Embodiment:
Below in conjunction with drawings and Examples the present invention is further described in detail:
The earth potential measuring method comprises following order and step:
A, in surveying the district layout rectangle or annular spread formula potential acquisition system survey grid concurrently, complexity according to coverage of survey area, geologic condition, arrange more than one and even N collecting unit, and host computer, main control unit are connected by data transmission cable with collecting unit; The annular survey grid be with the power supply well be the center of circle, collecting unit is placed on power supply Jing Chu, collecting unit is in the centre position of survey line, by more than 10 so that the survey line central point that constitutes of N collecting unit coincide with the center of circle of survey grid, and radially distribute, the survey line angle is identical, the survey line angle is 5 °-30 °, angle increases along with survey line quantity and reduces between survey line, the rectangle survey grid by more than 10 so that N collecting unit constitute equally spaced parallel survey line, be made up of 12 measuring points on the every survey line, 20~100 meters of measuring point spacings, the spacing of survey line are 50 meters.The measuring point spacing is influenced by measuring accuracy and tested reservoir depth of burial, and the dark more pole span of reservoir is big more usually, and the high more pole span of precision is more little.
B, 1.0-2.0 kilometer place arranges reference electrode outside survey grid, and reference electrode is connected with main control unit by lead, has constituted one between each node and the reference electrode in the survey grid and has independently measured the loop, formation ground collection survey grid;
C, select two mouthfuls of wells in surveying the district, wherein a bite well is as the power supply well, and another mouthful well is as junction box, links the current supply circuit that composition is powered to reservoir, formation emission coefficient with the high power digital signal source by will power well and junction box of cable; The power supply well should be selected independently water injection well, then needs to select one of them also to disconnect and the connecting line of other water injection well if group wells supplies water, and junction box should be selected oil well or the water injection well outside the tested block.
D, determine that high power digital signal source emissive power and transmission frequency, supply current are 8~10 amperes, transmission frequency is judged by surrender degree of depth formula:
Wherein: H
δBe the reservoir depth of burial, ρ is the average resistivity of the earth, f
bFrequency for transmitter;
E, when ground gather survey grid and emission coefficient networking and be provided with finish after, utilize the radio or the GPS time service method of synchronization, control acquisition system and emission coefficient synchronous working realize the collection of data;
F, carry out processing such as noise reduction process by the signal that acquisition system is collected, pick up amplitude with emission coefficient same frequency signal, calculate the potential data between each node and reference electrode in the survey grid, the annular survey grid is directly drawn the current potential cloud atlas or is drawn the cloud atlas of subsurface reservoir resistivity through Inversion Calculation according to potential data, the rectangle survey grid is directly drawn the current potential isogram or is drawn the isogram of subsurface reservoir resistivity through Inversion Calculation according to potential data, thereby obtain to survey the resistivity spatial distribution characteristic in district, and then obtain distribution of remaining oil rule in the oilfield reservoir.
Embodiment 1
A, utilize distributed parallel earth potential acquisition system layout rectangle survey grid in surveying the district, complexity according to coverage of survey area, geologic condition is arranged survey grid, the rectangle survey grid constitutes equally spaced parallel survey line by 10 collecting units, form by 12 measuring points on the every survey line, 50 meters of measuring point spacings, the spacing of survey line are 50 meters.
B, outside survey grid 1.0 kilometers locate to arrange reference electrode, reference electrode is connected with main control unit by lead, has constituted one between each node and the reference electrode in the survey grid and has independently measured the loop, constitutes ground and gathers survey grid;
C, select two mouthfuls of wells in surveying the district, wherein a bite well is as the power supply well, and another mouthful well is as junction box, links the current supply circuit that composition is powered to reservoir, formation emission coefficient with the high power digital signal source by will power well and junction box of cable; The power supply well should be selected independently water injection well, then needs to select one of them also to disconnect and the connecting line of other water injection well if group wells supplies water, and junction box should be selected oil well or the water injection well outside the tested block.
