A gamma calibration device and method for well maintenance

Abstract

The present application relates to well logging instrument experimental device field, especially to a gamma calibration device and calibration method for well maintenance, which comprises a calibration source ring sleeved on the outside of drill collar and a segmented source gun inserted therein, the outer wall of the drill collar is provided with elastic positioning members driven by elasticity, the inner wall of the source ring is provided with a limiting sliding groove and a limiting end face, the elastic positioning members are clamped into the limiting sliding groove to realize axial positioning by sliding the source ring along the drill collar, the source ring is rotated to abut against the limiting end face in the direction of the limiting end face, and the radial alignment of the collimating hole and the internal gamma sensor is realized. The source gun is divided into a front end source bin and a rear end driving rod, the separation and combination of the source gun can be realized by relatively rotating the rear end driving rod, and the shielding baffle inside the collimating hole is also synchronously linked to open and close. The present application realizes blind type anti-overrun centering without visual reference, and integrates the ray operation and the protection opening and closing structure, so as to improve the operation efficiency and avoid unnecessary ray irradiation risk.

Description

Technical Field

[0001] This invention relates to the field of logging instrument experimental devices, and more particularly to a gamma calibration device and calibration method for well maintenance. Background Technology

[0002] During well maintenance of oilfield measurement-while-drilling (MWD) and rotary steerable tools, it is essential to calibrate the internal azimuth gamma sensor to ensure measurement accuracy. Conventional gamma calibration typically involves placing a heavy calibration source ring containing a high-energy radiation source around the drill collar. The ring is then manually pushed, pulled, and rotated to align its collimation hole (radiation emission channel) with the gamma sensor inside the drill collar. To prevent unnecessary radiation exposure to operators from an uncalibrated source, the calibration source ring is usually equipped with a manually operable mechanical shield.

[0003] However, existing gamma calibration devices have significant shortcomings in practical operation. Firstly, blind positioning and alignment are extremely difficult. Because the gamma sensor is hidden inside the thick-walled drill collar, there is a lack of absolute physical limit reference externally. When operators push the source ring, which weighs tens of kilograms, across the smooth surface of the drill collar, it is very easy for the sensor to slip or overshoot, requiring repeated small-amplitude position adjustments, resulting in low positioning accuracy and long calibration time. Secondly, radiation protection and operational procedures are disconnected, leading to low work efficiency and potential for operational errors. The existing shielding baffle opening and closing mechanism and the insertion and removal of the radiation source are usually two independent actions. Operators need to separately locate and operate the mechanical switch of the baffle before and after inserting the radiation source. This not only makes the operation cumbersome and prolongs the overall calibration time, but also increases the risk of human error by overlooking to switch the baffle during multi-step operations, increasing potential safety hazards. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a gamma calibration device and calibration method for well maintenance.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A gamma calibration device for well maintenance includes a calibration source ring, a drill collar with a gamma sensor inside, and a source gun with a radiation source. The calibration source ring is sleeved and slidably disposed outside the drill collar. A blind groove is pre-set on the outer wall of the drill collar. An elastic positioning element is disposed in the blind groove, which is used to make the elastic positioning element have a preload force that protrudes outward along the radial direction of the drill collar when driven by the elastic element. The inner circumferential wall of the calibration source ring has a limiting groove. One end of the limiting groove is a limiting end face, and the other end is a lifting slope that smoothly transitions to the inner wall surface of the calibration source ring. The calibration source ring has a collimation hole that connects the inside and outside in the radial direction. The source gun can be movably inserted into the collimation hole. The source gun includes a detachably connected front source chamber and a rear drive rod. The radiation source is located at the end of the front source chamber. A shielding baffle is provided at the collimation hole on the inner side wall of the calibration source ring 1. A manually openable and closed sealing assembly is provided at the collimation hole on the outer side wall of the calibration source ring. When the calibration source ring slides along the drill collar axis, the elastic positioning member abuts against the inner wall of the calibration source ring. When the limiting slide groove moves axially to the elastic positioning member, the elastic positioning member is engaged in the limiting slide groove. When the calibration source ring rotates toward the limiting end face until the elastic positioning member abuts against the limiting end face, the collimation hole and the gamma sensor are coaxially aligned in the radial direction. The collimation hole is provided with an anti-rotation structure to constrain the rotation of the front source chamber. After the source gun is inserted into the collimation hole in a combined state, when the rear drive rod rotates relative to the front source chamber in the retraction direction and gradually disengages, the mechanical structure of the rear drive rod is in transmission cooperation with the shielding baffle to drive the shielding baffle to open.

[0006] Furthermore, the elastic positioning component includes a base and multiple elastic elements disposed at the bottom of the base. The top of the base has a wedge-shaped structure, and the two axial sides of the base are provided with inclined guide chamfers to guide the insertion and sliding of the calibration source ring. The elastic positioning component provides a continuous radial outward elastic force through the multiple elastic elements at the bottom, causing the wedge-shaped structure at the top of the base to fit tightly against the inner wall of the inserted calibration source ring. Since the drill collar often has dried mud or dirt adhering to its surface after downhole operations, when the calibration source ring slides along the axial direction of the drill collar, the top of the elastic positioning component, under the action of elastic force, scrapes away mud and other dirt from the sliding trajectory of the drill collar's outer wall and the inner wall of the calibration source ring during the relative sliding process. Combined with the inclined guide chamfers on both sides, this facilitates the insertion operation of the calibration source ring and eliminates potential source distance deviations caused by impurities.

