Adjustable critical flow injection allocation valve suitable for thermal production well and regulation and control method of adjustable critical flow injection allocation valve

Abstract

The invention discloses an adjustable critical flow injection allocation valve suitable for a thermal production well and a regulation and control method of the adjustable critical flow injection allocation valve. The technical problems that the tool preparation efficiency is low and the like are solved. The device comprises a supporting body, a plurality of mounting grooves are formed in the supporting body, a steam injection valve is arranged in at least one mounting groove, sealing plugs are arranged in the other mounting grooves respectively, an annular steam flow channel is formed in the inner wall of the supporting body, and the mounting grooves communicate with the steam flow channel; the steam injection valve comprises a valve body, a Venturi nozzle, a valve rod, a limiting part and a reducing part, step faces with the outer diameters sequentially reduced from top to bottom are formed on the surface of the reducing part, the different step faces are aligned to the pore throat face by adjusting the position of the valve rod, the area of an annular flow channel can be adjusted, and therefore the injection allocation amount is adjusted. According to the injection allocation valve, the injection allocation amount can be adjusted, secondary punching machining does not need to be conducted on parts, nozzles of multiple specifications and sizes do not need to be prepared either, the tool preparation efficiency is improved, and therefore the operation time efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of oil production engineering, and in particular relates to an adjustable critical flow injection valve suitable for thermal production wells and a control method thereof. Background Art

[0002] Nowadays, offshore oil fields are rich in heavy oil resources, of which unconventional heavy oil (formation crude oil viscosity greater than 350mPa.s) accounts for up to 30%. Due to the low production capacity and low oil production rate of unconventional heavy oil cold production, it is difficult to meet the needs of efficient development of offshore heavy oil. Thermal recovery is an effective technology for heavy oil development. At present, perforated pipes or fixed valves are used underground as the flow channel for steam injection into the formation. The layout position and aperture size are designed and calculated based on well logging data and reservoir analysis to achieve the purpose of balanced steam injection in each layer underground.

[0003] However, with the continuous injection of steam, especially in steam-huffing and puffing wells, the difference in steam absorption by the formation gradually increases. It is difficult to stabilize the steam injection volume at a relatively constant displacement using perforated pipes or fixed valves. In addition, before the completion of a new well, perforated pipes and fixed valves of various specifications and sizes must be prepared in advance based on the drilling test data. This places high demands on the timeliness of tool assembly, and there is also a risk of incorrect insertion during on-site construction, which needs to be improved. Summary of the invention

[0004] In order to solve all or part of the above problems, the purpose of the present invention is to provide an adjustable critical flow injection valve suitable for thermal recovery wells and a control method thereof. The injection valve itself can adjust the injection volume, and there is no need to perform secondary drilling processing on parts or prepare nozzles of multiple specifications and sizes, thereby improving tool preparation efficiency and thus improving operation 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, a plurality of mounting grooves arranged on the support body, at least one of the mounting grooves being detachably connected to a steam injection valve, and the remaining mounting grooves being detachably connected to sealing plugs, an annular steam flow channel being arranged on the inner wall of the support body, and a plurality of the mounting grooves being 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;

[0006] The steam injection valve comprises:

[0007] A valve body capable of being detachably connected to any of the mounting grooves;

[0008] A venturi nozzle is coaxially arranged in the valve body, and the inner wall of the venturi nozzle is composed of a flow guiding arc surface, a hole throat surface and a flow guiding inclined surface;

[0009] A valve stem is coaxially arranged in the Venturi nozzle, and the valve stem can be adjusted in position along its own axial direction;

[0010] A limiting portion, disposed on the valve body and used to fix the valve stem;

[0011] A diameter reducing portion is integrally formed on the valve stem, and an annular flow channel is formed between the diameter reducing portion and the hole throat surface;

[0012] The surface of the reducing portion forms a stepped surface whose outer diameter decreases from top to bottom. By adjusting the position of the valve stem so that different stepped surfaces are aligned with the throat surface, the annular flow channel area can be adjusted, thereby achieving injection volume adjustment.

[0013] 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 threadedly sleeved on the bottom of the valve seat, and the Venturi nozzle is coaxially arranged in the valve seat.

[0014] Optionally, the limiting portion includes an upper support ring and a lower support ring, and the upper support ring and the lower support ring are coaxially arranged in the valve body respectively, and a plurality of flow holes are respectively arranged on the upper support ring and the lower support ring, and the valve stem is threadedly connected to the upper support ring and the lower support ring respectively.

