Neutron generator sealing nipple with built-in detector

Abstract

The utility model provides a detector built-in neutron generator sealing short section, which is characterized in that a sealing short section is arranged between an upper acquisition short section and a lower acquisition short section, and the sealing short section comprises a sealing short section shell used for bearing pressure; the connector assemblies are arranged at the two ends of the sealing short section shell and form a sealing cavity with the sealing short section shell; the generator assembly is arranged in the sealed cavity and used for generating neutrons to activate oxygen elements in water, and the integrated packaging detector is arranged in the sealed cavity, connected with the generator assembly and used for detecting high-energy gamma rays released by activated oxygen atoms to calculate the water flow velocity. Therefore, the integrated packaging detector is installed in the sealing short section, the source distance of the integrated packaging detector can be effectively shortened, and the measurement precision of an instrument can be effectively improved in a measurement environment with small water flow flux.

Description

Technical Field

[0001] The utility model relates to the field of nuclear logging instruments, and more specifically, to a sealed short section with an internally mounted detector for a neutron generator. Background Technique

[0002] The principle of oxygen activation water flow logging technology is to activate water flow using high-energy oxygen atoms, and by measuring parameters such as the activation time, velocity, and direction of the water flow, combined with formation physical properties and fluid properties, to evaluate the flow state and properties of fluids in the formation.

[0003] Oxygen activation water flow logging technology uses high-energy neutrons generated by a neutron generator to collide with oxygen atoms in the surrounding medium, generating high-energy oxygen atoms. These high-energy oxygen atoms can activate the water flow, making it radioactive. By measuring the activation time and velocity of the water flow, the flow state and properties of fluids in the formation can be deduced.

[0004] To enable the instrument to have a larger measurement range, oxygen activation water flow logging instruments generally have multiple detectors with different source distances. The source distance design generally requires that the near source distance be small enough to ensure the measurement accuracy of the instrument at low flow rates, the medium source distance be moderate to meet most application requirements, and the far source distance be far enough to meet the requirements of some special high flow rate and large water injection volume measurements.

[0005] In the layout of traditional oxygen activation water flow logging instruments, the neutron generator short section is used to emit neutrons. Inside the neutron generator short section, generally from top to bottom are: the neutron tube, the high-voltage multiplier, and the transformer; both sides of the neutron generator short section are connected to the upper and lower acquisition short sections respectively through corresponding mechanical interfaces or electrical interfaces; the detectors for measurement are correspondingly distributed in the upper and lower acquisition short sections. Additionally, the connection sequence of the core components in the generator short section is: neutron tube, high-voltage multiplier, transformer. Such an arrangement method is beneficial for reducing the source distance of one side of the detector, but correspondingly increases the source distance of the other side of the detector.

[0006] For medium and far source distance detectors, the source distance design is generally less restricted, but for the near source distance, due to the limitations of the instrument installation structure and the mechanical interface dimensions between different instrument short sections, the near source distance detector cannot be placed close to the neutron tube. Considering improving the measurement accuracy of the instrument, the source distances of several detectors in the upper and lower acquisition short sections close to the sealed short section should be as small as possible. Therefore, generally, the sealed short section is made relatively compact. Nevertheless, the source distance of the near detector in common oxygen activation water flow logging instruments on the market can generally only be made about 350 - 370 mm.

[0007] The main factors restricting the further shortening of its source distance are:

[0008] 1. The neutron tube is not installed inside the instrument as an independent structure. Transformers, high-voltage multipliers, etc. that ensure its normal operation will occupy a certain axial length, thus affecting the short source distance.

[0009] 2. When the neutron tube is working under high voltage, it is generally placed in a sealed short section, and the sealed short section contains SF6 gas with a pressure of about 0.8 MPa. For some instruments with a relatively thick diameter, this sealed short section is placed inside the pressure-bearing housing of the instrument (generally this kind of sealed short section is called secondary sealing); but for small-diameter oxygen activation flow logging instruments, due to diameter limitations, a secondary sealing design cannot be made, and generally its pressure-bearing housing is also the housing of the sealed short section (this situation is generally called primary sealing).

