Torsional shear wave source device based on gas explosion source cavity and acquisition and processing method thereof

Abstract

The present invention provides a torsional shear wave source device based on a gas explosion source cavity and its acquisition and processing method. At each source point, clockwise and counterclockwise torsional shear wave source signals propagating downward are sequentially excited twice. A wired or wireless three-component or five-component detector deployed on the ground can sequentially record two torsional shear wave data with opposite polarization directions and parallel to the ground excited by the torsional shear wave source device. Because the torsional shear wave source device based on the gas explosion source cavity can simultaneously excite clockwise and / or counterclockwise torsional shear waves in multiple directions, according to the principle of energy superposition in the same direction, the two mutually orthogonal shear shear wave component signals extracted from the torsional shear wave data volume at any direction on the plane have much higher intensity and signal-to-noise ratio than the two mutually orthogonal shear shear wave component signals generated by the shear wave source device based on the gas explosion source cavity, thereby realizing pure torsional shear wave and converted longitudinal wave seismic exploration parallel to the ground.

Description

Technical Field

[0001] The present invention belongs to the field of excitation methods for seismic exploration sources in geophysical exploration technology, and specifically refers to a torsional shear wave source device based on a gas explosion source cavity and an acquisition and processing method thereof. Background Art

[0002] Seismic waves used in seismic exploration are artificially generated. Artificial sources are generally divided into two categories: explosive sources and non-explosive sources. Explosive sources primarily utilize solid explosive detonation, detonator detonation, and physical explosions (e.g., air guns, electric sparks, and heavy hammers). Each of these methods has limited excitation ranges and operating conditions.

[0003] Gas explosion sources are non-explosive seismic sources. They involve detonating a gas mixture (such as propane and oxygen) within a sealed cylindrical chamber, driving the chamber's movable floor into the ground and generating seismic waves. Similar to a hammer source, this type of source typically uses three or more pneumatic devices to ignite simultaneously, with the detonation signal transmitted by radio from a recording device. Gas explosion sources are mounted on heavy vehicles. The pulses they generate are rich in low frequencies, giving them greater penetrating power and are primarily used for land exploration. Gas explosion sources used in the ocean are called water pulses.

[0004] A gas explosion source, also known as an "air gun source," introduces a mixture of propane, oxygen, or air into a blast chamber, where it is detonated using an electric spark, either directly generating a shock wave or using the gas explosion to propel a heavy object into the ground. This can be used both at sea and on land. Other gases, such as ammonia and some nitrogen-carbon compounds, can also be used as explosives, but these mixtures require specialized detonation equipment. This type of source offers advantages over solid explosives in terms of transmission and represents a higher level of seismic energy among non-explosive sources. However, its disadvantage is the need to carry specialized gas containers and the associated risks.

[0005] Currently, various seismic source devices or equipment used on land in the seismic exploration industry can separately stimulate longitudinal wave source signals or shear wave source signals with different polarization directions. The invention patent application (202111595135.3: Shear wave source device and seismic data acquisition method based on a gas explosion source cavity) discloses a shear wave source device and seismic data acquisition method based on a gas explosion source cavity. The central axis is provided at the vertical center of a rectangular steel plate, and gas explosion source cavities are fixed on two vertical sides. The two gas explosion source cavities are located on either side of the rectangular steel plate; one side of the gas explosion source cavity is cut into a thinner cavity surface, and the opposite surface of the thin cavity surface is fixed to the surface of the rectangular steel plate; an electronic ignition gun is installed in the center of the gas explosion source cavity, and the gas explosion source cavity is connected to an explosion-proof metal gas tank. At each focal point, a shear shear wave source signal propagating downward and parallel to the focal line is sequentially excited, as is a shear shear wave source signal propagating downward and perpendicular to the focal line. Ground-based three-component geophones sequentially record the two mutually orthogonal shear waves parallel to the ground excited by this shear wave source device, and the converted longitudinal wave data perpendicular to the ground, truly enabling pure shear wave and converted longitudinal wave seismic exploration parallel to the ground. This source can only excite shear shear waves polarized in one direction at a time and cannot excite torsional shear waves. Summary of the Invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a torsional shear wave source device based on a gas explosion source cavity and a data acquisition and processing method thereof.

[0007] To achieve the above object, the technical solution of the present invention is:

[0008] The torsional shear wave source device based on the gas explosion source cavity includes at least two rectangular steel plates, each of which has a central axis at its vertical center. The gas explosion source cavity is fixed on both sides of the two vertical sides of the outer ends of each rectangular steel plate. When the gas explosion source cavity is excited twice, each rectangular steel plate rotates clockwise or counterclockwise around the central axis at the same time.

[0009] One side of the gas explosion source cavity is cut into a thinner cavity surface, and the opposite surface of the thin cavity surface is fixed to the surface of the outer end of the rectangular steel plate;

[0010] An electronic ignition gun is installed in the center of the gas explosion source cavity, and the electronic ignition gun is connected to the control unit through a wire;

[0011] The gas explosion source cavity is connected to the explosion-proof metal gas tank through a metal gas pipe. The explosion-proof metal gas tank stores compressed gas and supplies high-pressure gas to the gas explosion source cavity.

