CN106932814B - Marine High Resolution Stereoscopic Vertical Time Delay EDM Seismic Source - Google Patents

Abstract

The marine high-resolution stereoscopic vertical delay electric spark seismic source comprises a water control excitation unit with a time delay control circuit, a depth sensor and a cylindrical vertical array frame connected with the water control excitation unit through an energy transmission connecting cable, wherein a plurality of columnar electrode carriers with negative electrodes are arranged on the outer side of the frame and parallel to the axis of the frame, and the water control excitation unit is used for providing electric energy for the negative electrodes to perform energy excitation. When the device is used, electric energy is output to the cathode electrodes with different depths at different times, so that the seismic source wavelet with time delay is generated based on the difference of the spatial depths of the cathode electrodes. The design ensures that the positive and negative amplitudes of wavelets generated by a single cathode electrode are mutually overlapped through controlling the spatial arrangement of the electrodes and the excitation time delay, so that the virtual reflection is suppressed, the frequency band is widened, the main frequency is improved, the virtual reflection of the seismic wavelets generated by the excitation of the vertical time delay electric spark seismic source is maximized, and the resolution of the field data acquisition of the seismic exploration is greatly improved.

Description

Marine High Resolution Stereoscopic Vertical Time Delay EDM Seismic Source

technical field

The invention relates to an electric spark seismic source in the process of marine seismic exploration, in particular to a marine high-resolution three-dimensional vertical time-delay electric spark seismic source, which is used in a marine field high-resolution three-dimensional observation system to explore and collect seismic reflection information in the middle and shallow layers of the seabed and use it. in marine geological surveys.

Background technique

In the marine field seismic exploration work, the seismic source is the key equipment in the marine seismic exploration data acquisition system, especially for the exploration of the middle and shallow layers of the ocean, the electric spark is one of the important seismic sources. In recent years, with the advancement of high-resolution seismic data acquisition technology and the improvement of environmental protection awareness of acquisition personnel, spark source plays a major role in marine seismic exploration. At present, the EDM seismic sources commonly used in China are mainly the SIG series produced by the French S.I.G company, and the Geo-spark series produced by the Dutch Geo-Resources company. The relevant marine electric spark sources developed at home and abroad are mainly combined excitation in the form of planar arrays, and the wavelet energy is increased linearly by combination to achieve the purpose of increasing the penetration depth of seismic waves in seismic exploration. However, with the improvement of seismic exploration technology requirements, how to broaden the bandwidth of the source wavelet and increase its main frequency is a problem that geophysicists need to think about. How to suppress the virtual reflection brought by the water-vapor interface, how to increase the energy and penetration depth and other issues are the focus of this patent based on the existing technology.

Contents of the invention

The purpose of the present invention is to provide a marine high-resolution three-dimensional vertical time-delay electric spark seismic source, to improve the effect of the electric spark array to widen the frequency band and increase the main frequency through space and excitation time, and to generate high-resolution seismic wavelets to be suitable for marine high Identify relevant technical requirements for multi-channel seismic exploration systems.

According to the relationship between the bubble wall pressure and time generated by the single electrode, that is, the bubble pulse of the single electrode, the present invention regularly adjusts the excitation time interval of each single electrode, such as sinusoidal or exponential excitation time interval. According to the space and excitation time difference of each electrode, the marine high-resolution three-dimensional vertical time-delay electric spark source is constructed.

A marine high-resolution three-dimensional vertical time-delay electric spark seismic source is characterized in that it includes an above-water control excitation unit and an underwater depth sensor. The top of the array frame is connected, and the cylindrical vertical array frame is the entire source electrode carrier, which includes a plurality of columnar electrode carriers, and each columnar electrode carrier is evenly arranged around the axis of the cylindrical vertical array frame, and each columnar electrode The carriers are all parallel to the axis and have the same distance from the axis, and the distance between every two adjacent columnar electrode carriers is equal; each columnar electrode carrier has a plurality of cathode electrodes arranged at equal intervals along the length direction; the direction of each cathode electrode is the same And they are all located in the radial direction of the columnar electrode carrier; the above-water control excitation unit includes a time delay control circuit, and provides electric energy to the cathode electrodes of different depths at different times, so that the cathode electrodes of different depths are realized at different times. Perform energy stimulation.

