CN113655533B - A sandstone-type uranium mine borehole transient electromagnetic logging device and logging method thereof - Google Patents

Abstract

The present application discloses a sandstone-type uranium mine drilling transient electromagnetic logging device, including a probe tube, a transmitter placed in the probe tube, a receiving device, an internal connector and an external connector; the transmitter is located in the middle of the probe tube, and the receiving device is provided with four devices, which are respectively distributed at both ends of the transmitter, and the transmitter and the receiving device are fixedly connected to the internal connector, and the transmitter and the receiving device are connected to the external connector through the internal connector. The logging device is based on the principle of full-space transient electromagnetic detection, and the detection coil is arranged vertically in the borehole, which has good coupling with the geological body and avoids metal interference; it adopts a one-transmitter-multiple-receiver device, and the detection method is flexible, which can perform multiple coverage detections on geological bodies at different depths, and adding a magnetic core in the detection coil can effectively improve the strength of the induced signal and improve the signal-to-noise ratio, so as to obtain the electromagnetic field response characteristics of the geological body outside the hole wall.

Description

A sandstone-type uranium mine borehole transient electromagnetic logging device and logging method thereof

Technical Field

The present application belongs to the technical field of geophysical electromagnetic logging, and specifically relates to a sandstone-type uranium mine drilling transient electromagnetic logging detection device and a logging method thereof.

Background Art

Transient electromagnetic method (TEM) is a time domain artificial source electromagnetic depth sounding method based on the principle of electromagnetic induction. It is to pass a step current into the transmitting loop to excite the electromagnetic field. In the process of the excited primary pulse electromagnetic field propagating to the underground space, the underground geological body will generate an induced electromagnetic field (secondary field) that changes with time under the excitation of the primary field. The secondary field signal is extracted and analyzed by the receiving loop to obtain the geoelectric characteristics of different depths.

At present, with the realization of my country's "carbon neutrality" goal, the consumption of resources such as coal has been gradually reduced, making green and clean nuclear energy gradually occupy an important position in my country's energy structure, and uranium is the most important raw material for the development of nuclear energy. Since the 1990s, my country's uranium exploration has shifted from "hard rock type" to "sandstone type" in the north that can be leached in-situ. With the vigorous development of my country's national defense science and technology and nuclear energy, the demand for uranium is increasing.

Geophysical logging is based on the physical property differences (radioactivity, electrical properties, magnetism, etc.) of rocks (ores). It continuously measures at a certain speed in the borehole to obtain the logging parameters of the target body. Geophysical logging is an important geophysical method for detecting sandstone-type uranium deposits. Based on the response characteristics of geophysical logging, the uranium ore-bearing layer, grade and radioactive anomaly range are identified, the development and spatial distribution of sand bodies are inferred, the permeability of mineral-bearing aquifers is analyzed, and the geophysical characteristics of the target layer for sandstone-type uranium deposits and the relationship between uranium mineralization are studied.

The borehole transient electromagnetic method (BHTEM) uses a multi-turn small coil as a transmitting and receiving device, and places the two in the borehole, using different device forms to observe from top to bottom or from bottom to top in a certain step length, and the electromagnetic field has a full-space effect. The detection coil of the borehole transient electromagnetic method is closer to the target body and has better coupling with the geological body. The target body response received by its receiving coil is stronger, the detection depth is greater, the vertical resolution is higher, and the anti-interference ability is stronger than that of the ground.

The drilling holes in sandstone-type uranium deposits are vertical holes, and the conventional geophysical apparent resistivity logging information is limited to the hole, and cannot detect the electrical distribution of geological bodies at a certain depth outside the hole wall. The transient electromagnetic method has the advantages of high lateral resolution, small volume effect, and low resistance anomaly sensitivity. Detection in the borehole can better infer the spatial distribution characteristics of the ore-bearing sand body, divide the stratum lithology, and analyze the sampling and comprehensive research of ore physical parameters related to the calculation of uranium deposit resources and reserves. The conventional borehole transient electromagnetic method has a small detection device, which reduces the detection depth, and the effective receiving area of the receiving coil directly affects the quality of the received transient electromagnetic signal, resulting in large errors in subsequent data processing and interpretation and analysis of results. The receiving coil has a small effective area, and the received transient electromagnetic induction signal is weak and has poor stability, and the signal-to-noise ratio is low.