[0012] Optionally, a cement trough is further included, wherein the rectangular steel plate and the gas explosion source cavity fixed thereon are installed in the cement trough, and four long openings are opened on the side wall of the cement trough at positions opposite to the thin cavity surfaces of the four gas explosion source cavities.

[0013] Optionally, the control unit includes a GPS or Beidou timing, timing, and positioning module, as well as a wireless signal receiving and transmitting antenna and module.

[0014] Optionally, four gas explosion source cavities are respectively fixed on the four outer vertical edges of the rectangular steel plate, and two or three rectangular steel plates are combined to form a cross-shaped or M-shaped torsional shear wave source. The torsional shear wave source synchronously excites the two gas explosion source cavities on opposite sides of each rectangular steel plate at one time so that they simultaneously generate clockwise torsional shear waves, and then synchronously excites the other two gas explosion source cavities on opposite sides of each rectangular steel plate so that they simultaneously generate counterclockwise torsional shear waves.

[0015] Optionally, torsional shear wave source devices based on gas explosion source cavities are deployed on the ground in sequence according to a two-dimensional source survey line or a three-dimensional source survey network, and three-component detectors or five-component detectors are deployed on the ground in sequence according to a two-dimensional detector survey line or a three-dimensional detector survey network.

[0016] Optionally, the five-component detector consists of a vertical detector and four horizontal detectors orthogonal to the vertical detector, and the four horizontal detectors on the same plane are each at an angle of 45 degrees.

[0017] The acquisition and processing method of the torsional shear wave source device based on the gas explosion source cavity includes the following steps:

[0018] S1. Arrange three-component geophones or five-component geophones at all geophone positions on the ground within the torsional shear wave seismic exploration area according to the construction design, so that the directions of the two horizontal components of the three-component geophones or the two mutually orthogonal horizontal geophones of the five-component geophones are parallel and perpendicular to the geophone survey line respectively;

[0019] S2. Dig a square or circular earth pit on the ground within the torsional shear wave seismic exploration area at all artificial seismic source locations arranged according to the construction design, with one side of the square earth pit parallel to the seismic source line and the other side of the square earth pit perpendicular to the seismic source line; bury a cross-shaped or cross-shaped cement trough with a torsional shear wave seismic source device based on a gas explosion source cavity installed or a cross-shaped or cross-shaped torsional shear wave seismic source device based on a gas explosion source cavity installed into the square or circular earth pit, and then backfill the earth pit and compact the backfilled soil or silt;

[0020] S3. Excite all torsional shear wave sources arranged along the source line point by point: the control unit controls the synchronous opening of the explosion-proof metal gas tanks, and simultaneously supplies high-pressure gas to each gas explosion source cavity on the torsional shear wave source through the high-pressure resistant metal gas pipe;

[0021] S4. An electronic ignition gun connected to the control unit simultaneously detonates the high-pressure mixed gas in the two gas explosion source cavities on opposite sides of each rectangular steel plate at a pre-set time, and simultaneously transmits source onset synchronization information to the ground three-component or five-component geophone data acquisition and control system through its wireless signal receiving and transmitting module;

[0022] S5. When the pressure of the high-pressure explosive gas generated by the explosion of the high-pressure mixed gas in each detonated gas explosion source cavity reaches a certain threshold, the thin cavity surface of each gas explosion source cavity facing the rectangular steel plate is exploded at high speed, causing it to collide with the gas explosion source cavity and the walls of the two earth pits corresponding to the long openings in the cement trough at high speed in two opposite tangential directions, causing all the rectangular steel plates fixed to the gas explosion source cavity to rotate around the central axis;

[0023] S6. The combined force of each rotating high-strength rectangular steel plate causes the underground medium to generate a torsional shear wave polarized clockwise around the central axis;

[0024] S7. Then, the electronic ignition gun connected to the control unit simultaneously detonates the high-pressure mixed gas in the other two gas explosion source cavities on the square steel plates on the other two opposite sides of each rectangular steel plate at a pre-set time, and simultaneously transmits the source seismic synchronization information to the ground three-component or five-component geophone data acquisition and control system through its wireless signal receiving and transmitting module; repeating steps S4 to S5, the combined force of each rotating high-strength rectangular steel plate causes the underground medium to generate a torsional shear wave with counterclockwise polarization centered on the central axis;

[0025] S8. Three-component or five-component geophones arranged on the ground according to the design plan sequentially collect data of two direct and reflected torsional shear waves with opposite rotation directions and parallel to the ground generated by the two excitations at the earthquake source location;

[0026] S9, sequentially collecting two direct and reflected torsional shear wave data of two waves with opposite rotation directions and parallel to the ground at each earthquake source point position on the ground within the torsional shear wave seismic exploration area according to steps S3 to S8;