The aforementioned time delay control circuit enables the cathode electrodes of different depths to be excited at different times, and the excitation law includes sinusoidal or exponential excitation time intervals.

One of the sinusoidal excitation time intervals is: the shallowest cathode electrode is used as the initial excitation layer, and the excitation is delayed layer by layer, and the excitation time interval between each layer and the previous layer is T=K*sin( t/(N*π/2), K is the coefficient, which is a real number, t is the tth layer, and the number of N layers.

In actual work, the vertical array seismic source is placed vertically in seawater, and all electrodes are excited according to the preset time delay, so that the bubbles excited by each cathode electrode from top to bottom are delayed and superimposed, and the corresponding single-electrode wavelet The excitation time is different, so the result of mutual superposition makes the positive and negative amplitudes of the wavelets coherent, which can effectively suppress the ghost reflection of the sea surface.

The shape of the vertical array frame is a cylinder with a bottom diameter of 400 mm and a height of 2000 mm. It includes 16 columnar electrode carriers arranged vertically. The distance between two adjacent columnar electrode carriers is 2 cm. Each columnar electrode carrier is equipped with 100 All cathode electrodes belong to the same circuit, and the distance between two adjacent cathode electrodes is 2cm; all cathode electrodes are arranged in a grid pattern (each cathode electrode is equal to the distance between its upper, lower, left, and right adjacent cathode electrodes) .

The negative electrode is a copper wire wrapped with polyester material, and the energy range of a single electrode is 5-30J when it is discharged.

The balance counterweight ball 7 of free swing is installed on the bottom of the cylindrical vertical array frame.

The overall excitation energy range of the design source is 8000-48000J.

The anode watertight joint can be easily installed and disassembled, the balance weight ball is used for the balance adjustment of the vertical array frame in the free state in the water body, and the depth sensor is used to measure the sinking depth of the seismic source.

In order to ensure that the overall shaking of the vertical array electric spark source is not very violent under the sea conditions with large waves, the underwater part of the source is equipped with a balance ball at the bottom of the source. The balance ball includes the ball and the cylinder The rotating shaft at the bottom of the shaped vertical array frame, the counterweight ball and the rotating shaft are connected by a swing rod, the purpose is to eliminate the vibration of the source caused by the surge.

The method for generating seismic source wavelets using the above-mentioned marine high-resolution stereo phase-modulated seismic source is characterized in that it comprises the following steps:

The vibrator is carried on the working boat and driven to the predetermined sea area, the device is hoisted into the water, and the depth pressure sensor is used to detect whether it has reached the predetermined depth.

Output electric energy to the negative electrode, according to the difference in the depth of the negative electrode space of each layer, the negative electrodes of different depths in each layer are excited at different times, thereby generating the seismic source wavelet, so that the generated seismic source wavelet can be according to the negative electrode. The difference in time delay suppresses ghost reflections, thereby improving the energy of the source and the resolution of seismic wavelets, and is suitable for high-resolution marine seismic exploration.

The present invention has the following characteristics:

a. The marine high-resolution three-dimensional vertical time-delay EDM seismic source utilizes the existing technology of cathode electrode discharge consistency, and by controlling the spatial arrangement of the electrodes and the excitation time delay, the positive and negative amplitudes of the wavelets generated by a single cathode electrode are superimposed on each other, thereby suppressing Ghost reflection, broaden the frequency band and increase the main frequency. The time delay can use the time control integrated circuit in the water control excitation unit 1 to control the excitation time of each layer of cathode electrodes 6 to have a fixed delay, and the time delay is a natural logarithmic law, effectively systematically controlling the earthquake generated by the excitation of a single cathode electrode The wavelet suppresses the virtual reflection of the seismic wavelet generated by the vertical time delay electric spark source excitation to the maximum extent, and greatly improves the resolution of field data acquisition in seismic exploration.

