A piezoelectric geophone for deepwater node seismic exploration

Abstract

The present invention relates to the field of geophysical exploration, and specifically to a piezoelectric geophone for deepwater node seismic exploration. The piezoelectric geophone includes: a wiring member, an upper end cover, a lower end cover, a piezoelectric circular tube, a strut, an upper end lining, a lower end lining, and an electrode, wherein the wiring member is encapsulated on the outside of the upper end cover; the upper end lining and the lower end lining are respectively encapsulated at the two ends of the piezoelectric circular tube, the strut is arranged in the piezoelectric circular tube, and its two ends are passed through the upper end lining and the lower end lining, and correspondingly, the upper end cover and the lower end cover on the outside of the upper end lining and the lower end lining are respectively sheathed on the two ends of the strut; the electrode is arranged on the upper end cover, and is used to lead out the positive and negative poles of the piezoelectric circular tube. The piezoelectric ceramic circular tube detector of the present invention adopts a single-tube receiver, has a simple structure, is easy to assemble, and is extremely conducive to mass production.

Description

Technical Field

[0001] The present invention relates to the field of geophysical exploration, and in particular to a piezoelectric geophone for deep-water node seismic exploration. Background Art

[0002] With the progress of society and economic development, the world's demand for oil is increasing. The ratio of land to sea on Earth is approximately 7:3. Compared with land, the ocean contains more abundant oil resources. Therefore, offshore oil exploration is the main goal of modern oil exploration.

[0003] Currently, offshore oil exploration and data acquisition technologies are primarily categorized into streamer (TS) acquisition, ocean bottom cable (OBC) acquisition, ocean bottom seismograph (OBS), and ocean bottom node (OBN) acquisition. Ocean bottom node acquisition utilizes node seismographs deployed on the seafloor to record seismic signals generated by a source vessel in the seawater and reflected by the underlying strata. Compared to other acquisition technologies, it offers the following advantages: First, it is less susceptible to the effects of offshore infrastructure and can be performed in areas with densely populated production platforms and other obstructions, where TS acquisition is impractical. Second, it eliminates the constraints of cables, enabling the acquisition of seismic data over large offsets and wide azimuths. Third, compared to ocean bottom seismographs, ocean bottom node seismographs are less expensive and more easily and accurately deployed.

[0004] Piezoelectric geophones are the core sensing components of seafloor node seismometers. They utilize the piezoelectric effect of piezoelectric elements to convert acoustic pressure signals in seawater into electrical signals. Piezoelectric geophones of varying depths have been developed overseas for use in seafloor node seismic exploration. However, these geophones are restricted from exporting to depths of 1,000 meters or more. Therefore, designing a piezoelectric geophone suitable for deepwater applications is crucial for the development of deep-sea oil exploration technology in my country. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above problems and provide a piezoelectric geophone for deep-water node seismic exploration. The present invention is a piezoelectric ceramic circular tube geophone, which can be used for node seismic exploration at a water depth of 2000 meters.

[0006] To achieve the above-mentioned object, the present invention provides a piezoelectric geophone for 2000-meter deep-water node seismic exploration. The deep-water piezoelectric geophone comprises a wiring member, an upper end cover, a lower end cover, a piezoelectric circular tube, a support rod, an upper end lining, a lower end lining and an electrode, wherein:

[0007] The wiring member is encapsulated on the outer side of the upper end cover;

[0008] The upper end liner and the lower end liner are respectively encapsulated at the two ends of the piezoelectric circular tube, and the support rod is arranged in the piezoelectric circular tube, and its two ends are passed through the upper end liner and the lower end liner. Correspondingly, the upper end cover and the lower end cover on the outer side of the upper end liner and the lower end liner are respectively sealed at the two ends of the support rod;

[0009] The electrodes are arranged on the upper end cover and are used to lead out the positive and negative poles of the piezoelectric tube.

[0010] The piezoelectric circular tube is a piezoelectric ceramic circular tube, which adopts a single tube receiving method, is radially polarized, and the polarization direction is negative inside and positive outside; the hydrostatic pressure is resisted by the piezoelectric circular tube wall, upper end lining, lower end lining, upper end cover, lower end cover and metal support rods arranged inside the piezoelectric circular tube; the outside of the piezoelectric circular tube is watertight with a vulcanized rubber layer.

[0011] The piezoelectric tube is made of piezoelectric ceramic material, and can be made of one or more functional materials such as PZT-4, PZT-5, PZT-8, etc., and is the vibration sensing core component of the detector;

[0012] The upper end lining and the lower end lining are both made of insulating materials, such as epoxy foam, rigid polyurethane foam, nanocomposite foam, etc., which play the role of vibration decoupling between ceramic tubes and releasing radial hydrostatic pressure of the detector;

[0013] The upper end cover and the lower end cover can be made of metal materials such as stainless steel, iron, copper, etc., or can be made of high-hardness non-metallic materials such as pressure-resistant ceramics. The end cover plates serve to release the axial hydrostatic pressure of the detector.

[0014] High-hardness non-metallic materials and pressure-resistant ceramics are well known in the art.

