A loose broken formation core recovery measurement device and measurement method

Abstract

The application provides a loose broken formation core recovery rate measuring device, which comprises a core box, a front baffle and a movable baffle are arranged in the core box, a cover plate is arranged on the core box, a height adjusting assembly is arranged on one end of the core box close to the front baffle, the upper end of the front baffle is connected with the lower surface of the cover plate, a core density adjusting assembly is arranged on one end of the core box close to the movable baffle, the end of the core density adjusting assembly is connected with the movable baffle, a seismic source transmitter and two detectors are inlaidly arranged in the cover plate, a control instrument is arranged outside the core box, and the detectors and the core density adjusting assembly are electrically connected with the control instrument. The front baffle is designed, the cross-sectional area can be adjusted according to the actual size of the coring drilling tool, the device can automatically restore the compacted state of the loose broken formation to the greatest extent through the control of the control instrument by using the geophysical sensor technology, and the core recovery rate can be directly calculated and recorded, so that the problem that the loose broken core is difficult to be accurately measured on site is effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of engineering geological drilling technology, specifically relating to a device and method for measuring the core recovery rate of loose and fractured strata. Background Technology

[0002] Core recovery rate is an important basis for engineering geological analysis and evaluation during engineering geological exploration. Many factors influence core recovery rate, the primary one being rock mass quality. A high or low core recovery rate directly reflects the quality of the rock mass. For example, during field drilling, the core recovery rate is very low in fault fracture zones and weathered rocks, and the core recovery rate of weak mudstone and shale is far lower than that of hard and intact sandstone.

[0003] Chinese patent CN204478956 U discloses a core recovery rate calculation ruler, including a base plate with core recovery rate and advance length engraved on the vertical and horizontal axes respectively, and a ruler connected to the base plate by a clip; Chinese patent CN206192315 U discloses a drainage method core recovery rate measuring instrument, including an inner barrel, an outer barrel, and a measuring cylinder, which uses the drainage method to measure the recovery rate while simultaneously cleaning the core. Although the above two methods achieve the purpose of measuring core recovery rate, the operation still requires repeated manual operation, which is time-consuming, labor-intensive, prone to errors, and inefficient. In addition, the above measurement methods are mainly for relatively intact rock cores and cannot accurately measure the recovery rate of loose and broken strata. Moreover, the existing patented methods have a low degree of automation and cannot meet the development requirements of digital intelligent drilling.

[0004] Core recovery rate is defined as the percentage of the length of core samples retrieved from the borehole relative to the corresponding actual drilling footage. For more fractured formations, core recovery rate generally refers to the percentage of the total length of short columnar, disc-shaped, and composite columnar core samples, plus the length of fractured core samples loaded into a core tube of the same diameter, relative to the footage drilled in that run.

[0005] Currently, field exploration technicians typically use length calculation methods to determine core recovery rates. This method is convenient for measuring intact cylindrical cores, and the direct measurement results are relatively accurate. However, due to variations in strata during drilling operations, coring tools are frequently changed, resulting in inconsistent core diameters. Furthermore, the core boxes on-site are generally semi-cylindrical. Therefore, for cores with numerous fractures, broken and loose cores (mainly including sandy soils, gravelly soils, and extremely broken rocks), direct measurement with a measuring tape is impossible. Technicians generally estimate the core recovery rate range of loose and broken strata visually, leading to highly inaccurate results. Summary of the Invention

[0006] The purpose of this invention is to provide a core recovery rate measurement device for loose and fractured strata, which can at least solve some of the defects existing in the prior art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A core recovery rate measuring device for loose and fractured strata includes a core box for filling core samples to be tested. The core box contains a front baffle that can extend and retract along its height and a movable baffle that can move along its length. A cover plate is provided on the core box. A height adjustment component for adjusting the height of the cover plate is provided at one end of the core box near the front baffle. The upper end of the front baffle is connected to the lower surface of the cover plate. A core density adjustment component is provided at one end of the core box near the movable baffle. The end of the core density adjustment component is connected to the movable baffle, pushing the movable baffle to compress the core sample inside the core box. A seismic source transmitter for emitting surface wave signals is embedded and fixedly installed at one end of the cover plate. Two detectors are also embedded and slidably installed inside the cover plate for receiving the surface wave signals emitted by the seismic source transmitter. A controller is installed outside the core box. The detectors are electrically connected to the signal input terminal of the controller, and the core density adjustment component is electrically connected to the signal output terminal of the controller.