[0010] For primary-sealed instruments, the sealed short section is often only used to place necessary components such as neutron tubes, transformers, and high-voltage multipliers for the neutron tube. Then, the sealed short section makes mechanical and electrical connections with other instrument short sections through designed mechanical interfaces, and the mechanical interfaces between the sealed short sections will also affect the short source distance to a certain extent.

[0011] In summary, the existing sealed short sections of small-diameter neutron generators have the following deficiencies:

[0012] 1. Components such as transformers and high-voltage multipliers inside the sealed short section will affect the short source distance.

[0013] 2. The mechanical interfaces of the sealed short section will affect the short source distance. Summary of the Invention

[0014] The main purpose of the present invention is to provide a sealed short section of a detector-integrated neutron generator, so as to at least solve the problem in the prior art that due to only components such as neutron tubes, transformers, and high-voltage multipliers inside the sealed short section, when connected to other short sections through mechanical interfaces, the short source distance is limited.

[0015] To achieve the above purpose, the present invention provides a sealed short section of a detector-integrated neutron generator. The sealed short section is arranged between an upper acquisition short section and a lower acquisition short section. The sealed short section includes a sealed short section housing, two joint assemblies, a generator assembly, and an integrated packaged detector; the sealed short section housing is used for bearing pressure.

[0016] The two joint assemblies are correspondingly arranged at the connections of the two ends of the sealed short section housing with the upper acquisition short section and the lower acquisition short section to form a sealed cavity inside the sealed short section housing.

[0017] The generator assembly is arranged in the sealed cavity and is used for generating neutrons to activate oxygen elements in water.

[0018] The integrated packaged detector is disposed in the sealed cavity and connected to the generator assembly. The integrated packaged detector is used to detect the high-energy γ rays released by the activated oxygen atoms to calculate the water flow rate.

[0019] Furthermore, both of the joint assemblies are provided with multi-core nozzle sealing plugs, and the two multi-core nozzle sealing plugs are used to introduce insulating gas into the sealed cavity.

[0020] Furthermore, the generator assembly includes a neutron tube, a transformer, and a high-voltage multiplier; the neutron tube is disposed in the sealed cavity; the transformer and the high-voltage multiplier are correspondingly disposed on both sides of the neutron tube.

[0021] Furthermore, the integrated packaged detector includes a detector housing and a sealing structure;

[0022] One end of the detector housing is a closed end, and the other end of the detector housing is an open end; the sealing structure is embedded in the open end of the detector housing for isolating the inner cavity of the detector housing from the external positive pressure environment of the detector housing;

[0023] Wherein, a working circuit is installed outside the inner cavity of the detector housing; a photomultiplier tube and a NaI crystal are sequentially installed in the inner cavity of the detector housing from the open end to the closed end.

[0024] Furthermore, the sealing structure includes a sealing plug and a sealing ring; the sealing plug is embedded in the open end of the detector housing; the sealing ring is clamped between the sealing plug and the detector housing.

[0025] Furthermore, a plugging hole is formed in the sealing plug, and the integrated packaged detector further includes a plurality of sealing pins correspondingly installed in the plugging hole, and both ends of the sealing pin are welding cup structures;

[0026] Wherein, the welding cup structure on the side of the inner cavity of the detector housing is connected to the wire of the photomultiplier tube, and the welding cup structure at the other end is connected to the working circuit.

[0027] Furthermore, the integrated packaged detector further includes a shock pad and a wave spring; the shock pad is installed between the NaI crystal and the closed end; the wave spring is installed between the photomultiplier tube and the sealing plug.

[0028] Furthermore, the material of the sealing plug is polyether ether ketone.

[0029] Furthermore, there are multiple integrated packaged detectors.