In the related art, the invention patent with the application patent publication number CN112431586A discloses a method and device for collecting data in a borehole with a cable transient electromagnetic probe, which places the transient electromagnetic probe in a high-strength nylon drill rod, and leaves no conductive medium on both sides of the probe, and pushes the transient electromagnetic probe connected to the cable point by point for detection by pushing short rods section by section. However, this device is not cost-effective for deeper borehole detection and has low efficiency.

The invention patents with application publication numbers CN111734404A and CN111434887A provide a transient electromagnetic array induction logging device, which uses a one-transmit and eight-receive detection device to perform multiple measurements on a target body at a certain depth. However, the receiving coil of the device is located on the same side as the transmitting coil, and the detection coil itself is relatively small in the borehole, which causes the signal received by the receiving coil on the farther side to be relatively weak; the detection coil is coaxially arranged with the borehole, and the coupling degree with the geological target is poor, and it is easily interfered by metal at the wellhead direction.

The invention patent with the patent publication number CN209212233U discloses a transient electromagnetic logging device, which uses an overlapping loop device and embeds a magnetic core in the middle of the detection coil to focus the electromagnetic field generated by the excitation coil to obtain a more effective detection signal. However, due to the use of overlapping small loop devices, the self-inductance and shut-off time of the coil increase, resulting in a detection blind area at a certain depth.

Comprehensive research on borehole transient electromagnetic logging in China shows that it is widely used in petroleum logging and has developed rapidly. Although there are many transient electromagnetic logging patents, there are few in the field of sandstone uranium mine logging, and there are certain defects compared with sandstone uranium mine borehole logging.

Summary of the invention

The purpose of this application is to overcome the shortcomings of the above-mentioned device technology, so that the electromagnetic response is better coupled with the geological body, avoiding metal interference, performing multiple coverage detections on geological bodies at different depths, improving the induction signal strength and signal-to-noise ratio, and obtaining the electromagnetic field response characteristics of the geological body outside the hole wall, so as to achieve sampling analysis and comprehensive research on ore physical parameters related to uranium deposit resource reserve calculation.

In order to achieve the above-mentioned purpose, the present application adopts one of the following technical solutions: a sandstone-type uranium mine drilling transient electromagnetic logging device, comprising a probe, a transmitting device placed in the probe, a receiving device, an internal connecting piece and an external connecting piece; the transmitting device is located in the middle position inside the probe, and four receiving devices are provided, and the four receiving devices are respectively distributed at both ends of the transmitting device, the transmitting device and the receiving device are fixedly connected to the internal connecting piece, and the transmitting device and the receiving device are connected to the external connecting piece through the internal connecting piece.

Preferably, the probe tube is in the shape of a hollow cylinder, one end of the probe tube is connected to a conical plastic shell, and the other end is provided with a first protruding structure and a second protruding structure, and the outer wall of the first protruding structure is provided with a thread.

Preferably, the transmitting device is composed of a first magnetic core coil; the first magnetic core coil includes a first magnetic core and a multi-turn first coil, the first magnetic core is embedded in the center of the multi-turn first coil, the axis of the first magnetic core coincides with the axis of the multi-turn first coil and the two have the same length.

Preferably, the receiving device is composed of a second magnetic core coil, which includes a second magnetic core and a multi-turn second coil, the second magnetic core is embedded in the center of the multi-turn second coil, the axis of the second magnetic core coincides with the axis of the multi-turn second coil and the two have the same length.

Preferably, the first magnetic core and the second magnetic core are made of Mn—Zn ferrite material.

Preferably, the internal connecting member includes a central axis, which is located at the central axis position of the probe tube, and is fixedly connected to the probe tube. A plurality of connecting holes are provided on the central axis, and the plurality of connecting holes are distributed along the axial direction of the central axis; the connecting hole is in the shape of a hollow cylinder, and the first magnetic core coil and the second magnetic core coil are fixedly connected through the connecting hole.