[0009] Furthermore, the cover plate includes a positioning section and an opening / closing section connected by hinges, and the height adjustment component and the front baffle are both connected to the positioning section of the cover plate.

[0010] Furthermore, the cover plate is provided with a sliding groove for the detector to slide, and a first scale is engraved on the sliding groove.

[0011] Furthermore, the front baffle includes a first fixed plate, a first telescopic plate, and a first spring. The bottom of the first fixed plate is fixedly installed on the bottom plate of the core box. The lower part of the first telescopic plate is sleeved inside the first fixed plate, and the bottom of the first telescopic plate is connected to the bottom of the first fixed plate through the first spring. The top of the first telescopic plate is connected to the cover plate, and the first telescopic plate moves up and down synchronously with the cover plate.

[0012] Furthermore, a second scale is engraved on both sides of the core box to measure the extension height of the first telescopic plate of the front baffle.

[0013] Furthermore, the height adjustment assembly includes a guide rod and an adjustment bolt. The bottom of the guide rod is fixedly installed on the bottom plate of the core box. The bottom of the adjustment bolt is an enlarged port with a rotation damper, and the enlarged port is embedded in the bottom plate of the core box. The cover plate is provided with a round hole that mates with the guide rod and a threaded hole that is threadedly connected to the adjustment bolt.

[0014] Furthermore, the movable baffle includes a second fixed plate, a second telescopic plate, a second spring, and a pulley. The bottom plate of the core box is provided with a sliding groove. The bottom of the second fixed plate is slidably connected to the sliding groove through the pulley. The lower part of the second telescopic plate is sleeved inside the second fixed plate, and the bottom of the second telescopic plate is connected to the bottom of the second fixed plate through the second spring.

[0015] Furthermore, the core compaction adjustment component includes a servo motor, a push rod, and a pull-rope displacement sensor. One end of the push rod is connected to a movable baffle, and the other end is connected to the servo motor. The servo motor is electrically connected to a controller, which controls the servo motor to rotate forward and backward, thereby driving the push rod to move back and forth. The rope of the pull-rope displacement sensor is connected to the movable baffle through a fixed pulley to measure the movement distance of the core sample in the core box compressed by the movable baffle.

[0016] In addition, the present invention also provides a method for measuring the core recovery rate of loose and fractured strata, using the above-mentioned core recovery rate measuring device for loose and fractured strata, and the specific measurement steps are as follows:

[0017] 1) Directly measure the inner diameter d1 of the coring tool at the drilling site using a ruler, and calculate the cross-sectional area S1 = πd1 of the coring tool. 2 / 4; Then, the first drilling operation is carried out, and the actual drilling depth H1 of this operation is recorded and entered into the control instrument; at the same time, the actual wave velocity value V of the cored strata is detected and obtained using geophysical equipment. R And input it into the controller as the input wave velocity value;

[0018] 2) Adjust the height of the cover plate by adjusting the height of the height adjustment component, thereby adjusting the extension height of the front baffle so that the area of ​​the front baffle is equal to the cross-sectional area S1 of the core drill bit calculated in step 1).

[0019] 3) Open the cover plate, fill the core sample taken from the drilling site into the space between the front baffle and the moving baffle in the core box, and ensure that the core box is filled with core sample. Close the cover plate. At this time, the distance L between the front baffle and the moving baffle is input into the controller.

