An adjustable critical flow injection distribution valve suitable for thermal recovery wells and a regulating method thereof

Abstract

The application discloses a kind of adjustable critical flow injection distribution valves suitable for thermal recovery well and its regulation and control method, solve the technical problems such as low tool preparation efficiency.The device includes support body, support body is provided with multiple installation slots, at least one installation slot is provided with steam injection valve, the remaining installation slots are respectively provided with sealing plug, the inner wall of support body is provided with annular steam flow channel, and multiple installation slots are respectively communicated with steam flow channel;Steam injection valve includes valve body, venturi nozzle, valve stem, limiting portion and variable diameter portion, the surface of variable diameter portion forms the stepped surface of gradually decreasing from top to bottom, by adjusting the position of valve stem, different stepped surface is aligned with hole throat surface, the adjustment of annular flow channel area can be realized, so as to realize injection distribution adjustment.Injection distribution valve in the application can adjust injection distribution itself, without secondary punching processing to parts, also without preparing multiple specifications and sizes of nozzle, improve tool preparation efficiency, so as to improve operation efficiency.

Description

Technical Field

[0001] This invention belongs to the field of oil production engineering technology, specifically relating to an adjustable critical flow injection valve suitable for thermal recovery wells and its control method. Background Technology

[0002] Currently, offshore oilfields possess abundant heavy oil resources, with unconventional heavy oil (formation crude oil viscosity greater than 350 mPa·s) accounting for as much as 30%. Due to the low production capacity and slow extraction rate of unconventional heavy oil through cold recovery, it is difficult to meet the needs of efficient offshore heavy oil development. Thermal recovery is an effective technology for heavy oil development. Currently, perforated pipes or fixed valves are used downhole as the flow channels for steam injection into the formation. Their placement and orifice size are designed and calculated based on logging data and reservoir analysis to achieve balanced steam injection across all downhole sections.

[0003] However, as steam is continuously injected, especially in steam-injection wells, the differences in formation steam absorption gradually increase. It is difficult to stabilize the steam injection rate at a relatively constant level using perforated pipes or fixed valves. Furthermore, before the completion of a new well, perforated pipes and fixed valves of various specifications and sizes need to be prepared in advance based on drilling test data. This places high demands on the timeliness of tool assembly and also poses a risk of incorrect placement during on-site construction, which needs to be improved. Summary of the Invention

[0004] To address all or part of the aforementioned problems, the present invention aims to provide an adjustable critical flow injection valve and its control method suitable for thermal recovery wells. The injection valve itself can adjust the injection volume, eliminating the need for secondary drilling of components and the need to prepare multiple nozzles of different sizes, thereby improving tool preparation efficiency and thus increasing operational timeliness.

[0005] In a first aspect, the present invention provides an adjustable critical flow injection valve suitable for thermal recovery wells, comprising a vertically arranged support body, wherein the support body is provided with a plurality of mounting slots, at least one of the mounting slots is detachably connected to a steam injection valve, and the remaining mounting slots are respectively detachably connected to sealing plugs. The inner wall of the support body is provided with an annular steam flow channel, and the plurality of mounting slots are respectively connected to the steam flow channel, so that the hot steam flowing through the support body can be discharged to the formation through the steam injection valve. The steam injection valve includes: The valve body is detachably connected to any of the aforementioned mounting slots; A Venturi nozzle is coaxially disposed within the valve body, and the inner wall of the Venturi nozzle is composed of a guide arc surface, a throat surface, and a guide slope surface. The valve stem is coaxially disposed inside the venturi nozzle, and the valve stem can be adjusted in position along its own axis; A limiting part is provided on the valve body and is used to fix the valve stem; The variable diameter section is integrally formed on the valve stem, and an annular flow channel is formed between the variable diameter section and the orifice throat surface; The variable diameter section has a stepped surface with an outer diameter that decreases from top to bottom. By adjusting the position of the valve stem, different stepped surfaces can be aligned with the throat surface of the orifice, thereby adjusting the area of ​​the annular flow channel and thus adjusting the dispensing volume.

[0006] Optionally, the valve body includes a valve seat and a pressure cap, the valve seat can be threadedly connected to any of the mounting grooves, the pressure cap is threaded onto the bottom of the valve seat, and the venturi nozzle is coaxially disposed inside the valve seat.