[0007] Furthermore, after calibration, the calibration source ring is rotated towards the lifting ramp, causing the elastic positioning element to be pressed back into the blind groove along the lifting ramp to release the axial and circumferential positioning, allowing the calibration source ring to move out along the drill collar axis. The rigid limiting end face serves as the stopping point for circumferential rotation, preventing over-rotation. The lifting ramp at the other end functions as a mechanical unlocking mechanism. After calibration, the operator only needs to rotate the calibration source ring in the opposite direction, and the elastic positioning element will be gradually pressed downwards into the blind groove along the slope of the lifting ramp, thereby releasing the axial and circumferential locking without the need for additional unlocking tools, simplifying the disassembly process of the device.

[0008] Furthermore, the relative spatial geometric positions of the limiting end face, the central axis of the collimation hole, and the elastic positioning member and the gamma sensor inside the drill collar are matched, so that when the elastic positioning member physically abuts against the limiting end face, the central axis of the collimation hole passes precisely through the geometric center of the gamma sensor. Since the gamma sensor is deeply embedded inside the solid, thick-walled drill collar, its external view is completely obstructed, making traditional blind alignment time-consuming and labor-intensive. This application projects the invisible relative position of the sensor onto the structural dimensions of the limiting end face and the collimation hole through pre-processed geometric spatial substitution. The system automatically completes the external displacement mapping of the target point by relying on the mechanical rigidity constraint of the elastic positioning member against the limiting end face. Based on the alignment mechanism of rigid obstruction, the fine-tuning operation relying on manual experience is transformed into a simple blind operation of pushing in and rotating to the bottom, achieving automatic alignment of three-dimensional spatial coordinates.

[0009] Furthermore, the rear end face of the front-end source compartment has an internally threaded blind hole, and the front end of the rear-end drive rod has an externally threaded section that engages with the internally threaded blind hole. The front-end source compartment contains the radiation source and can be independently stored in a safe area during non-calibration phases. During separation and unspinning, the relative helical rotational displacement generated by the two provides a rotational power source for driving the internal shielding baffle, converting the external disassembly and assembly actions into the rotational driving force of the shielding baffle.

[0010] Furthermore, the anti-rotation structure consists of a spline ring fixedly embedded inside the collimation hole. The outer wall of the front source chamber is provided with a guide groove that physically interferes with the spline ring to restrict the circumferential degree of freedom of the front source chamber within the collimation hole. The guide pair formed by the spline ring and the guide groove only allows the front source chamber to translate along the central axis of the collimation hole, locking its rotational degree of freedom. This not only ensures that the rear drive rod can provide sufficient turning reaction torque to complete the threading action, but also ensures that the radiation source at the end of the front source chamber remains in the collimation hole or is removed synchronously with the rear drive rod.

[0011] Furthermore, a radial transmission pin is protruding from the outer circumference of the rear drive rod, and a force-receiving fork mechanism is connected to the shielding baffle. The force-receiving fork mechanism extends into the channel of the collimation hole. When the rear drive rod rotates in the retraction direction and disengages from the front source chamber, the radial transmission pin actuates the force-receiving fork mechanism, causing the shielding baffle to open the ray channel where the collimation hole is located. When the operator rotates the rear drive rod in the retraction direction, the rear drive rod retracts along a spiral trajectory, and the radial transmission pin fixed on it cuts into and actuates the force-receiving fork mechanism, causing displacement and thus rotating the shielding baffle. The operator does not need to perform a separate baffle opening step; the opening operation is completed synchronously inside simply by turning the handle, avoiding inconvenience and potential hazards caused by human forgetfulness.

[0012] Furthermore, the shielding baffle is provided with a transmission window for guiding the X-ray channel. When the rear drive rod rotates in the tightening direction and re-screws into the internal thread blind hole of the front source chamber, the radial transmission pin releases the force-bearing fork mechanism in the reverse direction. The shielding baffle is then closed by the reverse action of the radial transmission pin. After calibration, the operator needs to rotate the rear drive rod in the tightening direction to reassemble and extract the front source chamber. During this tightening process, the movement trajectory of the radial transmission pin reverses, applying a reverse force to the force-bearing fork mechanism, forcing the shielding baffle to move back in the reverse direction, moving its transmission window out of the optical path, and re-blocking the collimation hole with a solid body. As long as the source gun is in the retractable state, the X-ray channel is physically blocked and interlocked, thus preventing safety accidents caused by forgetting to close the shielding baffle.

