Halide scintillation crystal detector for petroleum logging

Abstract

The utility model belongs to the technical field of ionizing radiation detection, and particularly relates to a halide scintillation crystal detector for petroleum logging. The device comprises a shell and a reaction layer, the shell is a sealed shell, a scintillation crystal is packaged in the shell, and a light transmission device is coupled to a light emitting surface, corresponding to the scintillation crystal, of the shell; and the reaction layer is filled between the shell and the scintillation crystal and is used for absorbing water and oxygen. The utility model is used for solving the problem that the scintillation crystal is easy to deliquesce at high temperature. By filling the reaction layer in the shell for sealing and packaging the scintillation crystal, trace water and oxygen in a sealing system are removed by utilizing the reaction between the reaction layer and water and oxygen in the shell, so that the problem of deliquescence of the scintillation crystal caused by reaction between water and oxygen and the scintillation crystal is avoided.

Description

Technical Field

[0001] This invention belongs to the field of ionizing radiation detection technology, specifically relating to a halide scintillation crystal detector for oil well logging. Background Technology

[0002] With the development of industrial technology and the increasingly widespread application of crystal materials, some halide crystals, such as cerium-doped lanthanum bromide (LaBr3:Ce), cerium-doped lanthanum chloride (LaCl3:Ce), cerium-doped yttrium lithium cesium chloride (Ce:Cs2LiYCl6), cerium-doped lanthanum bromide lithium cesium (Ce:Cs2LiLaBr6), cerium-doped lutetium iodide (Ce:LuI3), europium-doped strontium iodide (Eu:SrI2), thallium-doped sodium iodide (Tl:NaI), thallium-doped cesium iodide (Tl:CsI), and sodium-doped cesium iodide (Na:CsI), have been widely used in related fields due to their excellent ionizing radiation detection performance.

[0003] Most halide crystal materials are hygroscopic and need to be encapsulated in a low-moisture environment before use. Currently, all crystal detectors used at room temperature are encapsulated in this way.

[0004] In ionizing radiation detection, there are some special environmental conditions, such as oil well logging, deep space exploration, and geological environment exploration. In these environments, the equipment will operate at high temperatures of 175°C and under strong vibration conditions, which introduces uncertainties to the accuracy of ionizing detection crystal materials. This can lead to problems such as deterioration of crystal scintillation performance, changes in the packaging structure causing changes in detector performance, and even crystal cracking.

[0005] At high temperatures, a low-water environment is insufficient because even extremely low water levels at high temperatures will still cause the halide crystals to become discolored, significantly reducing their scintillation performance. Furthermore, while dry air in detectors used at room temperature does not affect the scintillation performance of halide crystals, at high temperatures, oxygen in the dry air may react with the crystals, causing a decrease in the scintillation performance of the crystal detector. Therefore, preventing the halide crystals from reacting with water and oxygen under high-temperature conditions is a problem that urgently needs to be solved. Utility Model Content

[0006] To address the shortcomings of existing technologies, a halide scintillation crystal detector for oil well logging is provided to solve the problem of trace water reaction between the scintillation crystal and the sealed system at high temperatures. By filling a reaction layer inside the sealed housing of the scintillation crystal, the reaction layer reacts first with water and oxygen in the housing, thus avoiding the problem of deliquescence of the scintillation crystal caused by the reaction of water and oxygen with the crystal.

[0007] The technical solution of this utility model to solve the above-mentioned technical problems is as follows: A halide scintillation crystal detector for oil well logging, comprising:

[0008] The housing is a sealed housing, in which a scintillation crystal is encapsulated, and an optical transmission device is coupled to the housing corresponding to the light-emitting surface of the scintillation crystal;

[0009] A reaction layer, filling the space between the housing and the scintillation crystal, is used to react with water and oxygen.

[0010] Compared with existing technologies, the above technical solutions have the following beneficial effects:

[0011] By filling the housing containing the scintillation crystal with a reaction layer, the reaction layer reacts with water and oxygen in the housing first, thereby removing trace amounts of water and oxygen in the sealed environment. This avoids the problem of water and oxygen reacting with the scintillation crystal, which would otherwise cause a decrease in the performance of the scintillation crystal detector.