[0007] Optionally, the limiting part includes an upper support ring and a lower support ring, which are coaxially disposed in the valve body. The upper support ring and the lower support ring are respectively provided with a plurality of flow holes, and the valve stem is threadedly connected to the upper support ring and the lower support ring respectively.

[0008] Optionally, the steam injection valve further includes a support cylinder and a pressure stabilizing ring coaxially disposed within the valve seat. The support cylinder is located between the upper support ring and the Venturi nozzle, and the pressure stabilizing ring is located between the Venturi nozzle and the lower support ring. The upper support ring, support cylinder, venturi nozzle, pressure stabilizing ring, and lower support ring are movably connected to the valve seat, and the pressure cap presses the lower support ring, pressure stabilizing ring, venturi nozzle, support cylinder, and upper support ring into the valve seat. Anti-rotation parts are respectively provided between the valve seat and the upper and lower support rings, and the anti-rotation parts are used to restrict the upper and lower support rings from rotating along their own axial direction.

[0009] Optionally, a butterfly spring is provided between the valve seat and the pressure cap, and the valve seat presses the butterfly spring against the bottom of the lower support ring.

[0010] Optionally, the lower end of the valve stem is threaded with a lock nut, which can tightly abut against the disc spring and is used to restrict the upward movement of the valve stem.

[0011] Optionally, the axial length of the orifice throat, the inner diameter of the orifice throat, and the radius of the guide arc surface are equal.

[0012] Optionally, the axial length of the guide slope is at least equal to the inner diameter of the orifice throat.

[0013] Optionally, the angle between the guide slope and the axis of the venturi nozzle is 3-5°.

[0014] Secondly, the present invention provides a method for regulating an adjustable critical flow dispensing valve, comprising the following steps: S1, Based on the downhole tubing design scheme, obtain the positions h1, h2...h1 of the injection valves in each section. n and the reservoir's given injection volume Q m1 Q m2 ...Q mn ; S2, based on the wellhead steam injection pressure, injection rate, and steam dryness, and using the momentum conservation equation, the wellbore pressure and steam dryness at the first injection valve position h1 are obtained. The wellbore pressure at this point is considered as the injection valve inlet pressure P. in1 ; S3, Select the size of the Venturi nozzle based on the tool design space; S4, based on the first segment injection volume Q m1 Inlet pressure P of the filling valve in1 Steam dryness X s1 The critical flow steam injection algorithm formula is as follows:

[0015] The calculated injection volume is Q. m1 The required outer diameter of the variable diameter section of the valve stem, wherein: The coefficient of expansion is _____. The density of the liquid phase is... Let A1 be the gas phase density, A1 be the area of ​​the annular channel at position h1, and D be the inner diameter of the throat surface. The required outer diameter of the valve stem's variable diameter section to achieve the required reservoir injection volume; S5, continue calculating the injection valve inlet pressure P from position h1 to position h2. in2 Steam dryness X s2 And calculate the injection volume as Q. m2 The required outer diameter of the valve stem's variable diameter section is calculated by analogy, and the required outer diameter of the valve stem's variable diameter section is calculated for different filling volumes; S6, based on the lengths of each stepped surface on the variable diameter section, confirm the adjustment lengths L1, L2...L of the valve stem. N With displacement Q1, Q2...Q N The corresponding relationship is established, and the valve stem position is adjusted according to the actual required injection volume so that the corresponding stepped surface is aligned with the orifice throat surface.

[0016] As can be seen from the above technical solution, the adjustable critical flow injection valve and its control method for thermal recovery wells provided by the present invention have the following advantages: This adjustable critical flow dispensing valve allows for adjustment of the dispensing volume by changing the position of the valve stem. It eliminates the need for secondary drilling of parts and the need to prepare nozzles of multiple sizes, improving tool preparation efficiency, thereby increasing work efficiency and operational convenience.

[0017] Other features and advantages of the present invention will be set forth in the following description. Attached Figure Description

[0018] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the technical solutions of the present invention, and do not constitute a limitation on the technical solutions of the present invention.

