Shielded port for nuclear logging tool with gamma ray source

Abstract

A system includes a shield for a nuclear logging tool. The shield includes a shield insert configured to be mounted at least partially between a gamma ray source of the nuclear logging tool and a gamma ray detector of the nuclear logging tool inside the nuclear logging tool. A first portion of the shielding insert is configured to be mounted in a collar of a nuclear logging tool, and a second portion of the shielding insert is configured to be mounted in a chassis of the nuclear logging tool. The shield also includes a chassis shield block configured to be mounted between the gamma ray source and the gamma ray detector in the chassis, and a shield top plate configured to be coupled to the collar and at least partially retain the shield insert in the collar.

Description

Technical Field

[0001] The present disclosure relates generally to well logging techniques, and more particularly to making gamma ray density measurements of subsurface formations using a nuclear logging tool having a gamma ray source. Background Art

[0002] This section is intended to introduce the reader to various aspects of the art that may be related to various aspects of the present technology described and / or claimed below. It is believed that this discussion helps to provide the reader with background information to facilitate a better understanding of various aspects of the present disclosure. Therefore, it should be understood that these statements should be read from this perspective, rather than as an admission of the prior art.

[0003] Formation density is a key rock property used to evaluate hydrocarbon deposits. This property is typically determined by logging while drilling (LWD) during drilling of a borehole through the formation, or by wireline tools after the borehole has been drilled. Nuclear logging tools used for these measurements typically contain a radioactive isotope source (e.g., 137 Cs or 241 AmBe) and a radiation detector (e.g., a gamma ray detector). Formation density measurements involve the scattering of gamma rays through the formation. Formation density can be measured using a radioisotope source (e.g., 137 Cs or 241 AmBe is obtained by irradiating a formation with gamma rays. These gamma rays can be Compton scattered from electrons present in the formation before being detected by a gamma ray detector spaced a certain distance from the gamma ray source. Since the electron concentration is proportional to the atomic number of the element, and the degree to which the gamma rays are Compton scattered and returned to the gamma ray detector is related to the electron concentration, the density of the formation can be measured using this technique.

[0004] However, a gamma ray detector in a nuclear logging tool may detect gamma rays that are transmitted within the nuclear logging tool itself. For example, some gamma rays emitted from a gamma ray source may be transmitted within the nuclear logging tool, such as a chassis of the logging tool, a collar of the logging tool, or other tool structures. Gamma rays detected outside the formation may not provide substantial information about the properties of the formation, and may represent noise that is desired to be reduced or subtracted from the total signal received by the gamma ray detector. Therefore, there is a need for shielding in a nuclear logging tool, wherein the shielding blocks unwanted gamma ray transmissions within the nuclear logging tool. Summary of the invention

[0005] The following describes an overview of certain embodiments disclosed herein. It should be understood that these aspects are presented only to provide the reader with a brief overview of these specific embodiments, and these aspects are not intended to limit the scope of the present disclosure. In fact, the present disclosure may cover various aspects that may not be described below.

[0006] Certain embodiments of the present disclosure include a system comprising a shield for a nuclear logging tool. The shield includes a shield insert configured to be at least partially installed between a gamma ray source of the nuclear logging tool and a gamma ray detector of the nuclear logging tool inside the nuclear logging tool. A first portion of the shield insert is configured to be installed in a collar of the nuclear logging tool, and a second portion of the shield insert is configured to be installed in a chassis of the nuclear logging tool. The shield also includes a chassis shield block configured to be installed between a gamma ray source and a gamma ray detector in the chassis, and a shield top plate configured to be coupled to the collar and at least partially retain the shield insert in the collar.

[0007] Certain embodiments of the present disclosure include a nuclear logging tool. The nuclear logging tool includes a chassis, a collar disposed around the chassis, a gamma ray source configured to emit gamma rays through a first window in the collar, and a gamma ray detector configured to receive gamma rays through a second window in the collar, and the gamma ray source and the gamma ray detector are offset from each other along the axis of the chassis. The nuclear logging tool also includes a shield. The shield includes a shield insert that is at least partially installed between the gamma ray source and the gamma ray detector inside the nuclear logging tool. A first portion of the shield insert is installed in the collar, and a second portion of the shield insert is installed in the chassis. The shield also includes a chassis shield block installed between the gamma ray source and the gamma ray detector in the chassis. The shield also includes a shield top plate that is coupled to the collar and at least partially holds the shield insert in the collar.

[0008] Certain embodiments of the present disclosure also include a method, the method comprising: emitting gamma rays from a gamma ray source through a first window in a collar of a nuclear logging tool; receiving gamma rays at a gamma ray detector through a second window in the collar, and the gamma ray source and the gamma ray detector are offset from each other along an axis of a chassis of the nuclear logging tool; and shielding the gamma rays directly between the gamma ray source and the gamma ray detector inside the nuclear logging tool via a shield. The shield includes a shielding insert that is at least partially installed between the gamma ray source and the gamma ray detector inside the nuclear logging tool. A first portion of the shielding insert is installed in the collar, and a second portion of the shielding insert is installed in the chassis. The shield also includes a chassis shielding block installed between the gamma ray source and the gamma ray detector in the chassis. The shield also includes a shielding top plate that is coupled to the collar and at least partially retains the shielding insert in the collar.

[0009] With respect to various aspects of the present disclosure, there may be various improvements to the above-mentioned features. Additional features may also be incorporated into these various aspects. These improvements and additional features may exist alone or in any combination. For example, the various features discussed below with respect to one or more illustrated embodiments may be incorporated into any of the above-mentioned aspects of the present disclosure alone or in any combination. The brief overview presented above is intended only to familiarize the reader with certain aspects and contexts of the embodiments of the present disclosure, without limiting the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Various aspects of the present disclosure may be better understood upon reading the following detailed description and referring to the accompanying drawings, in which:

[0011] Figure 1 is a block diagram of a drilling system for performing gamma density measurements according to an embodiment;

[0012] Figure 2 is a diagram showing a method according to an embodiment of the present invention. Figure 1 A schematic block diagram of a perspective view of a nuclear logging tool used in a drilling system of;

[0013] Figure 3 According to an embodiment Figure 1 A partial perspective view of an illustrative embodiment of a nuclear logging tool for use in a drilling system of;

[0014] Figure 4 According to an embodiment Figure 1 A partial cross-sectional end view of a nuclear logging tool used in a drilling system of;

[0015] Figure 5 According to an embodiment Figure 1 A partial cross-sectional side view of a nuclear logging tool used in a drilling system of;

[0016] Figure 6 According to an embodiment Figure 1 A partial cross-sectional side view of a nuclear logging tool used in a drilling system of FIG. 1 , showing an embodiment of a shield of the nuclear logging tool;

[0017] Figure 7 According to an embodiment Figure 1 A partial cross-sectional side view of a nuclear logging tool for use in a drilling system of FIG. 1 , showing a second embodiment of a shield for the nuclear logging tool;

[0018] Figure 8 According to an embodiment Figure 1 A partial cross-sectional side view of a nuclear logging tool for use in a drilling system of FIG. 1 , showing a third embodiment of a shield for the nuclear logging tool; and

[0019] Fig. 9 According to an embodiment Figure 1 A partial cross-sectional side view of a nuclear logging tool for use in a drilling system of FIG. 1 , showing a fourth embodiment of a shield for the nuclear logging tool. DETAILED DESCRIPTION

[0020] One or more specific embodiments of the present disclosure will be described below. These described embodiments are merely examples of the currently disclosed technology. In addition, in order to provide a concise description of these embodiments, all features of the actual implementation may not be described in the specification. It should be understood that in the development of any such actual implementation, as in any engineering or design project, many implementation-specific decisions must be made to achieve the developer's specific goals, such as meeting system-related and business-related constraints, which may vary from implementation to implementation. In addition, it should be understood that such development efforts may be complex and time-consuming, but for ordinary technicians who benefit from the present disclosure, it is still a routine task of design, production and manufacturing.