[0013] Furthermore, the sealing assembly includes a vertical adjustment channel and a sealing pin. The vertical adjustment channel is vertically connected to the collimation hole, and the sealing pin is movably disposed within the vertical adjustment channel. The sealing pin has a through hole corresponding to the collimation hole for the source gun to pass through. The sealing pin is used to circumferentially rotate and seal the collimation hole from the outside after the source gun is withdrawn. Even after the rear drive rod is fully withdrawn, the collimation hole remains open to the outside. By manually rotating the sealing pin, the through hole is offset from the axis of the collimation hole, and the solid part of the sealing pin blocks the external passage.

[0014] Furthermore, the top of the sealing pin is provided with an operating part, and the bottom of the corresponding position of the collimation hole and the vertical adjustment channel is provided with a positioning seat to accommodate the sealing pin. The main body of the calibration source ring and the shielding baffle are both made of tungsten alloy or lead-based material with high-density radiation shielding function. The positioning seat provides alignment and bottom concentric support for the sealing pin, ensuring that the pin does not deflect under frequent opening and closing and industrial-grade vibration, and can maintain mechanical stability and radiation shielding continuity under extreme working conditions.

[0015] A device-based calibration method includes the following steps: S1: Press the elastic positioning element into the blind groove, and at the same time, put the calibration source ring on the outside of the drill collar and push it along the drill collar axis; S2: When the limiting slide groove in the calibration source ring moves to the elastic positioning element, the elastic positioning element is engaged in the limiting slide groove, thus completing the axial physical positioning of the calibration source ring; S3: Rotate the calibration source ring toward the limiting end face until the elastic positioning member is blocked by the limiting end face of the limiting slide and cannot continue to rotate. At this time, the radial alignment of the collimation hole and the gamma sensor in the drill collar is completed. S4: Screw the front source chamber holding the radiation source and the rear drive rod together to form a complete source gun, and insert and fix the source gun as a whole into the collimation hole; S5: Apply a rotational torque in the rewind direction to the rear drive rod. Since the front source chamber cannot rotate due to the anti-rotation structure, the rear drive rod triggers and pushes open the shielding baffle located on the inside while rewinding and disengaging, opening the X-ray channel for gamma calibration.

[0016] Furthermore, the following evacuation steps are included after the calibration is completed: S6: After calibration, apply a rotational torque in the tightening direction to the rear drive rod to re-tighten it to the front source chamber; S7: During this tightening process, the rear drive rod synchronously reverses the push of the shielding baffle, causing the shielding baffle to close and complete the safe shielding of the radiation source. Then, the entire segmented source gun will be pulled out of the collimation hole and the sealing assembly outside the collimation hole will be closed. S8: Rotate the calibration source ring in the opposite direction to the lifting ramp, so that the elastic positioning element slides out along the lifting ramp, release the axial positioning, and then move the calibration source ring out along the drill collar axis.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention provides an elastic positioning element on the outer wall of the drill collar and a limiting groove with a limiting end face on the inner wall of the calibration source ring. The operator only needs to push the source ring. When the elastic positioning element is inserted into the groove, the axial absolute positioning is completed. Then, the source ring is rotated in one direction until it stops rotating at the limiting end face, thus completing the circumferential alignment. This improves calibration efficiency and alignment accuracy. 2. This invention adopts a segmented source gun and an anti-rotation structure inside the collimation hole. By screwing in or out the rear drive rod, the operator can simultaneously engage and disengage the drive rod from the source chamber and mechanically move the internal shielding baffle using the radial transmission pin on the rear drive rod. This not only eliminates the need for additional independent opening and closing steps, effectively shortening the calibration process, but also avoids the operational error of manually missing the switch on the shielding baffle through mechanical linkage, greatly improving the ease of operation and the safety of the operation. Attached Figure Description

[0018] Figure 1 This is a calibration assembly diagram of the source ring and drill collar; Figure 2 This is a schematic diagram of the drill collar structure; Figure 3 This is a schematic diagram of the sealing pin structure; Figure 4 This is a schematic cross-sectional view of the calibration source ring; Figure 5 This is a schematic diagram of the shielding baffle. Figure 6 This is a top view of the cross-section of the calibration source ring; Figure 7 yes Figure 6 Enlarged view of point A in the middle; Figure 8 This is a schematic diagram of the source gun's structure; Figure labels: 1-calibration source ring, 2-drill collar, 3-source gun, 301-front source chamber, 302-rear drive rod, 4-elastic positioning component, 5-limiting slide groove, 501-limiting end face, 502-lifting inclined surface, 6-collimation hole, 7-shielding baffle, 8-spline ring, 9-guide groove, 10-radial transmission pin, 11-force-receiving fork mechanism, 12-transmission window, 13-vertical control channel, 14-sealing pin, 15-through hole, 16-operating part, 17-positioning round seat. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0020] Example 1, as Figures 1-8 As shown, the present invention discloses a gamma calibration device for well maintenance, comprising a calibration source ring 1, a drill collar 2 with a gamma sensor inside, and a source gun 3 with a radiation source. The calibration source ring 1 is sleeved and slidably disposed outside the drill collar 2. A blind groove is preset on the outer wall of the drill collar 2, and an elastic positioning member 4 is disposed in the blind groove, which is used to make the elastic positioning member 4 have a preload force that protrudes outward along the radial direction of the drill collar 2 when driven by the elastic member.