[0019] Figure 1 This is a cross-sectional view of the adjustable critical flow dispensing valve in an embodiment of the present invention; Figure 2 This is a cross-sectional view of the steam injection valve in an embodiment of the present invention; Figure 3 This is a cross-sectional view of a Venturi nozzle in an embodiment of the present invention; Figure 4 This is a cross-sectional view of the valve stem in an embodiment of the present invention.

[0020] Explanation of reference numerals in the attached figures: 1. Support body; 11. Receiving cylinder; 12. Lower connector; 2. Mounting groove; 3. Steam injection valve; 31. Valve body; 311. Valve seat; 312. Pressure cap; 32. Venturi nozzle; 321. Guide arc surface; 322. Throat surface; 323. Guide slope; 33. Valve stem; 34. Limiting part; 341. Upper support ring; 342. Lower support ring; 343. Flow hole; 344. Anti-reverse nut; 35. Variable diameter part; 36. Annular flow channel; 37. Stepped surface; 38. Support cylinder; 39. Pressure stabilizing ring; 40. Butterfly spring; 4. Sealing plug; 5. Steam flow channel; 6. Stepped surface; 7. Anti-rotation part; 71. Anti-rotation key; 72. Anti-rotation groove. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be arbitrarily combined with each other.

[0022] like Figure 1 , Figure 2 , Figure 3 , Figure 4The figure shown is an embodiment of the present invention. This embodiment discloses an adjustable critical flow injection valve suitable for thermal recovery wells, including a vertically arranged support body 1. The support body 1 includes a receiving cylinder 11 and a lower connector 12. The lower connector 12 is threaded onto the bottom of the receiving cylinder 11. The receiving cylinder 11 and the lower connector 12 are respectively used to connect with the well tubing string, and the interior of the receiving cylinder 11 and the lower connector 12 forms a steam channel for steam to pass through.

[0023] In one embodiment, such as Figure 1 As shown, the receiving cylinder 11 is provided with multiple mounting slots 2, which are arranged vertically and are evenly spaced along the circumference of the receiving cylinder 11. At least one mounting slot 2 is detachably connected to a steam injection valve 3, and the other mounting slots 2 are detachably connected to sealing plugs 4, so that the operator can select the number of steam injection valves 3 to install according to actual needs.

[0024] In one embodiment, such as Figure 1 As shown, the inner wall of the receiving cylinder 11 is provided with an annular steam flow channel 5 along its circumference, and multiple mounting slots 2 are respectively connected to the steam flow channel 5 so that the hot steam flowing through the steam channel can be discharged to the formation through the steam injection valve 3.

[0025] In this embodiment, the steam injection valve 3 and the sealing plug 4 can be threaded into either mounting groove 2, allowing for quick assembly and disassembly of the steam injection valve 3 and the sealing plug 4, thereby improving operational efficiency. The accompanying drawings of this embodiment only show the state of one steam injection valve 3 and one sealing plug 4.

[0026] In one embodiment, such as Figure 2 , Figure 3 , Figure 4 As shown, the steam injection valve 3 includes a cylindrical valve body 31, which can be detachably connected to any mounting slot 2. A venturi nozzle 32 is coaxially arranged inside the valve body 31. The inner wall of the venturi nozzle 32 is composed of a guide arc surface 321, a throat surface 322, and a guide slope surface 323, which are arranged sequentially from top to bottom.

[0027] In one embodiment, such as Figure 2 , Figure 3 , Figure 4As shown, a valve stem 33 is coaxially arranged inside the venturi nozzle 32, and the valve stem 33 can be adjusted in position along its own axis. At the same time, a limiting part 34 is provided on the valve body 31 for fixing the valve stem 33. A variable diameter part 35 is integrally formed on the valve stem 33, and an annular flow channel 36 is formed between the variable diameter part 35 and the orifice throat surface 322. Meanwhile, the surface of the variable diameter part 35 forms a stepped surface 37 with the outer diameter decreasing from top to bottom. By adjusting the position of the valve stem 33, different stepped surfaces 37 are aligned with the orifice throat surface 322, and the area of ​​the annular flow channel 36 can be adjusted, thereby realizing the adjustment of the dispensing volume.

