RU2328019C1 - Marine electrical exploration device and process of electrical exploration on run - Google Patents

Abstract

FIELD: physics; geophysics.

SUBSTANCE: current pulse is excited in the medium under investigation, and parameters of its induced polarisation are defined. Geoelectric section is generated to make a conclusion about the presence of hydrocarbon fields on the basis of abnormal manifestations of induced polarisation parameters. At that, electromagnetic and seismic waves are excited simultaneously or with a time shift. To excite the said waves unipolar rectangular impulses of direct current are generated, their absolute and relative duration depending on parameters of medium under investigation. In the beginning of timing pulse electric field is measured simultaneously at measuring probe groups of two detector lines towed at different depth. Besides, detector line depth and hydroacoustic pressure of seismic source are measured. Also a device is offered, which includes pulse generator, capacitor charging unit, power generator, bank of capacitors, switchboard, seismic emitter, transmitter/receiver line, receiver line, multi-channel gauge, echo-sounder, GPS satellite navigation receiver, signal processor.

EFFECT: higher reliability of research results.

18 cl, 6 dwg

Description

FIELD OF THE INVENTION

The group of inventions "Device for marine electrical exploration and the method of marine electrical exploration in the movement of a ship" relates to the field of exploration geophysics, in particular to geoelectrical exploration by the method of induced polarization in conjunction with the seismoelectric effect. It is used for sensing the seabed in the offshore zone and is intended for predicting deposits of hydrocarbons, water, hydrocarbon deposits and other related chemicals.

State of the art

The invention is known "Method and apparatus for offshore electromagnetic sounding utilizing wavelength effects to determine optimum source and detector positions", US patent, No. 4617518, Srnka, Oct.14, 1986, which used magnetic and electrical measurements of the parameters of the medium under study, but towed receiving line does not allow to take into account the vertical component of the electric field, which significantly reduces the reliability of the construction of the geoelectric section.

Known invention "Method of geoelectrical exploration", patent RU 2219568, Rykhlinsky N.I. et al., Feb. 2003, in which, to predict hydrocarbon deposits, a medium model was constructed that is closest in geometrical structure and electrical parameters to the studied one. In this case, the equation of mathematical physics was used for the intensity of the dipole source in an electrochemically polarized medium. However, this model, due to the multiplicity of solutions of the original equation, cannot adequately describe the medium under study and has a probabilistic nature.

The invention is known as "Remote reservoir resistivity mapping", US patent No. 6603313, Srnka, Aug.5, 2003, in which, based on previously obtained geological data on the presence of a hydrocarbon field, a spatial grid of sensors registering electromagnetic waves, rigidly fixed, was used for a more detailed determination of hydrocarbon deposits on the surface of the seabed. However, this method of determining the parameters of the studied medium cannot be applied in motion, since it has a stationary character.

The invention is known as "Geophysical prospecting", US patent No. 5877995, Thompson et al., Mar.2, 1999, which uses the electroseismic method for predicting hydrocarbon deposits, but not in marine conditions.

“Electromagnetic-to-seismic conversion: successful developments suggest viable applications in exploration and production”, AHThompson, Abstracts of EM Technical Session, SEG, Houston, 2005, which examined the basics of the seismoelectric and electroseismic method, but for determining hydrocarbon deposits on land .

The closest technical solution for the proposed device and method for marine reconnaissance is a "device for marine electrical reconnaissance in vessel motion and a method of marine electrical exploration", patent RU No. 2253881, Lisitsin ED et al., June 2005, in which multichannel multidimensional measurements of the investigated medium were used using recalculation of the obtained characteristics based on the selection of parameters of a layered conducting and polarizing medium. However, the proposed solution does not have sufficient spatial resolution due to the use of only one measuring cable, as well as the absence of an additional stimulating effect on the test medium of the seismic emitter.

Disclosure of invention

It is required to detect deposits of hydrocarbons and related substances based on the study of the effect of induced polarization.

The problem was solved by excitation of electromagnetic radiation pulses in the medium under study, causing the effect of induced polarization, with simultaneous excitation of the seismic wave at specified intervals, causing an additional change in the effect of induced polarization. In this case, two receiving electrode lines towed at different depths were used.

The technical result of the group of inventions is to increase the reliability of the research results.

The invention is illustrated by drawings, which show a device for marine electrical exploration and the relative position of its parts.

Brief Description of the Drawings

Figure 1 - General diagram of a device for determining the parameters of induced polarization.

Figure 2 - Arrangement of measuring cable lines and radiation sources relative to the vessel.