Preferably, the first coil and the second coil are connected to the external connecting piece through the central axis; one end of the external connecting piece is connected to a four-core communication cable connector, and the other end is connected to a four-core communication cable, and the four-core communication cable is electrically connected to the first coil and the second coil through the central axis.

Preferably, an internal connection hole is formed on the inner wall of the external connection member; and the second protrusion structure is connected to the external connection member via the internal connection hole.

Preferably, an arched groove is formed on the inner wall of the external connecting member; the probe tube is connected to other logging probe tubes through the threads and the arched groove on the outer wall of the first protruding structure.

In order to achieve the above-mentioned purpose, the present application adopts the following technical solution 2: A sandstone-type uranium mine borehole transient electromagnetic logging method, including S1, before logging, the borehole geology and hole body structure should be understood in detail, and irrelevant objects at the wellhead should be removed to ensure the safety of the well site;

S2. Before starting the logging instrument, the voltage and frequency of the external power supply must be carefully checked to ensure that they match the instrument. All switches and knobs must be in a safe position and the wiring must be correct. After repeated checks and confirmation, the instrument must be powered on.

S3. Connect the transient electromagnetic probe tube to other probe tubes for sandstone-type uranium mine logging through external connectors to form a combined probe tube. Before lowering the probe tube into the well, the probe tube connection and sealing should be carefully checked. Generally, double-layer sealing with soft rubber waterproof tape and electrical insulating tape is used. A weak point should be left at the connection between the probe tube and the cable. The breaking strength of the weak point shall not be greater than half of the maximum tensile force of the four-core communication cable.

S4, placing the sandstone-type uranium mine drilling transient electromagnetic logging device at the wellhead of the sandstone-type uranium mine drilling hole, and performing depth alignment, starting the transient electromagnetic host to supply power to the magnetic core transmitting coil to stimulate the generation of a primary field, starting the winch, controlling the probe to descend at a certain speed to perform transient electromagnetic detection and data collection, and using the magnetic core receiving device to receive the secondary field signal with geoelectric information of the formation outside the hole wall generated by the shutdown;

S5. The winch controls the descending speed of the four-core communication cable, and continuously measures point by point along the sandstone-type uranium ore borehole; and the winch speed can be controlled for the radioactive abnormal section stratum, and the measurement can be encrypted to improve the resolution;

S6. When the downhole probe of the transient electromagnetic logging device reaches the bottom of the hole, it should be immediately lifted more than 0.5m and the upward lifting measurement operation should be started as soon as possible.

Beneficial effects: 1. The device features a probe tube and a transmitter, a receiver, an internal connector and an external connector installed inside the probe tube; the transmitter is located in the middle of the probe tube, and the four receivers are arranged at both ends of the transmitter at a certain distance; the transmitter and the receiver are coils wound on a hollow cylinder, a ferrite core probe is placed inside the cylinder, and the transmitter and the receiver are connected to the internal connector; the receiving coil and the transmitter coil are connected to the external connector of the embedded four-core communication cable through the internal connector, and the probe tube can be connected to other logging probe tubes through the external connector and connected to the transient electromagnetic instrument with a communication cable. The logging device is based on the principle of full-space transient electromagnetic detection, the detection coil is arranged vertically in the borehole, and is well coupled with the geological body to avoid metal interference; it adopts a one-transmitter-multiple-receiver device, the detection method is flexible, and multiple coverage detections can be performed on geological bodies of different depths, and adding a magnetic core to the detection coil can effectively improve the strength of the induced signal and improve the signal-to-noise ratio to obtain the electromagnetic field response characteristics of the geological body outside the hole wall.

2. The present invention has a simple structure and is easy to implement in sandstone-type uranium mine drilling. The external connector used in the device can be connected to other existing sandstone-type uranium mine logging probes to improve logging efficiency. The most important thing is that the present invention can obtain the electrical characteristics of the strata at a certain depth outside the hole wall based on the "smoke ring effect" principle of electromagnetic induction, and image in real time, which can better infer the spatial distribution characteristics of the ore-bearing sand body, divide the strata lithology, and analyze the sampling and comprehensive research of ore physical parameters related to the calculation of uranium deposit resources and reserves. In addition, due to its transient electromagnetic method characteristics, the device can also be promoted and applied to hydrological borehole logging and other metal and non-metal mineral exploration, and has strong practicality.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings constituting a part of this application are used to provide a further understanding of this application, so that other features, purposes and advantages of this application become more obvious. The schematic embodiment drawings and their descriptions of this application are used to explain this application and do not constitute an improper limitation on this application. In the drawings:

FIG1 is a schematic diagram of the structure of an embodiment of the present application.