[0021] When introducing elements of various embodiments of the present disclosure, the articles "a," "an," and "the" are intended to indicate that there are one or more elements. The terms "comprising," "including," and "having" are intended to be inclusive, and mean that there may be additional elements in addition to the listed elements. Additionally, it should be understood that references to "one embodiment" or "an embodiment" of the present disclosure are not intended to be interpreted to exclude the existence of additional embodiments that also include the recited features.

[0022] As used herein, the terms "connect", "connection", "connected", "in connection with", and "connecting" are used to mean "directly connected with" or "connected with via one or more elements"; and the term "group" is used to mean "one element" or "more than one element". In addition, the terms "couple", "coupling", "coupled", and "coupled with" are used to mean "directly connected together" or "connected together via one or more elements".

[0023] In addition, as used herein, the terms "real-time," "real-time," or "substantially real-time" are used interchangeably and are intended to describe operations (e.g., computing operations) that are performed without any human-perceivable interruptions between operations. For example, as used herein, data associated with the systems described herein may be collected, transmitted, and / or used in control calculations "substantially in real time," such that data reading, data transmission, and / or data processing steps occur once per second, once every 0.1 seconds, once every 0.01 seconds, or even more frequently during operation of the system (e.g., while the system is operating). In addition, as used herein, the terms "continuously," "continuously," or "continuously" are intended to describe operations that are performed without any significant interruptions. For example, as used herein, control commands may be transmitted to certain devices every five minutes, every minute, every 30 seconds, every 15 seconds, every 10 seconds, every 5 seconds, or even more frequently, such that operating parameters of the devices may be adjusted without causing any significant interruption to the closed-loop control of the devices. Additionally, as used herein, the terms "automatic," "automated," "autonomous," and the like are intended to describe operations that are performed by a computer or are caused to be performed, for example, by a computing system (i.e., performed solely by the computing system without human intervention). Indeed, although certain operations described herein may not be explicitly described as being performed continuously and / or automatically in substantially real time during operation of a computing system and / or equipment controlled by the computing system, it should be understood that these operations may in fact be performed continuously and / or automatically in substantially real time during operation of the computing system and / or equipment controlled by the computing system to improve the functionality of the computing system (e.g., by not requiring human intervention, thereby facilitating faster operational decision making, and by, for example, eliminating the possibility of human error to improve the accuracy of operational decision making), as described in more detail herein.

[0024] The present embodiment relates to systems and techniques for obtaining accurate formation density using a nuclear logging tool with a gamma source and a gamma detector. For example, a nuclear logging tool for obtaining such a measurement may include a gamma ray source, one or more gamma ray detectors, and a data processing circuit. When the nuclear logging tool is lowered into a borehole of an underground formation, the gamma ray source may radiate gamma rays into the formation. The gamma rays interact with the borehole and formation atoms and are attenuated by the formation before reaching the gamma ray detector. The data processing circuit may determine the density of the formation based at least in part on the count of the detected gamma rays. In order to reduce or avoid the transmission of gamma rays from the gamma ray source to the interior of the nuclear logging tool or through the gamma ray detector of the nuclear logging tool, a shielded port may be used in the nuclear logging tool to fully shield or block the transmission of gamma rays from the gamma ray source to the interior of the nuclear logging tool or through the gamma ray detector of the nuclear logging tool, as described in more detail herein.

[0025] Considering the foregoing, Figure 1 A drilling system 10 is shown with a nuclear logging tool, as described in more detail herein. The drilling system 10 can be used to drill a well into a geological formation 12 and obtain gamma ray spectroscopy measurements that can be used to identify characteristics of the well. Figure 1 In the illustrated drilling system 10, a drill rig 14 at the surface 16 can rotate a drill string 18 having a drill bit 20 at its lower end. As the drill bit 20 rotates, a drilling fluid pump 22 is used to pump a drilling fluid 24 (commonly referred to as "mud" or "drilling mud") downwardly through the center of the drill string 18 to the drill bit 20 in the direction of the arrow. The drilling fluid 24, which is used to cool and lubricate the drill bit 20, exits the drill string 18 through the drill bit 20. The drilling fluid 24 then carries away drill cuttings from the bottom of the borehole 26 as it flows back to the surface 16 through the annulus 30 between the drill string 18 and the formation 12 as shown by the arrows. However, as described above, as the drilling fluid 24 flows through the annulus 30 between the drill string 18 and the formation 12, the drilling fluid 24 may begin to invade and mix with fluid stored in the formation 12, which may be referred to as formation fluid (e.g., natural gas or oil). At the surface 16 , the return drilling fluid 24 may be filtered and transported back to the mud pit 32 for reuse.

[0026] like Figure 1 As shown, the lower end of the drill string 18 includes a bottom hole assembly (BHA) 34, which may include a drill bit 20 and various downhole tools. The downhole tools can collect various information related to the drilling status of the geological formation 12 and / or the well. For example, a measurement while drilling (MWD) module 36 can measure certain drilling parameters, such as temperature, pressure, orientation, etc. of the drilling tool. Similarly, a logging while drilling (LWD) module 38 can measure the physical properties of the geological formation 12, such as density, porosity, resistivity, lithology, etc.

[0027] The LWD module 38 may collect various data 40 that may be stored and processed within the LWD module 38, or as Figure 1 As shown, it can be sent to the surface for processing. In an example of the present disclosure, the LWD module 38 can include a nuclear logging tool that can detect a gamma ray spectrum (e.g., the energy of formation gamma rays) that is produced when the gamma rays are emitted into the well. The energy range of the detected gamma rays can be visualized as a spectrum of the detected gamma rays. The collected data 40 can include counts of gamma rays and / or detected energies and gamma rays arriving at corresponding detectors in the LWD module 38. It should be understood that although Figure 1 The illustrated embodiment involves collecting data via LWD module 38, but in other embodiments, a wireline tool may be used as a delivery mode. In other words, the gamma ray nuclear logging tool may be deployed into the borehole 26 via LWD, wireline, coiled tubing, or any other suitable downhole delivery mode.

[0028] The data 40 may be sent to a data processing system 44 via a control and data acquisition system 42. The control and data acquisition system 42 may receive the data 40 in any suitable manner. In certain embodiments, the control and data acquisition system 42 may transmit the data 40 via an electrical signal pulsed through the geological formation 12 or via mud pulse telemetry using the drilling fluid 24. In other embodiments, the data 40 may be retrieved directly from the LWD module 38 when the LWD module 38 returns to the surface. As described in more detail herein, the control and data acquisition system 42 may be configured to estimate formation properties (e.g., porosity) using the nuclear data 40 provided by the LWD module 38. Additionally, in certain embodiments, the control and data acquisition system 42 may be configured to control any and all operating parameters of the BHA 34, including, but not limited to, the operation of the nuclear logging tools of the LWD module 38, as described in more detail herein.