[0012] Based on the above technical solution, the embodiments of this application can be further improved as follows:

[0013] In one embodiment, a reflective layer is further included, which covers a surface of the scintillation crystal other than its light-emitting surface, and the reactive layer is located between the reflective layer and the housing.

[0014] By setting a reflective layer, the surfaces of the scintillation crystal other than the light-emitting surface are wrapped to ensure the reflectivity of light. At the same time, the reflective layer is located between the scintillation crystal and the reaction layer, which can separate the reaction layer and prevent the reaction layer from directly contacting the surface of the scintillation crystal.

[0015] In one embodiment, a fixing member is further provided in the housing, the fixing member being disposed outside the reaction layer for isolating vibrations outside the housing.

[0016] In one embodiment, the fastener is a polytetrafluoroethylene (PTFE) fastener, and the reflective layer is a PTFE reflective layer.

[0017] By fully utilizing the high reflectivity of polytetrafluoroethylene (PTFE), the light-collecting ability of the scintillation crystal detector can be improved; and by utilizing the flexibility of PTFE, external vibrations can be filtered, thereby improving vibration resistance.

[0018] In one embodiment, the optical transmission device includes:

[0019] A window glass, which is sealed to the housing and corresponds to the light-emitting surface of the scintillating crystal;

[0020] A light guide is disposed in the housing, located between the window glass and the scintillation crystal.

[0021] By combining the window glass and the light guide, light is minimized from reflection and then output through the window glass, thus reducing light loss.

[0022] In one embodiment, an elastic element is provided in the housing, the elastic element being disposed at the end of the scintillation crystal away from the optical transmission device, for driving the scintillation crystal to couple with the optical transmission device.

[0023] In one embodiment, the material of the reaction layer is any one of magnesium, sodium, and potassium.

[0024] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0025] 1. Adding a reaction layer inside the housing removes trace amounts of water and oxygen from the system, ensuring that the scintillation performance of the halide crystal detector does not significantly decrease during operation due to the reaction between the halide crystal and water and oxygen.

[0026] 2. Use an optical transmission device to align the light-emitting surface of the scintillation crystal with the light source, and cover the other surfaces of the scintillation crystal with a reflective layer to reduce light loss.

[0027] 3. The reflective layer made of polytetrafluoroethylene (PTFE) makes full use of its high reflectivity, and the fasteners formed by PTFE make good use of its flexibility, thus improving the overall vibration reduction effect. Attached Figure Description

[0028] 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. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0030] Figure label:

[0031] 1. Window glass; 2. Reactive layer; 3. Light guide; 4. Fixing component; 5. Reflective layer; 6. Housing; 7. Back cover; 8. Crystal; 9. Elastic component. Detailed Implementation

[0032] 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.

[0033] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application shall have the ordinary meaning as understood by one of ordinary skill in the art to which this utility model pertains.

[0034] In the description of this application, it should be understood that the orientation or positional relationship indicated by terms, etc., is based on the orientation or positional relationship shown in the drawings and is only for the convenience of describing this utility model and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0035] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances. Example

[0036] like Figure 1 As shown, the present invention provides a halide scintillation crystal 8 detector for oil well logging, which includes: a housing 6, a scintillation crystal 8 and a reaction layer 2.

[0037] The housing 6 is a sealed housing 6, in which a scintillation crystal 8 is encapsulated. A light transmission device is coupled to the light-emitting surface of the scintillation crystal 8 on the housing 6. The light transmission device is located at one end of the housing 6 and can output the light emitted from the light-emitting surface of the scintillation crystal 8 with minimal loss.

[0038] The reaction layer 2 is filled between the housing 6 and the scintillation crystal 8. Specifically, the reaction layer 2 is not disposed between the light-emitting surface of the scintillation crystal 8 and the housing 6. The reaction layer 2 is used to absorb trace amounts of water and oxygen that enter the housing 6. By filling the housing 6 that seals and encapsulates the scintillation crystal 8 with the reaction layer 2, the reaction layer 2 reacts with the water and oxygen in the housing 6 at a lower temperature to remove trace amounts of water and oxygen in the housing 6, thus avoiding the problem of water and oxygen reacting with the scintillation crystal 8 and causing the scintillation crystal 8 to deliquesce.