[0015] Optionally, the steam injection valve further comprises a support tube and a pressure stabilizing ring coaxially arranged in the valve seat, the support tube 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;

[0016] The upper support ring, support tube, venturi nozzle, pressure stabilizing ring and lower support ring are respectively movably connected to the valve seat, and the pressure cap presses the lower support ring, pressure stabilizing ring, venturi nozzle, support tube and upper support ring into the valve seat, and a stopper is respectively provided between the valve seat and the upper support ring and the lower support ring, and the stopper is used to limit the upper support ring and the lower support ring from rotating along their own axis.

[0017] Optionally, a butterfly spring is arranged between the valve seat and the pressure cap, and the valve seat presses the butterfly spring against the bottom of the lower support ring.

[0018] Optionally, a stop nut is threadedly connected to the lower end of the valve stem, and the stop nut can be tightly abutted against the butterfly spring and is used to limit the upward movement of the valve stem.

[0019] Optionally, the axial length of the pore throat surface, the inner diameter of the pore throat surface and the radius of the guide arc surface are equal.

[0020] Optionally, the axial length of the guide slope is at least equal to the inner diameter of the pore throat surface.

[0021] Optionally, the angle between the guide slope and the axis of the Venturi nozzle is 3-5°.

[0022] In a second aspect, the present invention provides a method for controlling an adjustable critical flow injection valve, comprising the following steps:

[0023] S1, according to the downhole pipe design scheme, obtain the position of the injection valve in each layer h 1 、h 2 ……h n and the injection volume Q given by the reservoir m1 , Q m2 ...Q mn ;

[0024] S2, according to the wellhead steam injection pressure, injection displacement and steam dryness, and the momentum conservation equation, the first injection valve position h is obtained 1 The wellbore pressure and steam dryness at this time are regarded as the injection valve inlet pressure P in1 ;

[0025] S3, select the size of the Venturi nozzle according to the tool design space;

[0026] S4, according to the injection volume Q of the first layer m1 , injection valve inlet pressure P in1 , Steam dryness X s1 , through the critical flow steam injection algorithm formula:

[0027]

[0028] Calculate the injection volume as Q m1 The required outer diameter of the reducer of the valve stem, where: is the expansion coefficient, ρ L is the liquid density, ρ G is the gas phase density, A 1 h 1 The area of ​​the annular channel at position D, the inner diameter of the pore throat, d x The outer diameter of the reducer of the valve stem is required to achieve the required reservoir injection volume;

[0029] S5, continue along h 1 Position calculation to h 2 The injection valve inlet pressure at position P in2 , Steam dryness X s2 , and calculate the injection volume as Q m2 The required outer diameter of the reducing part of the valve stem at different injection volumes can be calculated by analogy.

[0030] S6, confirm the adjustment length L of the valve stem according to the length of each step surface on the reducer 1 , L 2 ...L N With displacement Q 1 , Q 2 ...Q N The corresponding relationship is calculated, and the valve stem position is adjusted according to the actual required injection volume, so that the corresponding step surface is aligned with the hole throat surface.

[0031] It can be seen from the above technical solution that the adjustable critical flow injection valve and control method thereof suitable for thermal recovery wells provided by the present invention have the following advantages:

[0032] The adjustable critical flow injection valve can adjust the position of the valve stem to adjust the injection volume. There is no need to perform secondary drilling on parts or prepare nozzles of multiple specifications and sizes, which improves tool preparation efficiency, thereby improving operation timeliness and operating convenience.

[0033] Other features and advantages of the present invention will be set forth in the description which follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] 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.

[0035] Figure 1 A cross-sectional view of an adjustable critical flow injection valve according to an embodiment of the present invention;

[0036] Figure 2 is a cross-sectional view of a steam injection valve according to an embodiment of the present invention;

[0037] Figure 3 is a cross-sectional view of a venturi nozzle in an embodiment of the present invention;

[0038] Figure 4 2 is a cross-sectional view of a valve stem in an embodiment of the present invention.

[0039] Description of reference numerals:

[0040] 1. Support body; 11. Socket tube; 12. Lower joint; 2. Mounting groove; 3. Steam injection valve; 31. Valve body; 311. Valve seat; 312. Pressure cap; 32. Venturi nozzle; 321. Guide arc surface; 322. Hole throat surface; 323. Guide slope; 33. Valve stem; 34. Limiting part; 341. Upper support ring; 342. Lower support ring; 343. Flow hole; 344. Retraction nut; 35. Variable diameter part; 36. Annular flow channel; 37. Step surface; 38. Support tube; 39. Pressure stabilizing ring; 40. Butterfly spring; 4. Sealing plug; 5. Steam flow channel; 6. Step surface; 7. Stop part; 7. Stop key; 72. Stop groove. DETAILED DESCRIPTION

[0041] 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.

