Three-stage sealing blowout preventer for oil well testing

Abstract

The utility model relates to a three -level sealed blowout preventer for oil well test, including the blowout preventer box, is equipped with the choke tube in the blowout preventer box lower part, is equipped with the lower piston in the blowout preventer box above the choke tube, is equipped with the first sealing packing ring in the blowout preventer box between the lower piston and the choke tube, is equipped with the overflow port on the blowout preventer box lateral wall, the outer sleeve of the stem of lower piston has the sealing sliding sleeve, is equipped with the oil pressure interface on the blowout preventer box lateral wall, is equipped with the upper piston in the blowout preventer box above the sealing sliding sleeve, is equipped with the second sealing packing ring in the blowout preventer box below the upper piston, is equipped with the overflow port on the blowout preventer box lateral wall, is equipped with the sealing lock cap in the blowout preventer box top, the blowout preventer box inner chamber is linked together with the oil pressure interface through the pressure transmission pipe of being equipped in the blowout preventer box lateral wall. This patent realizes the whole flow control of cable lowering and overflow plugging through the hydraulic pump control double piston extrusion seal, combines the dynamic pressure relief of upper and lower overflow port, solves the technical problem that the downhole liquid is still easy to spray from the top of blowout preventer head, pollutes the environment.

Description

Technical Field

[0001] This utility model relates to the field of oil well logging and testing technology, and in particular to a three-stage sealing blowout preventer for oil well testing. Background Technology

[0002] During well logging in oilfields, armored wireline logging cables are used to connect downhole logging instruments. To prevent wellhead overflow and environmental damage, a blowout preventer (BOP) is installed on the wellhead sealer. A BOP plug is screwed onto the upper end of the BOP via a BOP connector. A drainage chamber is located in the middle of the BOP plug, and an overflow port is connected to the side wall of the drainage chamber. The overflow port is connected to an overflow pipeline to collect the liquid in the wellbore into a designated container for treatment before it overflows, thus preventing environmental damage. Despite the height of the BOP, downhole liquid can still overflow upwards from the center hole of the BOP connector and enter the drainage chamber, flowing out from the overflow port on the side of the drainage chamber. Because existing BOP plugs only have one overflow port, when the downhole pressure is slightly high, downhole liquid can easily spray from the top of the BOP plug, causing environmental pollution. Furthermore, traditional devices rely on fixed packing for static sealing, making it impossible to adjust the sealing strength in real time according to well pressure fluctuations, resulting in overflow leakage rates >1L / min. Utility Model Content

[0003] To address the shortcomings of existing technologies, this utility model discloses a three-stage sealing blowout preventer for oil well testing, which solves the technical problems that downhole fluids can still easily spray out from the top of the blowout preventer, polluting the environment, and that the sealing force cannot be dynamically adjusted.

[0004] This utility model is achieved through the following technical solution:

[0005] A three-stage sealing blowout preventer (BOP) for oil well testing includes a blowout preventer box, a flow-blocking tube at the bottom of the BOP, a lower piston with a through-hole inside the BOP above the flow-blocking tube, a first sealing packing inside the BOP between the lower piston and the flow-blocking tube, a lower overflow port on the side wall of the BOP communicating with the inner cavity of the BOP located between the lower piston and the flow-blocking tube, a sealing sleeve sleeved on the rod of the lower piston, and an inner cavity on the side wall of the BOP communicating with the inner cavity of the BOP located between the sealing sleeve and the head of the lower piston. The hydraulic interface has an upper piston with a through-hole inside the blowout preventer box above the sealing sleeve. A second sealing packing is located inside the blowout preventer box below the upper piston. An upper overflow port is located on the side wall of the blowout preventer box and communicates with the inner cavity of the blowout preventer box located between the second sealing packing and the sealing sleeve. A sealing cap is located on the top of the blowout preventer box. The rod of the upper piston extends out of the sealing cap and extends outside the sealing cap. The inner cavity of the blowout preventer box between the head of the upper piston and the sealing cap is connected to the hydraulic interface through a pressure transmission pipe located on the side wall of the blowout preventer box.

[0006] In a further optimized configuration, the flow-blocking tube includes a zirconia ceramic tube and an alloy sleeve fitted over the outer wall of the zirconia ceramic tube. The zirconia ceramic tube is sealed to the alloy sleeve by vacuum brazing.

[0007] Furthermore, the inner sidewalls of both the upper and lower pistons are laser-clad with a nanocrystalline silicon carbide layer.

[0008] Further optimized, the sealing sleeve is a stepped sealing sleeve, and a shoulder is provided on the inner wall of the blowout preventer to restrict the upward movement of the stepped sealing sleeve.

[0009] Further optimized, a blocking sleeve is provided below the second sealing packing to abut against the second sealing packing, and a shoulder is provided on the inner wall of the blowout preventer to restrict the downward movement of the blocking sleeve.