FIG. 2 is a schematic diagram of the structure of the probe tube in an embodiment of the present application.

FIG. 3 is a schematic diagram of the structure of the first magnetic core coil in an embodiment of the present application.

FIG. 4 is a schematic diagram of the structure of the second magnetic core coil in the embodiment of the present application.

FIG. 5 is a schematic diagram of the structure of the internal connector of the well logging device of the present invention.

FIG. 6 is a schematic diagram of the structure of the external connecting parts of the well logging device of the present invention.

In the figure: 1. probe tube; 101. plastic shell; 102. first protruding structure; 103. second protruding structure; 104. thread; 2. transmitting device; 3. receiving device; 4. internal connecting piece; 401. central axis; 402. connecting hole; 5. external connecting piece; 501. four-core communication cable connector; 502. four-core communication cable; 503. arched groove; 504. internal connecting hole; 6. first magnetic core coil; 601. first magnetic core; 602. first coil; 7. second magnetic core coil; 701. second magnetic core; 702. second coil.

DETAILED DESCRIPTION

The present application is further described in detail below in conjunction with Figures 1 to 6.

In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

Embodiment 1: The embodiment of the present application discloses a sandstone-type uranium mine drilling transient electromagnetic logging device, comprising a probe tube 1, a transmitting device 2 placed in the probe tube 1, a receiving device 3, an internal connector 4 and an external connector 5; the probe tube 1 is made of a high-strength cylindrical hollow plastic shell; the transmitting device 2 is located in the middle position inside the probe tube 1, and four receiving devices 3 are provided, and the four receiving devices 3 are respectively distributed at both ends of the transmitting device 2, the transmitting device 2 and the receiving device 3 are fixedly connected to the internal connector 4, and the transmitting device 2 and the receiving device 3 are connected to the external connector 5 through the internal connector 4.

The probe tube 1 is in the shape of a hollow cylinder. One end of the probe tube 1 is connected to a conical plastic shell 101 , and the other end is provided with a first protruding structure 102 and a second protruding structure 103 . The outer wall of the first protruding structure 102 is provided with a thread 104 .

The transmitting device 2 is composed of a first magnetic core coil 6; the first magnetic core coil 6 includes a first magnetic core 601 and a multi-turn first coil 602, the first magnetic core 601 is embedded in the center of the multi-turn first coil 602, the axis of the first magnetic core 601 coincides with the axis of the multi-turn first coil 602 and the two have the same length.

The receiving device 3 is composed of a second magnetic core coil 7, which includes a second magnetic core 701 and a multi-turn second coil 702. The second magnetic core 701 is embedded in the center of the multi-turn second coil 702. The axis of the second magnetic core 701 coincides with the axis of the multi-turn second coil 702 and the two have the same length.

The first magnetic core 601 and the second magnetic core 701 are made of Mn—Zn ferrite material.

It should be noted that the diameter of the sandstone-type uranium ore borehole is generally 113mm or 130mm, with an inclination of 90°, and is a straight hole. The diameter of the probe tube of the logging device in the example of the present invention can generally be set to two specifications of 70mm and 80mm. However, in view of the drilling conditions and detection tasks, the embodiment of the present invention does not limit this.

The logging device in this example is based on the principle of full-space transient electromagnetic detection. The detection coil is arranged vertically in the borehole, which has good coupling with the geological body and avoids metal interference. It adopts a one-transmitter-multiple-receiver device with flexible detection mode, which can perform multiple coverage detections on geological bodies at different depths. Adding a magnetic core to the detection coil can effectively improve the induced signal strength and the signal-to-noise ratio, so as to obtain the electromagnetic field response characteristics of the geological body outside the hole wall.