D, determine that high power digital signal source emissive power and transmission frequency, supply current are 8 amperes, transmission frequency is judged by surrender degree of depth formula:
Wherein: H
δBe the reservoir depth of burial, ρ is the average resistivity of the earth, f
bFrequency for transmitter;
E, after acquisition system and the setting of emission coefficient parameter are finished, utilize the GPS time service method of synchronization, control acquisition system and emission coefficient synchronous working realize the collection of data.
F, carry out digital signal by the signal that acquisition system is collected, pick up amplitude with emission coefficient same frequency signal, calculate the potential data between each node and reference electrode in the survey grid, thereby be finally inversed by the resistivity spatial distribution characteristic of detected target body, realize distribution of remaining oil rule in the oilfield reservoir.
After test process finishes, will stop power supply in the high-power signal source, and the data that collect are carried out denoising to the while data acquisition system (DAS) and data are separated the volume processing.Can determine the line frequency of emission coefficient according to the well-log information of test site and the depth of burial that is studied reservoir, according to the sampling rate and the sampling length of power supply signal Frequency Design acquisition system, wherein concrete method for designing can be determined by following formula then:
Wherein: f
0Be fundamental frequency, f
1Be transmitter frequency, Δ t is the sampling rate of acquisition system, and this parameter should satisfy:
f
0=nf
1
Wherein: n is an integer, and promptly fundamental frequency is the integral multiple of transmission frequency.
The design of sampling length should be determined by following formula:
Wherein: L is the sampling length of acquisition system, and n is an integer, and satisfies L and can be divided exactly by 2,3 and 5.
The above-mentioned parameter design is provided with transmitter frequency and periodicity after finishing in high-power emissive source, parameters such as sampling rate and sampling length are set in the acquisition system, finishes the work that is provided with of parameter.Utilize the transmitter and the data collection system synchronizing work of radio or GPS time service synchro control transmitter, realize the collection of data.
The volume method of separating of image data is as described below:
Denoising
The signal of gathering is the f among Fig. 4
(t)With the n among Fig. 5
(t)Take advantage of and obtained a new signal r
(t):
r
t=f
(t)×n
(t)
Wherein: r
(t)Be the signal that collects, f
(t)Be signal source, n
(t)Be the place noise source, it is less and frequency shows as the wide spectrum characteristic that the place noise has amplitude, therefore needs to introduce wavelet transformation (Wavelet) instrument with its filtering.
r′
(t)=wden(r
(t))
Wherein: r '
(t)Be the signal after the denoising of process small echo, wden: be small echo denoising function.
Separate to compile and handle
In the signal after the above-mentioned denoising, have only the signal that has a same frequency with signal source to be only useful signal, utilize Fast Fourier Transform (FFT) (DFT) in the digital signal to realize decoding to useful signal for this reason.
Wherein: R
(ω)Be the Fourier spectrum of signal, get in this function with transmitting and have the signal of same frequency and calculate its amplitude spectrum, can obtain the voltage signal of actual measurement.
To obtain the potential value of each node in the test network at last, and show and data storage work with this one-tenth figure that carries out the current potential isoline.If test data does not satisfy test request, then can carry out the synchronous working of high-power signal source and acquisition system once more, carry out the repeated acquisition process of data.
Embodiment 2
A, utilize distributed parallel earth potential acquisition system layout rectangle survey grid in surveying the district, complexity according to coverage of survey area, geologic condition is arranged survey grid, the rectangle survey grid constitutes equally spaced parallel survey line by 20 collecting units, form by 12 measuring points on the every survey line, 50 meters of measuring point spacings, the spacing of survey line are 50 meters.