[0030] A sealed short section of a detector - built - in neutron generator applying the technical solution of the present utility model includes a sealed short section disposed between an upper acquisition short section and a lower acquisition short section. The sealed short section includes a sealed short - section housing for bearing pressure; a joint assembly disposed at both ends of the sealed short - section housing to form a sealed cavity with the sealed short - section housing; a generator assembly disposed in the sealed cavity for generating neutrons to activate oxygen elements in water, and an integrated - package detector disposed in the sealed cavity and connected to the generator assembly for detecting high - energy γ - rays released by the activated oxygen atoms to calculate the water flow velocity. Thus, installing the integrated - package detector in the sealed short section can effectively shorten the source distance of the integrated - package detector, and can effectively improve the measurement accuracy of the instrument in a measurement environment with a small water flow rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The schematic diagrams in the specification forming a part of this application are used to provide a further understanding of the present utility model. The schematic embodiments of the present utility model and their descriptions are used to explain the present utility model and do not constitute an improper limitation to the present utility model. In the drawings:

[0032] Figure 1 FIG. 9 is a schematic diagram of the first sealed short - section structure according to an embodiment of the present utility model;

[0033] Figure 2 FIG. 13 is a schematic diagram of an integrated - package detector structure according to an embodiment of the present utility model;

[0034] Figure 3 FIG. 17 is a schematic diagram of the first sealed short - section structure according to an embodiment of the present utility model.

[0035] REFERENCE NUMERALS:

[0036] 10, sealed short - section housing; 20, joint assembly; 21, multi - core air - nozzle sealing plug; 30, generator assembly; 31, neutron tube; 32, transformer; 33, high - voltage multiplier; 40, integrated - package detector; 41, detector housing; 42, sealing structure; 421, sealing plug; 422, sealing ring; 43, working circuit; 44, photomultiplier tube; 45, NaI crystal; 46, sealing pin; 47, shock - absorbing pad; 48, wave spring;

[0037] U1, first upper detector assembly; U2, second upper detector assembly; D, lower detector assembly; T, target point; A, source distance of the first upper detector assembly; B, source distance of the second upper detector assembly; C, source distance of the lower detector assembly. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The following will describe the present utility model in detail with reference to the drawings and in combination with the embodiments.

[0039] As Figure 1 shown, a sealed short section of a detector-integrated neutron generator is provided between an upper acquisition short section and a lower acquisition short section. The sealed short section includes a sealed short section housing 10, two joint assemblies 20, a generator assembly 30, and an integrated packaged detector 40. Among them, the sealed short section housing 10 is used for bearing pressure. The two joint assemblies 20 are correspondingly arranged at the connections of the two ends of the sealed short section housing 10 with the upper acquisition short section and the lower acquisition short section to form a sealed cavity within the sealed short section housing 10. The generator assembly 30 is arranged in the sealed cavity and is used to generate neutrons to activate the oxygen element in water. The integrated packaged detector 40 is arranged in the sealed cavity and is connected to the generator assembly 30. The integrated packaged detector 40 is used to detect the high-energy γ-rays released by the activated oxygen atoms to calculate the water flow velocity.

[0040] Specifically, the neutron generator is one of the core components of the oxygen activation water flow logging tool. Its main function is to emit neutrons. When these neutrons interact with the oxygen element in the aqueous solution in the wellbore, the oxygen element will be activated. The activated oxygen atoms have unstable properties and will release high-energy γ-rays. The detector is used to detect the high-energy γ-rays released by the activated oxygen atoms. When the activated water flows through the detector, the γ counting rate of the detector will increase. By measuring the activation time spectrum, the time for the water flow to flow from the neutron source to the detector can be calculated. Then, combined with the known distance from the neutron source to the detector, it can be used to calculate the water flow velocity.

[0041] In the oxygen activation water flow logging tool, the source distance refers to the distance between the measurement target point T of the neutron generator and the detector. When the source distance is large, the interaction range between the neutrons and the oxygen element in the aqueous solution in the wellbore will be correspondingly large, the detection depth is large, and the water flow velocity can be measured more accurately, especially in the case of a deeper wellbore or a faster water flow velocity. However, when the source distance is large, although the detection depth is large, the signal attenuation will become more serious and the measurement accuracy is poor. When the source distance is small, the interaction between the neutrons and the oxygen element is more concentrated, and the γ-ray signal received by the detector will be stronger, and the measurement accuracy and stability are high when measuring low flow rates.