[0029] In certain embodiments, the data processing system 44 may include a processor 46, a memory 48, a storage device 50, and / or a display 52. ​​The data processing system 44 may use the data 40 to determine various properties of the formation 12 using any suitable technique. As will be described in more detail herein, the LWD module 38 may use certain selected materials to reduce signal contamination of stray gamma rays. Therefore, when the data processing system 44 processes the data 40, the determined formation characteristics may be more accurate and / or precise than otherwise. To process the data 40, the processor 46 may execute instructions stored in the memory 48 and / or the storage device 50. Thus, the memory 48 and / or the storage device 50 of the data processing system 44 may be any suitable article that may store instructions. The memory 48 and / or the storage device 50 may be a ROM memory, a random access memory (RAM), a flash memory, an optical storage medium, or a hard drive, to name a few examples. The display 52 may be any suitable electronic display that may display well logging and / or other information related to the properties of the formation 12 measured by the LWD module 38. It should be understood that although the data processing system 44 is shown as being located at the surface, the data processing system 44 may be located in the LWD module 38. In such an embodiment, some of the data 40 may be processed in the LWD module 38, and the data 40 may be stored in the LWD module 38, while some of the data 40 may be sent to the surface in real time. This may be the case particularly in LWD, where a limited amount of data 40 may be transmitted to the surface during drilling or reaming operations.

[0030] As described in more detail herein, LWD module 38 may include a nuclear logging tool. Figure 2A schematic block diagram showing a perspective view of an embodiment of an LWD module 38 is illustrated, the LWD module 38 being or including a nuclear logging tool 54. In certain embodiments, the nuclear logging tool 54 may include a chassis 56 (e.g., an annular chassis), a collar 58 (e.g., an annular collar), and a flow path 60 (e.g., an annular flow path) extending through the nuclear logging tool 54. For ease of discussion, the nuclear logging tool 54 and its components may be described with reference to an axial axis or direction 80 (e.g., the coaxiality of the collar 58 and the chassis 56), a radial axis or direction 82, and a circumferential axis or direction 84. In certain embodiments, a gamma ray source 62 may be located at a first position within the nuclear logging tool 54, a first gamma ray detector 64 may be located at a second position axially spaced from the gamma ray source 62 along the axis 80, and a second gamma ray detector 66 may be located at a third position axially spaced from the gamma ray source 62 along the axis 80, wherein the third position is farther from the gamma ray source 62 along the axis 80 than the second position. A shield 70 comprising a dense shielding material (e.g., tungsten copper, HeavyMet made of tungsten nickel iron) can be disposed around the nuclear logging tool 54 at or near the second location to reduce unwanted gamma rays traveling directly from the gamma ray source 62 through the LWD tool to the gamma ray detector 64. It should be noted that the shield 70 can also be disposed at or near the third location to reduce unwanted gamma rays traveling directly from the gamma ray source 62 through the LWD tool to the gamma ray detector 66. The flow path 60 can be along an axis 80, and the central symmetry axis 59 of the flow path 60 can be offset from the central symmetry axis 61 of the collar 58 along a radial axis 82. Details of this embodiment and other embodiments of the spectroscopic logging tool employing the general configuration or aspects of the LWD module 38 and the nuclear logging tool 54 are contemplated for use with any suitable transport means, such as wireline, coiled tubing, logging while drilling (LWD), etc. Furthermore, additional equipment may be used to obtain information about the environment, such as the sigma of the formation 12, the sigma of the drilling fluid 24, density, borehole size, and slowdown length.

[0031] Typically, the gamma rays emitted by the gamma ray source 62 can interact with the surrounding formation 12. The formation gamma rays can be detected by a gamma ray detector (e.g., a first gamma ray detector 64, a second gamma ray detector 66). In some embodiments, the gamma ray detector can include a scintillation detector having a scintillation crystal and a photomultiplier. In some embodiments, the gamma ray detector (e.g., a first gamma ray detector 64, a second gamma ray detector 66) can detect a spectrum, i.e., an energy range, of the formation gamma rays. Figure 2The nuclear spectrum provided by the illustrated nuclear logging tool 54 can provide a wealth of information about the elemental composition of the material surrounding the nuclear logging tool 54. As described in more detail herein, the control and data acquisition system 42 can analyze the spectrum to obtain complementary information from different groups of elements, such as the elemental composition of the surrounding formation 12. The elemental yields from these spectra are responsive to the geochemistry of the formation rock as well as the solid organic matter, pore fluids, and the borehole 26.

[0032] As described in more detail herein, the shield 70 may include a dense shielding material (eg, tungsten copper, HeavyMet made of tungsten nickel iron) to reduce unwanted gamma rays traveling directly from the gamma ray source 62 to gamma ray detectors within the nuclear logging tool 54 . Figure 3 Shows Figure 1 and Figure 2 , further illustrating the shield 70. In the illustrated embodiment, the nuclear logging tool 54 includes a gamma ray source window 100 aligned with the gamma ray source 62, a detector window 102 aligned with the gamma ray detector 64, and the shield 70 disposed between the gamma ray source 62 and the gamma ray detector 64. It should be noted that although in Figure 3 In the illustrated embodiment, only the detector window 102 is shown, but individual detector windows may be aligned with corresponding gamma ray detectors (e.g., gamma ray detector 64, gamma ray detector 66). The shield 70 includes a chassis shield block 104 coupled to (e.g., recessed into) the chassis 56 and a shield assembly 106 coupled to (e.g., recessed into) the collar 58 in alignment with the chassis shield block 104. The shield assembly 106 may include a shield top plate 108 (e.g., a shield cover), a sealing member 110 (e.g., an annular seal cap) having an annular seal 114 disposed in an annular seal groove 112, a shield insert 116 (e.g., an annular shield insert), and a shield connection block 118 (e.g., a curved shield panel or a semi-annular panel), which may be arranged in sequence and / or coaxially with each other in the radial direction 82. Various aspects of the gamma ray source window 100, the detector window 102, and the shield 70 are discussed in further detail below.

[0033] In some embodiments, a gamma-ray source window 100 (e.g., a structural window panel or plug) can be installed in a window recess or opening 120 on the outside of the collar 58 at the location of the gamma-ray source 62, so that the gamma rays generated by the gamma-ray source 62 can be output to the formation 12 through the gamma-ray source window 100. The gamma-ray source window 100 can be made of a material with a low density and a lower average atomic number (Z) (e.g., polyetheretherketone (PEEK), a transparent or translucent material), which allows the transmission of gamma rays within a certain energy spectrum range. The gamma-ray source window 100 can be any shape suitable for covering the output gamma-ray beam of the gamma-ray source 62. For example, the gamma-ray source window 100 can be a truncated cylindrical structure 122 having the same axis of symmetry as the collar 58. For example, the truncated cylindrical structure 122 can have a rectangular outer perimeter or border 124, a flat or planar inner surface 126, and a curved outer surface 128. In certain embodiments, the curved outer surface 128 may mate with or contour to an outer surface 130 (eg, an outer annular surface) of the collar 58 .