[0020] 4) Adjust the two detectors to the designed positions and measure the distance x between the two detectors, then input the measurement into the controller;

[0021] 5) The controller controls the core compaction adjustment component to push the moving baffle to compact the core sample in the core box. At the same time, the controller automatically calculates the measured wave velocity value V of the core sample in the core box. R ', until condition |V is met R -V R '|≤0.01×V R At that time, the controller stops the core compaction adjustment component from pushing the moving baffle.

[0022] 6) After the core compaction adjustment component stops pushing the moving baffle, measure the actual advancing distance L1 of the moving baffle, and the controller automatically calculates the core recovery rate.

[0023] Furthermore, the wave velocity value obtained from the measured core sample inside the core box in step 5) Where f is the surface wave signal emitted by the seismic source transmitter, and x is the distance between the two detectors. This is the phase difference between the two signals received by the two detectors.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] (1) The loose and broken strata core recovery rate measuring device provided by the present invention is designed with a retractable front baffle, which can adjust the cross-sectional area according to the actual size of the core drilling tool in the field drilling construction, and can be used for core drilling tools of different diameters; at the same time, by using geophysical sensor technology, the device can automatically restore the compact state of the loose and broken strata to the greatest extent in the device through the controller, and directly calculate and record the core recovery rate, effectively solving the problem that it is difficult to accurately measure loose and broken cores in the field.

[0026] (2) The main structure of the loose and broken strata core recovery rate measuring device provided by the present invention is prefabricated and assembled with transparent tempered glass plates. It is flexible and convenient to disassemble, and the quality is controllable. It can adapt to the complex construction environment of the drilling site and can be widely used in on-site drilling construction. It has good social and economic benefits in promoting the rapid development of refined, information-based and intelligent drilling technology.

[0027] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the core recovery rate measuring device for loose and fractured strata of the present invention;

[0029] Figure 2 This is a top view of the core recovery rate measurement device for loose and fractured strata of the present invention;

[0030] Figure 3 This is a schematic diagram of the front baffle in the core recovery rate measurement device for loose and fractured strata of the present invention;

[0031] Figure 4 This is a schematic diagram of the moving baffle in the core recovery rate measurement device for loose and fractured strata of the present invention;

[0032] Figure 5 This is a schematic diagram of the working principle of the controller in the loose and fractured strata core recovery rate measuring device of the present invention;

[0033] Figure 6 This is a schematic diagram illustrating the measurement dimensions during the core recovery rate measurement process of loose and fractured strata in this invention.

[0034] Explanation of reference numerals in the attached drawings: 1. Core box; 2. Guide rod; 3. Adjusting bolt; 4. Second scale; 5. Hinge; 6. Detector; 7. Cover plate; 8. Front baffle; 9. Moving baffle; 10. Sliding groove; 11. Cable-stayed displacement sensor; 12. Servo motor; 13. Push rod; 14. Controller; 15. Seismic source transmitter; 16. First scale; 17. First telescopic plate; 18. First fixed plate; 19. First spring; 20. Second telescopic plate; 21. Second fixed plate; 22. Second spring; 23. Pulley. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation", "connection", and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, an abutting connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0038] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0039] like Figure 1 and Figure 2As shown, this embodiment provides a core recovery rate measurement device for loose and fractured strata, including a core box 1 for filling core samples to be tested. The core box 1 has a front baffle 8 that can extend and retract along its height direction and a movable baffle 9 that can move along its length direction. A cover plate 7 is provided on the core box 1. A height adjustment component for adjusting the height of the cover plate 7 is provided at one end of the core box 1 near the front baffle 8. The upper end of the front baffle 8 is connected to the lower surface of the cover plate 7. Adjusting the height of the cover plate 7 through the height adjustment component can adjust the extension and retraction height of the front baffle 8. Therefore, the cross-sectional area of ​​the front baffle 8 can be adjusted according to the actual size of the core drilling tool used in the field, thus accommodating core drilling tools of different diameters. A core density adjustment component is provided at one end of the core box 1 near the movable baffle 9. The end of the core density adjustment component is connected to the movable baffle 9, pushing the movable baffle 9 to compress the core sample inside the core box 1, thereby increasing the density of the core sample inside the core box 1. The density is basically consistent with the actual density of the formation. A seismic source transmitter 15 for transmitting surface wave signals is embedded and fixedly installed at one end of the cover plate 7. Two detectors 6 are also embedded and slidably installed inside the cover plate 7 to receive the surface wave signals emitted by the seismic source transmitter 15. A controller 14 is installed outside the core box 1. The detectors 6 are electrically connected to the signal input terminal of the controller 14. The controller 14 calculates the measured wave velocity value inside the core box 1 based on the received signal. At the same time, the core density adjustment component is electrically connected to the signal output terminal of the controller 14. The controller 14 adjusts the core density adjustment component to push the moving baffle 9 to compact the core sample inside the core box 1 based on the calculated measured wave velocity value until the measured wave velocity value inside the core box 1 is close to the input wave velocity. At this time, the core sample inside the core box 1 restores the compact state of the loose and broken formation to the greatest extent. Therefore, the core recovery rate of the core sample inside the core box 1 measured and calculated at this time is the actual core recovery rate of the loose and broken formation.