[0027] S10, combining the direct and reflected torsional shear wave data of two directions of rotation parallel to the ground collected from all earthquake source points in sequence, respectively, to form a three-dimensional or five-dimensional seismic data volume of torsional shear waves rotating in two directions;

[0028] S11. The vertical geophone of the three-component or five-component geophone deployed on the ground within the torsional shear wave seismic exploration area can record the vertical component data of the upward converted longitudinal wave generated by the downward torsional shear wave excited by the ground torsional shear wave source and reflected upward at various underground wave impedance interfaces back to the ground;

[0029] S12. With a focal point in the torsional shear wave seismic exploration area as the center, gather data of ground three-component or five-component geophones at all long, medium, and short offsets are collected at azimuth angles of 5 to 10 degrees. The velocities of the direct P-wave and the two mutually orthogonal shear shear waves are calculated point by point based on the straight-line distance from the focal point to each ground geophone and the first arrival times of the direct P-wave and the two mutually orthogonal shear shear waves.

[0030] S13, determining the azimuths of the velocities of the fastest and slowest direct P-waves and the two mutually orthogonal shear-waves in the torsional shear-wave seismic exploration work area based on the velocity distribution values ​​of the omnidirectional direct P-waves and the two mutually orthogonal shear-waves in the torsional shear-wave seismic exploration work area calculated in step S12;

[0031] S14, according to the azimuths of the fastest and slowest direct wave velocities in the work area determined in step S13, respectively rotating the 3D seismic converted P-wave vertical component data volume and the two direct and reflected torsional S-wave data volumes with opposite rotation directions and parallel to the ground acquired in step S11, to obtain a reflected P-wave vertical component data volume parallel to the fastest speed direction and a reflected P-wave vertical component data volume perpendicular to the fastest speed direction, and a reflected S-wave horizontal component data volume parallel to the fastest speed direction and a reflected S-wave horizontal component data volume perpendicular to the fastest speed direction;

[0032] S15. Perform imaging processing on the four sets of data volumes obtained in step S14, and perform detailed structural interpretation of the underground geological body and accurate prediction of fluid distribution by integrating the four sets of reflection wave imaging data volumes.

[0033] Optionally, the ground three-component or five-component geophone data acquisition and control system uses a ground wired three-component or five-component geophone, which is one of a wired three-component or five-component moving coil geophone, a wired three-component or five-component digital geophone, a wired three-component or five-component acceleration geophone, a wired three-component or five-component MEMS geophone, or a wired three-component or five-component fiber optic geophone.

[0034] Optionally, the ground three-component or five-component detector data acquisition and control system uses a ground wireless three-component or five-component detector, which is one of a wireless three-component or five-component moving coil detector, a wireless three-component or five-component digital detector, a wireless three-component or five-component acceleration detector, a wireless three-component or five-component MEMS detector, or a wireless three-component or five-component fiber optic detector.

[0035] The present invention provides a torsional shear wave source device based on a gas explosion source cavity and a data acquisition and processing method. The device can sequentially excite clockwise and counterclockwise torsional shear wave source signals that propagate downward at each source point twice. A wired or wireless three-component or five-component detector arranged on the ground can sequentially record the two torsional shear wave data excited by the torsional shear wave source device with opposite polarization directions and parallel to the ground. Through the data processing steps, shear shear wave data parallel to the source line and shear shear wave data perpendicular to the source line) and seismic converted longitudinal wave data perpendicular to the ground can be extracted from the three-component or five-component seismic data body recorded on the ground. Since the torsional shear wave source device based on the gas explosion source cavity can simultaneously excite clockwise and / or counterclockwise torsional shear waves in multiple (four, six, eight, ten) directions, according to the principle of energy superposition in the same direction, the two mutually orthogonal shear shear wave component signals at any direction on the plane extracted from the three-component or five-component torsional shear wave data volume recorded by the ground three-component or five-component geophone are much higher in intensity and signal-to-noise ratio than the two mutually orthogonal shear shear wave component signals generated by the shear wave source device based on the gas explosion source cavity, truly realizing pure torsional shear wave and converted longitudinal wave seismic exploration parallel to the ground. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the structure of the clockwise and counterclockwise torsional shear wave source device based on the gas explosion source cavity of the present invention;

[0037] Figure 2 2. It is a top view of the structure of the cross-shaped clockwise and counterclockwise torsional shear wave source device based on the gas explosion source cavity of the present invention;

[0038] Figure 3 3. It is a top view of the structure of the cross-shaped clockwise and counterclockwise torsional shear wave source device based on the gas explosion source cavity of the present invention;

[0039] Figure 4 1. It is a top view of a torsional shear wave source device module based on a gas explosion source cavity fixed in a cement tank according to the present invention;

[0040] Figure 5 It is a top view of a cross-shaped clockwise and counterclockwise torsional shear wave source device module based on a gas explosion source cavity fixed in a cement tank of the present invention;

[0041] Figure 6 It is a top view of a cross-shaped clockwise and counterclockwise torsional shear wave source device module based on a gas explosion source cavity fixed in a cement tank of the present invention;

[0042] Figure 7 It is a schematic structural diagram of a three-component geophone deployed on the ground according to the present invention;

[0043] Figure 8 is a top view of a five-component geophone structure arranged on the ground according to the present invention;

[0044] Figure 9 It is a top view of the five-component dual-detector structure arranged on the ground according to the present invention.