B, outside survey grid 1.5 kilometers locate to arrange reference electrode, reference electrode is connected with main control unit by lead, has constituted one between each node and the reference electrode in the survey grid and has independently measured the loop, constitutes ground and gathers survey grid;
C, select two mouthfuls of wells in surveying the district, wherein a bite well is as the power supply well, and another mouthful well is as junction box, links the current supply circuit that composition is powered to reservoir, formation emission coefficient with the high power digital signal source by will power well and junction box of cable; The power supply well should be selected independently water injection well, then needs to select one of them also to disconnect and the connecting line of other water injection well if group wells supplies water, and junction box should be selected oil well or the water injection well outside the tested block.
D, determine that high power digital signal source emissive power and transmission frequency, supply current are 10 amperes, transmission frequency is judged by surrender degree of depth formula:
Wherein: H
δBe the reservoir depth of burial, ρ is the average resistivity of the earth, f
bFrequency for transmitter;
E, after acquisition system and the setting of emission coefficient parameter are finished, utilize the GPS time service method of synchronization, control acquisition system and emission coefficient synchronous working realize the collection of data.
F, carry out digital signal by the signal that acquisition system is collected, pick up amplitude with emission coefficient same frequency signal, calculate the potential data between each node and reference electrode in the survey grid, thereby be finally inversed by the resistivity spatial distribution characteristic of detected target body, realize distribution of remaining oil rule in the oilfield reservoir.
After test process finishes, will stop power supply in the high-power signal source, and the data that collect are carried out denoising to the while data acquisition system (DAS) and data are separated the volume processing.Can determine the line frequency of emission coefficient according to the well-log information of test site and the depth of burial that is studied reservoir, according to the sampling rate and the sampling length of power supply signal Frequency Design acquisition system, wherein concrete method for designing can be determined by following formula then:
Wherein: f
0Be fundamental frequency, f
1Be transmitter frequency, Δ t is the sampling rate of acquisition system, and this parameter should satisfy:
f
0=nf
1
Wherein: n is an integer, and promptly fundamental frequency is the integral multiple of transmission frequency.
The design of sampling length should be determined by following formula:
Wherein: L is the sampling length of acquisition system, and n is an integer, and satisfies L and can be divided exactly by 2,3 and 5.
The above-mentioned parameter design is provided with transmitter frequency and periodicity after finishing in high-power emissive source, parameters such as sampling rate and sampling length are set in the acquisition system, finishes the work that is provided with of parameter.Utilize the transmitter and the data collection system synchronizing work of radio or GPS time service synchro control transmitter, realize the collection of data.
The volume method of separating of image data is as described below:
Denoising
The signal of gathering is the f among Fig. 4
(t)With the n among Fig. 5
(t)Take advantage of and obtained a new signal r
(t):
r
t=f
(t)×n
(t)
Wherein: r
(t)Be the signal that collects, f
(t)Be signal source, n
(t)Be the place noise source, it is less and frequency shows as the wide spectrum characteristic that the place noise has amplitude, therefore needs to introduce wavelet transformation (Wavelet) instrument with its filtering.
r′
(t)=wden(r
(t))
Wherein: r '
(t)Be the signal after the denoising of process small echo, wden: be small echo denoising function.
Separate to compile and handle
In the signal after the above-mentioned denoising, have only the signal that has a same frequency with signal source to be only useful signal, utilize Fast Fourier Transform (FFT) (DFT) in the digital signal to realize decoding to useful signal for this reason.
Wherein: R
(ω)Be the Fourier spectrum of signal, get in this function with transmitting and have the signal of same frequency and calculate its amplitude spectrum, can obtain the voltage signal of actual measurement.
To obtain the potential value of each node in the test network at last, and show and data storage work with this one-tenth figure that carries out the current potential isoline.If test data does not satisfy test request, then can carry out the synchronous working of high-power signal source and acquisition system once more, carry out the repeated acquisition process of data.
Embodiment 3
A, utilize distributed parallel earth potential acquisition system layout rectangle survey grid in surveying the district, complexity according to coverage of survey area, geologic condition is arranged survey grid, the rectangle survey grid constitutes equally spaced parallel survey line by 50 collecting units, form by 12 measuring points on the every survey line, 50 meters of measuring point spacings, the spacing of survey line are 50 meters.