[0015] The connecting piece can be made of hard aluminum alloy, stainless steel alloy, copper alloy and other materials, and is used to connect the detector sensing component and the seabed node, and at the same time provide a sealing surface for the watertight layer;

[0016] The support rods can be made of metal materials such as stainless steel, iron, copper, etc., or high-hardness non-metallic materials such as pressure-resistant ceramics. The support rods support the upper and lower end covers to improve the axial pressure bearing capacity of the end cover plates.

[0017] The terminal block is a sleeve structure, and a number of protrusions are arranged at intervals on the outside; the upper end cover is a frustum structure, and small holes are symmetrically arranged on the top surface of the frustum, and a groove is arranged in the middle position of the bottom surface of the frustum; the lower end cover is a frustum structure with a groove in the center; the piezoelectric circular tube is a tubular structure; the support rod is a columnar structure; the upper end liner is a structure of an annular boss arranged along the inner diameter edge of the disk, and a circular hole is arranged in the center of the upper end liner, and small holes are symmetrically arranged with the circular hole as the center; the lower end liner is a structure of an annular boss arranged along the inner diameter edge of the disk, and a circular hole is arranged in the center of the lower end liner; the electrode is a columnar structure with a protrusion radially arranged in the middle and upper part, and the protrusion is embedded in the small hole of the upper end cover.

[0018] The diameter of the metal support rod can be set in the range of 2-50 mm, and the length can be set in the range of 20-150 mm.

[0019] The wall thickness of the piezoelectric tube can be set in the range of 0-3mm and is not equal to 0, and the thickness of the upper end lining and the lower end lining can be set in the range of 0-8mm and is not equal to 0.

[0020] Compared with the prior art, the advantages of the present invention are:

[0021] The piezoelectric ceramic circular tube geophone of the present invention resists axial hydrostatic pressure by providing metal struts within the circular tube to support the upper and lower end caps. Its resistance to axial hydrostatic pressure is determined by the material, diameter, and length of the metal struts. It resists radial hydrostatic pressure by combining the parameters of the circular tube and the end liner. Its resistance to radial hydrostatic pressure is determined by the material and wall thickness of the circular tube, as well as the material and thickness of the end liner. In general, the present invention utilizes the rational selection of materials and geometric parameters for the end liner, end cap, metal rod, and ceramic tube, as well as the rational design of the spatial structure of the four, enabling it to be used for nodal seismic exploration in waters with a water depth of 2,000 meters or less. The piezoelectric ceramic circular tube geophone of the present invention utilizes a single-tube receiver, has a simple structure, is easy to assemble, and is highly suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the complete structure of the piezoelectric ceramic circular tube detector in the present invention;

[0023] Figure 2 is a schematic diagram of a wiring member in the present invention;

[0024] Figure 3 It is a schematic diagram of the upper end cover in the present invention;

[0025] Figure 4 Schematic diagram of the electrodes in the present invention;

[0026] Figure 5 It is a schematic diagram of the upper end lining in the present invention;

[0027] Figure 6 This is a schematic diagram of the piezoelectric ceramic tube in the present invention;

[0028] Figure 7 It is a schematic diagram of the support rod in the present invention;

[0029] Figure 8 It is a schematic diagram of the lower end lining in the present invention;

[0030] Figure 9 It is a schematic diagram of the lower end cover of the present invention;

[0031] Figure 10 It is a schematic diagram of a physical prototype of the present invention;

[0032] Figure 11 This is the low-frequency receiving sensitivity test result under normal pressure of the present invention;

[0033] Figure 12 This is the low-frequency receiving sensitivity test result under 20 MPa hydrostatic pressure of the present invention.

[0034] Reference numerals:

[0035] 1. Wiring piece, 2. Upper end cover, 3. Electrode, 4. Upper end lining, 5. Piezoelectric tube, 6. Support rod, 7. Lower end lining, 8. Lower end cover, 9. Rubber bladder. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to specific embodiments.

[0037] As attached Figure 1-12 As shown, this deep-water piezoelectric ceramic tube detector includes a wiring member 1, an upper end cover 2, an electrode 3, an upper end lining 4, a piezoelectric tube (piezoelectric ceramic tube) 5, a support rod 6, a lower end lining 7, a lower end cover 8, a rubber bag 9 and other parts.

[0038] In this embodiment, there is a total of one piezoelectric ceramic tube, which is made of "PZT-5" piezoelectric ceramic. The polarization mode is radial polarization, and the polarization direction is negative inside and positive outside. The preferred value of the diameter of the metal support rod (6) is 4mm, and the preferred value of the length is 36mm; the preferred value of the wall thickness of the piezoelectric tube (5) is 2mm, and the preferred value of the thickness of the upper end lining (4) and the lower end lining (7) is 2mm; the upper end lining 4 and the lower end lining 7 are respectively installed at the two ends of the piezoelectric ceramic tube 5, and then the support rod 6 is passed through the hole between the upper end lining 4 and the lower end lining 7 of the end lining, and then the upper end cover 2 and the lower end cover 8 are put on the two ends of the support rod and fixed with glue. Among them, the wall of the piezoelectric ceramic tube 5, the upper end lining 4 and the lower end lining 7 are used to resist the hydrostatic pressure in the radial direction of the detector, and the upper end cover 2, the lower end cover 8 and the support rod 6 are used to resist the hydrostatic pressure in the axial direction of the detector. The positive and negative poles of the piezoelectric ceramic tube 5 are led out through the electrode 3 on the upper end cover, and the wire is connected to the electrode 3 through the terminal 1. The entire detector is watertight through a watertight layer (vulcanized rubber layer), namely, a rubber bladder 9. The size of the terminal 1 is consistent with the interface size of the seabed node.