[0045] Figure numerals: 1- rectangular steel plate, 2- central axis, 3- gas explosion source cavity, 4- electronic ignition gun, 5- metal gas pipe, 6- thin cavity surface, 7- control unit, 8- wire, 9- explosion-proof metal gas tank, 10- cement tank, 11- long mouth, 31- first detector, 32- second detector, 33- third detector, 51- fourth detector, 52- fifth detector, 53- sixth detector, 54- seventh detector, 55- eighth detector. DETAILED DESCRIPTION

[0046] The present invention will be further described in detail below with reference to the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0047] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "longitudinal", "lateral", "horizontal", "inside", "outside", "front", "back", "top", "bottom", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship in which the inventive product is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0048] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "having," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific contexts.

[0049] Example 1

[0050] The embodiment of the torsional shear wave source device based on the gas explosion source cavity of the present invention is as follows:

[0051] refer to Figure 1The shear wave source device based on the gas explosion source cavity includes two rectangular steel plates 1, a central axis 2 is provided in the center of the rectangular steel plate 1, and also includes a square columnar high-temperature resistant and high-strength gas explosion source metal cavity 3, a control unit 7, and an explosion-proof metal gas tank 9; the gas explosion source cavity 3 is installed in four directions of the outer end of the rectangular steel plate 1.

[0052] The four vertical sides of the outer ends of each rectangular steel plate 1 are respectively fixed with gas explosion source cavities 3, and the four gas explosion source cavities 3 are respectively located on both sides of the two outer ends of the rectangular steel plate 1; the gas explosion source cavity 3 is a square columnar high-temperature resistant and high-strength metal cavity;

[0053] One side of the square columnar, high-temperature-resistant, high-strength gas explosion source cavity 3 is cut into a thinner cavity surface 6, which faces the outside of the rectangular steel plate 1. An electronic ignition gun 4 is installed in the center of the gas explosion source cavity 3, and the electronic ignition gun 4 is connected to the control unit 7;

[0054] The control unit 7 includes GPS or Beidou timing, timing, and positioning modules, as well as wireless signal receiving and transmitting antennas and modules.

[0055] The gas explosion source cavity 3 is connected to the explosion-proof metal gas tank 9 through a high-pressure resistant metal gas pipe 5. The explosion-proof metal gas tank 9 stores compressed gas and supplies high-pressure gas to the gas explosion source cavity 9.

[0056] Compressed gas is stored in a high-pressure, high-strength explosion-proof metal gas tank 9, and is supplied to the gas explosion source cavity 3 through a high-pressure metal gas pipe 5; the high-pressure gas is a mixture of propane, oxygen or air;

[0057] like Figure 2 As shown, four rectangular gas explosion source cavities are fixed simultaneously on the four outer vertical sides of the two sides of each rectangle. When excited twice respectively, the rectangular steel plate 1 can rotate clockwise and counterclockwise around the central axis 2.

[0058] like Figure 3 As shown, four gas explosion source cavities 3 are respectively fixed to the four outer vertical edges of a rectangular steel plate 1, and then two, three, or more rectangular steel plates 1 are assembled into a cross-shaped, cross-shaped, or more polygonal torsional shear wave source. This combined torsional shear wave source can simultaneously excite two gas explosion source cavities 3 on the square steel plates 1 on opposite sides of each rectangular steel plate 1 at a time, causing them to simultaneously generate clockwise torsional shear waves, and then synchronously excite the other two gas explosion source cavities 3 on the square steel plates 1 on opposite sides of each rectangular steel plate 1, causing them to simultaneously generate counterclockwise torsional shear waves.

[0059] like Figure 4As shown, the entire rectangular steel plate 1 of the torsional shear wave source device based on the gas explosion source cavity and the gas explosion source cavity 3 fixed thereon are installed in a cement tank 10 sealed on three sides. Four long openings 11 are opened on the side wall of the cement tank 10 at positions opposite to the thin cavity surfaces 6 of the four gas explosion source cavities 3.

[0060] like Figure 5 or Figure 6 As shown, we can put two ( Figure 5 ) or three ( Figure 6 ) The torsional shear wave source device module based on the gas explosion source cavity fixed in the cement tank is combined into a cross-shaped or M-shaped clockwise and counterclockwise torsional shear wave source device. When excited twice respectively, all the rectangular steel plates 1 can be rotated clockwise and counterclockwise around the central axis 2, and clockwise or counterclockwise torsional shear waves can be generated at the same time.