[0021] The inner circumferential wall of the calibration source ring 1 has a limiting groove 5. One end of the limiting groove 5 is a limiting end face 501, and the other end is a lifting inclined surface 502 that smoothly transitions to the inner wall surface of the calibration source ring 1. The calibration source ring 1 has a collimation hole 6 that connects the inside and outside. The source gun 3 can be movably inserted into the collimation hole 6. The source gun 3 includes a detachably connected front source chamber 301 and a rear drive rod 302. The radiation source is located at the end of the front source chamber 301. A shielding baffle 7 is provided at the collimation hole 6 on the inner side wall of the calibration source ring 1. A manually openable and closed sealing assembly is provided at the collimation hole 6 on the outer side wall of the calibration source ring 1.

[0022] When the calibration source ring 1 slides along the drill collar 2 axially, the elastic positioning member 4 abuts against the inner wall of the calibration source ring 1. When the limiting slide groove 5 axially moves to the elastic positioning member 4, the elastic positioning member 4 engages within the limiting slide groove 5. One end of the limiting slide groove 5 is a rigid limiting end face 501, and the other end is a lifting inclined surface 502 that smoothly transitions to the inner wall surface of the calibration source ring 1. The calibration source ring 1 rotates toward the limiting end face 501 until the elastic positioning member 4 abuts against it. When the limiting end face 501 is in the position, the collimation hole 6 and the gamma sensor are coaxially aligned in the radial direction. The collimation hole 6 is provided with an anti-rotation structure for constraining the rotation of the front source chamber 301. After the source gun 3 is inserted into the collimation hole 6 in a combined state, when the rear drive rod 302 rotates relative to the front source chamber 301 in the unrotation direction and gradually disengages, the mechanical structure of the rear drive rod 302 is in transmission cooperation with the shielding baffle 7 to drive the shielding baffle 7 to open.

[0023] The elastic positioning element 4 includes a base and multiple elastic elements disposed at the bottom of the base. The top of the base has a wedge-shaped structure, and the two axial sides of the base are provided with inclined guide chamfers to guide the insertion and sliding of the calibration source ring 1. Specifically, the elastic positioning element 4 provides a continuous radial outward elastic force through the multiple elastic elements at the bottom, so that the wedge-shaped structure at the top of the base is tightly attached to the inner wall of the inserted calibration source ring 1. Since the drill collar 2 often has dried mud or dirt adhering to its surface after downhole operation, when the calibration source ring 1 slides along the axial direction of the drill collar 2, the top of the elastic positioning element 4, under the action of elastic force, scrapes away the mud and dirt on the sliding trajectory of the outer wall of the drill collar 2 and the inner wall of the calibration source ring 1 during the relative sliding process. Combined with the inclined guide chamfers on both sides, it facilitates the insertion operation of the calibration source ring 1 and eliminates potential source distance deviations caused by impurities.

[0024] After calibration, the calibration source ring 1 is rotated towards the lifting ramp 502, causing the elastic positioning member 4 to be pressed back into the blind groove along the lifting ramp 502, thus releasing the axial and circumferential positioning and allowing the calibration source ring 1 to move out along the axial direction of the drill collar 2. Specifically, the rigid limiting end face 501 serves as the stop point for circumferential rotation, preventing over-rotation. The lifting ramp 502 at the other end functions as a mechanical unlocking mechanism. After calibration, the operator only needs to rotate the calibration source ring 1 in the opposite direction, and the elastic positioning member 4 will be gradually pressed downwards into the blind groove along the slope of the lifting ramp 502, thereby releasing the axial and circumferential locking without the need for additional unlocking tools, simplifying the disassembly process of the device.

[0025] The relative spatial geometric positions of the limiting end face 501, the central axis of the collimation hole 6, and the elastic positioning member 4 and the gamma sensor inside the drill collar 2 are matched so that when the elastic positioning member 4 physically abuts against the limiting end face 501, the central axis of the collimation hole 6 passes precisely through the geometric center of the gamma sensor. Specifically, since the gamma sensor is deeply embedded inside the solid, thick-walled drill collar 2, the external view is completely blocked, making traditional blind alignment time-consuming and labor-intensive. This application projects the invisible sensor relative position onto the structural dimensions of the limiting end face 501 and the collimation hole 6 through pre-processed geometric spatial substitution. The system automatically completes the external displacement mapping of the target point by relying on the mechanical rigidity constraint of the elastic positioning member 4 against the limiting end face 501. Based on the alignment mechanism of rigid obstruction, the fine-tuning operation that relies on human experience is transformed into a simple blind operation of pushing in and rotating to the bottom, realizing automatic alignment of three-dimensional spatial coordinates.