[0028] In this embodiment, the adjustable critical flow dispensing valve can adjust the dispensing amount by adjusting the position of the valve stem 33. In other words, the dispensing valve itself has the ability to adjust the dispensing amount, eliminating the need for secondary drilling of parts and the need to prepare multiple nozzles of different sizes, thereby improving tool preparation efficiency, thus improving work efficiency and operational convenience.

[0029] In one embodiment, such as Figure 2 As shown, the valve body 31 includes a cylindrical valve seat 311 and a pressure cap 312. The valve seat 311 can be threadedly connected to any mounting groove 2. The pressure cap 312 is threadedly fitted onto the bottom of the valve seat 311, and the venturi nozzle 32 is coaxially disposed inside the valve seat 311.

[0030] In one embodiment, such as Figure 2 As shown, the limiting part 34 includes an upper support ring 341 and a lower support ring 342, which are coaxially disposed within the valve body 31. Multiple flow holes 343 are provided on both the upper and lower support rings 341 and 342, respectively. The valve stem 33 is threadedly connected to both the upper and lower support rings 341 and 342. The threads between the upper and lower support rings 341 and 342 and the valve stem 33 secure the valve stem 33. Simultaneously, the upper and lower support rings 341 and 342 provide support and alignment, ensuring the valve stem 33 is centered within the venturi nozzle 32.

[0031] In one embodiment, such as Figure 2 As shown, the steam injection valve 3 also includes a support cylinder 38 and a pressure stabilizing ring 39 coaxially disposed within the valve seat 311. The support cylinder 38 is located between the upper support ring 341 and the venturi nozzle 32, and the pressure stabilizing ring 39 is located between the venturi nozzle 32 and the lower support ring 342.

[0032] In one embodiment, such as Figure 2As shown, the upper support ring 341, support cylinder 38, venturi nozzle 32, pressure stabilizing ring 39, and lower support ring 342 abut against each other in sequence and are movably connected to the valve seat 311. The inner wall of the valve seat 311 is provided with a stepped surface 6, and the top of the upper support ring 341 abuts against the stepped surface 6 to restrict the upward movement of the upper support ring 341. At the same time, a butterfly spring 40 is provided between the valve seat 311 and the pressure cap 312. The pressure cap 312 presses the butterfly spring 40 tightly against the bottom of the lower support ring 342, so that the pressure cap 312 presses and fixes the lower support ring 342, pressure stabilizing ring 39, venturi nozzle 32, support cylinder 38, and upper support ring 341 into the valve seat 311.

[0033] In one embodiment, such as Figure 2 As shown, anti-rotation portions 7 are respectively provided between the valve seat 311 and the upper support ring 341 and the lower support ring 342. The anti-rotation portions 7 are used to restrict the upper support ring 341 and the lower support ring 342 from rotating along their own axial direction. In this embodiment, the anti-rotation portions 7 adopt the cooperation of anti-rotation keys 71 and anti-rotation grooves 72. That is, anti-rotation keys 71 are respectively provided on the upper support ring 341 and the lower support ring 342, and the inner wall of the valve seat 311 is provided with an anti-rotation groove 72. When the anti-rotation key 71 is engaged in the anti-rotation groove 72, the upper support ring 341 and the lower support ring 342 can be limited.

[0034] In one embodiment, such as Figure 2 As shown, the lower end of the valve stem 33 is threaded with a lock nut 344. The lock nut 344 can abut tightly against the disc spring 40 and is used to restrict the upward movement of the valve stem 33, that is, to achieve the anti-reverse locking of the valve stem 33, so as to ensure a constant dispensing volume.

[0035] In one embodiment, such as Figure 2 , Figure 3 As shown, the axial length of the orifice throat 322, the inner diameter of the orifice throat 322, and the radius of the guide arc surface 321 are equal. The axial length of the guide slope 323 is at least equal to the inner diameter of the orifice throat 322. The angle between the guide slope 323 and the axis of the venturi nozzle 32 is 3-5°.

[0036] As can be seen from the above, the adjustable critical flow dispensing valve can achieve rapid adjustment of dispensing volume. Compared with the existing technology, it does not require secondary drilling of parts, nor does it require preparing nozzles of multiple sizes, thus improving tool preparation efficiency, thereby improving work efficiency and operation convenience.