[0040] In a more detailed implementation, the core box 1 is a rectangular hollow box structure with an open upper surface, composed of five connected panels, and is made of transparent tempered glass. The cover plate 7 is made of the same material as the core box 1, also transparent tempered glass, and its size matches and fits the core box 1.

[0041] Furthermore, the cover plate 7 is designed in two parts, including a positioning section and an opening / closing section connected by a hinge 5. The positioning section and the opening / closing section can be opened and closed. A handle is provided at the end of the opening / closing section to facilitate the filling of loose and broken rock cores into the core box 1. The height adjustment component and the front baffle 8 are both connected to the positioning section of the cover plate 7. At the same time, an embedded seismic source transmitter 15 is installed in the middle of the front end of the cover plate 7, and a sliding groove for the detectors 6 is provided in the middle of the rear end of the cover plate 7. The sliding groove is engraved with a first scale 16. The two detectors 6 can be adjusted to a suitable position according to the measurement requirements, and the distance between the two detectors 6 can be directly read by the first scale 16.

[0042] Optional implementation methods, such as Figure 3 As shown, the front baffle 8 includes a first fixed plate 18, a first telescopic plate 17, and a first spring 19. The bottom of the first fixed plate 18 is fixedly installed on the bottom plate of the core box 1 and cannot be moved. The lower part of the first telescopic plate 17 is sleeved inside the first fixed plate 18, and the bottom of the first telescopic plate 17 is connected to the bottom of the first fixed plate 18 through the first spring 19. The top of the first telescopic plate 17 is connected to the cover plate 7. When the height adjustment component moves the cover plate 7 up and down, the first telescopic plate 17 can move up and down synchronously with the cover plate 7, thereby realizing the adjustment of the cross-sectional area of ​​the core recovery rate measuring device. In this embodiment, the front baffle 7 can be prefabricated using a transparent tempered glass plate, and its specific size can be adapted to the core box 1. It can be customized according to the specific needs of actual drilling operations.

[0043] For example: measuring the minimum inner diameter d of the coring tool used at a drilling site. min and maximum inner diameter d max The minimum cross-sectional area of ​​the coring drill bit can be calculated to be S. min =πd min 2 / 4 and the maximum cross-sectional area is S max =πd max 2 / 4; Because the core recovery rate measuring device is a prefabricated device, such as Figure 6 As shown, B1 is the variable height of the first telescopic plate 17 of the front baffle 7, which can change with the adjustment of the height adjustment component; B2 is the height of the first fixed plate 18 of the front baffle 7; B is the width of the core box 1; B2 and B are both constant lengths and cannot be adjusted. Therefore, their specific dimensions are selected and manufactured according to the cross-sectional area of ​​the core drilling tool, ensuring that B×B2≤S min That's fine. Due to the loose and broken rock core, on-site drilling generally requires each drilling run to be no more than 1m. Therefore, the total length L of the core box 1 of this core recovery rate measuring device is generally 1.2m.