b. Cathode discharge is an existing technology. The characteristic of this technology is that electrode discharge does not consume materials and can maintain the wavelet consistency of a single electrode.

c. In order to ensure that the overall shaking of the source is not very violent under the sea conditions with large swells, a balance weight ball is installed at the bottom of the source. The purpose is to use the free swing of the balance weight ball to limit the shaking angle of the vertical array source.

d. Using the depth pressure sensor 4, real-time transmission is used to determine the sinking depth of the cylinder, which is used to calculate the space distance for suppressing the ghost reflection.

e. The entire electrode arrangement is 16 symmetrical columnar electrode carriers, which are symmetrical to the centerline of the entire electrode frame and arranged at equal intervals on the side of the cylinder.

f. 100 electrodes arranged at equal intervals on each columnar carrier, all electrodes belong to the same circuit, and the electrode spacing is 2cm. With such an arrangement, the different spatial depths of the cathode electrodes 6 are utilized, so that the seismic wavelets generated by the cathode electrodes 6 at the same depth can be delayed and superimposed on each other, effectively suppressing sea surface ghost reflections.

g. The overall frame 4 of the seismic source is 400mm in diameter at the bottom and 2000mm in height. All electrodes belong to the same circuit and are excited simultaneously. The columnar electrode carriers 5 are separated by 2 cm, and a total of 16 columnar electrode carriers 5 surround the vertical array. The length of the negative electrode 6 on each columnar electrode carrier 5 is 2 cm, and the diameter of the bottom area is 5 mm. The structure of the cathode electrode 6 is a discharge copper wire 9 wrapped with a polyester material 10 .

Description of drawings

Fig. 1 is a schematic diagram of the marine high-resolution three-dimensional vertical time-delay electric spark source of the present invention.

Figure 2 Schematic diagram of a single columnar electrode carrier

Figure 3 Schematic diagram of a single cathode electrode

Figure 4 is a perspective view of the overall frame of the seismic source, the columnar electrode carrier and the cathode electrode.

Fig. 5 is the seismic source wavelet produced when the total discharge capacity is 8000J by using the marine high-resolution three-dimensional vertical time-delay electric spark seismic source of the present invention.

Fig. 6 is the amplitude spectrum of the source wavelet shown in Fig. 5 .

Among them, 1. Water control excitation unit, 2. Energy transmission cable, 3. Anode watertight joint, 4. Cylindrical vertical array frame, 5. Columnar electrode carrier, 6. Cathode electrode, 7. Balance weight ball, 8. Depth Sensor, 9, discharge copper wire, polyester material 10.

Detailed ways

As shown in Figures 1-4, a marine high-resolution three-dimensional vertical time-delay electric spark seismic source is characterized in that it includes an above-water control excitation unit 1 and an underwater depth sensor 8, and the above-water control excitation unit 1 is equipped with an anode The energy transmission connection cable 2 of the watertight joint 3 is connected to the top of the cylindrical vertical array frame 4, the cylindrical vertical array frame 4 is the entire seismic source electrode carrier, and it includes a plurality of columnar electrode carriers 5, each of the columnar electrodes The carriers 5 are evenly arranged around the axis of the cylindrical vertical array frame 4, each columnar electrode carrier 5 is parallel to the axis and at the same distance from the axis, and the distance between every two adjacent columnar electrode carriers 5 is equal; each columnar electrode A plurality of cathode electrodes 6 are arranged at equal intervals along the length direction on the carrier 5; each cathode electrode 6 has the same direction and is located in the radial direction of the columnar electrode carrier 5;

The above-water control and excitation unit 1 includes a time delay control circuit, and provides electric energy to the cathode electrodes 6 at different depths at different times, so that the cathode electrodes 6 at different depths can be excited at different times.

The aforementioned time delay control circuit enables the cathode electrodes 6 with different depths to be excited with energy at different times, and the excitation rules include sinusoidal or exponential excitation time intervals.