[0042] like Figure 1 , Figure 2 , Figure 3 , Figure 4 An embodiment of the present invention is shown, in which an adjustable critical flow injection valve suitable for thermal recovery wells is disclosed, including a vertically arranged support body 1, and the support body 1 includes a receiving tube 11 and a lower joint 12, the lower joint 12 is threadedly sleeved on the bottom of the receiving tube 11, the receiving tube 11 and the lower joint 12 are respectively used to connect with the oil well pipe string, and the receiving tube 11 and the lower joint 12 form a steam channel for steam to pass through.

[0043] In one embodiment, Figure 1 As shown, a plurality of mounting grooves 2 are provided on the receiving tube 11, the mounting grooves 2 are vertically arranged, and the plurality of mounting grooves 2 are arranged at equal intervals along the circumference of the receiving tube 11. A steam injection valve 3 is detachably connected to at least one mounting groove 2, and sealing plugs 4 are detachably connected to the remaining mounting grooves 2, so that the staff can select the number of steam injection valves 3 to be installed according to actual needs.

[0044] In one embodiment, Figure 1 As shown, the inner wall of the receiving tube 11 is provided with an annular steam flow channel 5 along its circumference, and a plurality of mounting grooves 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.

[0045] In this embodiment, the steam injection valve 3 and the sealing plug 4 can be respectively threadedly connected to any mounting groove 2, so that the steam injection valve 3 and the sealing plug 4 can be quickly disassembled and assembled, thereby improving the operation time efficiency. The drawings of this embodiment only show the state of one steam injection valve 3 and one sealing plug 4.

[0046] In one embodiment, Figure 2 , Figure 3 , Figure 4 As shown, the steam injection valve 3 includes a cylindrical valve body 31, and the valve body 31 can be detachably connected to any mounting groove 2. A venturi nozzle 32 is coaxially arranged in the valve body 31, and the inner wall of the venturi nozzle 32 is composed of a guide arc surface 321, a hole throat surface 322 and a guide inclined surface 323, and the guide arc surface 321, the hole throat surface 322 and the guide inclined surface 323 are arranged in sequence from top to bottom.

[0047] In one embodiment, Figure 2 , Figure 3 , Figure 4 As shown, a valve stem 33 is coaxially arranged in the venturi nozzle 32, and the valve stem 33 can be adjusted in position along its own axial direction. At the same time, a limiter 34 for fixing the valve stem 33 is arranged on the valve body 31. A reducing portion 35 is integrally formed and connected to the valve stem 33, and an annular flow channel 36 is formed between the reducing portion 35 and the throat surface 322. At the same time, a stepped surface 37 whose outer diameter decreases from top to bottom is formed on the surface of the reducing portion 35. By adjusting the position of the valve stem 33, different stepped surfaces 37 are aligned with the throat surface 322, so that the area of ​​the annular flow channel 36 can be adjusted, thereby achieving the adjustment of the injection amount.

[0048] The adjustable critical flow dispensing valve in this embodiment can adjust the dispensing amount by adjusting the position of the valve stem 33, that is, the dispensing valve itself has the ability to adjust the dispensing amount. There is no need to perform secondary drilling processing on parts, nor is there a need to prepare nozzles of multiple specifications and sizes, which improves tool preparation efficiency, thereby improving work timeliness and improving operational convenience.

[0049] In one embodiment, 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 sleeved on the bottom of the valve seat 311 , and the Venturi nozzle 32 is coaxially arranged in the valve seat 311 .

[0050] In one embodiment, Figure 2 As shown, the limiting part 34 includes an upper support ring 341 and a lower support ring 342, which are coaxially arranged in the valve body 31, and a plurality of flow holes 343 are arranged on the upper support ring 341 and the lower support ring 342, respectively, and the valve stem 33 is threadedly connected with the upper support ring 341 and the lower support ring 342. The threads between the upper support ring 341, the lower support ring 342 and the valve stem 33 can fix the valve stem 33, and at the same time, the upper support ring 341 and the lower support ring 342 can also play a role of supporting and straightening, so that the valve stem 33 is centered in the venturi nozzle 32.

[0051] In one embodiment, Figure 2 As shown, the steam injection valve 3 also includes a support tube 38 and a pressure stabilizing ring 39 coaxially arranged in the valve seat 311 . The support tube 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 .