[0026] The rear end face of the front source chamber 301 is provided with an internally threaded blind hole, and the front end of the rear drive rod 302 is provided with an externally threaded section that engages with the internally threaded blind hole. Specifically, the front source chamber 301 contains the radiation source and can be independently stored in a safe area during the non-calibration phase. To prevent radiation leakage from the radiation source in the non-calibration state, the front source chamber 301 is made entirely of high-density radiation shielding materials such as tungsten alloy or lead-based materials to ensure personnel safety when the source gun 3 is removed as a whole or stored separately. During separation and unspinning, the relative helical rotational displacement generated by the two provides a rotational power source for driving the internal shielding baffle 7, converting the external disassembly and assembly actions into the rotational driving force of the shielding baffle 7.

[0027] The anti-rotation structure is a spline ring 8 fixedly embedded inside the collimation hole 6. The outer wall of the front source chamber 301 is provided with a guide groove 9 that physically interferes with the spline ring 8 to restrict the circumferential degree of freedom of the front source chamber 301 within the collimation hole 6. Specifically, if the front source chamber 301 does not have an anti-rotation function, it will rotate along with the rear drive rod 302 when it is screwed in or out, causing the threads of the two to be unable to separate or lock. The guide pair formed by the spline ring 8 and the guide groove 9 only allows the front source chamber 301 to translate along the central axis of the collimation hole 6, locking its rotational degree of freedom. This not only ensures that the rear drive rod 302 can provide sufficient turning reaction torque to complete the threading action, but also ensures that the radiation source at the end of the front source chamber 301 remains in the collimation hole 6 or is removed synchronously with the rear drive rod 302.

[0028] A radial transmission pin 10 is protruding from the outer circumference of the rear drive rod 302. A force-receiving fork mechanism 11 is connected to the shielding baffle 7. The force-receiving fork mechanism 11 extends into the channel of the collimation hole 6. When the rear drive rod 302 rotates in the retraction direction and disengages from the front source chamber 301, the radial transmission pin 10 actuates the force-receiving fork mechanism 11, causing the shielding baffle 7 to open the ray channel where the collimation hole 6 is located. Specifically, the shielding baffle 7 is eccentrically pivotally connected to the side of the collimation hole 6, and its rotation axis is parallel to the central axis of the collimation hole 6 and has a radial offset distance, so that the shielding baffle 7 can rotate into or out of the optical path of the collimation hole 6 in a fan-shaped trajectory. The force-receiving fork mechanism 11 includes a rotating sleeve sleeved and pivotally mounted on the inner wall of the collimation hole 6. The outer wall of the rotating sleeve is connected to the rotation shaft of the shielding baffle 7 through a gear pair or a lever. The inner wall of the rotating sleeve has an axially extending elongated groove. When the operator rotates the rear drive rod 302 in the retraction direction, the rear drive rod 302 retracts along a spiral trajectory, and the radial transmission pin 10 fixed thereon cuts into the elongated slot. During this transmission process, the axial retraction displacement of the radial transmission pin 10 slides freely within the elongated slot without axial interference, while its rotational displacement pushes the slot wall, forcing the force-bearing fork mechanism 11 to undergo pure rotational displacement, thereby rotating the shielding baffle 7. The operator does not need to perform a separate baffle opening step; the opening operation is automatically completed internally with just the turning of the handle, avoiding inconvenience and potential hazards caused by human forgetfulness. Preferably, a limiting groove is provided in the collimation hole 6 along the channel direction of the collimation hole 6, and the force-bearing fork mechanism 11 is disposed in the limiting groove. At the same time, a limiting baffle is provided in the limiting groove to prevent the force-bearing fork mechanism 11 from radially deviating, ensuring that the force-bearing fork mechanism 11 does not detach from the radial transmission pin 10 during transmission. In addition, the width of the engagement point of the force-bearing shift fork mechanism 11 is greater than the width of the radial transmission pin 10, in order to ensure that the radial transmission pin 10 will undergo axial displacement when the rear drive rod 302 rotates, so as to ensure that the radial transmission pin 10 is always connected to the engagement point of the force-bearing shift fork mechanism 11.

[0029] The shielding baffle 7 is provided with a transmission window 12 for guiding the X-ray channel. When the rear drive rod 302 rotates in the tightening direction and re-screws into the internal thread blind hole of the front source chamber 301, the radial transmission pin 10 releases the force-bearing fork mechanism 11 in the reverse direction. The shielding baffle 7 is then pushed in the reverse direction by the radial transmission pin 10 to close the collimation hole 6. Specifically, after calibration, the operator needs to rotate the rear drive rod 302 in the tightening direction to reassemble and extract the front source chamber 301. During this tightening process, the movement trajectory of the radial transmission pin 10 reverses, applying a reverse pushing force to the force-bearing fork mechanism 11, forcing the shielding baffle 7 to move back in the reverse direction, moving its transmission window 12 out of the optical path, and re-blocking the collimation hole 6 with a solid body. As long as the source gun 3 is in the retractable state, the X-ray channel is physically blocked and interlocked, thus preventing safety accidents caused by forgetting to close the shielding baffle 7. In addition, after the source gun 3 is completely removed from the calibration source ring 1, since the front end of the front source chamber 301 is the emission port of the radiation source, the operator can screw a special tungsten alloy shielding protection cap on the front end of the front source chamber 301, or insert the complete source gun 3 into the radiation-proof transfer lead container for locking, thereby achieving radiation shielding protection for the radiation source during its external transit.