B, outside survey grid 2 kilometers locate to arrange reference electrode, reference electrode is connected with main control unit by lead, has constituted one between each node and the reference electrode in the survey grid and has independently measured the loop, constitutes ground and gathers survey grid;
C, select two mouthfuls of wells in surveying the district, wherein a bite well is as the power supply well, and another mouthful well is as junction box, links the current supply circuit that composition is powered to reservoir, formation emission coefficient with the high power digital signal source by will power well and junction box of cable; The power supply well should be selected independently water injection well, then needs to select one of them also to disconnect and the connecting line of other water injection well if group wells supplies water, and junction box should be selected oil well or the water injection well outside the tested block.
D, determine that high power digital signal source emissive power and transmission frequency, supply current are 9 amperes, transmission frequency is judged by surrender degree of depth formula:
Wherein: H
δBe the reservoir depth of burial, ρ is the average resistivity of the earth, f
bFrequency for transmitter;
E, after acquisition system and the setting of emission coefficient parameter are finished, utilize the GPS time service method of synchronization, control acquisition system and emission coefficient synchronous working realize the collection of data.
F, carry out digital signal by the signal that acquisition system is collected, pick up amplitude with emission coefficient same frequency signal, calculate the potential data between each node and reference electrode in the survey grid, thereby be finally inversed by the resistivity spatial distribution characteristic of detected target body, realize distribution of remaining oil rule in the oilfield reservoir.
After test process finishes, will stop power supply in the high-power signal source, and the data that collect are carried out denoising to the while data acquisition system (DAS) and data are separated the volume processing.Can determine the line frequency of emission coefficient according to the well-log information of test site and the depth of burial that is studied reservoir, according to the sampling rate and the sampling length of power supply signal Frequency Design acquisition system, wherein concrete method for designing can be determined by following formula then:
Wherein: f
0Be fundamental frequency, f
1Be transmitter frequency, Δ t is the sampling rate of acquisition system, and this parameter should satisfy:
f
0=nf
1
Wherein: n is an integer, and promptly fundamental frequency is the integral multiple of transmission frequency.
The design of sampling length should be determined by following formula:
Wherein: L is the sampling length of acquisition system, and n is an integer, and satisfies L and can be divided exactly by 2,3 and 5.
The above-mentioned parameter design is provided with transmitter frequency and periodicity after finishing in high-power emissive source, parameters such as sampling rate and sampling length are set in the acquisition system, finishes the work that is provided with of parameter.Utilize the transmitter and the data collection system synchronizing work of radio or GPS time service synchro control transmitter, realize the collection of data.
The volume method of separating of image data is as described below:
Denoising
The signal of gathering is the f among Fig. 4
(t)With the n among Fig. 5
(t)Take advantage of and obtained a new signal r
(t):
r
t=f
(t)×n
(t)
Wherein: r
(t)Be the signal that collects, f
(t)Be signal source, n
(t)Be the place noise source, it is less and frequency shows as the wide spectrum characteristic that the place noise has amplitude, therefore needs to introduce wavelet transformation (Wavelet) instrument with its filtering.
r′
(t)=wden(r
(t))
Wherein: r '
(t)Be the signal after the denoising of process small echo, wden: be small echo denoising function.
Separate to compile and handle
In the signal after the above-mentioned denoising, have only the signal that has a same frequency with signal source to be only useful signal, utilize Fast Fourier Transform (FFT) (DFT) in the digital signal to realize decoding to useful signal for this reason.
Wherein: R
(ω)Be the Fourier spectrum of signal, get in this function with transmitting and have the signal of same frequency and calculate its amplitude spectrum, can obtain the voltage signal of actual measurement.
