RU2018882C1 - Device for processing seismic signals - Google Patents

Abstract

FIELD: seismic survey. SUBSTANCE: device has initial data unit, six filters, two sign commutators, two control pulse shapers, three adders and three subtracters. Device makes it possible to detect three components of full vector of P-wave and full vector of S-wave or Lg-wave. EFFECT: improved accuracy. 3 cl, 3 dwg

Description

 The invention relates to the field of seismology, in particular to devices for processing seismic information that extract linearly polarized longitudinal P-waves and S-waves or P-waves and Lg-waves, while ensuring the requirements of high efficiency of isolation, speed and ease of implementation.

 Such requirements are imposed on devices for conducting seismic observations in the field when searching for natural resources and other geophysical works.

 A device is known that allows to isolate signals of linearly polarized P and S waves with a known direction to the source [1].

The device contains a source information block - a two-component seismometer and a link consisting of two-input adders and subtracters, the inputs of which are paired and connected to the corresponding outputs of the source information block, and their outputs are the outputs of the device. Measuring axis seismometer such devices are arranged in one plane at an angle of ⁴⁵ ° to the vertical, and the seismometer is located in the space so that the wave front propagation is perpendicular to this plane. This orientation of the instrument axes allows you to select some projections of the P and S wave vectors proportional to the seismic energy reflected from the underground layers by adding and subtracting the initially recorded signals U _X and U _Y along the two measuring axes of the seismometer.

 The device is quite simple to implement, it is characterized by high speed, since the registration and processing of signals is carried out in real time.

 However, the accuracy of determining the vectors of P and S waves is insufficient, since the three components of the full vector are not determined. The accuracy of the selection of both P and Lg waves is low. The efficiency of the device is relatively low due to the fact that in real conditions the exact direction to the source is not always known.

 The closest technical solution to the claimed for a greater number of similar essential features and the achieved effect is a seismic signal processing device in which P and S waves are extracted in a known direction to the signal source [2].

 The device comprises a source information unit, a sign switch, four amplifiers, a coding unit, a decoder, a two-input adder, a controlled adder, a registration unit, and the three inputs of the sign switch are connected respectively to the three outputs of the source information block, the fourth and fifth outputs of which are connected respectively to the first inputs blocks of registration and coding, the output of the latter is connected to the control inputs of the adders, the inputs of which through amplifiers are connected to the corresponding outputs of the sign switch.

 The device is quite complicated. Real P-wave and S-wave seismic signals have a slightly different frequency range. Therefore, when isolating P- and S-wave signals from common registered signals, the accuracy of determining the components of the full vector is somewhat limited. In addition, there remains a significant error in determining the components of the full vector of Lg waves having a frequency spectrum different from P waves.

 The purpose of the invention is to reduce the errors in determining the components of the full vector of P and S waves, as well as the components of the full vector of P and Lg waves.

 The purpose of the seismic signal processing device when extracting P- and S-waves or P- and Lg-waves in a known direction to a signal source containing a source information block, a sign switch, two two-input adders, is achieved by the fact that six filters are additionally introduced into it , the second switchboard of the sign, two shapers of control pulses, the third two-input adder, three two-input subtracters, and the block of initial information is made in the form of a three-component seismometer, the measuring axes of which are orthogonal, while the inputs the first and fourth, second and fifth, third and sixth filters are interconnected and connected to the three outputs of the source information block. The inputs of the first sign switch are connected in parallel with the corresponding inputs of the first control pulse shaper, and the inputs of the second sign switch are connected in parallel with the corresponding inputs of the second control pulse shaper. Moreover, the outputs of the first and second control pulse shapers are respectively connected to the fourth inputs of the first and second sign switches. The outputs of the first, second and third filters are connected to the inputs of the first sign switch, which are also connected to the first inputs of the adders, the second inputs of which are connected to the outputs of the first sign switch, and the outputs of the fourth, fifth and sixth filters are connected to the inputs of the second sign switch, which are also connected with the first inputs of the subtractors, the second inputs of which are connected with the outputs of the second switch sign. The outputs of the adders and subtracters are the outputs of the full vector of P and S waves.

 The sign switch contains three controlled amplifiers, the first inputs of which are connected to the three corresponding inputs of the sign switch, the fourth input of which is connected to the second inputs of the controlled amplifiers, the outputs of which are connected to the three corresponding outputs of the sign switch. The control pulse shaper contains three limiter amplifiers, the inputs of which are connected to the corresponding inputs of the control pulse shaper, five digital elements NOT, two AND-NOT elements and an OR-NOT element. In this case, the three inputs of the first AND-NOT element and the three outputs of the amplifier-limiters (comparators) are connected in pairs to the inputs of the first three NOT elements, the outputs of which are connected to the three inputs of the second AND element, the outputs of the AND elements are pairwise connected to the inputs of the fourth and the fifth element NOT, the outputs of which are connected to the element OR-NOT, the output of which is connected to the output of the shaper control pulses.