[0044] Furthermore, to facilitate direct measurement and reading of the variable height B1 of the first telescopic plate 17 of the front baffle 7, a second scale 4 can be engraved on both side walls of the core box 1. The starting point of the lower end of the second scale 4 is flush with the upper surface of the first fixed plate 18 of the front baffle 7, so that the extension height of the first telescopic plate 17 can be directly read through the second scale 4. Specifically, the second scale 4 consists of long and short lines engraved on the panels on both sides of the core box 1, with short lines spaced 1mm apart and a long line every 10mm, facilitating scale reading.

[0045] One specific implementation method, such as Figure 1 As shown, the height adjustment assembly includes a guide rod 2 and an adjusting bolt 3. The guide rod 2 is placed at the front end of the core box 1, and its bottom is fixedly installed on the bottom plate of the core box 1. A circular hole that mates with the guide rod 2 is opened at the center of the front end of the cover plate 7. The cover plate 7 is fitted onto the guide rod 2 through the circular hole, and the guide rod 2 serves as a guide, ensuring that the cover plate 7 moves up and down along the guide rod 2. The bottom of the adjusting bolt 3 is an enlarged port with a rotation damper, and this enlarged port is embedded in the bottom plate of the core box 1, ensuring that the adjusting bolt 3 can rotate when a certain rotational force is applied at a fixed position. Simultaneously, the front end of the cover plate 7 has a threaded hole that connects to the adjusting bolt 3, so that when the adjusting bolt 3 is rotated, the cover plate 7 can move up and down along the adjusting bolt 3. The threaded fixing ensures that the cover plate 7 will not slide up or down. Optimally, to ensure the balance of the up and down movement of the cover plate 7, two adjusting bolts 3 can be provided at the front end of the core box 1, with both sides of the front end of the cover plate 7 connected to the adjusting bolts 3.

[0046] The movable baffle 9 is a structure that can move along the bottom of the core box 1. One specific embodiment of its internal structure is as follows: Figure 4 As shown, the movable baffle 9 includes a second fixed plate 21, a second telescopic plate 20, a second spring 22, and a pulley 23. The bottom plate of the core box 1 is provided with a sliding groove 10. The bottom of the second fixed plate 21 is slidably connected to the sliding groove 10 through the pulley 23. The lower part of the second telescopic plate 20 is sleeved inside the second fixed plate 21, and the bottom of the second telescopic plate 20 is connected to the bottom of the second fixed plate 21 through the second spring 22. The maximum height of the second telescopic plate 20 is consistent with the height of the side panel of the core box 1. When the cover plate 7 is kept horizontal after the core is filled, the movable baffle 9 is pushed, and the second telescopic plate 20 is pressed to the corresponding position, which plays the role of blocking the loose and broken core.

[0047] One specific implementation method, such as Figure 1 and Figure 2As shown, the core compaction adjustment component includes a servo motor 12, a push rod 13, and a pull-rope displacement sensor 11. One end of the push rod 13 is connected to the moving baffle 9, and the other end is connected to the servo motor 12. The servo motor 12 is electrically connected to the controller 14. The controller 14 controls the servo motor 12 to rotate forward and backward, thereby moving the push rod 13 back and forth to restore the compaction of loose and broken strata. The rope of the pull-rope displacement sensor 11 is connected to the moving baffle 9 through a fixed pulley. When the moving baffle 9 moves along the sliding groove 10, the rope of the pull-rope displacement sensor 11 is stretched or extended accordingly. The pull-rope displacement sensor 11 can measure the moving distance of the core sample in the core box compressed by the moving baffle 9 and transmit the measurement data to the controller 14 for core recovery rate calculation.