[0052] In one embodiment, Figure 2 As shown, the upper support ring 341, the support cylinder 38, the venturi nozzle 32, the pressure stabilizing ring 39 and the lower support ring 342 are abutted in sequence and are respectively movably connected with the valve seat 311. The inner wall of the valve seat 311 is provided with a step surface 6, and the top of the upper support ring 341 abuts against the step surface 6 to limit 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, and the pressure cap 312 presses the butterfly spring 40 against the bottom of the lower support ring 342, so that the pressure cap 312 presses and fixes the lower support ring 342, the pressure stabilizing ring 39, the venturi nozzle 32, the support cylinder 38 and the upper support ring 341 in the valve seat 311.

[0053] In one embodiment, Figure 2 As shown, a stopper 7 is provided between the valve seat 311 and the upper support ring 341 and the lower support ring 342, and the stopper 7 is used to limit the upper support ring 341 and the lower support ring 342 from rotating along their own axis. In this embodiment, the stopper 7 adopts the cooperation of the stopper key 7 and the stopper groove 72, that is, the upper support ring 341 and the lower support ring 342 are provided with the stopper key 7, and the inner wall of the valve seat 311 is provided with the stopper groove 72. When the stopper key 7 is stuck in the stopper groove 72, the upper support ring 341 and the lower support ring 342 can be limited.

[0054] In one embodiment, Figure 2 As shown, the lower end of the valve stem 33 is threadedly connected with a stop nut 344, which can tightly abut against the butterfly spring 40 and is used to limit the upward movement of the valve stem 33, that is, to achieve anti-retraction locking of the valve stem 33 to ensure a constant injection volume.

[0055] In one embodiment, Figure 2 , Figure 3 As shown, the axial length of the pore throat surface 322, the inner diameter of the pore throat surface 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 pore throat surface 322, and the angle between the guide slope 323 and the axis of the Venturi nozzle 32 is 3-5°.

[0056] From the above, it can be seen that the use of this adjustable critical flow injection valve can achieve rapid adjustment of the injection volume. Compared with the existing technology, there is no need to perform secondary drilling processing on parts, nor is there a need to prepare nozzles of multiple specifications and sizes, which improves tool preparation efficiency, thereby improving operation timeliness and improving operational convenience.

[0057] 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. If the outlet pressure is further reduced, the flow rate will remain constant. This means that the flow has reached a critical state. In this state, the interference downstream of the device is completely blocked, that is, the change in formation pressure (i.e., the change in pressure behind the valve) can be shielded, so that the flow rate can always remain highly constant.

[0058] This embodiment also discloses a method for controlling an adjustable critical flow injection valve, comprising the following steps:

[0059] S1, according to the downhole pipe design scheme, obtain the position of the injection valve in each layer h 1 、h 2 ……h n and the injection volume Q given by the reservoir m1 , Q m2 ...Q mn ;

[0060] S2, according to the wellhead steam injection pressure, injection displacement and steam dryness, and the momentum conservation equation, the first injection valve position h is obtained 1 The wellbore pressure and steam dryness at this time are regarded as the injection valve inlet pressure P in1 ;

[0061] S3, select the size of the Venturi nozzle according to the tool design space;

[0062] S4, according to the injection volume Q of the first layer m1 , injection valve inlet pressure P in1 , Steam dryness X s1 , through the critical flow steam injection algorithm formula:

[0063]

[0064] Calculate the injection volume as Q m1 The required outer diameter of the reducer of the valve stem, where: is the expansion coefficient, ρ L is the liquid density, ρ G is the gas phase density, A 1 h 1 The area of ​​the annular channel at position D, the inner diameter of the pore throat, d xThe outer diameter of the reducer of the valve stem is required to achieve the required reservoir injection volume;

[0065] S5, continue along h 1 Position calculation to h 2 The injection valve inlet pressure at position P in2 , Steam dryness X s2 , and calculate the injection volume as Q m2 The required outer diameter of the reducing part of the valve stem at different injection volumes can be calculated by analogy.

[0066] S6, confirm the adjustment length L of the valve stem according to the length of each step surface on the reducer 1 , L 2 ...L N With displacement Q 1 , Q 2 ...Q N The corresponding relationship is calculated, and the valve stem position is adjusted according to the actual required injection volume, so that the corresponding step surface is aligned with the hole throat surface.

[0067] 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.

[0068] 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.