To obtain the potential value of each node in the test network at last, and show and data storage work with this one-tenth figure that carries out the current potential isoline.If test data does not satisfy test request, then can carry out the synchronous working of high-power signal source and acquisition system once more, carry out the repeated acquisition process of data.
Embodiment 4
A, utilize distributed parallel earth potential acquisition system annular survey grid of layout in surveying the district, complexity according to coverage of survey area, geologic condition is arranged survey grid, the annular survey grid be with the power supply well be the center of circle, collecting unit is placed on power supply Jing Chu, collecting unit is in the centre position of survey line, the survey line central point that is made of 10 collecting units coincides with the center of circle of survey grid, and radially distribute, angle is identical between survey line, angle increases along with survey line quantity and reduces between survey line, and survey line then its angle is 18 °.
B, outside survey grid 1.0 kilometers locate to arrange reference electrode, reference electrode is connected with main control unit by lead, has constituted one between each node and the reference electrode in the survey grid and has independently measured the loop, constitutes ground and gathers survey grid;
C, select two mouthfuls of wells in surveying the district, wherein a bite well is as the power supply well, and another mouthful well is as junction box, links the current supply circuit that composition is powered to reservoir, formation emission coefficient with the high power digital signal source by will power well and junction box of cable; The power supply well should be selected independently water injection well, then needs to select one of them also to disconnect and the connecting line of other water injection well if group wells supplies water, and junction box should be selected oil well or the water injection well outside the tested block.
D, determine that high power digital signal source emissive power and transmission frequency, supply current are 8 amperes, transmission frequency is judged by surrender degree of depth formula:
Wherein: H
δBe the reservoir depth of burial, ρ is the average resistivity of the earth, f
bFrequency for transmitter;
E, after acquisition system and the setting of emission coefficient parameter are finished, utilize the GPS time service method of synchronization, control acquisition system and emission coefficient synchronous working realize the collection of data.
F, carry out digital signal by the signal that acquisition system is collected, pick up amplitude with emission coefficient same frequency signal, calculate the potential data between each node and reference electrode in the survey grid, thereby be finally inversed by the resistivity spatial distribution characteristic of detected target body, realize distribution of remaining oil rule in the oilfield reservoir.
After test process finishes, will stop power supply in the high-power signal source, and the data that collect are carried out denoising to the while data acquisition system (DAS) and data are separated the volume processing.Can determine the line frequency of emission coefficient according to the well-log information of test site and the depth of burial that is studied reservoir, according to the sampling rate and the sampling length of power supply signal Frequency Design acquisition system, wherein concrete method for designing can be determined by following formula then:
Wherein: f
0Be fundamental frequency, f
1Be transmitter frequency, Δ t is the sampling rate of acquisition system, and this parameter should satisfy:
f
0=nf
1
Wherein: n is an integer, and promptly fundamental frequency is the integral multiple of transmission frequency.
The design of sampling length should be determined by following formula:
Wherein: L is the sampling length of acquisition system, and n is an integer, and satisfies L and can be divided exactly by 2,3 and 5.
The above-mentioned parameter design is provided with transmitter frequency and periodicity after finishing in high-power emissive source, parameters such as sampling rate and sampling length are set in the acquisition system, finishes the work that is provided with of parameter.Utilize the transmitter and the data collection system synchronizing work of radio or GPS time service synchro control transmitter, realize the collection of data.
The volume method of separating of image data is as described below:
Denoising
The signal of gathering is the f among Fig. 4
(t)With the n among Fig. 5
(t)Take advantage of and obtained a new signal r
(t):
r
t=f
(t)×n
(t)
Wherein: r
(t)Be the signal that collects, f
(t)Be signal source, n
(t)Be the place noise source, it is less and frequency shows as the wide spectrum characteristic that the place noise has amplitude, therefore needs to introduce wavelet transformation (Wavelet) instrument with its filtering.
r′
(t)=wden(r
(t))
Wherein: r '
(t)Be the signal after the denoising of process small echo, wden: be small echo denoising function.