Figure 3 - Diagram of the propagation of seismic (21) and electromagnetic (22) waves over a hydrocarbon field (24), as well as a reflected electromagnetic wave (23), which is detected by symmetrically located electrodes M1, O1, N1 and M2, O2, N2, and also asymmetrically located electrodes M3, O3, N3.

Figure 4 is a graph illustrating the cycle of the device:

a) is a clock pulse with duration t0-t1;

b) is the pulse of electromagnetic radiation with a duration t0-t3;

c) - pulse of seismic radiation with a duration of t4-t5;

d) is the shape of the electric field recorded on one of the pairs of receiving electrodes.

The problem will be solved using a device for marine electrical exploration containing a pulse generator (1), a block for charging capacitors (2), which is powered by a generator (3), a block of capacitors (4), a switch (5), which forms two sequences of unipolar rectangular pulses of constant current, a seismic emitter (6) with an adjustable length of the discharge gap exciting the seismic wave (21), a transceiver line (7) that excites an electromagnetic wave (22) and carries receiving electrodes (18), a pressure sensor (19), a hydrophone (twenty) , a receiving line (8) with similar electrodes, sensors and hydrophones, a multi-channel measuring device (9), an echo sounder (10), a satellite navigation receiver of a global positioning system (GPS) (11) and a processor for processing signals (12), characterized in that the switch (5) ensures the formation of rectangular current pulses over two channels with a duration of 0.1 to 10 seconds and a current strength of 0 to 2500 A on the supply electrodes (13, 14) of the electromagnetic radiator and on the electrodes (15, 16) of the seismic radiator ( 6), towed behind the stern of the vessel for a given depth, the transceiver line (7), with a measuring part length of at least 2000 m, is made in the form of a multi-core geophysical cable with neutral buoyancy with depth-stabilizing depth-stabilizing cables (17) located at the ends of the transceiver line (7) copper that provide spatial orientation of the cable (7) electrodes (13, 14), symmetrically arranged graphite electrodes (18), pressure sensors (19), hydrophones (20), and a receiving line (8) having a measuring part length of at least 1000 m, made in the form of multicores geophysical cable with neutral buoyancy, with deep-seated cable orientation in space, stabilization stabilizers (17), symmetrically arranged graphite electrodes (18), pressure sensors (19), hydrophones (20).

In addition, the capacitor charging unit provides an adjustable capacitor charge speed from 0 to 50 A DC, the capacitor charging unit provides an adjustable capacitor charging speed from 0 to 3000 V DC, the capacitance of the capacitor unit is from 300 to 500 mF, the distance between the electrodes the seismic transmitter is 1 to 10 m, the transceiver line has 3 to 6 pressure sensors, the transceiver line has 3 to 6 hydrophones, the transceiver line has 6 to 12 depth stabilizers eniya, the receiving line has from 2 to 3, the pressure sensors, receiving line has from 2 to 3 hydrophones receiving line has from 3 to 6 stabilizers penetration.

The implementation of the invention

When the vessel exits to the start point of the profile, the processor (12), the control pulse generator (1), the unit for charging capacitors (2), the multi-channel measuring device (9), the echo sounder (10), GPS (11) are launched and the capacitor unit starts charging ( 4) to a given voltage level. At a given navigation point, determined by the GPS system (11), a clock pulse is generated with a duration of 10 to 15 s, by means of which, at time t0, the high-voltage switches of the two-channel switch (5) are opened and the discharge of capacitors, respectively, through the electrodes (13, 14) begins with excitation of an electromagnetic wave (22) and through electrodes (15, 16) with excitation of a seismic wave (21). Each channel is discharged with a duration of 0.2 to 0.5 s, after which the capacitors again begin to charge. The discharge parameters are controlled by a multichannel measuring device (9).

Simultaneously with the discharge at time t0, data collection begins with groups of measuring electrodes M1, O1, N1 and M2, O2, N2 of the transceiver line (7) and M3, O3, N3, of the reception line (8), as well as from all sensors pressure (19), hydrophones (20), echo sounder (10) and GPS (11). The constant component of the electrical conductivity of the medium is measured at electrodes A, B and N3, N4.

Data from all devices is recorded on a hard drive and assigned to the current navigation point. The end of data reading is determined by the end of the clock pulse. After the signal appears on the charge of the capacitor block to a predetermined level, the next clock pulse is applied and the operation of the system is repeated.

In the process of passing the geological profile by the vessel, a database is formed of parameters of the medium under study, such as electrical conductivity, polarizability and the decay time constant of electrode potentials, which together determine the effect of the induced polarization.