 In FIG. 1 shows a functional diagram of a device; figure 2 - diagram of the switch sign; figure 3 - diagram of the shaper control pulses.

 The device contains a three-component block 1 of the source information, two triples of filters 2-1, 2-2, 2-3 and 2-4, 2-5, 2-6, sign switches 3-1 and 3-2, shapers 4-1, 4-2 control pulses, adders 5-1, 5-2, 5-3 and subtractors 6-1, 6-2, 6-3.

 The blocks in the seismic information processing device are connected as follows.

 Three outputs of block 1 of the initial information are connected to three inputs of the first and second triples of filters 2-1 - 2-6 pairwise connected. Three inputs of the same name of the first commutator of the sign 3-1 and the first driver 4-1 of the control pulses are connected in parallel. The three inputs of the same name of the second commutator of the sign 3-2 and the second driver 4-2 of the control pulses are also connected in parallel. The outputs of the first and second drivers 4-1 and 4-2 of the control pulses are connected to the fourth (control) inputs of the first and second switches of the sign 3-1 and 3-2. Three outputs of the first three filters 2-1 - 2-3 are connected to three inputs of the first switch sign 3-1, and three outputs of the second three filters 2-4 - 2-6 are connected to three inputs of the second switch sign 3-2. Three of the same inputs and outputs of the first switch sign 3-1 connected to two inputs of each of the three adders 5-1 - 5-3, and three of the same inputs and outputs of the second switch sign 3-2 - with two inputs of each of the subtractors 6-1 - 6-3. Three outputs of adders 5-1, 5-2, 5-3 and three outputs of subtractors 6-1, 6-2, 6-3 are the outputs of the device.

 Each switch sign 3-1 and 3-2 contains three controlled amplifiers 7-1 - 7-3, the first inputs of which are connected to the corresponding input of the sign switch. The second (control) inputs of the controlled amplifiers 7-1 - 7-3 are interconnected and connected to the fourth (control) input of the sign switch. The outputs of the controlled amplifiers are connected to the outputs of the switch sign.

 Each driver 4-1 and 4-2 of the control pulses contains three amplifier-limiter (comparator) 8-1 - 8-3, three inverters 9-1 - 9-3, two three-input logic circuits AND 10-1.10- 2, two inverters NOT 11-1 and 11-2, OR-NOT 12. The inputs of the amplifier-limiters (comparators) 8-1 - 8-3 are connected to the corresponding inputs of the shaper 4-1 control pulses. In pairs, the three inputs of the first I-NOT 10-1 element and the three outputs of the amplifier-limiters (comparators) 8-1 - 8-3 are connected to the inputs of the first three elements NOT 9-1 - 9-3, the outputs of which are connected to the three inputs of the second of the AND-NOT 10-2 element, and the outputs of the AND-NOT 10-1 and 10-2 elements are paired with the inputs of the fourth and fifth elements NOT 11-1 and 11-2, the outputs of which are connected to the OR-NOT 12 element, the output of which connected to the output of the shaper 4-1 control pulses.

 Block 1 of the initial information is a three-component seismometer, the measuring axes of which are orthogonal to each other and which may include amplifiers and common filters.

 A device for processing seismic signals works as follows.

 The measuring axes of the three-component seismometer of block 1 of the initial information are located along the axes of the Cartesian coordinates X, Y, Z, which are oriented in space, for example, so that the X, Y axes are located in the horizontal plane, one of the axes is directed north, the other east. and the Z axis is vertically up.

 Consider the option when the seismic source is located, for example, in the direction of the third quadrant relative to the seismometer. With this arrangement of the source relative to the coordinate system, we select the conditions in the form of a combination of signs with respect to the directions of the measuring axes, when the analyzed signals have the same signs.

 The P wave is linearly polarized in the vertical plane, and its full vector has projections on the vertical and horizontal plane. For particles in the period of time when their movements coincide with the direction of propagation of the wave front, the first part of the condition is satisfied, i.e. the signs of the signals along the three components will be positive, and in the period of time when the movement of particles in the wave is opposite to the direction of propagation of the P-wave, the second part of the condition is satisfied, i.e. signs of signals along the same axes will be negative, but they have the same signs.

 The combination of signs can be any, depending on the relative position of the seismic source, the seismometer and the selected direction of its measuring axes.