[0061] like Figure 7 and Figure 8 As shown, three-component or five-component geophones are sequentially deployed on the ground along a two-dimensional geophone survey line or a three-dimensional geophone survey network. The three-component geophone consists of a first geophone 31, a second geophone 32, and a third geophone 33. The first geophone 31 is arranged in the Z-axis direction, the second geophone 32 is arranged in the Y-axis direction, and the third geophone 33 is arranged in the X-axis direction. The five-component geophone consists of a fourth geophone 51 in a vertical direction and four horizontal geophones orthogonal to the fourth geophone. The horizontal geophones are sequentially divided into a fifth geophone 52, a sixth geophone 53, a seventh geophone 54, and an eighth geophone 55. The four horizontal geophones (the fifth geophone 52, the sixth geophone 53, the seventh geophone 54, and the eighth geophone 55, all identical) on the same plane are each angled 45 degrees apart to collect torsional shear wave seismic data on the ground.

[0062] Figure 9 FIG. 1 is a top view of the five-component dual-detector structure arranged on the ground according to the present invention. Figure 9 As shown in the figure, two detectors in the same direction are used for signal acquisition and superposition in each component to improve the signal-to-noise ratio. Specifically, the upper and lower primary detectors are arranged along the vertical component direction, and eight horizontal detectors are arranged in the middle at a 45-degree azimuth angle. Every two horizontal detectors are arranged along the same horizontal azimuth line. Together, these ten detectors form a five-component detector combination, with each component containing a pair of detectors.

[0063] The ground three-component or five-component geophone data acquisition and control system uses a ground wired three-component or five-component geophone, which is one of a wired three-component or five-component moving coil geophone, a wired three-component or five-component digital geophone, a wired three-component or five-component acceleration geophone, a wired three-component or five-component MEMS geophone, or a wired three-component or five-component fiber optic geophone.

[0064] The ground three-component or five-component geophone data acquisition and control system uses a ground wireless three-component or five-component geophone, which is one of a wireless three-component or five-component moving coil geophone, a wireless three-component or five-component digital geophone, a wireless three-component or five-component acceleration geophone, a wireless three-component or five-component MEMS geophone, or a wireless three-component or five-component fiber optic geophone.

[0065] The acquisition and processing method of the torsional shear wave source device based on the gas explosion source cavity comprises the following steps:

[0066] S1. Arrange three-component geophones or five-component geophones at all geophone positions on the ground within the torsional shear wave seismic exploration area according to the construction design, so that the directions of the two horizontal components of the three-component geophones or the two mutually orthogonal horizontal geophones of the five-component geophones are parallel and perpendicular to the geophone survey line respectively;

[0067] S2. Dig a square or circular pit on the ground within the torsional shear wave seismic exploration area according to all artificial seismic source positions arranged in the construction design, with one side of the square pit parallel to the seismic source line and the other side of the rectangular pit perpendicular to the seismic source line; bury a cross-shaped or cross-shaped cement trough 10 with a torsional shear wave source device based on a gas explosion source cavity installed or a cross-shaped or cross-shaped torsional shear wave source device based on a gas explosion source cavity installed into the square or circular pit, then backfill the pit and compact the backfilled soil or silt;

[0068] S3, point by point excitation of all torsional shear wave sources arranged along the source line: the control unit 7 controls the synchronous opening of the explosion-proof metal gas tank 9, and simultaneously supplies high-pressure gas to each gas explosion source cavity 3 on the torsional shear wave source through the high-pressure resistant metal gas pipe 5;

[0069] S4, the electronic ignition gun 4 connected to the control unit 7 simultaneously detonates the high-pressure mixed gas in the two gas explosion source cavities 3 on the square steel plates 1 on the opposite sides of each rectangular steel plate 1 at a pre-set time, and at the same time sends the source seismic synchronization information to the ground three-component detector data acquisition and control system through its wireless signal receiving and transmitting module;

[0070] S5. When the pressure of the high-pressure explosive gas generated by the explosion of the high-pressure mixed gas in each detonated gas explosion source cavity 3 reaches a certain threshold, the thin cavity surface 6 of each gas explosion source cavity 3 facing the outside of the rectangular steel plate 1 is exploded at high speed, so that it hits the gas explosion source cavity 3 and the wall of the two earth pits corresponding to the long opening 11 opened on the cement trough 10 at high speed in two opposite tangential directions, causing the rectangular steel plate 1 fixed to the gas explosion source cavity 3 to rotate around the central axis 2;

[0071] S6. The combined force of each rotating high-strength rectangular steel plate 1 causes the underground medium to generate a torsional shear wave polarized in a clockwise direction centered on the central axis 2;

[0072] S7, then the electronic ignition gun 4 connected to the control unit 7 simultaneously detonates the high-pressure mixed gas in the other two gas explosion source cavities 3 on opposite sides of each rectangular steel plate 1 at a pre-set time, and at the same time sends the source seismic synchronization information to the ground three-component or five-component detector data acquisition and control system through its wireless signal receiving and transmitting module; repeating steps S4 to S5, the combined force of each rotating high-strength rectangular steel plate 1 causes the underground medium to generate a torsional shear wave with counterclockwise polarization centered on the central axis 2;