[0030] The sealing assembly includes a vertical adjustment channel 13 and a sealing pin 14. The vertical adjustment channel 13 is vertically connected to the collimation hole 6. The sealing pin 14 is movably disposed within the vertical adjustment channel 13. The sealing pin 14 has a through hole 15 corresponding to the collimation hole 6 for the source gun 3 to pass through. The sealing pin 14 is used to circumferentially rotate and seal the channel between the collimation hole 6 and the outside after the source gun 3 is withdrawn. Specifically, after the calibration operation is completed and the source gun 3 is completely withdrawn from the collimation hole 6, the operator immediately manually rotates the sealing pin 14 to offset the through hole 15 from the axis of the collimation hole 6, and the solid part of the sealing pin 14 instantly blocks the external passage. Similarly, during the calibration preparation stage, before the source gun 3 is fully inserted into the collimation hole 6, the operator needs to rotate the sealing pin 14 in the reverse direction to restore the coaxial connection between the through hole 15 and the collimation hole 6, allowing the source gun 3 to pass through and penetrate deep into the channel. This not only protects against dust and moisture intrusion that could affect the precision mechanism but also increases operational safety.

[0031] The top of the plugging pin 14 is provided with an operating part 16, and the bottom of the collimation hole 6 and the vertical adjustment channel 13 are provided with positioning seats 17 to accommodate the plugging pin 14. The main body of the calibration source ring 1 and the shielding baffle 7 are both made of tungsten alloy or lead-based material with high-density radiation shielding function. Specifically, since gamma calibration involves a high-penetration, high-radiation source, ordinary metals are difficult to meet the protection requirements in a limited space. The main body of the calibration source ring 1 and the shielding baffle 7 are made of high-density, high-atomic-number tungsten alloy or lead-based material, which can physically absorb and attenuate gamma rays at weak points by orders of magnitude, ensuring that the dose equivalent rate outside the device is far below the occupational safety limit. At the same time, the positioning seat 17 provides alignment and bottom concentric support for the plugging pin 14, ensuring that the pin does not deflect under frequent opening and closing and industrial-grade vibration, and can maintain mechanical stability and radiation shielding continuity under extreme conditions.

[0032] Example 2, based on Example 1, proposes a device-based calibration method, including the following steps: S1: The operator first presses the elastic positioning element 4 into the pre-set blind groove on the outer wall of the drill collar 2 to keep it in a compressed state, and then puts the calibration source ring 1 on the outside of the drill collar 2. Preferably, the calibration source ring 1 is set on a sliding carriage with a support structure. The sliding carriage allows the calibration source ring 1 to slide along the axial direction of the fixed drill collar 2, and the support structure allows the calibration source ring 1 to be adjusted circumferentially. During the process of pushing the calibration source ring 1 along the axial direction of the drill collar 2, the elastic positioning element 4, driven by the bottom elastic element, slides against the inner wall of the calibration source ring 1 with its wedge-shaped top, which not only provides guiding support for the sliding, but also scrapes away the mud and dirt on the surface of the drill collar 2.

[0033] S2: As the calibration source ring 1 continues to move axially, when the limiting groove 5 on the inner wall of the calibration source ring 1 moves to the position of the elastic positioning member 4, the elastic positioning member 4 engages inside the limiting groove 5. At this time, due to the physical engagement between the components, the operator can feel the limiting feedback, and the calibration source ring 1 can no longer slide axially.

[0034] S3: After axial locking, the operator rotates the calibration source ring 1 unidirectionally toward the limiting end face 501. During this process, the elastic positioning member 4 slides relative to the limiting groove 5, which is arranged in an arc shape, until the side of the elastic positioning member 4 physically collides with and abuts against the rigid limiting end face 501 at one end of the limiting groove 5, and the calibration source ring 1 is blocked and cannot continue to rotate. At this time, through the previous spatial geometric matching, the central axis of the collimation hole 6 is radially aligned with the gamma sensor inside the drill collar 2.

[0035] Example 3, based on Example 2, proposes a device-based calibration method, which further includes: S4: During the calibration preparation stage, the front source chamber 301 holding the high-energy radiation source is screwed together with the rear drive rod 302 to form a complete source gun 3. Then, the source gun 3 is pushed in along the collimation hole 6, and the guide groove 9 on the outer wall of the front source chamber 301 is physically interfered with and inserted into the spline ring 8 inside the collimation hole 6, thereby constraining the front source chamber 301 in the channel and restricting its circumferential rotation.

[0036] S5: Apply a rotational torque in the unspinning direction to the rear drive rod 302. Since the front source chamber 301 cannot rotate due to the restriction of the spline ring 8, as the rear drive rod 302 unspins and separates from the front source chamber 301, the radial transmission pin 10 on its outer circumference rotates synchronously and precisely actuates the force-bearing fork mechanism 11 within the channel, rotating the shielding baffle 7 and aligning the transmission window 12 with the internal X-ray path, thereby opening the X-ray channel for gamma calibration. This step synchronously achieves the mechanical linkage between source chamber unlocking and X-ray window opening.

