RU28923U1 - Multicomponent receiver for seismic exploration on the shelf and in transitional zones of land-sea - Google Patents

Description

MULTI-COMPONENT RECEIVER FOR SEISMIC EXPLORATION ON THE SHELF AND IN TRANSITIONS

ZONE SUSHA - SEA

The technical solution relates to the technique of seismic exploration in the waters and the constructive implementation of seismic signal receivers for seismic exploration on the shelf and in transitional zones of land-sea.

Known devices 1, 2, 8, 9 for offshore seismic exploration, containing an on-board computer installed on board a supporting research vessel (NIS), and a carrier of geophysical equipment made in the form of a seismic cable towed behind the NIS and placed at the bottom in it by blocks of bottom seismic receivers.

The main problem of seismic exploration in the water area is the creation of adequate seismic receivers (receiving seismic modules) with sufficiently high accuracy, reliability and reliability of the registration of seismic signals.

Known 4, 5, 6 three-component installation of geophones, containing, as a rule, three seismic geophones (a description of which is given, for example, in 9), intended mainly for land work. The multiwave seismic survey (MVS) method uses traditional installations 4, 5, containing three receivers

IPC: 001U 1 / 16.1 / 38

seismic signals (MSS), consisting of two horizontal and one vertical MSS (for the three components x, y, z). However, such installations require complex, expensive and at the same time insufficiently reliable mechanical means of self-orientation (gimbly). At the same time, the MSS in the water areas have insufficient accuracy (see 1,2, 8) and, as a result, insufficient adequacy for the correct interpretation of seismic data.

An alternative to installations with complex and expensive orientation (self-orientation) devices can be MSS modules equipped with orientation sensors that can determine the actual position of the MSS installation in space.

Thus, the well-known PSS 2, 4 installation includes three (or four) receivers and a spatial orientation sensor rigidly connected to the installation. In this case, the first - third MSS are located at an angle of 120, and the fourth (vertical) receiver is located in the center of the installation. Gyroscopic sensors or orientation devices along the Earth's magnetic field (inclinometers) are used as orientation sensors in installation 4. Orientation sensors can also be made 7 in the form of a complex electronic circuit.

However, the complexity and cumbersomeness of the known PSS 4, 7 installations, which, moreover, require their control from a ground station, do not allow, in some cases, to be used for correct detailed seismic exploration, especially when installing at the bottom of water areas.

Thus, the known devices 2, 4, 5, 7, 8 do not allow to obtain the potential accuracy and reliability of seismic data, especially when shooting in water areas, it is cumbersome and expensive to manufacture, and the orientation of the installation from the MSS requires special equipment and adequate construction of seismic 3

module taking into account the complex criterion “complexity - cost accuracy - efficiency.

The well-known receiving seismic module 3 includes an installation of four MSS and a gravitational orientation sensor rigidly connected with it, made in the form of a ball (or pendulum) of conductive material that closes sector contacts located along the circular guides of the cylindrical housing of the MSS module. In this case, the first and third MSS are located at an angle of 120 in the plane orthogonal to the observation line, and the sensitivity axis of the fourth receiver is placed along the horizontal observation line. The orientation sensor of module 3 has at least 12 sector contacts corresponding to a sector angle of not more than 30 °.

The known device 1 for polarization reconnaissance, adopted as a prototype, contains an airborne part mounted on the IPR and outboard receivers placed on the bottom made in the form of combined hose or cable module geophonic and hydrophone types, each of which is designed to record all types (component ) elastic waves or specialized in the reception of one field component with a given polarization. As a receiving seismic module 1, as a rule, device 3 is used.

However, in some cases, it is advisable to use proximity sensors with increased accuracy (with the ability to determine the orientation angle up to 3 °) as orientation sensors in a multicomponent receiving device, and include several repeater amplifiers in the design of the bottom braid to ensure adequate signals on board the NIS with a large the length of seismic streamers laid on the bottom.

The essence of the proposed technical solution is to create a multicomponent receiving device for seismic exploration on the shelf and in the transition zones of land-sea, incorporating such receiving seismic modules, which, by means of a special constructive design of the MSS system and MSS orientation sensors in space, would reduce the shooting error and carry out multicomponent (including MVS) shooting, providing a sufficiently high sensitivity and measurement accuracy relatively simple and universal a greasy device with a non-contact orientation sensor without the use of complex and expensive self-orientation systems.

The main technical result of the proposed technical solution is to increase the accuracy, reliability and reliability of seismic surveys and, as a consequence, to increase the information content of seismic data while reducing the complexity and cost of work. This ensures the optimality of indicators according to the criterion "complexity - cost - accuracy - efficiency, i.e. achieving maximum accuracy and efficiency with acceptable complexity and cost of the device.

The technical result is achieved as follows.

A multicomponent receiving device (MPU) for offshore seismic exploration and in land-sea transition zones is characterized by the availability of hardware and software and contains an onboard computing module (BWM) installed on board a supporting research vessel (NIS) and a carrier of geophysical equipment (PGA), made in the form of at least one towed NIS and laid on the bottom of the seismic streamer with the blocks of seismic receivers of geophonic and hydrophone placed in it.