One of the sinusoidal excitation time intervals is: the shallowest cathode electrode 6 is the initial excitation layer, and the excitation is delayed layer by layer, and the excitation time interval between each layer and the previous layer is T=K*sin (t/(N*π/2), K is the coefficient, t is the tth layer, and the number of N layers.

In actual work, the vertical array seismic source is placed vertically in seawater, and all electrodes are excited according to the preset time delay, so that the bubbles excited by each cathode electrode 6 from top to bottom are delayed and superimposed, and the corresponding single-electrode electrodes The wave excitation time is different, so the result of mutual superposition makes the positive and negative amplitudes of the sub-waves coherent, which can effectively suppress the ghost reflection of the sea surface.

The method for generating seismic source wavelets using the above-mentioned marine high-resolution stereo phase-modulated seismic source is characterized in that it comprises the following steps:

The vibrator is carried on the working boat and travels to the predetermined sea area, the device is hoisted into the water, and the depth pressure sensor 8 is used to detect whether it has reached the predetermined depth,

To output electric energy to the cathode electrode 6, according to the difference in the spatial depth of each layer of cathode electrodes 6, the cathode electrodes 6 of different depths in each layer are excited at different times to generate seismic source wavelets, so that the generated seismic source wavelets can be generated according to The difference in time delay of the cathode electrode 6 suppresses the ghost reflection, thereby improving the energy of the source and the resolution of the seismic wavelet, and is suitable for marine high-resolution seismic exploration.

Example

The shape of the vertical array frame 4 is a cylinder with a bottom diameter of 400 mm and a height of 2000 mm. It includes 16 columnar electrode carriers 5 arranged vertically. The distance between two adjacent columnar electrode carriers 5 is 2 cm. Each columnar electrode carrier 5 There are 100 cathode electrodes 6 on the top, all cathode electrodes 6 belong to the same circuit, and the distance between two adjacent cathode electrodes 6 is 2cm; all cathode electrodes 6 are arranged in grid form.

The negative electrode 6 is a copper wire wrapped with polyester material, and the energy range of a single electrode is 5-30J when it is discharged.

The overall excitation energy range of the design source is 8000-48000J.

The anode watertight joint 3 can be easily installed and disassembled, the balance weight ball 7 is used for balance adjustment of the vertical array frame in a free state in the water body, and the depth sensor 8 is used for measuring the sinking depth of the seismic source.

In order to ensure that the overall shaking of the vertical array electric spark source is not very violent under the sea conditions with large swells, the additional balance weight ball 7 of the underwater part of the source is placed at the bottom of the source, and the balance weight ball 7 includes the balance ball and The rotating shaft located at the bottom of the cylindrical vertical array frame 4, the counterweight ball and the rotating shaft are connected by a swing rod, the purpose is to eliminate the vibration of the source due to the surge.

The energy transmission cable 2 is about 150m long, and a depth sensor 8 is installed on the top of the overall frame 4 of the seismic source. The balance weight ball 7 and the cathode electrode 6 are all integrated and installed on the overall frame 4 of the seismic source. Among them, every 100 cathode electrodes are integrated on a columnar electrode carrier, and then 20 columnar electrode carriers are sequentially installed on the cylindrical side of the overall frame of the seismic source.

The above-mentioned 150m connecting cable 2 integrates multi-strand cables, which are connected through the anode watertight joint 3 . It includes 20 strands of cathode wire and anode wire for charging and discharging of power supply (corresponding to the number of columnar electrode carriers), 1 strand of real-time transmission line for depth sensor, and 1 strand of ground wire. Various cables are wrapped and integrated with insulating soft metal materials to prevent inductive effects between cables. All cable joints are integrated in the anode watertight joint 3, and the connection between the indoor unit and the outdoor unit is realized in the joint.

Based on the prior art of cathode discharge, the present invention utilizes the time-delay excitation and spatial depth position relationship of different cathode electrodes, comprehensively calculates the time delay of source wavelets, and performs dislocation superposition to suppress ghost reflection phenomenon.