[0042] As Figure 1As shown, in the present application, the sealing nipple housing 10 is the pressure-bearing housing of the neutron generator and also the sealing housing of the sealing nipple. The two ends of the sealing nipple housing 10 are respectively connected with the joint assemblies 20 by threads. The joint assemblies 20 at both ends are respectively connected to the upper acquisition nipple and the lower acquisition nipple through mechanical interfaces or electrical connections, and both joint assemblies 20 form a sealed cavity with the sealing nipple housing 10 through O-ring seals 422. Among them, the upper acquisition nipple and the lower acquisition nipple are distinguished according to their relative positions with the generator assembly 30 during use. In the vertical state, the one located above the generator assembly 30 is the upper acquisition nipple, and the one located below is the lower acquisition nipple. The integrated packaged detector 40 installed in the sealed cavity of the sealing nipple is electrically connected to the generator assembly 30, avoiding the influence of the mechanical interface on the source distance, greatly shortening the source distance of the near detector, and being able to effectively improve the measurement accuracy of the instrument in the measurement environment with low flow rate flux.

[0043] In a possible implementation manner, both joint assemblies 20 have multi-core nozzle sealing plugs 21, and the two multi-core nozzle sealing plugs 21 are used to introduce insulating gas into the sealed cavity.

[0044] Specifically, the inside of the sealing nipple is filled with about 0.8 MPa of SF6 insulating gas through the nozzles of the multi-core nozzle sealing plugs 21. By introducing insulating gas into the sealed cavity, the neutron generator assembly 30 and the detector are protected from the risk of electrical interference or short circuit. In addition, the multi-core nozzle sealing plugs 21 are precisely designed and can effectively prevent external gas or liquid from entering the sealed cavity, ensuring that the neutron generator assembly 30 and the integrated packaged detector 40 work in a stable and dry environment.

[0045] In a possible implementation manner, the generator assembly 30 includes a neutron tube 31, a transformer 32, and a high-voltage multiplier 33;

[0046] The neutron tube 31 is arranged in the sealed cavity, and the transformer 32 and the high-voltage multiplier 33 are correspondingly arranged on both sides of the neutron tube 31.

[0047] Specifically, the core components of the generator assembly 30 include the neutron tube 31, the transformer 32, and the high-voltage multiplier 33. As Figure 2 shown, in the present application, the transformer 32 and the high-voltage multiplier 33 are respectively placed on both sides of the neutron tube 31, balancing the near-source distances on the upper and lower sides.

[0048] In a possible implementation manner, the integrated packaged detector 40 includes:

[0049] A detector housing 41, one end of the detector housing 41 is a closed end, and the other end of the detector housing 41 is an open end;

[0050] A sealing structure 42 is embedded in the open end of the detector housing 41 for isolating the internal cavity of the detector housing 41 from the external positive pressure environment of the detector housing 41;

[0051] Wherein, a working circuit 43 is installed outside the internal cavity of the detector housing 41; an electron multiplier tube 44 and a NaI crystal 45 are successively installed in the internal cavity of the detector housing 41 from the open end to the closed end.

[0052] Specifically, as Figure 2 shown, the working circuit 43 includes a high-voltage circuit and a processing circuit. The working circuit 43 is not affected during operation in SF6 gas under a certain positive pressure. However, the NaI crystal 45 and the electron multiplier tube 44 are different. Both are of the sealing structure 42. Especially for the electron multiplier tube 44, its structure is a vacuum glass enclosed cavity. If it is directly exposed to a gas environment under a certain positive pressure during operation, it may cause its structure to fail or be damaged, making it unable to work properly. Therefore, by installing the working circuit 43 outside the internal cavity of the detector housing 41 and installing the electron multiplier tube 44 and the NaI crystal 45 in the internal cavity of the detector housing 41, it can be ensured that the crystal and the electron multiplier tube 44 can still work properly in the positive pressure environment within the sealing nipple.

[0053] In a possible implementation manner, the sealing structure 42 includes:

[0054] A sealing plug 421 is embedded in the open end of the detector housing 41;

[0055] A sealing ring 422 is clamped between the sealing plug 421 and the detector housing 41.

[0056] Specifically, due to material, processing accuracy or minor errors during the installation process, there may be a minor gap between the sealing plug 421 and the detector housing 41. The sealing ring 422 has excellent elasticity and corrosion resistance, forming a tight and lasting seal between the sealing plug 421 and the detector housing 41. In addition, the sealing ring 422 can also adapt to different working environments and pressure conditions, providing reliable sealing protection to separate the internal cavity of the detector from the external positive pressure environment.