[0048] Specifically, in this embodiment, the controller 14 is a data input, acquisition, processing, storage, and display device, and its working principle is as follows: Figure 5 As shown, the device consists of a charging power supply, a controller, a memory, and a low-power display screen. The controller mainly processes the signals received by the pull-rope displacement sensor 11, the seismic source transmitter 15, and the detector 16, and controls the servo motor 12 to rotate forward and backward, driving the push rod 13 to move back and forth, thereby restoring the density of the loose and broken strata. The core recovery rate calculated by the controller is displayed on the low-power display panel and the data is saved to the memory. The controller 14 is also equipped with a switch and a USB data transmission port.

[0049] According to the definition of core recovery rate, the key to measuring the recovery rate of loose and fractured cores is to accurately measure the length of the core actually extracted by the drill bit within a core tube of the same diameter. Since the volume of the extracted core is constant, under the condition that the cross-sectional area of ​​the measuring device and the coring drill bit are the same, after restoring the density of the loose and fractured formation in the measuring device, the measured core length at this point is the actual length of the core extracted from the drill bit. Therefore, the core recovery rate measurement process using the loose and fractured formation core recovery rate measuring device of this embodiment is as follows.

[0050] (1) Measure the inner diameter d1 of the core drilling tool at the drilling site directly with a ruler, and calculate the cross-sectional area S1 = πd1 of the core drilling tool. 2 / 4; Then, the first drilling operation is carried out, the actual drilling depth H1 of this operation is recorded, and the data is entered into the controller 14.

[0051] The actual wave velocity value V of the drilled core strata was obtained by using geophysical equipment. R The actual wave velocity value is then input into the controller 14 as the input wave velocity value. The detection of this actual wave velocity value is a conventional detection method in this field, and its specific process will not be described in detail here.

[0052] (2) Adjust the height of the cover plate 7 by adjusting the height of the height adjustment component, thereby adjusting the extension height of the front baffle 8 so that the area of ​​the front baffle 8 is equal to the cross-sectional area S1 of the core drill bit calculated in step (1).

[0053] Specifically, rotating the adjusting bolt 3 adjusts the height of the cover plate 7, thereby adjusting the height of the first telescopic plate 17 of the front baffle 8, so that the extension height of the first telescopic plate 17 is B1 = S1 / B - B2, where B2 is the height of the first fixed plate 18 of the front baffle 8 and B is the width of the core box 1.

[0054] (3) Open the hinge section of the cover plate 7, fill the core sample taken from the drilling site into the core box 1 between the front baffle 8 and the movable baffle 9, and ensure that the core box 1 is filled with the core sample. Cover the cover plate. At this time, the distance L between the front baffle 8 and the movable baffle 9 is input into the controller 14.

[0055] (4) Adjust the two detectors 6 to the designed position, and directly read the distance x between the two detectors 6 through the first scale 16 and input it into the controller 14.

[0056] Specifically, the geophone should be adjusted to be above the rock core to be tested inside the core box. Under normal circumstances, the distance between the two geophones should be more than half the thickness of the rock core to be tested, that is, (B1+B2)>x≥(B1+B2) / 2, and the distance y from the source transmitter to the nearest geophone is equal to the distance x between the two geophones, that is, y=x.

[0057] (5) The controller 14 controls the core compaction adjustment component to push the moving baffle 9 to compact the core sample in the core box 1. At the same time, the controller 14 automatically calculates the measured wave velocity value V of the core sample in the core box 1. R ', until condition |V is met R -V R '|≤0.01×V R At that time, the controller 14 controls the core compaction adjustment component to stop pushing the moving baffle 9.