[0037] Preferably, if the drill collar 2 is equipped with multiple gamma sensors to be tested, each gamma sensor is provided with a corresponding elastic positioning element 4. By detecting each segment and repeatedly executing the above steps S2-S5, the multi-segment calibration operation can be completed.

[0038] Example 4, based on Example 3, proposes a calibration method that includes the following withdrawal steps after calibration: S6: After the gamma calibration data acquisition is completed, the operator applies a rotational torque in the tightening direction to the separated rear drive rod 302, so that its front external thread section is screwed back into and secured in the internal thread blind hole of the front source chamber 301.

[0039] S7: During this tightening process, the radial transmission pin 10 reverses its movement trajectory, simultaneously releasing or actuating the force-bearing fork mechanism 11, forcing the shielding baffle 7 back to its initial position. This completely seals the collimation hole 6 with its solid portion, completing the safety shielding of the radiation source. After the front source chamber 301 and the rear drive rod 302 are firmly reassembled into a complete segmented source gun 3, the operator pulls it out of the collimation hole 6 as a whole, and then closes the external channel of the collimation hole 6 by rotating the sealing pin 14 through the top operating part 16.

[0040] S8: Rotate the calibration source ring 1 in the opposite direction to the lifting ramp 502. The elastic positioning element 4, which was originally stuck in the limiting groove 5, will slide relative to the lifting ramp 502. Under the wedge-shaped downward pressure of the ramp, the elastic positioning element 4 will be gradually and smoothly pressed back into the blind groove of the drill collar 2, thereby automatically releasing the axial and circumferential limiting of the calibration source ring 1. Then, the operator can move the calibration source ring 1 outward along the axial direction of the drill collar 2 as a whole, completing the entire calibration and removal operation.

[0041] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A gamma calibration device for well maintenance, comprising a calibration source ring (1), a drill collar (2) with a gamma sensor inside, and a source gun (3) with a radiation source, wherein the calibration source ring (1) is sleeved and slidably disposed outside the drill collar (2), characterized in that: The outer wall of the drill collar (2) is provided with a blind groove, and an elastic positioning element (4) is provided in the blind groove to make the elastic positioning element (4) have a pre-tightening force that protrudes outward along the radial direction of the drill collar (2) driven by the elastic element. The inner circumferential wall of the calibration source ring (1) is provided with a limiting groove (5) in the circumferential direction. One end of the limiting groove (5) is provided as a limiting end face (501), and the other end is provided as a lifting inclined surface (502) that smoothly transitions to the inner wall surface of the calibration source ring (1). The calibration source ring (1) is provided with a collimation hole (6) that connects the inside and outside in the radial direction. The source gun (3) can be movably inserted into the collimation hole (6). The source gun (3) includes a front source chamber (301) and a rear drive rod (302) that can be detachably connected. The radiation source is provided at the end of the front source chamber (301). A shielding baffle (7) is provided at the collimation hole (6) on the inner side wall of the calibration source ring (1). A manually openable and closed sealing assembly is provided at the collimation hole (6) on the outer side wall of the calibration source ring (1). When the calibration source ring (1) slides along the axial direction of the drill collar (2), the elastic positioning member (4) abuts against the inner wall of the calibration source ring (1). When the limiting slide groove (5) moves axially to the elastic positioning member (4), the elastic positioning member (4) is engaged in the limiting slide groove (5). When the calibration source ring (1) rotates toward the limiting end face (501) until the elastic positioning member (4) abuts against the limiting end face (501), the collimation hole (6) and the gamma The sensors are coaxially aligned in the radial direction. The collimation hole (6) is provided with an anti-rotation structure to constrain the rotation of the front source chamber (301). After the source gun (3) is inserted into the collimation hole (6) in a combined state, when the rear drive rod (302) rotates relative to the front source chamber (301) in the unrotation direction and gradually disengages, the mechanical structure of the rear drive rod (302) is in transmission cooperation with the shielding baffle (7) to drive the shielding baffle (7) to open.

2. The gamma calibration device for well maintenance according to claim 1, characterized in that: The elastic positioning element (4) includes a base and a plurality of elastic elements disposed at the bottom of the base. The top of the base has a wedge-shaped structure, and the two axial sides of the base are provided with inclined guide chamfers to guide the insertion and sliding of the calibration source ring (1).

3. A gamma calibration device for well maintenance according to claim 1, characterized in that: After calibration, the calibration source ring (1) is rotated toward the lifting ramp (502) so that the elastic positioning member (4) is pressed back into the blind groove along the lifting ramp (502) to release the axial and circumferential positioning, and the calibration source ring (1) is moved out along the drill collar (2) axially.