[0039] The piezoelectric ceramic circular tube detector of this embodiment was subjected to normal pressure and pressurized sensitivity tests. The normal pressure sensitivity test used a closed cavity comparison method, and the test frequency was 1 Hz to 2 kHz. Figure 11 The pressure sensitivity test method used is the coupled cavity reciprocity method, and the test frequency is 20Hz to 1kHz. Figure 12 This is the pressure test result.

[0040] Any content not described in detail in the present invention can be based on conventional technical knowledge in the art.

[0041] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and are intended to be encompassed by the claims of the present invention.

Claims

1. A piezoelectric geophone for deepwater node seismic exploration, characterized in that: The piezoelectric detector comprises: a connecting piece (1), an upper end cover (2), a lower end cover (8), a piezoelectric circular tube (5), a support rod (6), an upper end lining (4), a lower end lining (7) and an electrode (3), wherein: The connecting piece (1) is encapsulated on the outside of the upper end cover (2); The upper end liner (4) and the lower end liner (7) are respectively encapsulated at the two ends of the piezoelectric circular tube (5); the support rod (6) is arranged in the piezoelectric circular tube (5), and its two ends are passed through the upper end liner (4) and the lower end liner (7); correspondingly, the upper end cover (2) and the lower end cover (8) on the outer sides of the upper end liner (4) and the lower end liner (7) are respectively encapsulated at the two ends of the support rod (6); The electrode (3) is arranged on the upper end cover (2) and is used to lead out the positive and negative electrodes of the piezoelectric circular tube (5); The connecting piece (1) is a sleeve structure, and a plurality of protrusions are arranged at intervals on the outside; the entire piezoelectric geophone is watertight through a watertight layer (9), and the connecting piece (1) is used to connect the geophone sensing component and the seabed node, and at the same time provides a sealing surface for the watertight layer (9); The upper end cover (2) is a frustum structure, with small holes symmetrically arranged on the top surface of the frustum, and a groove is arranged in the middle position of the bottom surface of the frustum; the lower end cover (8) is a frustum structure with a groove arranged in the center; The piezoelectric circular tube (5) is a tubular structure; the support rod (6) is a columnar structure; The upper end liner (4) is a structure of an annular boss arranged along the inner diameter edge of the disc, and a circular hole is arranged at the center of the upper end liner, and small holes are arranged symmetrically with the circular hole as the center; the lower end liner (7) is a structure of an annular boss arranged along the inner diameter edge of the disc, and a circular hole is arranged at the center of the lower end liner (7); The electrode (3) is a columnar structure with a protrusion radially arranged in the middle and upper part, and the protrusion is embedded in the small hole of the upper end cover (2); The diameter of the support rod (6) is 2-50 mm, and the length is 20-150 mm; the wall thickness of the piezoelectric tube (5) is 0-3 mm, and is not equal to 0; the thickness of the upper end lining (4) and the lower end lining (7) are both 0-8 mm, and are not equal to 0.

2. The piezoelectric detector according to claim 1, wherein The piezoelectric detector adopts a single tube receiving method, the polarization mode is radial polarization, and the polarization direction is negative inside and positive outside.

3. The piezoelectric detector according to claim 1, wherein The outside of the piezoelectric circular tube (5) is watertight with a vulcanized rubber layer.

4. The piezoelectric detector according to claim 1, wherein The piezoelectric circular tube (5) is made of piezoelectric ceramic material, the upper end lining (4) and the lower end lining (7) are both made of insulating material, the upper end cover (2) and the lower end cover (8) are both made of metal material or high-hardness non-metal material, the connecting piece (1) is made of alloy material, and the support rod (6) is made of metal material or high-hardness non-metal material.

5. The piezoelectric detector according to claim 4, wherein The insulating material includes epoxy foam, rigid polyurethane foam or nanocomposite foam; The metal material includes stainless steel, iron or copper; The high-hardness non-metallic material is pressure-resistant ceramic; The alloy material includes hard aluminum alloy, stainless steel alloy or copper alloy.

6. The piezoelectric detector according to claim 1, wherein The support rod (6), upper end cover (2) and lower end cover (8) are used to resist the hydrostatic pressure in the axial direction of the detector; the wall of the piezoelectric circular tube (5), upper end lining (4) and lower end lining (7) are used to resist the hydrostatic pressure in the radial direction of the detector.

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