[0058] Specifically, the wave velocity calculation principle within the core recovery rate measurement device is as follows: The surface wave signal emitted by the source transmitter 15 is received by two detectors 6 spaced x apart after passing through the filled core. The two detectors 6 receive time-domain signals A1(t) and A2(t), which are essentially vertical components. Due to the time lag in wave propagation, the two signals have a phase difference. Therefore, the time Δt required for the wave to propagate between the two detectors 6 is:

[0059]

[0060] The distance between the two detectors 6 is x, and the wave velocity V of the Rayleigh wave obtained corresponding to the frequency f is calculated. R 'for:

[0061]

[0062] When the controller 14 is switched on, the controller 14 automatically calculates the wave velocity value V obtained from the actual measurement inside the device. R ', and sends a signal to control the servo motor 12, which drives the push rod 13 to push the moving baffle 9 to compact the loose and broken rock core until the condition is met: |V R -V R '|≤0.01×V R At this time, the servo motor 12 stops pushing and displays the message "Compactation completed" on the low-power display screen of the controller 14. At this time, the density of the loose and broken rock core in the core box 1 is basically consistent with the actual density of the stratum.

[0063] Furthermore, to improve detection accuracy, the frequency f of the Rayleigh wave signal excited by the seismic source transmitter can be appropriately increased, as can the detector spacing x.

[0064] (6) After the servo motor 12 stops pushing, click the "Calculate" button. Through the internally installed pull-rope displacement sensor 11, the actual advancing distance L1 of the moving baffle 9 can be directly measured. Then, the core recovery rate of the first pass can be automatically calculated directly by the processor of the controller 14. It also automatically records and stores the data.

[0065] Drilling continues for the second round. If the inner diameter of the core drill bit is the same as the previous round, the device does not need to adjust the height of the first telescopic plate 17 of the front baffle 8. When drilling is completed, the above steps are repeated to calculate the core recovery rate of the second round. If the inner diameter of the core drill bit is adjusted, the height of the first telescopic plate 17 of the front baffle 8 is adjusted accordingly. The above steps are repeated to accurately calculate and record the core recovery rate of the corresponding round.

[0066] The above examples are merely illustrative of the present invention and do not constitute a limitation on the scope of protection of the present invention. All designs that are the same as or similar to the present invention are within the scope of protection of the present invention.

Claims

1. A device for measuring the core recovery rate of loose and fractured strata, characterized in that: The system includes a core box for filling core samples for testing. The core box contains a front baffle that can extend and retract along its height and a movable baffle that can move along its length. A cover plate is provided on the core box. A height adjustment component for adjusting the height of the cover plate is located at one end of the core box near the front baffle. The upper end of the front baffle is connected to the lower surface of the cover plate. A core density adjustment component is located at one end of the core box near the movable baffle. The end of the core density adjustment component is connected to the movable baffle, pushing the movable baffle to compress the core sample inside the core box. A seismic source transmitter for emitting surface wave signals is embedded and fixedly installed at one end of the cover plate. Two detectors are also embedded and slidably installed inside the cover plate to receive the surface wave signals emitted by the seismic source transmitter. A controller is installed outside the core box. The detectors are electrically connected to the signal input terminal of the controller. The core density... The compactness adjustment component is electrically connected to the signal output terminal of the controller. The controller calculates the measured wave velocity value inside the core box based on the received signal from the detector, and controls the core compactness adjustment component to push the moving baffle to compact the core sample inside the core box based on the calculated measured wave velocity value. The pushing of the moving baffle stops when the measured wave velocity value inside the core box is close to the input wave velocity value. The controller then calculates the core recovery rate based on the actual advancing distance of the moving baffle. The core compactness adjustment component includes a servo motor, a push rod, and a pull-rope displacement sensor. One end of the push rod is connected to the moving baffle, and the other end is connected to the servo motor. The servo motor is electrically connected to the controller. The controller controls the servo motor to rotate forward and backward to drive the push rod to move back and forth. The rope of the pull-rope displacement sensor is connected to the moving baffle through a fixed pulley to measure the moving distance of the moving baffle compressing the core sample inside the core box.

2. The core recovery rate measurement device for loose and fractured strata as described in claim 1, characterized in that: The cover plate includes a positioning section and an opening / closing section connected by hinges, and the height adjustment component and the front baffle are both connected to the positioning section of the cover plate.