From the outputs of a three-component seismometer, quasi-sinusoidal electrical signals corresponding to the studied vibrations are recorded. The signals U _X , U _Y , U _Z from the output of block 1 of the initial information are correlated with each other in time for P, S, and Lg waves, the degree of their correlation is determined by the degree of linearity of the polarization of the waves.

Signals U _X , U _Y , U _Z containing the studied vibrations of different types of waves are filtered by the first three filters 2-1 - 2-3, highlighting the frequency range corresponding to the P-wave signals, and filtered by the second three filters 2-4 - 2- 6, highlighting the frequency range corresponding to the signals of S-waves or Lg-waves. After that, at the output of the first three filters receive the first three additional signals U _f1X , U _f1Y , U _f1Z , and at the output of the second three - the second three additional signals U _f2X , U _f2Y , U _f2Z . After that, the signs of the corresponding triples of the generated additional signals are analyzed at each moment of time, and the third and fourth triples of additional signals are formed respectively by the control signals from the outputs of the shapers 4-1, 4-2 of the control pulses.

When forming the third three additional signals U _f3X , U _f3Y , U _f3Z and the fourth three additional signals U _f4X , U _f4Y , U _f4Z, their values will be equal, respectively, U _f3X = U _f1X , U _f3Y = U _f1Y , U _f3Z = U _f1Z and U _f4X = U _f2X , U _f4Y = U _f2Y, U _f4Z = U _f2Z at those times when the signs of the signals U _f1X , U _f1Y , U _f1Z and U _f2X , U _f2Y , U _f2Z will coincide with the selected combination of signs. And at those times when the sign of at least one of the analyzed signals of the corresponding triple does not coincide with the sign of the other analyzed signal of its triple, i.e. if the condition for the chosen combination of signs is not satisfied, then U _f3X = -U _f1X, U _f3Y = -U _f1Y , U _f3Z = -U _f1Z . After that, six more signals are generated equal to the half-sums and half-differences of the generated additional signals
(U _f1X + U _f3X ) / 2; (U _f1Y + U _f3X ) / 2;
(U _f1Z + U _f3Z ) / 2;
(1)
(U _f2X -U _f4X ) / 2; (U _f2Y -U _f4Y ) / 2;
(U _f2Z -U _f4Z ) / 2.

 P-waves are polarized in a vertical plane coinciding with the direction of propagation of the seismic wave, and the movement of particles in the S-wave or Lg-wave occurs in a plane perpendicular to the direction of propagation of the wave front.

 Since the condition of the combination of signs for the example was chosen in accordance with the movement of particles in the P-wave, the half-sum signals in expression (1) will correspond to the components of the full P-wave vector, and the signals of the half-differences of stresses in expression (1) will correspond to the components of the full vector S-waves or Lg-waves.

 If we choose a combination of signs in accordance with the motion of particles in the S- or Lg-wave, then when adding additional signals, the components of the S- or Lg-wave would be highlighted, and when subtracting the signals, the components of the P-wave would be highlighted.

 The output signals of half-sums and half-differences are further further filtered by frequency.

 The device shown in figure 1, implements the option when in the combination of signs for the first part of the condition all signs are positive, and in combination for the second part of the condition all signs are negative.

 The device operates as follows.

Three electrical voltages U _X , U _Y , U _Z are generated at the three outputs of the source information block 1, which are supplied to the first and second three of filters 2-1 - 2-6, and the first three of the filtered additional voltage signals U _{f1X are} obtained at the output of the first three , U _f1Y , U _f1Z , and at the output of the second triple of filters, voltages corresponding to the second triple of filtered additional signals U _f2X , U _f2Y , U _f2Z differ in the upper cutoff frequency. The voltages corresponding to the first and second triples of additional signals are supplied respectively to the three inputs of the first and second switches of the sign 3-1 and 3-2. These signals are proportional to the input seismic effect, for example, the speed of soil vibrations along the corresponding measuring axis of the three-component block 1 of the source information. The control inputs of the first and second switches of the sign 3-1 and 3-2 receive control signals of logical "1" or "0" from the outputs of the first and second drivers 4-1 and 4-2 of the control pulses, respectively, which are formed as follows.

The filtered voltages U _f1X , U _f1Y , U _f1Z are supplied to the inputs of the first _driver 4-1 of the control pulses and logical “1” signals are generated at its output if the voltage of the same sign is at its inputs, or a logical “0” signal is generated if at least one signal has the opposite sign compared to other input voltages.