It can be seen from Fig. 5 and Fig. 6 that the source wavelet generated by the present invention has the characteristics of high bandwidth, high resolution and good suppression of ghost reflection, which meets the requirements of marine high-resolution seismic exploration.

Claims (8)

1. A marine high-resolution three-dimensional vertical time-delay electric spark source, characterized in that it includes an above-water control excitation unit (1) and an underwater depth sensor (8), and the above-water control excitation unit (1) is equipped with an anode The energy transmission connecting cable (2) of the watertight joint (3) is connected to the top end of the cylindrical vertical array frame (4), which is the entire seismic source electrode carrier, which includes multiple columnar electrode carriers (5), each columnar electrode carrier (5) is uniformly arranged around the axis of the cylindrical vertical array frame (4), each columnar electrode carrier (5) is parallel to the axis and the distance from the axis is equal, each adjacent The distances between the two columnar electrode carriers (5) are equal; multiple cathode electrodes (6) are arranged at equal intervals along the length direction on each columnar electrode carrier (5); each cathode electrode (6) has the same direction and is located at In the radial direction of the columnar electrode carrier (5); the above-water control excitation unit (1) includes a time delay control circuit, and provides electric energy to the cathode electrodes (6) of different depths at different times, so that the cathode electrodes (6) of different depths The electrodes (6) realize energy excitation at different times. 2. A marine high-resolution three-dimensional vertical time-delay electric spark seismic source as claimed in claim 1, characterized in that the cathode electrodes (6) at different depths are excited at different times by using the time-delay control circuit, and the excitation Laws include sinusoidal or exponential firing intervals. 3. A marine high-resolution three-dimensional vertical time-delay electric spark seismic source as claimed in claim 2, characterized in that one of the sinusoidal excitation time intervals is: starting from the shallowest cathode electrode (6) The initial excitation layer, the excitation is delayed layer by layer, and the excitation time interval between each layer and the previous layer is T=K*sin(t/(N*π/2), K is a coefficient, which is a real number, and t is the tth layer , N layers. 4. A marine high-resolution three-dimensional vertical time-delay electric spark source as claimed in claim 1, characterized in that the shape of the cylindrical vertical array frame (4) is a cylinder with a bottom diameter of 400mm and a height of 2000mm, It includes 16 columnar electrode carriers (5) arranged vertically, the distance between two adjacent columnar electrode carriers (5) is 2cm, each columnar electrode carrier (5) is equipped with 100 cathode electrodes (6), all cathode The electrodes (6) belong to the same circuit, and the distance between two adjacent cathode electrodes (6) is 2cm; all the cathode electrodes (6) are arranged in a grid. 5. A marine high-resolution three-dimensional vertical time-delay electric spark seismic source as claimed in claim 4, characterized in that the cathode electrode (6) is a copper wire wrapped by polyester material, and the energy range of a single electrode discharge is 5-30J. 6. A marine high-resolution three-dimensional vertical time-delay electric spark seismic source as claimed in claim 1, characterized in that a freely swinging balance weight ball (7) is installed at the bottom of the cylindrical vertical array frame (4). 7. A marine high-resolution three-dimensional vertical time-delay electric spark seismic source as claimed in claim 5, characterized in that the overall excitation energy range of the seismic source is 8000-48000J. 8. utilize the described ocean high-resolution three-dimensional vertical time-delay electric spark seismic source of claim 1 to produce the method for seismic source wavelet, it is characterized in that comprising the following steps: The vibrator is carried on the working boat and driven to the predetermined sea area, the device is hoisted into the water, and the depth pressure sensor (8) is used to detect whether it has reached the predetermined depth, Output electric energy to the cathode electrode (6), according to the difference in spatial depth of the cathode electrode (6) of each layer, the cathode electrodes (6) of different depths in each layer are excited at different times, thereby generating the source wavelet, which makes the generation The seismic source wavelet can differentially suppress ghost reflections according to the difference in time delay of the cathode electrode (6), thereby improving the energy of the seismic source and the resolution of the seismic wavelet, and is suitable for marine high-resolution seismic exploration.