[0037] Under certain inlet parameters, when the outlet pressure of the device through which the medium flows reaches a certain critical value, the flow rate of the medium will reach a maximum value. Further reducing the outlet pressure will not change the flow rate. This indicates that the flow has reached a critical state. In this state, the interference downstream of the device is completely blocked, which means that the changes in formation pressure (i.e., the changes in the pressure after the valve) can be shielded, so that the flow rate can always remain highly constant.

[0038] This embodiment also discloses a method for controlling an adjustable critical flow dispensing valve, including the following steps: S1, Based on the downhole tubing design scheme, obtain the positions h1, h2...h1 of the injection valves in each section. n and the reservoir's given injection volume Q m1 Q m2 ...Q mn ; S2, based on the wellhead steam injection pressure, injection rate, and steam dryness, and using the momentum conservation equation, the wellbore pressure and steam dryness at the first injection valve position h1 are obtained. The wellbore pressure at this point is considered as the injection valve inlet pressure P. in1 ; S3, Select the size of the Venturi nozzle based on the tool design space; S4, based on the first segment injection volume Q m1 Inlet pressure P of the filling valve in1 Steam dryness X s1 The critical flow steam injection algorithm formula is as follows:

[0039] The calculated injection volume is Q. m1 The required outer diameter of the variable diameter section of the valve stem, wherein: The coefficient of expansion is _____. The density of the liquid phase is... Let A1 be the gas phase density, A1 be the area of ​​the annular channel at position h1, and D be the inner diameter of the throat surface. The required outer diameter of the valve stem's variable diameter section to achieve the required reservoir injection volume; S5, continue calculating the injection valve inlet pressure P from position h1 to position h2. in2 Steam dryness X s2 And calculate the injection volume as Q. m2 The required outer diameter of the valve stem's variable diameter section is calculated by analogy, and the required outer diameter of the valve stem's variable diameter section is calculated for different filling volumes; S6, based on the lengths of each stepped surface on the variable diameter section, confirm the adjustment lengths L1, L2...L of the valve stem. N With displacement Q1, Q2...Q NThe corresponding relationship is established, and the valve stem position is adjusted according to the actual required injection volume so that the corresponding stepped surface is aligned with the orifice throat surface.

[0040] It should be noted that, unless otherwise stated, the technical or scientific terms used in this invention should have the ordinary meaning as understood by one of ordinary skill in the art.

[0041] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly defined.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within 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 the embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An adjustable critical flow injection valve suitable for thermal recovery wells, characterized in that, The system includes a vertically arranged support body (1), which has multiple mounting slots (2). At least one of the mounting slots (2) is detachably connected to a steam injection valve (3), and the other mounting slots (2) are detachably connected to sealing plugs (4). The inner wall of the support body (1) is provided with an annular steam flow channel (5), and the multiple mounting slots (2) are respectively connected to the steam flow channel (5) so that the hot steam flowing through the support body (1) can be discharged to the formation through the steam injection valve (3). The steam injection valve (3) includes: The valve body (31) is detachably connected to any of the mounting slots (2); The Venturi nozzle (32) is coaxially disposed inside the valve body (31), and the inner wall of the Venturi nozzle (32) is composed of a flow guiding arc surface (321), a throat surface (322), and a flow guiding inclined surface (323); The valve stem (33) is coaxially disposed inside the venturi nozzle (32), and the valve stem (33) can be adjusted in position along its own axis; A limiting part (34) is provided on the valve body (31) and is used to fix the valve stem (33); A variable diameter section (35) is integrally formed on the valve stem (33), and an annular flow channel (36) is formed between the variable diameter section (35) and the orifice throat surface (322); The variable diameter section (35) has a stepped surface (37) with an outer diameter decreasing from top to bottom. By adjusting the position of the valve stem (33), different stepped surfaces (37) can be aligned with the throat surface (322), thereby adjusting the area of ​​the annular flow channel (36) and thus adjusting the dispensing amount.

2. The adjustable critical flow dispensing valve according to claim 1, characterized in that, The valve body (31) includes a valve seat (311) and a pressure cap (312). The valve seat (311) can be threadedly connected to any of the mounting grooves (2). The pressure cap (312) is threadedly fitted onto the bottom of the valve seat (311), and the Venturi nozzle (32) is coaxially disposed inside the valve seat (311).