[0073] S8. Three-component or five-component geophones deployed on the ground according to the design plan sequentially collect data on the direct and reflected torsional shear waves with opposite rotation (polarization) directions and parallel to the ground generated by the two excitations at the earthquake source location;

[0074] S9, sequentially collecting two direct and reflected torsional shear wave data of two excitations with opposite rotation (polarization) directions and parallel to the ground at each earthquake source point position on the ground within the torsional shear wave seismic exploration area according to steps S3 to S8;

[0075] S10, combining the direct and reflected torsional shear wave data of two oppositely rotated (polarized) directions and parallel to the ground collected from all earthquake source points, respectively, to form a three-dimensional or five-dimensional seismic data volume of torsional shear waves of two rotational (polarized) directions;

[0076] S11. The vertical geophone of a three-component or five-component geophone deployed on the ground within the torsional shear wave seismic exploration area can record the vertical component data of the upward converted longitudinal wave generated by the downward torsional shear wave excited by the ground torsional shear wave source and reflected upward from various underground wave impedance interfaces back to the ground; the two mutually orthogonal horizontal geophones can record the direct and reflected shear shear wave data of two mutually orthogonal and horizontally polarized waves along the geophone direction; the horizontal geophone within the five-component geophone deployed on the ground within the torsional shear wave seismic exploration area can record the direct and reflected torsional shear wave data of two oppositely rotated (polarized) directions and parallel to the ground along the geophone direction;

[0077] S12. With a focal point in the torsional shear wave seismic exploration area as the center, gather data of ground three-component or five-component geophones at all long, medium, and short offsets are collected at azimuth angles of 5 to 10 degrees. The velocities of the direct P-wave and the two mutually orthogonal shear shear waves are calculated point by point based on the straight-line distance from the focal point to each ground geophone and the first arrival times of the direct P-wave and the two mutually orthogonal shear shear waves.

[0078] S13, determining the azimuths of the velocities of the fastest and slowest direct P-waves and the two mutually orthogonal shear-waves in the torsional shear-wave seismic exploration work area based on the velocity distribution values ​​of the omnidirectional direct P-waves and the two mutually orthogonal shear-waves in the torsional shear-wave seismic exploration work area calculated in step S12;

[0079] S14, according to the azimuths of the fastest and slowest direct wave velocities in the work area determined in step S13, respectively rotating the 3D seismic converted P-wave vertical component data volume and the two direct and reflected torsional S-wave data volumes with opposite rotation (polarization) directions and parallel to the ground acquired in step S11, to obtain a reflected P-wave vertical component data volume parallel to the fastest speed direction and a reflected P-wave vertical component data volume perpendicular to the fastest speed direction, and a reflected S-wave horizontal component data volume parallel to the fastest speed direction and a reflected S-wave horizontal component data volume perpendicular to the fastest speed direction;

[0080] S15. Perform imaging processing on the four sets of data volumes obtained in step S14, and integrate the four sets of reflection wave imaging data volumes to perform detailed structural interpretation and accurate prediction of fluid distribution of underground geological bodies including faults and fracture zones, fracture zones, and underground rock layers under the influence of underground principal stress.

[0081] Extracting the P-wave travel time data and S-wave travel time data from the three-component seismic data in step S14 and calculating the straight-line distance between the torsional S-wave source device and each block of three-component or five-component seismic data receiving point to obtain the fast P-wave velocity, slow P-wave velocity, time difference between fast and slow P-waves, fast and slow P-wave azimuths, fast S-wave velocity, slow S-wave velocity, time difference between fast and slow S-waves, and fast and slow S-wave azimuths;

[0082] Extracting the P-wave amplitude, P-wave reflection coefficient, P-wave AVO characteristics, P-wave time-frequency characteristics, S-wave amplitude, S-wave reflection coefficient, S-wave AVO characteristics, S-wave bright spots (or dark spots), P-wave to S-wave amplitude ratio, and S-wave time-frequency characteristics from the three-component seismic data in step S14; evaluating the underground geological structure morphology and characteristics and the type and distribution range of fluid in the pores;

[0083] Extracting seismic wave attribute data of the P-wave and S-wave from the three-component seismic data in step S14, performing P-wave and S-wave waveform classification, and obtaining P-wave coherence volume, P-wave curvature volume, P-wave dip and azimuth volume, S-wave coherence volume, S-wave curvature volume, and S-wave dip and azimuth volume;

[0084] The longitudinal wave impedance (I P ), shear wave impedance (I S ), elastic impedance (Ie), elastic impedance coefficient (Ce), longitudinal and transverse wave velocity ratio (γ0), Poisson's ratio (σ), Lame constant (λ), shear modulus (μ), longitudinal wave absorption coefficient (Q P ), longitudinal wave viscosity coefficient, shear wave absorption coefficient (Q S ), shear wave viscosity coefficient, ratio of longitudinal and shear wave absorption coefficients, and frequency variation characteristics of longitudinal and shear waves.