The advantage of this device lies in the fact that such a spatial structure of the receiving electrodes is used in which the dipole emitting an electromagnetic wave (13, 14) is located symmetrically with respect to the groups of receiving electrodes M1, O1, N1 and M2, O2, N3, which makes it possible to more accurately determine the contour assumed hydrocarbon deposits (24) and eliminate noise interference, since the signals received on different sides relative to the centrally located emitting dipole have different signs. In addition, significantly longer than in the prototype, namely at least 2000 m, the length of the emitting dipole can reduce the attenuation of the waves during their propagation in liquid and silt media. An additional receiving line (8), which is towed in the bottom layers, will allow us to fix the vertical and radial component of the change in the parameters of stimulated polarization.

The adopted spatial geometry of the receiving and transmitting lines, together with the ability to accurately position the emitting and receiving electrodes relative to the estimated hydrocarbon deposits, can significantly increase the resolution of the device.

Thus, a technical result is achieved - increasing the reliability of the research results.

The closest method to the proposed method of marine reconnaissance is "a device for marine electrical exploration in the movement of a ship and a method of marine electrical exploration", patent RU No. 2253881, Lisitsin ED et al., June 2005.

Using the above-described device for marine electrical exploration, the following method of marine electrical exploration is carried out in the movement of the vessel. The method of marine electrical exploration is characterized in that they perform profiling by excitation in the test medium at the same time or with a temporary shift of electromagnetic and seismic waves, for the excitation of which they form unipolar rectangular pulses of direct current for the channel of electromagnetic and seismic waves, the duration and duty cycle of which depends on the parameters of the studied medium , at the beginning of the clock pulse carry out simultaneous measurement of the electric field on the groups of receiving electrodes two towed towing lines at different depths, and also measure the immersion depth of the receiving lines and sonar pressure from the seismic source.

In addition, the power of the source of electromagnetic waves is from 80 to 150 kJ, the power of the source of seismic waves is from 50 to 100 kJ, DC pulses have a duration of 0.1 to 10 s, the immersion depth of the towed transceiver line is from 10 to 20 m from the sea surface, the immersion depth of the towed receiving line from 10 to 20 m from the surface of the sea bottom, the towing speed of the receiving and transmitting and receiving lines from 0.5 to 4 knots.

The method is illustrated by drawings.

Figure 5 - Areas highlighted by a dashed line correspond to known hydrocarbon deposits. Profiles of experimental work are indicated by solid straight lines. The areas highlighted in gray correspond to hydrocarbon deposits recorded by the method of induced polarization.

6. - Geoelectric section along the profile of the site:

a) the amplitude of the selected abnormal signal;

b) the selection of the frontal phase of the abnormal signal.

Profiling is performed during a vessel moving at a speed of 0.5 to 4.0 knots with a transceiver towed at different depths (7) and a reception line (8). When the ship enters a given water area, a processor (12), a control pulse generator (1), a unit for charging capacitors (2), a multi-channel measuring device (9), an echo sounder (10), GPS (11) are launched and the capacitor block starts charging (4 ) to a given voltage level. At a given navigation point, determined by the GPS system (11), a clock pulse is generated with a duration of 10 to 15 s, by means of which, at time t0, the high-voltage switches of the two-channel switch (5) are opened and the discharge of capacitors, respectively, through the electrodes (13, 14) begins with excitation of an electromagnetic wave and through electrodes (15, 16) with excitation of a seismic wave. Excitation of a seismic wave can be carried out with a time shift relative to an electromagnetic wave or be absent altogether. Each channel is discharged with a duration of 0.2 to 0.5 s, after which the capacitors again begin to charge.

Simultaneously with the discharge at time t0, data collection begins with all pairs of receiving electrodes (18), pressure sensors (19), hydrophones (20), echo sounder (10) and GPS (11). Data from all devices is recorded on a hard drive and assigned to the current navigation point. The end of data reading is determined by the end of the clock pulse. After the signal appears on the charge of the capacitor block to a predetermined level, the next clock pulse is applied and the operation of the system is repeated. As you progress through the geological profile, a process of accumulation of the database of electrophysical parameters of the studied medium takes place.

Further, based on the anomalous behavior of such parameters of the studied medium as electrical conductivity, polarizability and the decay time constant of electrode potentials, as well as their dependence on the conditions of excitation of electromagnetic and seismic waves, the results are interpreted in terms of the presence of hydrocarbon deposits.