The MPU differs from the prototype in that the blocks of the bottom seismic receivers are made in the form of receiving seismic modules (PSM) connected to each other and to the BVM cable sections, each of the PSM includes three piezoelectric accelerometers, a hydrophone and a PSM orientation sensor, outputs which are connected to the inputs of the electronics unit, consisting of preamplifiers, filters and analog-to-digital converters (ADC). Piezo-accelerometers in the PSM are located along mutually orthogonal components x, y, z, the hydrophone is located in the center of the PSM housing along its axis, and the PSM orientation sensor, rigidly connected to the piezo-accelerometer-hydrophone system, is designed as a non-contact PSM rotation angle sensor relative to the vertical and includes between the LEDs and photodiodes a transparent disk with a displaced center of gravity and with a gray barcode printed on it. Moreover, the disk is mounted in a plane orthogonal to the observation line, with the possibility of free rotation relative to the axis of the PSM housing and has at least 128 discrete positions corresponding to a rotation sector angle of not more than 3 °.

In addition, the MPU is characterized in that the part of the seismic streamer connecting its bottom-mounted part to the BVM is equipped with relay amplifier modules for exchanging information between the PSM and BVM via cable sections from an armored multicore cable that contain six conductive wires for power supply from side of the NIS to the PHA and two twisted pairs for supplying control and synchronizing signals from the side of the NIS to the PHA and transmitting digital seismic data from the PSM and data on the orientation of the PSM to the BVM.

Dd) (5

in special cases of MPU implementation, the part of the spit laid to the bottom includes up to 120 PSM with an outer diameter of not more than 0.07 m, connected by cable sections up to 25 m in length with a cable diameter of not more than 0.03 m, and the part of the seismic spit connecting the bottom with the BVM up to 6 amplifier modules of repeaters with an outer diameter of not more than 0.07 m, connected by cable sections up to 50 m long, with a total length of cable sections of up to 3200 m, a length of each PSM not more than 0.6 m and a length of modules of amplifiers-repeaters not more than 0.03 m.

The MPU difference is also that the BVM includes the PSM interface board connected by the inputs and outputs, a personal computer with a special software package, a laser printer and a magneto-optical drive with a data stream of at least 1 Mbit / s and a capacity of 5.2 GB, as well as blocks supply of BVM and PSM.

At the same time, in some cases, threshold devices can be added to the PSM to fix noise and ensure registration of seismic information only when the bottom part of the seismic streamer and PSM are completely laid to the bottom of the water area.

Pa figure 1 presents the General scheme of MPU for seismic exploration on the shelf and in the transition zones of land - sea, figure 2 shows a diagram of the structural design of the PSM.

MPU (figure 1) contains BVM 1 installed on board the NIS 2, PGA (seismicity) 3 with receiving seismic modules PSM 4, cable sections 5 and modules 6 of the amplifier-transponders. PSM 4 (figure 2) includes a cylindrical housing 7, a block of three piezoelectric accelerometers 8, a hydrophone 9, a PSM orientation sensor 10 and an electronics block 11 (preamplifiers, filters, ADCs, threshold devices). 6

The work of the MPU in terms of differences from the work of the prototype and analogues 1 3 is as follows.

When laying seismic streamers 3 from the NIS 2, seismic receivers (piezo-accelerometers) 8 PSM 4 receive the x, y, z components of the displacement wave field, and the hydrophone 9 acoustic pressure waves. Three receivers 8 located in a plane orthogonal to the observation line allow us to determine the fixed components of the wave field in the form of projections of the readings of the receivers in the selected directions, i.e. make multi-component shooting. Depending on the orientation of the PSM 4, the orientation sensor 10 generates signals that, together with the signals from the receivers 8 and the hydrophone 9, enter the electronics unit 11. In the orientation sensor 10, a system of optical fibers (emitters) and photodiodes (receivers) in conjunction with a transparent disk with an offset center gravity and with the Gray barcode printed on it allows you to determine the orientation of the housing 7 PSM 4 with an accuracy of 3 °. The displacement of the center of gravity of the disk will ensure its adequate placement in the field of gravity of the Earth due to free rotation relative to the axis of the housing 7 PSM 4, realizing a non-contact gravitational orientation sensor. The signals from the sensors 8, 9, as well as from the orientation sensor 10, converted to digital form by means of an ADC of the electronics unit 11, are supplied for accumulation and further processing to the BVM 2 (seismic station).

To optimize the aggregate of geophysical information obtained in special cases, the part of the streamer laid at the bottom includes up to 120 PSM 4 with an outer diameter of not more than 0.07 m, connected by cable sections 5 up to 25 m long with a cable diameter of not more than 0.03 m, and part of the seismic streamer 3 connecting the bottom with BVM 1, includes up to 6 modules 6 amplifiers 7

repeaters with an outer diameter of not more than 0.07 m, connected by cable sections 5 up to 50 m long, with a total length of cable sections 5 to 3200 m, length of each PSM 4 not more than 0.6 m and length of modules 6 of repeater amplifiers not more than 0.03 m. At the same time, in PSM 4 (in electronics block 11), similarly to 1, threshold devices can be added to fix noise and ensure registration of seismic information only when the bottom part of seismic streamer 3 and PSM 4 are completely laid to the bottom of the water area.