[0034] In addition, a detector window 102 (e.g., a structural window panel or plug) can be installed in a window recess or opening 132 on the outside of the collar 58 at the location of the gamma ray detector 64, so that the gamma ray detector 64 can receive gamma rays from the formation 12 through the detector window 102. The detector window 102 can be made of a material with a low density and a lower average atomic number (Z) (e.g., polyetheretherketone (PEEK), a transparent or translucent material), which allows transmission of gamma rays within a certain energy spectrum range. The detector window 102 can have any shape suitable for receiving an input gamma ray beam from the formation 12. For example, in the illustrated embodiment, the detector window 102 can be a cylindrical structure 134 having a cylindrical sidewall 136, a flat or planar inner surface 138, and a curved outer surface 140. In some embodiments, the curved outer surface 140 can match the outer surface 130 (e.g., an outer annular surface) of the collar 58.

[0035] A chassis shield block 104 (e.g., a curved shield panel or a semi-annular panel) can be disposed in a recess 142 formed in the chassis 56 between the gamma ray source 62 and the gamma ray detector 64. The chassis shield block 104 can have a rectangular perimeter 144, an inner surface 146 (e.g., a curved or flat inner surface), and an outer surface 148 (e.g., a curved or flat outer surface). In some embodiments, the chassis shield block 104 can have a thickness 150 (e.g., a uniform thickness and / or a variable thickness) between the inner surface 146 and the outer surface 148. For example, the inner surface 146 and the outer surface 148 can be parallel to each other to define a uniform thickness 150. The chassis shielding block 104 can be made of a dense shielding material (e.g., tungsten copper, HeavyMet made of tungsten nickel iron) and can be a relatively large block (e.g., compared to the size of the gamma ray source 62) having a size that fits in the recess 142 between the gamma ray source 62 and the gamma ray detector 64 to reduce unwanted gamma rays traveling directly from the gamma ray source 62 to the gamma ray detector 64 in the chassis 56.

[0036] like Figure 3 As further shown, the shield assembly 106 can be inserted into the shield port 152 in the collar 58 and partially inserted into the recess 154 in the chassis shield block 104 between the gamma ray source 62 and the gamma ray detector 64 to further block or shield the transmission of gamma rays from the gamma ray source 62 through the collar 58 to the gamma ray detector 64. The shield assembly 106 can be axially disposed between the gamma ray source 62 and the gamma ray detector 64 in a straight line (e.g., an axial line in the axial direction 80), wherein the shield assembly 106 radially overlaps a radial length 156 of the gamma ray source 62 in the radial direction 82, and the shield assembly 106 circumferentially overlaps the gamma ray source 62 and the gamma ray detector 64 in the circumferential direction 84. In some embodiments, a shield width or diameter 158 of the shield assembly 106 is greater than a source width or diameter 160 of the gamma ray source 62. As described above, the shielding top plate 108, the sealing member 110, the shielding insert 116, and the shielding connection block 118 may be arranged in a sequential arrangement and / or coaxially with each other in the radial direction 82. For example, the shielding top plate 108 may be radially disposed above and coupled to the sealing member 110 within the shielding port 152, the sealing member 110 may be radially disposed above and coupled to the shielding insert 116 in the shielding port 152, and the shielding insert 116 may be radially disposed above and coupled to the shielding connection block 118, which is disposed in the recess 154 in the chassis shielding block 104.

[0037] The components of the shield assembly 106 may have various shapes to facilitate insertion and / or removal from the shield port 152 and the recess 154 while the collar 58 is disposed around the chassis 56, the gamma ray source 62, and the gamma ray detector 64. The shield top plate 108 may have a truncated cylindrical structure 162 having the same axis of symmetry as the collar 58. For example, the truncated cylindrical structure 162 may have a rectangular outer perimeter or border 164, a flat or planar inner surface 166, and a curved outer surface 168. In some embodiments, the curved outer surface 168 may match or contour with the outer surface 130 (e.g., an annular outer surface) of the collar 58. However, in some embodiments, the shield top plate 108 may be an annular plug, a flat circular cover, or another suitable shape. In some embodiments, the sealing component 110 and the shield insert 116 may be, for example, Figure 3 The shielding connection block 118 may be a circular component, a rectangular component, an elliptical component, or other shape as shown. In some embodiments, the shielding connection block 118 (e.g., a curved shielding panel or a semi-circular panel) may have a rectangular perimeter 170, an inner surface 172 (e.g., a curved or flat inner surface) and an outer surface 174 (e.g., a curved or flat outer surface). In some embodiments, the shielding connection block 118 may have a thickness 176 (e.g., uniform thickness and / or variable thickness) between the inner surface 172 and the outer surface 174. For example, the inner surface 172 and the outer surface 174 may be parallel to each other to define a uniform thickness 176. The inner surface 172 of the shielding connection block 118 may also be contoured to fit along the outer surface 148 (e.g., a curved or flat outer surface) and / or within a recess 154 in the chassis shielding block 104. The shielding connection block 118 may be used to connect the shielding insert 116 to the chassis shielding block 104. The shielding top plate 108 may be used to hold the sealing component 110 and the shielding insert 116 to the shielding connection block 118. The shield top plate 108, the shield insert 116, and the shield connection block 118 can be made of a dense shielding material (e.g., tungsten copper, HeavyMet made of tungsten nickel iron). In some embodiments, the sealing component 110 can be made of a metal for machining purposes (e.g., steel, stainless steel, nickel-based alloys, copper-based alloys), such as Monel, Inconel, MP35N, 17-4PH, beryllium copper. In some embodiments, the sealing component 110 can be made of a dense shielding material.

[0038] Figure 4 yes Figure 1-3 FIG. 5 is a partial cross-sectional end view of a nuclear logging tool 54 further illustrating details of the shield 70 having a shield assembly 106 inserted into a shield port 152 in the collar 58 and partially into a recess 154 in the chassis shield block 104. Figure 4As shown, the collar 58 (e.g., an annular collar) is disposed in a coaxial or concentric arrangement around the chassis 56 (e.g., an annular chassis) such that an inner surface 190 (e.g., an inner annular surface) of the collar 58 faces and / or contacts an outer surface 192 (e.g., an outer annular surface) of the chassis 56. The chassis shield block 104 is disposed in a recess 142 in the chassis 56, wherein the recess 142 extends radially inward from the outer surface 192 of the chassis 56 into an inner portion 194 of the chassis 56. In certain embodiments, the recess 142 in the chassis 56 is a rectangular slot having flat side surfaces 196 and a flat bottom surface 198 to mate with a rectangular perimeter 144 and an inner surface 146 of the chassis shield block 104. The chassis shield block 104 may be sized to be substantially larger than the gamma ray source 62 and / or the gamma ray detector 64. In the illustrated embodiment, the width 200 and height 202 of the chassis shield block 104 may be at least equal to or greater than 20%, 30%, 40%, or 50% of the diameter 204 of the chassis 56. Additionally, the width 200 and height 202 of the chassis shield block 104 may be at least equal to or greater than 1.1, 1.2, 1.3, 1.4, 1.5, 2, 3, or 4 times the diameter 160 of the gamma ray source 62. Thus, the chassis shield block 104 may be a relatively large block (e.g., compared to the size of the gamma ray source 62) located in the chassis 56. Figure 3 , Figure 4 and Figure 5 , the gamma ray source 62 may be located at a position along the radial direction 82 such that the gamma ray source 62 is radially separated or offset from the gamma ray detector 64 .