[0039] The material of the reaction layer 2 is any one of magnesium, sodium, and potassium.

[0040] The reaction layer 2 is preferably made of magnesium sheet. Taking advantage of the reactivity of magnesium, when the temperature rises to a certain level, water and oxygen react with magnesium before reacting with halide crystal 8. This can remove a small amount of water and oxygen from the system, so that the scintillation performance of halide crystal 8 detector does not decrease significantly during operation due to the reaction of halide crystal 8 with water and oxygen.

[0041] To improve the reflection efficiency of the scintillation crystal 8, a reflective layer 5 is also included. The reflective layer 5 covers the surface of the scintillation crystal 8 that is different from its light-emitting surface, and the reaction layer 2 is located between the reflective layer 5 and the housing 6.

[0042] Specifically, the reflective layer 5 can be made of polytetrafluoroethylene (PTFE), which has a reflectivity of up to 99%, ensuring that the light generated by the scintillation crystal 8 due to ionizing radiation is not lost as much as possible. By setting the reflective layer 5, the surfaces of the scintillation crystal 8 other than the light-emitting surface are wrapped up to ensure the reflectivity of the light.

[0043] Meanwhile, the reflective layer 5 is located between the scintillation crystal 8 and the reaction layer 2, which can separate the reaction layer 2 and prevent the reaction layer 2 from directly contacting the surface of the scintillation crystal 8.

[0044] To ensure the stability of the scintillation crystal 8 in the housing 6, a fixing member 4 is also provided in the housing 6. The fixing member 4 is located outside the reaction layer 2. After the scintillation crystal 8, the reflective layer 5 and the reaction layer 2 are covered by the fixing member 4, they come into contact with the inside of the housing 6. The fixing member 4 is used to isolate the vibration outside the housing 6.

[0045] Among them, the fastener 4 is a polytetrafluoroethylene (PTFE) fastener. PTFE has good flexibility, which is fully utilized to filter external vibrations and improve vibration resistance.

[0046] In this embodiment, the optical transmission device includes: a window glass 1 and a light guide 3, wherein the light guide 3 is a sheet-shaped light guide.

[0047] The window glass 1 can be made of materials such as K9, quartz or sapphire. The window glass 1 is sealed to the housing 6 and corresponds to the light-emitting surface of the scintillating crystal 8.

[0048] Specifically, the housing 6 is cylindrical to match the scintillation crystal 8, and an opening is formed at one end of the housing 6. The window glass 1 is correspondingly set at the opening. The window glass 1 is located at the top of the housing 6, and the opening is located at the bottom of the housing 6. The bottom is connected to the housing 6 through a metal back cover 7 to form a closed whole. After the internal components of the housing 6 are loaded, the back cover 7 is welded and fixed to the bottom of the housing 6 to form an encapsulation.

[0049] To ensure the stability of the window glass 1, a limit ring is provided on the inner wall of the opening of the housing 6 to hold the window glass 1 in place. The top surface of the window glass 1 has a chamfer that matches the limit ring on the corresponding limit block.

[0050] The light guide 3 is disposed in the housing 6, located between the window glass 1 and the scintillation crystal 8. Through the cooperation of the window glass 1 and the light guide 3, the light passes through the light guide 3 and is output through the window glass 1 with minimal reflection, thereby reducing light loss.

[0051] To ensure good coupling between the scintillation crystal 8, the light guide 3, and the window glass 1, an elastic element 9 is provided in the housing 6. The elastic element 9 is located at the end of the scintillation crystal 8 away from the light transmission device. The elastic element 9 can be implemented using a corrugated spring or the like, and is used to provide elastic force to push the scintillation crystal 8 and the light guide 3 onto the window glass 1, thereby promoting good coupling between the scintillation crystal 8 and the light transmission device.