The internal connecting part 4 includes a central axis 401, which is located at the central axis position of the probe tube 1. The central axis 401 is fixedly connected to the probe tube 1. A plurality of connecting holes 402 are opened on the central axis 401, and the plurality of connecting holes 402 are distributed along the axial direction of the central axis 401; the connecting hole 402 is a hollow cylindrical shape, and the first magnetic core coil 6 and the second magnetic core coil 7 are fixedly connected through the connecting hole 402.

The first coil 602 and the second coil 702 are connected to the external connecting part 5 through the central axis 401; one end of the external connecting part 5 is connected to a four-core communication cable connector 501, and the other end is connected to a four-core communication cable 502, and the four-core communication cable 502 is electrically connected to the first coil 602 and the second coil 702 through the central axis 401.

An internal connection hole 504 is formed on the inner wall of the external connection member 5 ; the second protruding structure 103 is connected to the external connection member 5 via the internal connection hole 504 .

An arched groove 503 is formed on the inner wall of the external connection member 5; the probe 1 is connected to other logging probes through the threads 104 on the outer wall of the first protruding structure 102 and the arched groove 503 and is connected to the transient electromagnetic instrument through a communication cable.

Embodiment 2: A sandstone-type uranium mine borehole transient electromagnetic logging method, comprising S1, before logging, a detailed understanding of the borehole geology and borehole structure should be obtained, and irrelevant objects at the wellhead should be removed to ensure the safety of the well site;

S2. Before starting the logging instrument, the voltage and frequency of the external power supply must be carefully checked to ensure that they match the instrument. All switches and knobs must be in a safe position and the wiring must be correct. After repeated checks and confirmation, the instrument must be powered on.

S3. Connect the transient electromagnetic probe 1 to other probes for sandstone-type uranium mine logging through the external connector 5 to form a combined probe. Before lowering the probe 1 into the well, the connection and sealing of the probe 1 should be carefully checked. Generally, a double-layer sealing of soft rubber waterproof tape and electrical insulating tape is used. A weak point should be left at the connection between the probe 1 and the cable. The breaking strength of the weak point shall not be greater than half of the maximum tensile force of the four-core communication cable 502.

S4, placing the sandstone-type uranium mine drilling transient electromagnetic logging device at the wellhead of the sandstone-type uranium mine drilling hole, and performing depth alignment, starting the transient electromagnetic host to supply power to the magnetic core transmitting coil to stimulate the generation of a primary field, starting the winch, controlling the probe 1 to descend at a certain speed to perform transient electromagnetic detection and data collection, and using the magnetic core receiving device 3 to receive the secondary field signal with geoelectric information of the formation outside the hole wall generated by the shutdown;

S5. The descent speed of the four-core communication cable 502 is controlled by a winch, and continuous measurements are made point by point along the sandstone-type uranium ore borehole; and the winch speed can be controlled for the radioactive abnormal section stratum, and encrypted measurements are made thereon to improve the resolution;

S6. When the downhole probe of the transient electromagnetic logging device reaches the bottom of the hole, it should be immediately lifted more than 0.5m and the upward lifting measurement operation should be started as soon as possible.

Finally, it should be noted that the above is only a preferred embodiment of the present application and is not intended to limit the scope of protection of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims (2)

1. The sandstone uranium deposit drilling transient electromagnetic logging device is characterized by comprising a probe tube (1), a transmitting device (2), a receiving device (3), an internal connecting piece (4) and an external connecting piece (5), wherein the transmitting device (2), the receiving device (3) and the external connecting piece (5) are arranged in the probe tube (1); the transmitting device (2) is positioned at the middle position inside the probe tube (1), the receiving devices (3) are four, the four receiving devices (3) are respectively distributed at two ends of the transmitting device (2), the transmitting device (2) and the receiving device (3) are fixedly connected to the internal connecting piece (4) together, and the transmitting device (2) and the receiving device (3) are connected to the external connecting piece (5) through the internal connecting piece (4); the probe tube (1) is hollow cylindrical, one end of the probe tube (1) is connected with a conical plastic shell (101), the other end of the probe tube is provided with a first protruding structure (102) and a second protruding structure (103), and the outer wall of the first protruding structure (102) is provided with threads (104); the transmitting device (2) is formed by a first magnetic core coil (6); the first magnetic core coil (6) comprises a first magnetic core (601) and a plurality of turns of first coils (602), the first magnetic core (601) is inlaid in the center of the plurality of turns of first coils (602), and the axis of the first magnetic core (601) is coincident with the axis of the plurality of turns of first coils (602) and the lengths of the first magnetic core and the axis of the plurality of turns of first coils are the same; the receiving device (3) is composed of a second magnetic core coil (7), the second magnetic core coil (7) comprises a second magnetic core (701) and a plurality of turns of second coils (702), the second magnetic core (701) is inlaid in the center of the plurality of turns of second coils (702), and the axis of the second magnetic core (701) is coincident with the axis of the plurality of turns of second coils (702) and the two are identical in length;