[0039] like Figure 4 As further shown in FIG. 1 , the shielding top plate 108 (e.g., shielding cover), the sealing member 110 (e.g., annular sealing cap), the shielding connection block 118 (e.g., curved shielding panel or semi-annular panel), and the chassis shielding block 104 are arranged in sequence with each other and / or coaxially with each other in the radial direction 82. As described above, the shielding top plate 108 has a truncated cylindrical structure 162 having a flat or planar inner surface 166 disposed against the sealing member 110 and a curved outer surface 168 contoured along the outer surface 130 (e.g., annular outer surface) of the collar 58. The shielding top plate 108 can be disposed in the first opening portion 206 of the shielding port 152, wherein the first opening portion 206 can have a rectangular shape (e.g., a rectangular recess) to receive and hold the shielding top plate 108.

[0040] The sealing member 110 may be disposed in the second opening portion 208 of the shielded port 152, wherein the second opening portion 208 may include a first annular aperture sized to receive and retain the sealing member 110. For example, the annular seal 114 in the annular sealing groove 112 of the sealing member 110 may be configured to seal along the second opening portion 208 (e.g., the first annular aperture). The illustrated sealing member 110 (e.g., an annular sealing cap) has a cup-shaped structure 210 having a circular top wall 212 coupled to an annular side wall 214, wherein the cup-shaped structure 210 defines an inner annular chamber 216.

[0041] The shield insert 116 includes an annular flange 218 axially disposed between a first annular portion 220 (e.g., an annular head) and a second annular portion 222 (e.g., an annular body). The first annular portion 220 is disposed in the inner annular chamber 216 of the sealing component 110. The annular flange 218 abuts a bottom surface 224 of the annular sidewall 214 of the sealing component 110 and a bottom annular ledge 226 of the second opening portion 208 of the shield port 152. The second annular portion 222 extends through a third opening portion 228 (e.g., a second annular hole) of the shield port 152.

[0042] At least some of the components of the shield assembly 106 (e.g., the shield top plate 108, the sealing component 110, and the shield insert 116) are configured to be radially inserted into the shield port 152 in the radially inward direction using gradually decreasing cross-sectional areas of the components and the shield port 152. As shown, the annular flange 218 has a larger diameter than the first annular portion 220 and the second annular portion 222 of the shield insert 116, and the first annular portion 220 has a larger diameter than the second annular portion 222 of the shield insert 116. In addition, the first opening portion 206 (e.g., a rectangular recess) has a larger size than the first diameter of the second opening portion 208 (e.g., a first annular hole) of the shield port 152, and the first diameter of the second opening portion 208 (e.g., the first annular hole) is greater than the second diameter of the third opening portion 228 (e.g., the second annular hole) of the shield port 152, so that the size (e.g., width or diameter) of the shield port 152 gradually decreases in the radially inward direction and gradually increases in the radially outward direction. This gradually changing size of the shield port 152 facilitates the insertion and removal of at least a portion of the shield assembly 106 (e.g., the shield top plate 108, the sealing component 110, and the shield insert 116) from the exterior of the collar 58 of the nuclear logging tool 54, while the shield connection block 118 and the chassis shield block 104 can be installed on the chassis 56 before and / or during assembly of the collar 58 around the chassis 56. Other details of the shield assembly 106 are discussed in further detail below.

[0043] Figure 5 yes Figures 1 to 4 54, further illustrating the gamma ray paths outside the nuclear logging tool 54 and partially inside the nuclear logging tool 54 and blocked by the shield 70. Figure 5 As shown, gamma rays may be generated by the gamma ray source 62 and transmitted within the collar 58. Some gamma rays may travel along a path 230 within the collar 58 and be blocked by the shield assembly 106 (e.g., by the shield top plate 108 or the shield insert 116). These gamma rays may be blocked by the dense shielding material of the shield assembly 106 and may not be received by the gamma ray detector 64. Some gamma rays may travel along a path 232 within the collar 58 and be attenuated by the shield assembly 106 (e.g., by the sealing member 110). These gamma rays may be attenuated by the metal material of the shield assembly 106, and only a portion of these gamma rays may be received by the gamma ray detector 64. Some gamma rays may travel through the gamma ray window 100 and exit to the formation 12. These gamma rays may travel along a path 234, which may extend to the formation 12, and return to the detector window 102 and be received by the gamma ray detector 64. Those gamma rays that travel along paths 230 and 232 may not provide substantive information about the properties of the formation and may represent noise that needs to be subtracted from the total signal received by the gamma ray detector 64. Those gamma rays that travel along path 234 may provide information about the properties of the formation and may be included in the signal of the gamma ray detector 64. Thus, by using the shielding assembly 106, gamma rays transmitted from the gamma ray source 62 to the gamma ray detector 64 within or through the nuclear logging tool (e.g., the chassis 56, the collar 58) may be substantially reduced.

[0044] Figure 6 yes Figure 1-51 , further illustrating an embodiment of a shield 70 having a threaded fastener assembly 240 coupling the shield insert 116 and the shield connection block 118 together. In the illustrated embodiment, the threaded fastener assembly 240 includes a male fastener 242 (e.g., a bolt) and a female fastener 244 (e.g., a nut). The male fastener 242 includes a head 246, a shaft 248 coupled to and extending radially from the head 246, and a threaded portion 250 (e.g., male threads) along the shaft 248. The head 246 may be a tool-engageable head having a tool interface 252, such as a male or female tool interface having a flat, groove, or other torque transmission feature, which is configured to transmit torque from the tool to the male fastener 242. The female fastener 244 includes a threaded hole 254 (e.g., female threads) extending through a fastener body 256 (e.g., a rectangular block or a hexagonal block). The fasteners 256 may be made of a different material (e.g., steel) than the shield connection block 118. The male fasteners 242 are configured to be threaded into the female fasteners 244 to radially draw the shield insert 116 and the shield connection block 118 together, thereby securing the shield insert 116 and the shield connection block 118 within the nuclear logging tool 54.

[0045] In the illustrated embodiment, the shield 70 is assembled into the nuclear logging tool 54 partially before the collar 58 is installed about the chassis 56 and partially after the collar 58 is installed about the chassis 56. For example, before the collar 58 is installed about the chassis 56, the chassis shield block 104 can be installed into the recess 142 in the chassis 56, the female fastener 244 can be installed into the recess 258 in the inner surface 172 of the shield connection block 118, and the shield connection block 118 (with the female fastener 244) can be installed into the recess 154 in the chassis shield block 104. The recess 258 and the female fastener 244 can have complementary anti-rotation shapes (e.g., rectangular, hexagonal, or other non-circular shapes) that interface with each other so that the female fastener 244 does not rotate during rotation of the male fastener 242, as described below. Initially, the shield connection block 118 (having the female threaded fasteners 244) may be inserted into the recess 154 in the radially inward direction 82 such that the inner surface 172 of the shield connection block 118 contacts or abuts the bottom surface 260 of the recess 154 and the outer surface 174 of the shield connection block 118 is flush with, recessed into, or slightly protrudes from the outer surface 148 of the chassis shield block 104. The collar 58 may then be installed around the chassis 56, the chassis shield block 104, and the shield connection block 118. After the collar 58 has been installed around the chassis 56, the remaining components of the shield 70 (e.g., the shield assembly 106) may be installed externally through the shield port 152 in the collar 58.