Depending on the selected control signal - logical "0" or logical "1" - in the first switch of sign 3-1, when the condition of the combination of signs is satisfied, additional signals U _f3X = U _f1X , U _f3Y = U _f1Y , U are generated at its outputs _f3Z + U _f1Z , and when the conditions of the selected combination of signs are not satisfied, then signals U _f3X = -U _f1X , U _f3Y = -U _f1Y , U _f3Z = -U _f1Z are generated at its outputs.

The filtered voltages U _f2X , U _f2Y , U _f2Z go to the inputs of the second _driver 4-2 control pulses and the output signals are logical "1", if the voltage is of the same sign at its inputs, or a logical signal "0" is formed if at least one signal has the opposite sign compared to other input voltages.

Depending on the selected control signal - logical "0" or logical "1" - in the second switch of sign 3-2, when the condition of the combination of signs is satisfied, additional signals U _f4X = U _f2X , U _f4Y = U _f2Y , U are generated at its outputs _f4Z = U _f2Z , and when the conditions of the selected combination of signs are not satisfied, then signals U _f4X = -U _f2X , U _f4Y = -U _f2Y , U _f4Z = -U _f2Z are generated at its outputs.

Each pair of signals: U _f1X , U _f3X ; U _f1Y , U _f3Y ; U _f1Z , U _f3Z from the input and output of the switch of the sign 3-1 of the same name goes to the two inputs of the adders 5-1 - 5-3, respectively, and each pair of signals U _f2X , U _f4X ; U _f2Y , U _f4Y ; U _f2Z , U _f4Z from the input and output of the switch 3-2 of the same name goes to the two inputs of the subtractors 6-1 - 6-3, respectively. Adders and subtractors have transmission coefficients K _i = 0.5. Half-sums and half-differences of additional signals are formed at their outputs, respectively: (U _f1i + U _f3i ) / 2 and (U _f2i - U _f4i ) / 2, where i is the corresponding index of the component.

 For the selected condition of the combination of signs in accordance with the characteristic of the P-wave, the signals determining the components of the P-wave will be allocated at the output of the adders 5i, and the signals defining the components of the S-wave will be output at the output of the subtractors 6i.

 The device has a high speed, since the measurement of signals and the subsequent processing of directly electrical analogs of the signals to determine the components of the vectors is carried out in real time. The error in determining the components of the vectors of P- and S-waves is lower than in the prototype, since the analysis of the signals is carried out in the optimal frequency range for each type of wave at each moment in time for three components. Processing of real seismic signals using the proposed device, confirmed the effectiveness of the device and the reduction of the error in determining the components of the full vector of the studied oscillations.

Claims (3)

 1. DEVICE FOR PROCESSING SEISMIC SIGNALS when extracting P- and S-waves or P- and Lg-waves in a known direction to a signal source containing a source information block, a first sign switch, two two-input adders, characterized in that six are additionally introduced into it filters, a second sign switcher, two control pulse shapers, a third two-input adder, three two-input subtracters, and the source information block is made in the form of a three-component seismometer, the measuring axes of which are orthogonal, while The odes of the first and fourth, second, fifth, third and sixth filters are interconnected and connected to the three outputs of the source information block, the inputs of the first sign switch are parallel connected to the corresponding inputs of the first control pulse shaper, and the inputs of the second sign switch are parallel connected to the corresponding inputs of the second shaper control pulses, while the outputs of the first and second shapers of control pulses are respectively connected to the fourth inputs of the first and second of the first sign switch, the outputs of the first, second and third filters are connected respectively to the inputs of the first sign switch, which are also connected to the first inputs of the adders, the second inputs of which are connected respectively to the outputs of the first sign switch, and the outputs of the fourth, fifth and sixth filters, respectively, to the inputs the second sign switch, which are also connected to the first inputs of the subtracters, the second inputs of which are connected respectively to the outputs of the second sign switch, while the outputs of the adders and itateley are the outputs of the full vector of P- and S-waves.  2. The device according to claim 1, characterized in that the switch sign contains three controlled amplifiers, the first inputs of which are connected to the three corresponding inputs of the switch sign, the fourth input of which is connected to the second inputs of the controlled amplifiers, the outputs of which are connected to three corresponding outputs of the switch sign.  3. The device according to claim 1, characterized in that the control pulse shaper comprises three limiter amplifiers, the inputs of which are connected to the corresponding inputs of the control pulse shaper, five digital elements NOT, two AND elements and NOT, or NOT, pairwise the connected three inputs of the first element AND are NOT and the three outputs of the amplifier-limiters (comparators) are connected to the inputs of the first three elements NOT, the outputs of which are connected to the three inputs of the second element AND are NOT, the outputs of the elements AND are NOT pairwise connected to the inputs fourth and fifth elements NO, the outputs of which are connected to an OR - NOT, the output of which is connected to the output of the control pulses.

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