[0052] Experiments were conducted on detectors using and without magnesium sheets. Specifically, high-temperature thermal cycling tests were performed using lanthanum bromide crystal detectors and sodium iodide crystal detectors. The detectors were placed in an oven and heated to 175°C at a rate of 1°C / min, held at this temperature for 4 hours, and then cooled to 25°C at a rate of 1°C / min, undergoing three thermal cycles. Scintillation performance was tested after each thermal cycle. During testing, a 0.2 mCi 137Cs radioactive source (662 keV) was placed at the rear end of the crystal detector. The same conditions were used for each test, including a Beijing Hamamatsu CR173 photomultiplier tube, high voltage, amplification factor, ambient temperature, and radioactive source position. The test results are shown in Tables 1 and 2.

[0053] Table 1. Thermal cycling results of a Φ25mm×100mm lanthanum bromide (LaBr3:Ce) crystal detector

[0054] Number of thermal cycles / Sample name 662keV full-energy peak position 662keV energy resolution 0 / LB 678.8 4.3% 1 / LB 567.2 4.7% 2 / LB 480.3 5.3% 3 / LB 426.69 5.9% 0 / LB-Mg 651.62 4.5% 1 / LB-Mg 648.97 4.5% 2 / LB-Mg 649.54 4.5% 3 / LB-Mg 648.5 4.5%

[0055] Table 2. Thermal cycling test results of a Φ50mm×300mm sodium iodide (NaI:Tl) crystal detector

[0056] Number of thermal cycles / Sample name 662keV full-energy peak position 662keV energy resolution 0 / NI 295.1 8.3% 1 / NI 275.7 8.7% 2 / NI 251.2 9.0% 3 / NI 233.4 9.1% 0 / NI-Mg 315.6 8.2% 1 / NI-Mg 314.5 8.0% 2 / NI-Mg 317 8.2% 3 / NI-Mg 315.3 8.2%

[0057] In Table 1, LB represents a lanthanum bromide crystal detector without magnesium foil encapsulation, and LB-Mg represents a lanthanum bromide crystal detector with magnesium foil encapsulation.

[0058] In Table 2, NI represents a sodium iodide crystal detector without magnesium foil encapsulation, and NI-Mg represents a sodium iodide crystal detector with magnesium foil encapsulation.

[0059] The table shows that for both halide crystal detectors, the scintillation performance of the detector without a magnesium sheet decreased after each thermal cycle, while the scintillation performance of the detector with a magnesium sheet was almost unaffected by thermal cycling. This indicates that the use of a magnesium sheet in detector fabrication can improve the high-temperature stability of the detector's scintillation performance.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the 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 therein. 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.

Claims

1. A halide scintillation crystal detector for oil well logging, characterized in that, include: The housing is a sealed housing, in which a scintillation crystal is encapsulated, and an optical transmission device is coupled to the housing corresponding to the light-emitting surface of the scintillation crystal; A reaction layer, filling the space between the housing and the scintillation crystal, is used to react with water and oxygen.

2. The halide scintillation crystal detector according to claim 1, characterized in that, It also includes a reflective layer that covers the surface of the scintillation crystal that is different from its light-emitting surface, and a reactive layer that is located between the reflective layer and the housing.

3. The halide scintillation crystal detector according to claim 2, characterized in that, It also includes a fixing member disposed in the housing, the fixing member being disposed outside the reaction layer, for isolating the vibration outside the housing.

4. The halide scintillation crystal detector according to claim 3, characterized in that, The fastener is a polytetrafluoroethylene (PTFE) fastener, and the reflective layer is a PTFE reflective layer.

5. The halide scintillation crystal detector according to claim 1, characterized in that, The optical transmission device includes: A window glass, which is sealed to the housing and corresponds to the light-emitting surface of the scintillating crystal; A light guide is disposed in the housing, located between the window glass and the scintillation crystal.

6. The halide scintillation crystal detector according to claim 1, characterized in that, An elastic element is provided in the housing, and the elastic element is located at the end of the scintillation crystal away from the optical transmission device, for driving the scintillation crystal to couple with the optical transmission device.

7. The halide scintillation crystal detector according to claim 1, characterized in that, The material of the reaction layer is any one of magnesium, sodium, and potassium.

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