[0046] like Figure 6 As further shown in FIG. 8 , the shield insert 116 can be installed into the shield port 152 in the radially inward direction 82 until the second annular portion 222 of the shield insert 116 extends through the third opening portion 228 (e.g., the second annular hole) in the collar 58 and extends into the recess 262 in the top surface 174 of the shield connection block 118. The size and shape of the recess 262 and the second annular portion 222 can be designed to mate with each other, such as an annular interface. In addition, the shield insert 116 can be installed in the radially inward direction 82 until the annular flange 218 abuts the bottom annular ledge 226 of the second opening portion 208 (e.g., the annular portion 264) of the collar 58. Subsequently, the male threaded fastener 242 can be inserted through the fastener receptacle 266 in the shield insert 116, through the fastener receptacle 268 in the shield connection block 118, and into the threaded hole 254 in the female threaded fastener 244. The torque tool may then engage the head 246 (e.g., torque interface 252) to rotate the male threaded fastener 242 such that the threaded portion 250 of the shaft 248 is threaded into the threaded hole 254 in the female threaded fastener 244 and the head 246 is recessed into the head recess 270 along an outer surface 272 (e.g., top surface) of the shield insert 116. As the torque tool progressively tightens the male threaded fastener 242 with the female threaded fastener 244, the threaded fastener assembly 240 radially compresses the shield insert 116 and the shield connection block 118 radially around the annular portion 264 of the collar 58. Thus, tightening of the threaded fastener assembly 240 causes a radially inward force of the annular flange 218 of the shield insert 116 against the bottom annular ledge 226 at the annular portion 264, and a radially outward force of the outer surface 174 of the shield connection block 118 against the inner surface 190 of the collar 58. Thus, the threaded fastener assembly 240 removably couples the shield insert 116 to the shield connection block 118 while the collar 58 is installed about the chassis 56 .

[0047] The shielding assembly 106 further includes a sealing member 110 and a shielding top plate 108. Figure 6As shown, after installing the male threaded fastener 266, the sealing component 110 can be installed into the second opening portion 208 (e.g., the first annular hole) of the shield port 152 in the radially inward direction 82 until the sealing component 110 substantially surrounds the first annular portion 220 of the shield insert 116. The sealing component 110 has a cup-shaped structure 210 defining an inner annular chamber 216, which receives the first annular portion 220 of the shield insert 116. The circular top wall 212 of the cup-shaped structure 210 extends over and covers the male threaded fastener 242, which has a head 246 disposed in the head recess 270. The annular sidewall 214 of the cup-shaped structure 210 also includes an annular seal 114 in the annular sealing groove 112, wherein the annular seal 114 seals the second opening portion 208 (e.g., the first annular hole) of the shield port 152 to block fluid leakage into the nuclear logging tool 54. In some embodiments, the shield assembly 106 may include one or more fasteners to couple the seal component 110 to the collar 58 .

[0048] In the illustrated embodiment, after the sealing member 110 is installed, the shielding top plate 108 can be installed in the first opening portion 206 above the sealing member 110 in the radially inward direction 82. The shielding top plate 108 can be removably coupled to the collar 58 via one or more fasteners 274 (such as threaded fasteners). For example, the fasteners 274 can couple the shielding top plate 108 to the collar 58 in a boundary portion 276 of the shielding top plate 108 outside the perimeter of the sealing member 110. However, any suitable arrangement of the fasteners 274 can be used to couple the shielding top plate 108 to the collar 58. The shield 70 can be removed in a removal process having a reverse order to the installation process described in detail above. In addition, the shielding member 70 can have various modifications in terms of the placement and / or geometry of the components while still being able to perform an installation and removal process that is at least partially performed when the collar 58 is installed around the chassis 56.

[0049] exist Figure 6 In the illustrated embodiment, a spring 278 may be inserted between the sealing component 110 and the shield insert 116 (e.g., between the outer surface 272 and the sealing component 110) to support or compensate for thermal expansion caused by components made of different materials. For example, the spring may include a coil spring, a spring washer, an elastomeric insert, or any combination thereof.

[0050] Figure 7 yes Figure 1-6 54 further illustrates a second embodiment of the shield 70 having a threaded fastener assembly 240 coupling the shield insert 116 and the shield connection block 118 together. Figure 7 Examples and Figure 6 The embodiments are basically the same, except Figure 7 The threaded fastener assembly 240 in the embodiment of the present invention integrates the female threaded fastener 244 with the shield connection block 118 into a single-piece structure 280 (e.g., a shield connection block 118 with an integrated female threaded fastener 244). In other words, the single-piece structure 280 includes the shield connection block 118 and the female threaded fastener 244 as a single continuous piece of material, wherein the threaded hole 254 (e.g., female threads) extends through the single-piece structure 280 instead of a separate fastener body 256. In some embodiments, Figure 7 The shielding connection block 118 in the embodiment can be made of metal (eg, steel, stainless steel, nickel-based alloy, copper-based alloy), and Figure 6 The shield connection block 118 in the embodiment shown in FIG. 1 may be made of a dense shielding material (eg, HeavyMet made of tungsten copper, tungsten nickel iron). Figure 6 and Figure 7 In the same reference numerals, the same components are shown. Figure 7 The components are the same as those referenced above. Figure 6 The description is basically the same.

[0051] Figure 8 yes Figure 1-6 The partial cross-sectional side view of the nuclear logging tool 54 further illustrates a third embodiment of the shield 70 having a threaded fastener assembly 240 that couples the shield insert 116 and a first chassis portion 300 (e.g., a radially protruding annular portion) of the chassis 56 through an opening 302 (e.g., an annular opening) on ​​the chassis shield block 104. Figure 8 Examples and Figure 7 The embodiments are basically the same, except Figure 8 The shield insert 116 in the embodiment of FIG. 5 is connected to the base frame 56 through the shield block 104 without using the shield connection block 118. Figure 6 and Figure 8 In the drawings, the same components are indicated by the same component numbers. Unless otherwise specified, the components are the same as those in the above reference Figure 6 The description is basically the same. Figure 82, the first chassis portion 300 may include a threaded hole 304 (e.g., a female thread) extending through the first chassis portion 300. The male threaded fastener 242 is configured to be screwed into the threaded hole 304 of the first chassis portion 300 to radially draw the shield insert 116 and the chassis 56 together to secure the shield insert 116 within the nuclear logging tool 54. The first chassis portion 300 may have a width or diameter 306 and is supported by a second chassis portion 308 (e.g., a radially protruding annular portion) having a width or diameter 310. In some embodiments, the width or diameter 310 may be greater than the width or diameter 306.

[0052] As shown, the first chassis portion 300 and the second chassis portion 308 together define a stepped annular protrusion 312 that extends radially outward from the chassis 58 into a stepped annular seat 314 in the chassis shield block 104. The stepped annular seat 314 includes a first seat 316 (e.g., an annular seat) that is sized to receive the second ring portion 222 of the shield insert 116 and the first chassis portion 300 of the stepped annular protrusion 312. The stepped annular seat 314 also includes a second seat 318 (e.g., an annular seat) that is sized to receive the second chassis portion 308 of the stepped annular protrusion 312. In operation, when the male threaded fastener 242 engages the threaded aperture 304 of the first chassis portion 300 , the shield insert 116 is urged radially inward into the first receptacle 316 against the first chassis portion 300 , thereby removably securing the shield insert 116 within the collar 58 .