Separate to compile and handle
In the signal after the above-mentioned denoising, have only the signal that has a same frequency with signal source to be only useful signal, utilize Fast Fourier Transform (FFT) (DFT) in the digital signal to realize decoding to useful signal for this reason.
Wherein: R
(ω)Be the Fourier spectrum of signal, get in this function with transmitting and have the signal of same frequency and calculate its amplitude spectrum, can obtain the voltage signal of actual measurement.
To obtain the potential value of each node in the test network at last, and show and data storage work with this one-tenth figure that carries out the current potential isoline.If test data does not satisfy test request, then can carry out the synchronous working of high-power signal source and acquisition system once more, carry out the repeated acquisition process of data.
Embodiment 5
A, utilize distributed parallel earth potential acquisition system annular survey grid of layout in surveying the district, complexity according to coverage of survey area, geologic condition is arranged survey grid, the annular survey grid be with the power supply well be the center of circle, collecting unit is placed on power supply Jing Chu, and collecting unit is in the centre position of survey line, and the survey line central point that is made of 20 collecting units coincides with the center of circle of survey grid, and radially distribute, angle is identical between survey line, and angle increases along with survey line quantity and reduces between survey line, and survey line then its angle is 9 degree.
B, outside survey grid 1.0 kilometers locate to arrange reference electrode, reference electrode is connected with main control unit by lead, has constituted one between each node and the reference electrode in the survey grid and has independently measured the loop, constitutes ground and gathers survey grid;
C, select two mouthfuls of wells in surveying the district, wherein a bite well is as the power supply well, and another mouthful well is as junction box, links the current supply circuit that composition is powered to reservoir, formation emission coefficient with the high power digital signal source by will power well and junction box of cable; The power supply well should be selected independently water injection well, then needs to select one of them also to disconnect and the connecting line of other water injection well if group wells supplies water, and junction box should be selected oil well or the water injection well outside the tested block.
D, determine that high power digital signal source emissive power and transmission frequency, supply current are 8~10 amperes, transmission frequency is judged by surrender degree of depth formula:
Wherein: H
δBe the reservoir depth of burial, ρ is the average resistivity of the earth, f
bFrequency for transmitter;
E, after acquisition system and the setting of emission coefficient parameter are finished, utilize the GPS time service method of synchronization, control acquisition system and emission coefficient synchronous working realize the collection of data.
F, carry out digital signal by the signal that acquisition system is collected, pick up amplitude with emission coefficient same frequency signal, calculate the potential data between each node and reference electrode in the survey grid, thereby be finally inversed by the resistivity spatial distribution characteristic of detected target body, realize distribution of remaining oil rule in the oilfield reservoir.
After test process finishes, will stop power supply in the high-power signal source, and the data that collect are carried out denoising to the while data acquisition system (DAS) and data are separated the volume processing.Can determine the line frequency of emission coefficient according to the well-log information of test site and the depth of burial that is studied reservoir, according to the sampling rate and the sampling length of power supply signal Frequency Design acquisition system, wherein concrete method for designing can be determined by following formula then:
Wherein: f
0Be fundamental frequency, f
1Be transmitter frequency, Δ t is the sampling rate of acquisition system, and this parameter should satisfy:
f
0=nf
1
Wherein: n is an integer, and promptly fundamental frequency is the integral multiple of transmission frequency.
The design of sampling length should be determined by following formula:
Wherein: L is the sampling length of acquisition system, and n is an integer, and satisfies L and can be divided exactly by 2,3 and 5.
The above-mentioned parameter design is provided with transmitter frequency and periodicity after finishing in high-power emissive source, parameters such as sampling rate and sampling length are set in the acquisition system, finishes the work that is provided with of parameter.Utilize the transmitter and the data collection system synchronizing work of radio or GPS time service synchro control transmitter, realize the collection of data.