3. The adjustable critical flow dispensing valve according to claim 2, characterized in that, The limiting part (34) includes an upper support ring (341) and a lower support ring (342). The upper support ring (341) and the lower support ring (342) are coaxially disposed in the valve body (31). The upper support ring (341) and the lower support ring (342) are respectively provided with a plurality of flow holes (343), and the valve stem (33) is threadedly connected to the upper support ring (341) and the lower support ring (342).

4. The adjustable critical flow dispensing valve according to claim 3, characterized in that, The steam injection valve (3) also includes a support cylinder (38) and a pressure stabilizing ring (39) coaxially disposed in the valve seat (311). The support cylinder (38) is located between the upper support ring (341) and the Venturi nozzle (32), and the pressure stabilizing ring (39) is located between the Venturi nozzle (32) and the lower support ring (342). The upper support ring (341), support cylinder (38), venturi nozzle (32), pressure stabilizing ring (39), and lower support ring (342) are movably connected to the valve seat (311), and the pressure cap (312) presses the lower support ring (342), pressure stabilizing ring (39), venturi nozzle (32), support cylinder (38), and upper support ring (341) into the valve seat (311). Anti-rotation part (7) is provided between the valve seat (311), the upper support ring (341), and the lower support ring (342), respectively. The anti-rotation part (7) is used to restrict the upper support ring (341) and the lower support ring (342) from rotating along their own axial direction.

5. The adjustable critical flow dispensing valve according to claim 4, characterized in that, A butterfly spring (40) is provided between the valve seat (311) and the pressure cap (312), and the valve seat (311) presses the butterfly spring (40) against the bottom of the lower support ring (342).

6. The adjustable critical flow dispensing valve according to claim 5, characterized in that, The lower end of the valve stem (33) is threaded with a stop nut (344), which can abut against the disc spring (40) and is used to restrict the upward movement of the valve stem (33).

7. The adjustable critical flow dispensing valve according to claim 1, characterized in that, The axial length of the orifice throat (322), the inner diameter of the orifice throat (322), and the radius of the guide arc surface (321) are equal.

8. The adjustable critical flow dispensing valve according to claim 7, characterized in that, The axial length of the guide slope (323) is at least equal to the inner diameter of the throat surface (322).

9. The adjustable critical flow dispensing valve according to claim 8, characterized in that, The angle between the guide slope (323) and the axis of the venturi nozzle (32) is 3-5°.

10. A method for controlling an adjustable critical flow dispensing valve according to any one of claims 1-9, characterized in that, Includes the following steps: S1, Based on the downhole tubing design scheme, obtain the positions h1, h2...h1 of the injection valves in each section. n and the reservoir's given injection volume Q m1 Q m2 ...Q mn ; S2, based on the wellhead steam injection pressure, injection rate, and steam dryness, and using the momentum conservation equation, the wellbore pressure and steam dryness at the first injection valve position h1 are obtained. The wellbore pressure at this point is considered as the injection valve inlet pressure P. in1 ; S3, Select the size of the Venturi nozzle based on the tool design space; S4, based on the first segment injection volume Q m1 Inlet pressure P of the filling valve in1 Steam dryness X s1 The critical flow steam injection algorithm formula is as follows: The calculated injection volume is Q. m1 The required outer diameter of the variable diameter section of the valve stem, wherein: ρ is the coefficient of expansion. L ρ is the density of the liquid phase. G Where A is the gas phase density, A1 is the area of ​​the annular channel at position h1, D is the inner diameter of the throat surface, and d is the gas phase density. x The required outer diameter of the valve stem's variable diameter section to achieve the required reservoir injection volume; S5, continue calculating the injection valve inlet pressure P from position h1 to position h2. in2 Steam dryness X s2 And calculate the injection volume as Q. m2 The required outer diameter of the valve stem's variable diameter section is calculated by analogy, and the required outer diameter of the valve stem's variable diameter section is calculated for different filling volumes; S6, based on the lengths of each stepped surface on the variable diameter section, confirm the adjustment lengths L1, L2...L of the valve stem. N With displacement Q1, Q2...Q N The corresponding relationship is established, and the valve stem position is adjusted according to the actual required injection volume so that the corresponding stepped surface is aligned with the orifice throat surface.

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