[0053] Fig. 9 yes Figure 1-6 FIG. 5 is a partial cross-sectional side view of the nuclear logging tool 54 further illustrating the fourth embodiment of the shield 70 without the threaded fastener assembly 240 and the shield connection block 118 . Fig. 9 Examples and Figure 6 The embodiments are basically the same, except Fig. 9 The shield insert 116 of the embodiment of FIG. 1 is coupled to the shield block 104 without the use of the threaded fastener assembly 240. Figure 6 and Figure 8 In the drawings, the same components are indicated by the same component numbers. Unless otherwise specified, the components are the same as those in the above reference Figure 6 The description is basically the same. Fig. 9, the shield insert 116 can extend radially into a recess 350 (e.g., an annular recess) in the chassis shield block 104, wherein the shield insert 116 is held in place by the seal member 110 and the shield top plate 108. For example, the shield top plate 108 can be secured to the collar 58 by threaded fasteners 274, a brazed joint, a welded joint, an adhesive joint, or a combination thereof between the shield top plate 108 and the collar 58. In some embodiments, the brazed joint, the welded joint, and / or the adhesive joint can couple the shield insert 116 and the seal member 110, the seal member 110 and the shield top plate 108, or a combination thereof. In some embodiments, the brazed joint, the welded joint, and / or the adhesive joint can couple the collar 58 to one or more of the shield insert 116, the seal member 110, and the shield top plate 108.

[0054] A technical effect of the disclosed embodiments is to provide shielding within the nuclear logging tool 54, such as within the collar 58 between the gamma ray source 62 and the gamma ray detector 64, thereby reducing the likelihood of unwanted gamma ray transmission within the nuclear logging tool 54 without allowing the gamma rays to pass through the formation outside the nuclear logging tool 54. The disclosed embodiments provide a shield 70 having a shield assembly 106 coupled to (e.g., recessed into) the collar 58 aligned with the chassis shield block 104. The shield assembly 106 is at least partially insertable and removable while the collar 58 is mounted around the chassis 56. For example, the shield assembly 106 may include at least a shield top plate 108, a sealing member 110, and a shield insert 116 that may be radially inserted or removed when the collar 58 is mounted around the chassis 56. The shield 70 helps block undesirable gamma ray transmission to reduce noise while allowing desired gamma ray transmission to pass through the formation outside of the nuclear logging tool 54 between the gamma ray source 62 and the gamma ray detector 64 .

[0055] The subject matter described in detail above may be defined by one or more clauses, as described below.

[0056] A system includes a shield for a nuclear logging tool. The shield includes a shield insert configured to be at least partially installed inside the nuclear logging tool between a gamma ray source and a gamma ray detector of the nuclear logging tool. A first portion of the shield insert is configured to be installed in a collar of the nuclear logging tool, and a second portion of the shield insert is configured to be installed in a chassis of the nuclear logging tool. The shield also includes a chassis shield block configured to be installed between the gamma ray source and the gamma ray detector in the chassis, and a shield top plate configured to be coupled to the collar and at least partially retain the shield insert in the collar.

[0057] The system of any of the preceding clauses, wherein the shielding insert is made of a dense shielding material.

[0058] The system of any of the preceding clauses, wherein the chassis shielding block is made of a dense shielding material.

[0059] The system of any of the preceding clauses, comprising a sealing component coupled to the shielding insert and configured to seal the shielding insert in the collar.

[0060] A system according to any of the preceding clauses, wherein the sealing component is brazed to the shielding insert.

[0061] A system according to any of the preceding clauses, wherein the calculated first formation density is used to compensate the calculated second formation density to obtain a compensated formation density.

[0062] The system of any of the preceding clauses, comprising a shield connection block configured to couple the shield insert to the chassis shield block.

[0063] A system according to any of the preceding clauses, wherein the shielding connection block is made of a dense shielding material.

[0064] The system of any of the preceding clauses, comprising a threaded fastener configured to couple the shield insert and the shield connection block together.

[0065] The system of any of the preceding clauses, comprising a threaded fastener configured to couple the shield insert and the chassis shield block together.

[0066] A system according to any of the preceding clauses, comprising a nuclear logging tool, the nuclear logging tool comprising a collar arranged around a chassis, wherein a shielding port extends radially through the collar toward the chassis, a shielding insert is arranged in the shielding port above a chassis shielding block, a sealing component is arranged in the shielding port above the shielding insert, and a shielding top plate is connected to the collar above the sealing component.

[0067] A system according to any of the preceding clauses, wherein the shielding port comprises an annular sealing port having a first annular hole, a second annular hole and an annular ledge between the first annular hole and the second annular hole, wherein the sealing component comprises an annular sealing cap having a cup-shaped structure disposed in the first annular hole, wherein the first portion of the shielding insert comprises a first annular portion disposed in the cup-shaped structure, the second portion of the shielding insert comprises a second annular portion disposed in the second annular hole, and an annular flange of the shielding insert is disposed between the cup-shaped structure and the annular ledge.

[0068] The system of any of the preceding clauses, wherein a first threaded fastener extends through the shield insert and is coupled to a second threaded fastener in a shield connection block, a chassis shield block, or a chassis, wherein the first threaded fastener and the second threaded fastener are configured to be threaded together to retain the shield insert in the shield port.

[0069] The system of any preceding clause, wherein the shield top plate is coupled to the collar via one or more of a fastener, a brazed joint, a welded joint, or an adhesive joint.

[0070] A nuclear logging tool includes a chassis, a collar arranged around the chassis, a gamma ray source configured to emit gamma rays through a first window in the collar, and a gamma ray detector configured to receive gamma rays through a second window in the collar, and the gamma ray source and the gamma ray detector are offset from each other along the axis of the chassis. The nuclear logging tool also includes a shield. The shield includes a shield insert that is at least partially installed between the gamma ray source and the gamma ray detector inside the nuclear logging tool. A first portion of the shield insert is installed in the collar, and a second portion of the shield insert is installed in the chassis. The shield also includes a chassis shield block installed between the gamma ray source and the gamma ray detector in the chassis. The shield also includes a shield top plate that is coupled to the collar and at least partially holds the shield insert in the collar.

[0071] A nuclear logging tool according to the preceding clause, wherein the shielding port extends radially through the collar toward the chassis, a shielding insert is disposed in the shielding port above the chassis shielding block, a sealing component is disposed in the shielding port above the shielding insert, and a shielding top plate is coupled to the collar above the sealing component.

[0072] A nuclear logging tool according to the preceding clause, wherein the shielding port comprises an annular sealing port having a first annular hole, a second annular hole and an annular ledge between the first annular hole and the second annular hole, wherein the sealing component comprises an annular sealing cap having a cup-shaped structure arranged in the first annular hole, wherein the first part of the shielding insert comprises a first annular part arranged in the cup-shaped structure, the second part of the shielding insert comprises a second annular part arranged in the second annular hole, and an annular flange of the shielding insert is arranged between the cup-shaped structure and the annular ledge.

[0073] The nuclear logging tool according to the preceding clause comprises a shielding connection block configured to connect a shielding insert to a chassis shielding block, wherein a first threaded fastener extends through the shielding insert and is connected to a second threaded fastener in the shielding connection block, the chassis shielding block or the chassis, wherein the first threaded fastener and the second threaded fastener are configured to be threadedly connected together to hold the shielding insert in the shielding port.