[0057] In a possible implementation manner, a plugging hole is provided on the sealing plug 421. The integrated packaged detector 40 further includes:

[0058] A plurality of sealing pins 46 are correspondingly installed in the plugging holes, and both ends of the sealing pins 46 are in the form of welding cups;

[0059] Wherein, the welding cup structure on the side of the internal cavity of the detector housing 41 is connected to the wire of the electron multiplier tube 44, and the welding cup structure at the other end is connected to the working circuit 43.

[0060] Specifically, asFigure 2 As shown, since the photomultiplier tube 44 is a vacuum electron device and there are wires, in order to facilitate the extraction of the wires, a plug hole is provided in the sealing plug 421, and the number of plug holes corresponds to the number of wires on the photomultiplier tube 44. A sealing pin 46 is installed in the plug hole, and the sealing pin 46 and the sealing plug 421 are also sealed with an O-ring 422. The O-ring 422 is also an O-ring 422. Both ends of the sealing pin 46 are in the structure of welding cups. The wires of the photomultiplier tube 44 are respectively welded to the inner welding cups of the corresponding sealing pins 46, and the outer welding cups of each sealing pin 46 are correspondingly connected to the high-voltage circuit and the processing circuit by means of lead welding; the high-voltage circuit and the processing circuit are fixed to the circuit skeleton by screws. The design of the sealing pin 46 enables the wires of the photomultiplier tube 44 to be conveniently led out through the plug holes and connected to the external circuit, simplifying the connection structure.

[0061] In a possible implementation manner, the integrated package detector 40 further includes:

[0062] A shock pad 47, installed between the NaI crystal 45 and the closed end;

[0063] A wave spring 48, installed between the photomultiplier tube 44 and the sealing plug 421.

[0064] Specifically, as Figure 2 shown, the shock pad 47 can effectively absorb and disperse the vibration interference from the ground, water flow or other factors during the use of the instrument, thereby protecting the sensitive components inside the detector from vibration interference and ensuring the accuracy and stability of the measurement results. Inside the detector, the wave spring 48 is installed near the photomultiplier tube 44 to provide additional support and protection for the photomultiplier tube 44. When the detector is subjected to external pressure or vibration, the wave spring 48 can use its elastic deformation to absorb and disperse these pressures, protecting components such as the photomultiplier tube 44 from damage.

[0065] In a possible implementation manner, the material of the sealing plug 421 is polyether ether ketone.

[0066] Specifically, to ensure that the sealing plug 421 has good insulation performance, the sealing plug 421 is made of polyether ether ketone (PEEK) material. The polyether ether ketone (PEEK) material has a high volume resistivity and a low dielectric constant, and can maintain good insulation performance under high-frequency and high-voltage conditions.

[0067] In a possible implementation manner, there are multiple integrated package detectors 40.

[0068] Specifically, according to the specific source spacing design requirements, multiple integrated packaged detectors 40 connected in series inside the sealing nipple can be connected in series according to the source spacing design, and are respectively arranged on both sides of the generator assembly 30, which can balance and reduce the source spacing of the detectors to the greatest extent.

[0069] Embodiment

[0070] As Figure 3 shown, inside the sealing nipple, a second upper detector assembly U2, a first upper detector assembly U1, a neutron tube 31, a transformer 32, a high voltage multiplier 33, and a lower detector assembly D are sequentially arranged from top to bottom.

[0071] The upper part of the sealing nipple housing 10 is connected to the joint assembly 20 by a threaded connection, and the lower part of the sealing nipple housing 10 is connected to the joint assembly 20 by a threaded connection. The second upper detector assembly U2 and the first upper detector assembly U1 are located above the generator assembly 30, and the lower detector assembly D is located below the generator assembly 30. With the design and layout in this application, A can reach 260 mm, C can reach 305 mm, and the size of C is correspondingly smaller than the source spacing of the detector located below the neutron generator assembly in the traditional oxygen activation water flow logging tool.