[0010] In a further optimized configuration, the flow-blocking tube is detachably connected to the blowout preventer via a blocking nut.

[0011] The beneficial effects of this utility model are as follows:

[0012] This patented technology uses a hydraulic pump to control a dual-piston compression seal, and adjusts the compression pressure in real time (0-100MPa adjustable). Combined with dynamic pressure relief from the upper and lower overflow ports, it achieves full-process control of cable lowering and overflow sealing, solving the technical problem that downhole liquid can still easily spray out from the top of the blowout preventer, polluting the environment. Attached Figure Description

[0013] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or components are generally identified by similar reference numerals. In the drawings, the elements or components are not necessarily drawn to scale.

[0014] Figure 1 This is a schematic diagram of the structure of this utility model;

[0015] In the diagram, 1. Blowout preventer box, 2. Lower piston, 3. First sealing packing, 4. Lower overflow port, 5. Hydraulic interface, 6. Upper piston, 7. Second sealing packing, 8. Upper overflow port, 9. Sealing cap, 10. Pressure transmission pipe, 11. Blowout preventer connector, 12. Blowout preventer, 13. Steel wire armored cable, 14. Zirconia ceramic tube, 15. Alloy sleeve, 16. Sealing sleeve, 17. Barrier sleeve, 18. Barrier nut, 19. Nanocrystalline silicon carbide layer. Detailed Implementation

[0016] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0017] like Figure 1 As shown, a three-stage sealing blowout preventer for oil well testing includes a blowout preventer box 1, a flow-blocking pipe at the lower part of the blowout preventer box 1, a lower piston 2 with a through-hole inside the blowout preventer box 1 above the flow-blocking pipe, a first sealing packing 3 inside the blowout preventer box 1 between the lower piston 2 and the flow-blocking pipe, a lower overflow port 4 on the side wall of the blowout preventer box 1 communicating with the inner cavity of the blowout preventer box 1 located between the lower piston 2 and the flow-blocking pipe, a sealing sleeve 16 sleeved on the rod of the lower piston 2, and an oil pressure port on the side wall of the blowout preventer box 1 communicating with the inner cavity of the blowout preventer box 1 located between the sealing sleeve 4 and the head of the lower piston 2. Interface 5, an upper piston 6 with a through-hole is provided in the blowout preventer 1 above the sealing sleeve 16, a second sealing packing 7 is provided in the blowout preventer 1 below the upper piston 6, an upper overflow port 8 is provided on the side wall of the blowout preventer 1 and communicates with the inner cavity of the blowout preventer 1 located between the second sealing packing 7 and the sealing sleeve 16, a sealing cap 9 is provided on the top of the blowout preventer 1, the rod of the upper piston 6 extends out of the sealing cap 9 and the inner cavity of the blowout preventer 1 between the head of the upper piston 6 and the sealing cap 9 is connected to the hydraulic interface 5 through a pressure transmission pipe 10 provided on the side wall of the blowout preventer 1.

[0018] The first sealing packing 3 and the second sealing packing 7 are made of fluororubber-aramid fiber composite gradient material with a surface hardness of Shore A98 and a core hardness of Shore A75. The radial shrinkage rate after pressure is ≥45%. The oil pressure interface 5 is connected to the hydraulic pump. The blowout preventer of this patent is connected to the blowout preventer pipe 12 through the blowout preventer pipe joint 11.

[0019] During the cable lowering stage, the lower overflow port 4 is opened to release pressure. The hydraulic pump drives the lower piston 2 to release the pressure of the first sealing packing 3, controlling the pressure release of the lower overflow port 4, and the cable is successfully lowered into the well.

[0020] After the cable is in place, the overflow sealing stage begins. The lower overflow port 4 is closed, and the flow-blocking pipe achieves primary blowout prevention, blocking most of the fluid coming from downhole. However, if the well pressure is high, fluid will continue to rise through the gaps in the wire-armored cable 13. After the hydraulic pump starts, high-pressure hydraulic oil enters the blowout preventer box 1 through the oil pressure port 5. Under the pressure of the high-pressure oil, the upper piston 6 and lower piston 2 simultaneously push the first sealing packing 3 and the second sealing packing 7, forcing the sealing packings to squeeze inwards and outwards respectively, thus sealing the wire-armored cable and achieving secondary and tertiary blowout prevention. The secondary and tertiary blowout prevention continue to block fluid coming out from the gaps in the wire-armored cable. A very small portion of the fluid exits through the upper overflow port 8 and flows into the recovery tank, preventing fluid from spraying out and causing environmental pollution.

[0021] Based on well pressure fluctuations (±10MPa), the hydraulic pump automatically adjusts the piston pressure to maintain the sealing interface pressure at 25±0.5MPa, thus preventing overpressure damage to the cable.

[0022] This patent uses a hydraulic pump to control a dual-piston compression seal, adjusting the compression pressure in real time (0-100MPa adjustable), combined with dynamic pressure relief from the upper and lower overflow ports, to achieve full-process control of cable lowering and overflow sealing.