3. The core recovery rate measurement device for loose and fractured strata as described in claim 1, characterized in that: The cover plate has a sliding groove for the detector to slide in, and a first scale is engraved on the sliding groove.

4. The core recovery rate measuring device for loose and fractured strata as described in claim 1, characterized in that: The front baffle includes a first fixed plate, a first telescopic plate and a first spring. The bottom of the first fixed plate is fixedly installed on the bottom plate of the core box. The lower part of the first telescopic plate is sleeved inside the first fixed plate, and the bottom of the first telescopic plate is connected to the bottom of the first fixed plate through the first spring. The top of the first telescopic plate is connected to the cover plate, and the first telescopic plate moves up and down synchronously with the cover plate.

5. The core recovery rate measuring device for loose and fractured strata as described in claim 4, characterized in that: The core box has a second scale engraved on both sides of its side walls, which is used to measure the extension height of the first telescopic plate of the front baffle.

6. The core recovery rate measurement device for loose and fractured strata as described in claim 1, characterized in that: The height adjustment assembly includes a guide rod and an adjustment bolt. The bottom of the guide rod is fixedly installed on the bottom plate of the core box. The bottom of the adjustment bolt is an enlarged port with a rotation damper, and the enlarged port is embedded in the bottom plate of the core box. The cover plate has a round hole that mates with the guide rod and a threaded hole that is threadedly connected to the adjustment bolt.

7. The core recovery rate measuring device for loose and fractured strata as described in claim 1, characterized in that: The movable baffle includes a second fixed plate, a second telescopic plate, a second spring, and a pulley. The bottom plate of the core box is provided with a sliding groove. The bottom of the second fixed plate is slidably connected to the sliding groove through the pulley. The lower part of the second telescopic plate is sleeved inside the second fixed plate, and the bottom of the second telescopic plate is connected to the bottom of the second fixed plate through the second spring.

8. A method for measuring the core recovery rate of loose and fractured strata, characterized in that, The core recovery rate measurement device for loose and fractured strata as described in any one of claims 1 to 7 is used, and the specific measurement steps are as follows: 1) Directly measure the inner diameter d1 of the coring tool at the drilling site using a ruler, and calculate the cross-sectional area S1=πd1 of the coring tool. 2 / 4; Then, the first drilling operation is carried out, and the actual drilling depth H1 of this operation is recorded and entered into the control instrument; at the same time, the actual wave velocity value V of the cored strata is detected and obtained using geophysical equipment. R And input it into the controller as the input wave velocity value; 2) Adjust the height of the cover plate by adjusting the height of the height adjustment component, thereby adjusting the extension height of the front baffle so that the area of ​​the front baffle is equal to the cross-sectional area S1 of the core drill bit calculated in step 1). 3) Open the cover plate, fill the core sample taken from the drilling site into the space between the front baffle and the moving baffle in the core box, and ensure that the core box is filled with core sample. Close the cover plate, and then input the distance L between the front baffle and the moving baffle into the controller. 4) Adjust the two detectors to the designed positions and measure the distance x between the two detectors, then input the measurement into the controller; 5) The controller controls the core compaction adjustment component to push the moving baffle to compact the core sample in the core box. At the same time, the controller automatically calculates the measured wave velocity value of the core sample in the core box. until the conditions are met. At that time, the controller stops the core compaction adjustment component from pushing the moving baffle. 6) After the core compaction adjustment component stops pushing the moving baffle, the actual advancing distance L1 of the moving baffle is measured, and the controller automatically calculates the core recovery rate. .

9. The method for measuring the core recovery rate of loose and fractured strata as described in claim 8, characterized in that, The wave velocity value obtained from the measured core sample inside the core box in step 5) Where f is the surface wave signal emitted by the seismic source transmitter, and x is the distance between the two detectors. This is the phase difference between the two signals received by the two detectors.

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