[0072] Among them, in each detector inside the sealing nipple, the photomultiplier tube 44 has 3 wires. Corresponding sealing plugs 421 are provided with 3 insertion holes, and sealing pins 46 are installed in the openings. The sealing pins 46 and the insertion holes are also sealed with O-rings; both ends of the sealing pins 46 are in the structure of welding cups. The 3 wires of the photomultiplier tube 44 are respectively welded to the inner welding cups of the 3 sealing pins 46, and the outer welding cups of the 3 sealing pins 46 are connected to the high voltage circuit and the processing circuit of the working circuit 43 by means of lead welding; the working circuit 43 is fixed to the circuit skeleton by screws. When each detector inside the sealing nipple is packaged, a shock pad 47, a NaI crystal 45, a photomultiplier tube 44, a wave spring 48, etc. are sequentially installed in the detector housing 41.

[0073] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A sealed short section of a detector-integrated neutron generator, the sealed short section being disposed between an upper acquisition short section and a lower acquisition short section, characterized in that, The sealed nipple includes: A sealed nipple housing (10) for withstanding pressure; Two joint assemblies (20) which are correspondingly arranged at the joints of the two ends of the sealed nipple housing (10) with the upper acquisition nipple and the lower acquisition nipple to form a sealed cavity within the sealed nipple housing (10); A generator assembly (30) arranged within the sealed cavity for generating neutrons to activate oxygen elements in water; An integrated packaged detector (40) arranged within the sealed cavity and connected to the generator assembly (30), and the integrated packaged detector (40) is used to detect high-energy γ-rays released by the activated oxygen atoms to calculate the water flow rate.

2. The detector-integrated neutron generator sealed nipple according to claim 1, wherein: Both of the two joint assemblies (20) are provided with multi-core nozzle sealing plugs (21), and the two multi-core nozzle sealing plugs (21) are used to introduce insulating gas into the sealed cavity.

3. A sealed short section of a detector-integrated neutron generator according to claim 1, characterized in that, The generator assembly (30) includes: A neutron tube (31) arranged within the sealed cavity; A transformer (32) and a high-voltage multiplier (33), and the transformer (32) and the high-voltage multiplier (33) are correspondingly arranged on both sides of the neutron tube (31).

4. A sealed short section of a detector-integrated neutron generator according to claim 1, characterized in that, The integrated packaged detector (40) includes: A detector housing (41), one end of the detector housing (41) is a closed end, and the other end of the detector housing (41) is an open end; A sealing structure (42) embedded at the open end of the detector housing (41) for isolating the internal cavity of the detector housing (41) from the external positive pressure environment of the detector housing (41); Wherein, a working circuit (43) is installed outside the internal cavity of the detector housing (41); a photomultiplier tube (44) and a NaI crystal (45) are sequentially installed in the internal cavity of the detector housing (41) from the open end to the closed end.

5. A sealed short section of a detector-integrated neutron generator according to claim 4, characterized in that, The sealing structure (42) includes: A sealing plug (421) embedded at the open end of the detector housing (41); A sealing ring (422) clamped between the sealing plug (421) and the detector housing (41).

6. A sealed short section of a detector-integrated neutron generator according to claim 5, characterized in that, A plugging hole is formed on the sealing plug (421), and the integrated packaged detector (40) further includes: A plurality of sealing pins (46) correspondingly installed in the plugging hole, and both ends of the sealing pins (46) are in the structure of welding cups; Wherein, the welding cup structure on the side of the internal cavity of the detector housing (41) is connected to the wire of the photomultiplier tube (44), and the welding cup structure at the other end is connected to the working circuit (43).

7. A sealed short section of a detector-integrated neutron generator according to claim 5, characterized in that, The integrated packaged detector (40) further includes: A shock pad (47) installed between the NaI crystal (45) and the closed end; A wave spring (48) installed between the photomultiplier tube (44) and the sealing plug (421).

8. A sealed short section of a detector-integrated neutron generator according to claim 5, characterized in that, The material of the sealing plug (421) is polyether ether ketone.

9. A sealed short section of a detector-integrated neutron generator according to claim 1, characterized in that, There are multiple integrated packaged detectors (40).

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