4. A gamma calibration device for well maintenance according to claim 3, characterized in that: The relative spatial geometric positions of the limiting end face (501), the central axis of the collimation hole (6), and the relative spatial geometric positions of the elastic positioning member (4) and the gamma sensor inside the drill collar (2) are matched so that when the elastic positioning member (4) physically abuts against the limiting end face (501), the central axis of the collimation hole (6) passes through the geometric center of the gamma sensor.

5. A gamma calibration device for well maintenance according to claim 1, characterized in that: The rear end face of the front source chamber (301) is provided with an internal thread blind hole, and the front end of the rear drive rod (302) is provided with an external thread section that engages with the internal thread blind hole.

6. A gamma calibration device for well maintenance according to claim 5, characterized in that: The anti-rotation structure is a spline ring (8) fixedly embedded inside the collimation hole (6). The outer wall of the front source chamber (301) is provided with a guide groove (9) that physically interferes with the spline ring (8) to limit the circumferential degree of freedom of the front source chamber (301) in the collimation hole (6).

7. A gamma calibration device for well maintenance according to claim 5, characterized in that: A radial transmission pin (10) is protruding on the outer circumference of the rear drive rod (302). A force-receiving fork mechanism (11) is connected to the shielding baffle (7). The force-receiving fork mechanism (11) extends into the channel of the collimation hole (6). When the rear drive rod (302) rotates in the rewind direction and disengages from the front source chamber (301), the radial transmission pin (10) moves the force-receiving fork mechanism (11), causing the shielding baffle (7) to open the ray channel where the collimation hole (6) is located.

8. A gamma calibration device for well maintenance according to claim 7, characterized in that: The shielding baffle (7) is provided with a transmission window (12) for guiding the ray channel. When the rear drive rod (302) rotates in the tightening direction and re-screws into the internal thread blind hole of the front source chamber (301), the radial transmission pin (10) releases the force-bearing fork mechanism (11) in the reverse direction. The shielding baffle (7) is pushed in the reverse direction by the radial transmission pin (10) and closes the collimation hole (6).

9. A gamma calibration device for well maintenance according to claim 1, characterized in that: The sealing assembly includes a vertical control channel (13) and a sealing pin (14). The vertical control channel (13) is vertically connected to the collimation hole (6). The sealing pin (14) is movably disposed in the vertical control channel (13). The sealing pin (14) is provided with a through hole (15) corresponding to the collimation hole (6) for the source gun (3) to pass through. The sealing pin (14) is used to circumferentially rotate and seal the collimation hole (6) and the external channel after the source gun (3) is pulled out.

10. A gamma calibration device for well maintenance according to claim 9, characterized in that: The top of the sealing pin (14) is provided with an operating part (16), and the bottom of the collimation hole (6) and the vertical adjustment channel (13) is provided with a positioning round seat (17) to accommodate the sealing pin (14). The main body of the calibration source ring (1) and the shielding baffle (7) are both made of tungsten alloy or lead-based material with high-density radiation shielding function.

11. A calibration method for a gamma calibration device for well maintenance according to any one of claims 1-10, characterized in that, Includes the following steps: S1: Press the elastic positioning element (4) into the blind groove, and at the same time put the calibration source ring (1) on the outside of the drill collar (2) and push it along the axial direction of the drill collar (2); S2: When the limiting slide (5) in the calibration source ring (1) moves to the elastic positioning member (4), the elastic positioning member (4) is engaged in the limiting slide (5) to complete the axial physical positioning of the calibration source ring (1); S3: Rotate the calibration source ring (1) toward the limiting end face (501) until the elastic positioning member (4) is blocked by the limiting end face (501) of the limiting slide groove (5) and cannot continue to rotate. At this time, the radial alignment of the collimation hole (6) and the gamma sensor in the drill collar (2) is completed.

12. The calibration method for a gamma calibration device for well maintenance according to claim 11, characterized in that, Also includes: S4: Screw the front source chamber (301) holding the radioactive source and the rear drive rod (302) together to form a complete source gun (3), and insert the source gun (3) as a whole into the collimation hole (6); S5: Apply a rotational torque in the rewind direction to the rear drive rod (302). Since the front source chamber (301) is restricted from rotating by the anti-rotation structure, the rear drive rod (302) triggers and pushes open the shielding baffle (7) located on the inner side while rewinding and disengaging, thus opening the X-ray channel for gamma calibration.

13. A calibration method for a gamma calibration device for well maintenance according to claim 12, characterized in that, The following evacuation steps are included after calibration: S6: After calibration, apply a rotational torque in the tightening direction to the rear drive rod (302) to re-tighten it to the front source chamber (301); S7: During this tightening process, the rear drive rod (302) synchronously reverses the push of the shielding baffle (7), so that the shielding baffle (7) closes to complete the safety shielding of the radiation source. Then, the entire segmented source gun (3) is pulled out of the collimation hole (6) and the sealing assembly outside the collimation hole (6) is closed. S8: Rotate the calibration source ring (1) in the opposite direction toward the lifting ramp (502) to make the elastic positioning member (4) slide out along the lifting ramp (502), release the axial positioning, and then move the calibration source ring (1) out along the drill collar (2) axially.

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