[0085] The four sets of reflection wave imaging data were inverted and processed respectively to extract relevant attributes, and the fluids in the underground geological bodies and underground rock pores were identified, predicted and evaluated, ultimately achieving comprehensive prediction, evaluation and quantitative interpretation of the fluid distribution in the oil and gas reservoirs.

[0086] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Based on the technical essence of the present invention and within the spirit and principles of the present invention, any simple modification, equivalent replacement and improvement of the above embodiment shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A torsional shear wave source device based on a gas explosion source cavity, characterized in that: The invention comprises at least two rectangular steel plates (1), wherein a central axis (2) is provided at the vertical center of each rectangular steel plate (1), and a gas explosion source cavity (3) is fixed on both sides of the vertical sides of the two outer ends of each rectangular steel plate (1); when the gas explosion source cavity (3) is excited twice respectively, each rectangular steel plate (1) rotates around the central axis (2) simultaneously in a clockwise or counterclockwise direction; One side surface of the gas explosion source cavity (3) is cut into a thin cavity surface (6), and the opposite surface of the thin cavity surface (6) is fixed to the surface of the outer end of the rectangular steel plate (1); An electronic ignition gun (4) is installed in the center of the gas explosion source cavity (3), and the electronic ignition gun (4) is connected to the control unit (7) via a wire (8); The gas explosion source cavity (3) is connected to the explosion-proof metal gas tank (9) through a metal gas pipe (5); the explosion-proof metal gas tank (9) stores compressed gas and supplies high-pressure gas to the gas explosion source cavity (3); Four gas explosion source cavities (3) are respectively fixed on the four outer vertical edges of each rectangular steel plate (1). Two or three rectangular steel plates (1) are combined to form a cross-shaped or cross-shaped torsional shear wave source. The torsional shear wave source synchronously excites two gas explosion source cavities (3) on opposite sides of each rectangular steel plate (1) at one time to simultaneously generate torsional shear waves in a clockwise direction, and then synchronously excites the other two gas explosion source cavities (3) on opposite sides of each rectangular steel plate (1) to simultaneously generate torsional shear waves in a counterclockwise direction.

2. The torsional shear wave source device based on the gas explosion source cavity according to claim 1 is characterized in that: The invention also includes a cement trough (10), wherein the rectangular steel plate (1) and the gas explosion source cavity (3) fixed thereon are installed in the cement trough (10), and four long openings (11) are opened on the side wall of the cement trough (10) at positions opposite to the thin cavity surfaces (6) of the four gas explosion source cavities (3).

3. The torsional shear wave source device based on the gas explosion source cavity according to claim 1 is characterized in that: The control unit (7) includes a GPS or Beidou timing, timing, and positioning module, and also includes a wireless signal receiving and transmitting antenna and module.

4. The torsional shear wave source device based on the gas explosion source cavity according to claim 1 is characterized in that: Torsional shear wave source devices based on gas explosion source cavities are sequentially arranged on the ground according to two-dimensional source survey lines or three-dimensional source survey networks, and three-component geophones or five-component geophones are sequentially arranged on the ground according to two-dimensional geophone survey lines or three-dimensional geophone survey networks.

5. The torsional shear wave source device based on the gas explosion source cavity according to claim 4 is characterized in that: The five-component detector consists of a vertical detector and four horizontal detectors orthogonal to the vertical detector. The four horizontal detectors on the same horizontal plane have an angle of 45 degrees between them.