Thus, due to the special structural design of the PSM MPU and the proximity sensor of the orientation of its body in space, the accuracy, reliability and reliability of seismic surveys are increased. At the same time, PSMs were performed without complex and expensive, their self-orientation systems, which ensures the optimality of indicators according to the criterion “cost complexity - accuracy - efficiency.

BACKGROUND OF THE INVENTION

I. Prototype and analogues:

1.Pat. RF №2072534, IPC G 01 V 1/38, publ.: 01/27/97: AB “Inventions, 1997, No. 3, p.357 (prototype).

2. Pat. S111A No. 4942557, MKI G 01 V 1/38, NKI 367/15, publ.: 17.07.90. (analogue).

Z. St.-on at the PM of the Russian Federation No. 10889, IPC G 01 V 1/16, publ. 08.16.99, OB “PMPO, 1999, No. 8, p. 120 (analog).

P. Additional sources of prior art:

4.Galperin E.I., Ivanov L.I., Mirzoyan Yu.D. Application of the polarization method of seismic prospecting for oil and gas exploration / Overview. Ser. “Oil and gas geology and geophysics. -M.: VNIIOENG, 1981, 55p.

iOl

5.Pat. RF №2030766, IPC G 01 V 1/00, publ.: AB “Inventions, 1995, No. 7, p.210.

6.A.S. USSR No. 688885, MKI G O V 1/16, publ.: AB “Inventions, 1979, No. 36, p. 161.

7.Pat. RF №2107312, IPC G 01 V 1/22, publ.: 20.03.98: OB “Inventions, 1998, No. 8, p. 474 - 475.

8.Pat. PCT WO 85/05461, MKI G 01 V 1/38, publ.: 05.12.85.

9. Seismic exploration. Handbook of Geophysics / Ed. I.I. Gurvich, V.P. Nomokonov. - M .: Nedra, 1981 (p. 226 - 227).

lui

Claims (5)

1. A multi-component receiving device (MPU) for offshore seismic exploration and in transitional land-sea zones, characterized by the availability of hardware and software and containing an onboard computing module (BWM) installed on board a supporting research vessel (NIS), and a carrier geophysical equipment (NGA), made in the form of at least one towed NIS and laid on the bottom of a seismic streamer with blocks of bottom seismic receivers of geophonic and hydrophone types placed in it, etc. than the blocks of the bottom seismic receivers made in the form of receiving seismic modules (PSM) connected to each other and to the BVM cable sections, each of the PSM includes three piezoelectric accelerometers located in a cylindrical housing, a hydrophone and a PSM orientation sensor, the outputs of which are connected to the inputs of the electronics unit, which consists of of preamplifiers, filters, and analog-to-digital converters, piezoaccelerometers in the PSM are located along mutually orthogonal components x, y, z, the hydrophone is located in the center of the PSM housing along its axis, and the sensor of orientation of the PSM, rigidly connected to the piezoelectric accelerometers-hydrophone system, is made in the form of a non-contact sensor of the angle of rotation of the PSM relative to the vertical and includes a transparent disk located between the LEDs and photodiodes with a shifted center of gravity and with a gray barcode printed on it, while the disk is mounted in the plane orthogonal line of observation with the possibility of free rotation relative to the axis of the PSM body and has at least 128 discrete positions corresponding to a rotation sector angle of not more than 3 °. 2. MPU according to claim 1, characterized in that the part of the seismic streamer connecting its bottom-mounted part to the BVM is equipped with relay amplifier modules for exchanging information between the PSM and BVM via cable sections from an armored multicore cable that contain six conductive cores for supplying power from the NIS to the NGA and two twisted pairs for supplying control and synchronizing signals from the NIS to the NGA and transmitting digital seismic data from the PSM and data on the orientation of the PSM to the BVM. 3. MPU according to claims 1 and 2, characterized in that the part of the spit laid to the bottom includes up to 120 PSM with an outer diameter of not more than 0.07 m, connected by cable sections up to 25 m long with a cable diameter of not more than 0.03 m, and the part of the seismic streamer connecting the bottom with the BVM includes up to 6 amplifier modules of repeaters with an outer diameter of not more than 0.07 m, connected by cable sections up to 50 m long, with a total length of cable sections up to 3200 m, each PSM length not more than 0.6 m and the length of the modules of amplifiers-repeaters of not more than 0.03 m. 4. MPU according to claim 1, characterized in that the BVM includes a PSM interface board connected by inputs and outputs, a personal computer with a special mathematical software package, a laser printer, and a magneto-optical drive with an information flow of at least 1 Mbps and a capacity of 5.2 GB, as well as BVM and PSM power supplies. 5. MPU according to claim 1, characterized in that the PSM additionally includes threshold devices for fixing noise and ensuring the registration of seismic information only when the bottom part of the seismic streamer and PSM are completely laid to the bottom of the water area.