The advantage of this method lies in the fact that the use of a long-wave electromagnetic pulse of increased power in combination with exposure to seismic emitter at specified intervals gives more accurate information about the parameters of the medium under study.

Thus, a technical result is achieved - increasing the reliability of the research results.

Claims (18)

1. Device for marine electrical exploration, containing a pulse generator, a unit for charging capacitors that is powered by a generator, a block of capacitors, a switch that generates two sequences of unipolar rectangular pulses of direct current, a seismic emitter with an adjustable length of the discharge gap, exciting a seismic wave, a transceiver line, which excites an electromagnetic wave and carries receiving electrodes and sensors, a receiving line with similar electrodes and sensors, multi-channel measuring device, echo sounder, global navigation system (GPS) satellite navigation receiver and signal processing processor, characterized in that the switch provides the formation of rectangular current pulses with a duration of 0.1 to 10 s and a current of 0 to 2500 A on two channels the supply electrodes of the electromagnetic radiator and on the electrodes of the seismic radiator, towed behind the stern of the vessel at a given depth, the transceiver line, having a measuring part length of at least 2000 m, is made in the form of multi-strands geophysical cable with neutral buoyancy, with depth-guiding spatial orientation of the cable in space, copper electrodes at the ends of the transceiver line, symmetrically arranged graphite electrodes, pressure sensors, hydrophones, and a receiving line having a measuring part length of at least 1000 m, made in in the form of a multicore geophysical cable with neutral buoyancy, with stabilizing spatial orientation of the cable in space ramie penetration symmetrically arranged graphite electrodes, pressure sensors, the hydrophones. 2. The device for marine electrical exploration according to claim 1, characterized in that the unit for charging capacitors provides an adjustable charge speed of capacitors from 0 to 50 A DC. 3. The device for marine electrical exploration according to claim 1, characterized in that the unit for charging capacitors provides an adjustable charge speed of capacitors from 0 to 3000 V DC. 4. The device for marine electrical exploration according to claim 1, characterized in that the capacitance of the block of capacitors is from 300 to 500 mF. 5. The device for marine electrical exploration according to claim 1, characterized in that the distance between the electrodes of the seismic emitter is from 1 to 10 m 6. The device for marine electrical exploration according to claim 1, characterized in that the transceiver line has from 3 to 6 pressure sensors. 7. The device for marine electrical exploration according to claim 1, characterized in that the transceiver line has from 3 to 6 hydrophones. 8. The device for marine electrical exploration according to claim 1, characterized in that the transceiver line has from 6 to 12 depth stabilizers. 9. The device for marine electrical exploration according to claim 1, characterized in that the receiving line has from 2 to 3 pressure sensors. 10. The device for marine electrical exploration according to claim 1, characterized in that the receiving line has from 2 to 3 hydrophones. 11. The device for marine electrical exploration according to claim 1, characterized in that the receiving line has from 3 to 6 depth stabilizers. 12. The method of marine electrical exploration in the movement of a ship, based on the fact that they perform a study of the geological environment along the observation profile by exciting current pulses in the test medium and determine the parameters of the induced polarization of the test medium, build a geoelectric section and draw a conclusion about the presence of hydrocarbon deposits according to the identified anomalies of parameters induced polarization, characterized in that they perform profiling by excitation in the test medium simultaneously or with a temporary shift of the electromagnet total and seismic waves, for the excitation of which form, respectively, for the channel of electromagnetic and seismic waves unipolar rectangular pulses of direct current, the duration and duty cycle of which depends on the parameters of the medium under study, at the beginning of the clock pulse, simultaneously measure the electric field at the groups of receiving electrodes of two towed at different depths receiving lines, and also measure the immersion depth of the receiving lines and sonar pressure from the seismic source. 13. The method of marine electrical exploration according to item 12, characterized in that the power of the source of electromagnetic waves is from 80 to 150 kJ. 14. The method of marine electrical exploration according to item 12, wherein the power of the source of seismic waves is from 50 to 100 kJ. 15. The method of marine electrical exploration according to item 12, characterized in that the DC pulses have a duration of from 0.1 to 10 s. 16. The method of marine electrical exploration according to item 12, characterized in that the immersion depth of the towed transceiver line is from 10 to 20 m from the sea surface. 17. The method of marine electrical exploration according to item 12, characterized in that the immersion depth of the towed receiving line is from 10 to 20 m from the surface of the bottom of the sea. 18. The method of marine electrical exploration according to item 12, characterized in that the towing speed of the transceiver and receiving line is from 0.5 to 4 knots.

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