the stop cap are disengaged, and the salvage tool lifts the upper joint, the salvage cap and the upper sand-proof steam injection pipe column out of the ground.

2. The thermal recovery well sand prevention steam injection and fishing integrated completion string according to claim 1, characterized in that: The sand control functional pipe column is a slotted screen pipe or a perforated pipe coated filter screen pipe.

3. The thermal recovery well sand prevention steam injection and fishing integrated completion string according to claim 2, characterized in that: The sand control functional pipe column is alternately provided with sealing sections and sand control flow sections, and the inside and outside of the screen pipe in the sand control flow section are connected.

4. The thermal recovery well sand prevention steam injection and fishing integrated completion string according to claim 1, characterized in that: The diameter of the circular baffle is smaller than the maximum diameter of the outer side of the trumpet-shaped channel, and larger than the diameter of the cylindrical channel.

5. The thermal recovery well sand prevention steam injection and fishing integrated completion string according to claim 1, characterized in that: The outer side of the bottom of the steam injection string body is connected to a flow centralizer through a thread, and the flow centralizer is configured in a gear shape to ensure that the upper and lower parts of the flow centralizer are connected, that is, the annulus between the steam injection function string and the sand control function string is connected up and down.

6. The thermal recovery well sand prevention steam injection and fishing integrated completion string according to claim 1, characterized in that: The upper part of the upper joint is a casing stepped buckle or an oblong buckle, which is used to connect the sand prevention steam injection pipe column located above.

7. The thermal recovery well sand prevention steam injection and fishing integrated completion string according to claim 1, characterized in that: A stop boss is arranged inside the upper joint, which limits the upward movement of the salvage cap during the process of salvaging the sand prevention steam injection pipe column.

8. The thermal recovery well sand prevention steam injection and fishing integrated completion string according to claim 1, characterized in that: A plurality of grooves are arranged at the lower part of the upper joint, which respectively limit the sliding locking blocks.

9. The thermal recovery well sand prevention steam injection and fishing integrated completion string according to claim 8, characterized in that: The sliding lock blocks are distributed along the circumference, and a slope is arranged on the outer side to match the gradually contracting trumpet shape on the inner side of the blocking cap.

10. The thermal recovery well sand prevention steam injection and fishing integrated completion string according to claim 1, characterized in that: The upper hanger is arranged above the oil layer section, and the bottom packer is arranged below the oil layer section. During the production process, some finer formation sand enters the sand control steam injection string, sinks downward in the annulus between the sand control functional string and the steam injection functional string, and finally falls into the sand settling pocket.

11. The thermal recovery well sand prevention steam injection and fishing integrated completion string according to claim 1, characterized in that: During the steam injection process, the pressure in the steam injection function string increases; under the action of high-temperature hot steam, the thermal sealing ring expands to seal the annulus between the sand control function string and the steam injection function string.

12. The thermal recovery well sand prevention steam injection and fishing integrated completion string according to claim 1, characterized in that: The salvaging device is stressed by the sliding locking block during the lowering process.

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