6. The acquisition and processing method of the torsional shear wave source device based on the gas explosion source cavity according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Arrange three-component geophones or five-component geophones at all geophone positions on the ground within the torsional shear wave seismic exploration area according to the construction design, so that the directions of the two horizontal components of the three-component geophones or the two mutually orthogonal horizontal geophones of the five-component geophones are parallel and perpendicular to the geophone survey line respectively; S2. Dig a square or circular earth pit on the ground of the torsional shear wave seismic exploration area at all artificial seismic source positions arranged according to the construction design, with one side of the square earth pit parallel to the seismic source line and the other side of the square earth pit perpendicular to the seismic source line; bury a cross-shaped or cross-shaped cement trough (10) in which a torsional shear wave seismic source device based on a gas explosion source cavity is installed and fixed, or a cross-shaped or cross-shaped torsional shear wave seismic source device based on a gas explosion source cavity is installed and fixed into the square or circular earth pit, and then backfill the earth pit and compact the backfilled soil or silt; S3, point by point excitation of all torsional shear wave sources arranged along the source line: the control unit (7) controls the synchronous opening of the explosion-proof metal gas tank (9), and simultaneously supplies high-pressure gas to each gas explosion source cavity (3) on the torsional shear wave source through the high-pressure resistant metal gas pipe (5); S4, the electronic ignition gun (4) connected to the control unit (7) simultaneously detonates the high-pressure mixed gas in the two gas explosion source cavities (3) on opposite sides of each rectangular steel plate (1) at a pre-designed time, and at the same time sends the source seismic synchronization information to the ground three-component or five-component detector data acquisition and control system through its wireless signal receiving and transmitting module; S5. When the pressure of the high-pressure explosive gas generated by the explosion of the high-pressure mixed gas in each detonated gas explosion source cavity (3) reaches a certain threshold, the thin cavity surface (6) of each gas explosion source cavity (3) facing the outside of the rectangular steel plate (1) is exploded at high speed, so that it hits the gas explosion source cavity (3) and the wall of the two earth pits corresponding to the long opening (11) opened on the cement trough (10) at high speed along two opposite tangential directions, causing all the rectangular steel plates (1) fixed to the gas explosion source cavity (3) to rotate around the central axis; S6. The combined force of each rotating high-strength rectangular steel plate (1) causes the underground medium to generate a torsional shear wave polarized in a clockwise direction centered on the central axis (2); S7, then the electronic ignition gun (4) connected to the control unit (7) simultaneously detonates the high-pressure mixed gas of the other two gas explosion source cavities (3) on the square steel plates (1) on the other two opposite sides of each rectangular steel plate (1) at a pre-designed time, and at the same time sends the source seismic synchronization information to the ground three-component or five-component detector data acquisition and control system through its wireless signal receiving and transmitting module; repeating the steps of S4 to S5, the combined force of each rotating high-strength rectangular steel plate (1) causes the underground medium to generate a torsional shear wave with a counterclockwise polarization centered on the central axis (2); S8. Three-component or five-component geophones arranged on the ground according to the design plan sequentially collect data of two direct and reflected torsional shear waves with opposite rotation directions and parallel to the ground generated by the two excitations at the earthquake source location; S9, sequentially collecting two direct and reflected torsional shear wave data of two waves with opposite rotation directions and parallel to the ground at each earthquake source point position on the ground within the torsional shear wave seismic exploration area according to steps S3 to S8; S10, combining the direct and reflected torsional shear wave data of two directions of rotation parallel to the ground collected from all earthquake source points in sequence, respectively, to form a three-dimensional or five-dimensional seismic data volume of torsional shear waves rotating in two directions; S11. The vertical geophone of the three-component or five-component geophone deployed on the ground within the torsional shear wave seismic exploration area can record the vertical component data of the upward converted longitudinal wave generated by the downward torsional shear wave excited by the ground torsional shear wave source and reflected upward at various underground wave impedance interfaces back to the ground; S12. With a focal point in the torsional shear wave seismic exploration area as the center, gather data of ground three-component or five-component geophones at all long, medium, and short offsets are collected at azimuth angles of 5 to 10 degrees. The velocities of the direct P-wave and the two mutually orthogonal shear shear waves are calculated point by point based on the straight-line distance from the focal point to each ground geophone and the first arrival times of the direct P-wave and the two mutually orthogonal shear shear waves. S13, determining the azimuths of the velocities of the fastest and slowest direct P-waves and the two mutually orthogonal shear-waves in the torsional shear-wave seismic exploration work area based on the velocity distribution values ​​of the omnidirectional direct P-waves and the two mutually orthogonal shear-waves in the torsional shear-wave seismic exploration work area calculated in step S12; S14, according to the azimuths of the fastest and slowest direct wave velocities in the work area determined in step S13, respectively rotating the 3D seismic converted P-wave vertical component data volume and the two direct and reflected torsional S-wave data volumes with opposite rotation directions and parallel to the ground acquired in step S11, to obtain a reflected P-wave vertical component data volume parallel to the fastest speed direction and a reflected P-wave vertical component data volume perpendicular to the fastest speed direction, and a reflected S-wave horizontal component data volume parallel to the fastest speed direction and a reflected S-wave horizontal component data volume perpendicular to the fastest speed direction; S15. Perform imaging processing on the four sets of data volumes obtained in step S14, and perform detailed structural interpretation of the underground geological body and accurate prediction of fluid distribution by integrating the four sets of reflection wave imaging data volumes.

7. The seismic data acquisition method of the shear wave source device based on the gas explosion source cavity according to claim 6, characterized in that: The ground three-component or five-component geophone data acquisition and control system uses a ground wired three-component or five-component geophone, which is one of a wired three-component or five-component moving coil geophone, a wired three-component or five-component digital geophone, a wired three-component or five-component acceleration geophone, a wired three-component or five-component MEMS geophone, or a wired three-component or five-component fiber optic geophone.

8. The seismic data acquisition method of the shear wave source device based on the gas explosion source cavity according to claim 6, characterized in that: The ground three-component or five-component geophone data acquisition and control system uses a ground wireless three-component or five-component geophone, which is one of a wireless three-component or five-component moving coil geophone, a wireless three-component or five-component digital geophone, a wireless three-component or five-component acceleration geophone, a wireless three-component or five-component MEMS geophone, or a wireless three-component or five-component fiber optic geophone.

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