the first magnetic core (601) and the second magnetic core (701) are made of Mn-Zn ferrite materials;

The inner connecting piece (4) comprises a central shaft (401), the central shaft (401) is positioned at the central axis of the probe tube (1), the central shaft (401) is fixedly connected to the probe tube (1), a plurality of connecting holes (402) are formed in the central shaft (401), and the connecting holes (402) are distributed along the axial direction of the central shaft (401); the connecting hole (402) is hollow cylindrical, and the first magnetic core coil (6) and the second magnetic core coil (7) penetrate through the connecting hole (402) to be fixedly connected; the axes of the first magnetic core coil (6) and the second magnetic core coil (7) are perpendicular to the central shaft (401);

the first coil (602) and the second coil (702) are connected to the external connection piece (5) through the central shaft (401);

One end in the external connecting piece (5) is connected with a four-core communication cable connector (501), the other end is connected with a four-core communication cable (502), and the four-core communication cable (502) is electrically connected with the first coil (602) and the second coil (702) through the central shaft (401);

An inner connecting hole (504) is formed in the inner wall of the outer connecting piece (5); the second protruding structure (103) is connected with an external connecting piece (5) through the internal connecting hole (504);

an arch-shaped groove (503) is formed in the inner wall of the external connecting piece (5); the probe (1) is connected to other logging probes through threads (104) and arched grooves (503) on the outer wall of the first protruding structure (102).

2. A logging method using a sandstone uranium ore borehole transient electromagnetic logging device of claim 1, wherein: comprising

S1, knowing the drilling geology and the structure condition of a hole body in detail before logging, removing irrelevant objects at a wellhead, and ensuring the safety of a well site;

S2, before the logging instrument is started, the matching degree of the voltage and frequency of an external power supply and instrument equipment must be carefully checked; each switch and each knob are in a safe position, are correctly connected, and are electrified to be started after repeated checking and confirmation;

S3, connecting the transient electromagnetic probe tube (1) with other probe tubes of the sandstone-type uranium deposit logging through an external connecting piece (5) to form a combined probe tube; the connection and sealing condition of the exploratory tube (1) should be carefully checked before the exploratory tube (1) goes into the well, and a soft rubber waterproof adhesive tape and an electric insulating adhesive tape are generally adopted for double-layer sealing; and a weak point is reserved at the joint of the probe tube (1) and the cable, and the breaking strength of the weak point is not more than half of the maximum tensile force of the four-core communication cable (502);

S4, placing a sandstone-type uranium deposit drilling transient electromagnetic logging device at the drilling wellhead position of the sandstone-type uranium deposit, performing depth alignment, starting a transient electromagnetic host to supply power to a magnetic core transmitting coil, exciting to generate a primary field, starting a winch, controlling a certain-speed descending probe (1) to perform transient electromagnetic detection and data acquisition, and receiving a secondary field signal with ground electric information of the peripheral stratum of a hole wall, which is generated by turn-off, by using a magnetic core receiving device (3);

S5, controlling the descending speed of the four-core communication cable (502) through a winch, and continuously measuring the descending speed point by point along the sandstone-type uranium deposit drilling hole; the winch speed can be controlled for the stratum of the radioactive abnormal section, encryption measurement can be carried out on the stratum of the radioactive abnormal section, and the resolution ratio is improved;

s6, the transient electromagnetic logging device is lifted to be more than 0.5m immediately after the downhole probe tube is lowered to the bottom of the hole, and meanwhile lifting measurement operation is started upwards as soon as possible.