[0069] 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. An adjustable critical flow injection valve suitable for thermal recovery wells, characterized in that: The invention comprises a vertically arranged support body (1), wherein a plurality of mounting grooves (2) are arranged on the support body (1), a steam injection valve (3) is detachably connected to at least one of the mounting grooves (2), and sealing plugs (4) are detachably connected to the remaining mounting grooves (2), and an annular steam flow channel (5) is arranged on the inner wall of the support body (1), and the plurality of mounting grooves (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) comprises: A valve body (31) capable of being detachably connected to any of the mounting grooves (2); A venturi nozzle (32) is coaxially arranged in the valve body (31), and the inner wall of the venturi nozzle (32) is composed of a flow guiding arc surface (321), a hole throat surface (322) and a flow guiding inclined surface (323); A valve stem (33) is coaxially arranged in the Venturi nozzle (32), and the valve stem (33) can be adjusted in position along its own axial direction; A limiting portion (34) is provided on the valve body (31) and is used to fix the valve stem (33); A diameter reducing portion (35) is integrally formed and arranged on the valve stem (33), and an annular flow channel (36) is formed between the diameter reducing portion (35) and the hole throat surface (322); The surface of the reducing portion (35) forms a stepped surface (37) whose outer diameter decreases from top to bottom. By adjusting the position of the valve stem (33) so that different stepped surfaces (37) are aligned with the throat surface (322), the area of ​​the annular flow channel (36) can be adjusted, thereby achieving adjustment of the injection volume.

2. The adjustable critical flow injection valve according to claim 1, characterized in that: The valve body (31) comprises 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 sleeved on the bottom of the valve seat (311); and the Venturi nozzle (32) is coaxially arranged in the valve seat (311).

3. The adjustable critical flow injection valve according to claim 2, characterized in that: The limiting portion (34) comprises an upper supporting ring (341) and a lower supporting ring (342), wherein the upper supporting ring (341) and the lower supporting ring (342) are respectively coaxially arranged in the valve body (31), and a plurality of flow holes (343) are respectively arranged on the upper supporting ring (341) and the lower supporting ring (342), and the valve stem (33) is respectively threadedly connected to the upper supporting ring (341) and the lower supporting ring (342).

4. The adjustable critical flow injection valve according to claim 3, characterized in that: The steam injection valve (3) further comprises a support tube (38) and a pressure stabilizing ring (39) coaxially arranged in the valve seat (311), wherein the support tube (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), the support tube (38), the Venturi nozzle (32), the pressure-stabilizing ring (39) and the lower support ring (342) are respectively movably connected to the valve seat (311), and the pressure cap (312) presses the lower support ring (342), the pressure-stabilizing ring (39), the Venturi nozzle (32), the support tube (38) and the upper support ring (341) into the valve seat (311), and a stopper (7) is respectively provided between the valve seat (311) and the upper support ring (341) and the lower support ring (342), and the stopper (7) is used to limit the upper support ring (341) and the lower support ring (342) from rotating along their own axes.

5. The adjustable critical flow injection valve according to claim 4, characterized in that: A butterfly spring (40) is arranged 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 injection valve according to claim 5, characterized in that: The lower end of the valve stem (33) is threadedly connected with a stop nut (344), and the stop nut (344) can be tightly abutted against the butterfly spring (40) and is used to limit the upward movement of the valve stem (33).

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

8. The adjustable critical flow injection 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 pore throat surface (322).

9. The adjustable critical flow injection 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 injection valve according to any one of claims 1 to 9, characterized in that: The steps include: S1, according to the downhole pipe design scheme, obtain the position of injection valves in each layer h1, h2...h n and the injection volume Q given by the reservoir m1 , Q m2 ...Q mn ; S2, according to the wellhead steam injection pressure, injection displacement and steam dryness, and through the momentum conservation equation, the wellbore pressure and steam dryness at the first injection valve position h1 are obtained. The wellbore pressure at this time is regarded as the injection valve inlet pressure P in1 ; S3, select the size of the Venturi nozzle according to the tool design space; S4, according to the injection volume Q of the first layer m1 , injection valve inlet pressure P in1 , Steam dryness X s1 , through the critical flow steam injection algorithm formula: Calculate the injection volume as Q m1 The required outer diameter of the reducer of the valve stem, where: is the expansion coefficient, ρ L is the liquid density, ρ G is the gas phase density, A1 is the area of ​​the annular channel at position h1, D is the inner diameter of the pore throat, d x The outer diameter of the reducer of the valve stem is required to achieve the required reservoir injection volume; S5, continue to calculate along the h1 position to the injection valve inlet pressure P at the h2 position in2 , Steam dryness X s2 , and calculate the injection volume as Q m2 The required outer diameter of the reducing part of the valve stem at different injection volumes can be calculated by analogy. S6, according to the length of each step surface on the reducer, confirm the adjustment length L1, L2...L of the valve stem N With displacement Q1, Q2...Q N The corresponding relationship is calculated, and the valve stem position is adjusted according to the actual required injection volume, so that the corresponding step surface is aligned with the hole throat surface.

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