[0074] A method includes emitting gamma rays from a gamma ray source through a first window in a collar of a nuclear logging tool; receiving gamma rays at a gamma ray detector through a second window in the collar, and the gamma ray source and the gamma ray detector are offset from each other along an axis of a chassis of the nuclear logging tool; and shielding the gamma rays directly between the gamma ray source and the gamma ray detector inside the nuclear logging tool via a shield. The shield includes a shield insert that is at least partially installed between the gamma ray source and the gamma ray detector inside the nuclear logging tool. A first portion of the shield insert is installed in the collar, and a second portion of the shield insert is installed in the chassis. The shield also includes a chassis shield block installed between the gamma ray source and the gamma ray detector in the chassis. The shield also includes a shield top plate that is coupled to the collar and at least partially retains the shield insert in the collar.

[0075] A method according to any preceding clause, wherein emitting gamma rays comprises directing gamma rays through a geological formation, receiving gamma rays comprises receiving the gamma rays after passing through the geological formation, and shielding the gamma rays comprises reducing noise associated with gamma rays that do not pass through the geological formation.

[0076] The above specific embodiments have been shown by way of example, and it should be understood that these embodiments may allow various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the specific forms disclosed, but to cover all modifications, equivalents and substitutes that fall within the spirit and scope of the present disclosure.

[0077] In the claims, means-plus-function clauses are intended to cover structures described herein as performing the recited function and to encompass not only structural equivalents but also equivalent structures. Thus, for example, while a nail and a screw may not be structural equivalents because a nail employs a cylindrical surface to fasten wooden parts together while a screw employs a helical surface, in the context of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intent of the applicant not to invoke 35 U.S.C. § 112, paragraph 6, for any limitation of any claim herein except for those claims that expressly employ the phrase "means for" and the associated function.

Claims

1. A system comprising: A shielding component for a nuclear logging tool, the shielding component for the nuclear logging tool comprising: a shielding insert configured to be at least partially mounted within the nuclear logging tool between a gamma ray source and a gamma ray detector of the nuclear logging tool, wherein a first portion of the shielding insert is configured to be mounted in a collar of the nuclear logging tool and a second portion of the shielding insert is configured to be mounted in a chassis of the nuclear logging tool; a chassis shielding block configured to be mounted in the chassis between the gamma ray source and the gamma ray detector; and A shield top plate is configured to be coupled to the collar and to at least partially retain the shield insert within the collar. 2 . The system of claim 1 , wherein the shielding insert is made of a dense shielding material.

3. The system of claim 2, wherein the chassis shielding block is made of a dense shielding material. 4 . The system of claim 1 , further comprising a sealing component coupled to the shield insert and configured to seal the shield insert within the collar. The system of claim 4 , wherein the sealing component is brazed to the shielding insert.

6. The system of claim 4, further comprising a spring disposed between the sealing component and the shield insert.

7. The system of claim 1, further comprising a shield connection block configured to couple the shield insert to the chassis shield block.

8. The system of claim 7, wherein the shield connection block is made of a dense shielding material.

9. The system of claim 7, further comprising a threaded fastener configured to couple the shield insert and the shield connection block together.

10. The system of claim 1, further comprising a threaded fastener configured to couple the shield insert and the chassis shield block together.

11. The system of claim 7, further comprising the nuclear logging tool comprising a collar disposed about the chassis, wherein a shielding port extends radially through the collar toward the chassis, the shielding insert being disposed in the shielding port above the chassis shielding block, a sealing component being disposed in the shielding port above the shielding insert, and the shielding top plate being coupled to the collar above the sealing component.

12. A system according to claim 11, wherein the shielding port includes an annular sealing port having a first annular hole, a second annular hole and an annular ledge between the first annular hole and the second annular hole, wherein the sealing component includes an annular sealing cap having a cup-shaped structure arranged in the first annular hole, wherein the first part of the shielding insert includes a first annular portion arranged in the cup-shaped structure, the second part of the shielding insert includes a second annular portion arranged in the second annular hole, and the annular flange of the shielding insert is arranged between the cup-shaped structure and the annular ledge.

13. The system of claim 12, wherein a first threaded fastener extends through the shielding insert and is coupled to a second threaded fastener in the shielding connection block, the chassis shielding block, or the chassis, wherein the first threaded fastener and the second threaded fastener are configured to be threaded together to retain the shielding insert in the shielding port.

14. The system of claim 12, wherein the shield top plate is coupled to the collar via one or more of a fastener, a brazed joint, a welded joint, or an adhesive joint.

15. A nuclear well logging tool comprising: chassis; a collar disposed around the chassis; a gamma ray source configured to emit gamma rays through a first window in the collar; a gamma ray detector configured to receive gamma rays through a second window in the collar, wherein the gamma ray source and the gamma ray detector are offset from one another along an axis of the chassis; and A shielding member, the shielding member comprising: a shield insert mounted at least partially between a gamma ray source and a gamma ray detector within the nuclear logging tool, wherein a first portion of the shield insert is mounted in the collar and a second portion of the shield insert is mounted in the chassis; a chassis shielding block mounted between a gamma ray source and a gamma ray detector in the chassis; and A shield top plate is coupled to the collar and at least partially retains the shield insert within the collar.

16. The nuclear logging tool of claim 15, wherein a shielding port extends radially through the collar toward the chassis, the shielding insert is disposed in the shielding port above the chassis shielding block, a sealing component is disposed in the shielding port above the shielding insert, and the shielding top plate is coupled to the collar above the sealing component.

17. A nuclear logging tool according to claim 16, wherein the shielding port includes an annular sealing port having a first annular hole, a second annular hole and an annular ledge between the first annular hole and the second annular hole, wherein the sealing component includes an annular sealing cap having a cup-shaped structure arranged in the first annular hole, wherein the first part of the shielding insert includes a first annular part arranged in the cup-shaped structure, the second part of the shielding insert includes a second annular part arranged in the second annular hole, and the annular flange of the shielding insert is arranged between the cup-shaped structure and the annular ledge.

18. The nuclear logging tool according to claim 17 further includes a shielding connection block, which is constructed to connect the shielding insert to the chassis shielding block, wherein a first threaded fastener extends through the shielding insert and is connected to the shielding connection block, the chassis shielding block or a second threaded fastener in the chassis, wherein the first threaded fastener and the second threaded fastener are constructed to be threaded together to hold the shielding insert in the shielding port.

19. A method comprising: emitting gamma rays from a gamma ray source through a first window in a collar of a nuclear logging tool; receiving gamma rays at a gamma ray detector through a second window in the collar, wherein the gamma ray source and the gamma ray detector are offset from one another along an axis of a chassis of the nuclear logging tool; and shielding gamma rays via a shield directly between a gamma ray source and a gamma ray detector inside the nuclear logging tool, wherein the shield comprises: a shield insert mounted at least partially between a gamma ray source and a gamma ray detector within the nuclear logging tool, wherein a first portion of the shield insert is mounted in the collar and a second portion of the shield insert is mounted in the chassis; a chassis shielding block mounted between a gamma ray source and a gamma ray detector in the chassis; and A shield top plate is coupled to the collar and at least partially retains the shield insert within the collar.

20. The method of claim 19, wherein emitting the gamma rays comprises directing the gamma rays through a geological formation, receiving the gamma rays comprises receiving the gamma rays after passing through the geological formation, and shielding the gamma rays comprises reducing noise associated with gamma rays that do not pass through the geological formation.

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