[0023] In some embodiments, the flow-blocking pipe includes a zirconia ceramic tube 14 and an alloy sleeve 15 fitted over the outer wall of the zirconia ceramic tube 14. The zirconia ceramic tube 14 is sealed to the alloy sleeve 15 by vacuum brazing. Traditional steel flow-blocking pipes suffer from inner diameter uniformity errors of ±0.1mm and surface roughness Ra≥0.5μm due to processing limitations. The friction coefficient when cables pass through is ≥0.18, resulting in armor layer wear rate >5%. The flow-blocking pipe of this patent uses a zirconia ceramic tube with an inner diameter uniformity error ≤0.02mm, reducing cable wear rate by 95% compared to existing steel flow-blocking pipes. Steel materials have low hardness (HV 200-300), resulting in a wear rate ≥15μm / 10,000 cycles under sand-containing fluid scouring, requiring ≥10 replacements per well per year, with maintenance costs exceeding 100,000 yuan. In contrast, the outer layer of the flow-blocking pipe in this patent uses an alloy sleeve, such as one made of Inconel 718 alloy, extending the maintenance-free period of the flow-blocking pipe to 3 years.

[0024] In some embodiments, the inner sidewalls of both the upper piston 6 and the lower piston 2 are laser-clad with a nanocrystalline silicon carbide layer 19. The working surfaces of the two pistons are made of ceramic material. Utilizing the good machining accuracy and low surface roughness of ceramic material, the coaxiality of the pistons can be improved, and the radial runout of the piston can be maintained at <3μm, with the maximum scratch depth on the surface of the cable armor layer ≤0.8μm.

[0025] In some embodiments, the sealing sleeve 16 is a stepped sealing sleeve, and a shoulder is provided on the inner wall of the blowout preventer 1 to restrict the upward movement of the stepped sealing sleeve.

[0026] In some embodiments, a blocking sleeve 17 is provided below the second sealing packing 7 to abut against the second sealing packing 7, and a shoulder is provided on the inner wall of the blowout preventer 1 to restrict the downward movement of the blocking sleeve 17.

[0027] In some embodiments, the flow-blocking tube is detachably connected to the blowout preventer box 1 via a blocking nut 18.

[0028] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model 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. Such 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 this utility model, and they should all be covered within the scope of the claims and specification of this utility model. For those skilled in the art, any alternative improvements or transformations made to the implementation of this utility model fall within the protection scope of this utility model.

[0029] Any aspects of this utility model not described in detail are known to those skilled in the art.

Claims

1. A three-stage sealed blowout preventer for oil well testing, characterized in that: The system includes a blowout preventer (BOP), a baffle tube at the bottom, a lower piston with a through-hole inside the BOP above the baffle tube, a first sealing packing inside the BOP between the lower piston and the baffle tube, a lower overflow port on the side wall of the BOP communicating with the inner cavity of the BOP located between the lower piston and the baffle tube, a sealing sleeve sleeved on the rod of the lower piston, a hydraulic port on the side wall of the BOP communicating with the inner cavity of the BOP between the sealing sleeve and the head of the lower piston, and an upper piston with a through-hole inside the BOP above the sealing sleeve. The blowout preventer box below the plug is equipped with a second sealing packing. An upper overflow port is provided on the side wall of the blowout preventer box, which is connected to the inner cavity of the blowout preventer box located between the second sealing packing and the sealing sleeve. A sealing cap is provided on the top of the blowout preventer box. The rod of the upper piston extends out of the sealing cap and beyond the sealing cap. The inner cavity of the blowout preventer box between the head of the upper piston and the sealing cap is connected to the hydraulic interface through a pressure transmission pipe provided on the side wall of the blowout preventer box. The flow-blocking pipe includes a zirconia ceramic tube and an alloy sleeve sleeved on the outer wall of the zirconia ceramic tube. The zirconia ceramic tube is vacuum brazed to seal the alloy sleeve.

2. The three-stage sealing blowout preventer for oil well testing according to claim 1, characterized in that: The inner sidewalls of both the upper and lower pistons are laser-clad with nanocrystalline silicon carbide layers.

3. The three-stage sealing blowout preventer for oil well testing according to claim 1, characterized in that: The sealing sleeve is a stepped sealing sleeve, and a shoulder is provided on the inner wall of the blowout preventer to restrict the upward movement of the stepped sealing sleeve.

4. The three-stage sealing blowout preventer for oil well testing according to claim 1, characterized in that: A blocking sleeve is provided below the second sealing packing to abut against the second sealing packing, and a shoulder is provided on the inner wall of the blowout preventer to restrict the downward movement of the blocking sleeve.

5. The three-stage sealing blowout preventer for oil well testing according to claim 1, characterized in that: The flow-blocking tube is detachably connected to the blowout preventer via a blocking nut.

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