The volume method of separating of image data is as described below:
Denoising
The signal of gathering is the f among Fig. 4
(t)With the n among Fig. 5
(t)Take advantage of and obtained a new signal r
(t):
r
t=f
(t)×n
(t)
Wherein: r
(t)Be the signal that collects, f
(t)Be signal source, n
(t)Be the place noise source, it is less and frequency shows as the wide spectrum characteristic that the place noise has amplitude, therefore needs to introduce wavelet transformation (Wavelet) instrument with its filtering.
r′
(t)=wden(r
(t))
Wherein: r '
(t)Be the signal after the denoising of process small echo, wden: be small echo denoising function.
Separate to compile and handle
In the signal after the above-mentioned denoising, have only the signal that has a same frequency with signal source to be only useful signal, utilize Fast Fourier Transform (FFT) (DFT) in the digital signal to realize decoding to useful signal for this reason.
Wherein: R
(ω)Be the Fourier spectrum of signal, get in this function with transmitting and have the signal of same frequency and calculate its amplitude spectrum, can obtain the voltage signal of actual measurement.
To obtain the potential value of each node in the test network at last, and show and data storage work with this one-tenth figure that carries out the current potential isoline.If test data does not satisfy test request, then can carry out the synchronous working of high-power signal source and acquisition system once more, carry out the repeated acquisition process of data.
Embodiment 6
A, utilize distributed parallel earth potential acquisition system annular survey grid of layout in surveying the district, complexity according to coverage of survey area, geologic condition is arranged survey grid, the annular survey grid be with the power supply well be the center of circle, collecting unit is placed on power supply Jing Chu, and collecting unit is in the centre position of survey line, and the survey line central point that is made of 6 collecting units coincides with the center of circle of survey grid, and radially distribute, angle is identical between survey line, and angle increases along with survey line quantity and reduces between survey line, and survey line then its angle is 30 degree.
B, outside survey grid 1.0 kilometers locate to arrange reference electrode, reference electrode is connected with main control unit by lead, has constituted one between each node and the reference electrode in the survey grid and has independently measured the loop, constitutes ground and gathers survey grid;
C, select two mouthfuls of wells in surveying the district, wherein a bite well is as the power supply well, and another mouthful well is as junction box, links the current supply circuit that composition is powered to reservoir, formation emission coefficient with the high power digital signal source by will power well and junction box of cable; The power supply well should be selected independently water injection well, then needs to select one of them also to disconnect and the connecting line of other water injection well if group wells supplies water, and junction box should be selected oil well or the water injection well outside the tested block.
D, determine that high power digital signal source emissive power and transmission frequency, supply current are 8~10 amperes, transmission frequency is judged by surrender degree of depth formula:
Wherein: H
δBe the reservoir depth of burial, ρ is the average resistivity of the earth, f
bFrequency for transmitter;
E, after acquisition system and the setting of emission coefficient parameter are finished, utilize the GPS time service method of synchronization, control acquisition system and emission coefficient synchronous working realize the collection of data.
F, carry out digital signal by the signal that acquisition system is collected, pick up amplitude with emission coefficient same frequency signal, calculate the potential data between each node and reference electrode in the survey grid, thereby be finally inversed by the resistivity spatial distribution characteristic of detected target body, realize distribution of remaining oil rule in the oilfield reservoir.
After test process finishes, will stop power supply in the high-power signal source, and the data that collect are carried out denoising to the while data acquisition system (DAS) and data are separated the volume processing.Can determine the line frequency of emission coefficient according to the well-log information of test site and the depth of burial that is studied reservoir, according to the sampling rate and the sampling length of power supply signal Frequency Design acquisition system, wherein concrete method for designing can be determined by following formula then:
Wherein: f
0Be fundamental frequency, f
1Be transmitter frequency, Δ t is the sampling rate of acquisition system, and this parameter should satisfy:
f
0=nf
1
Wherein: n is an integer, and promptly fundamental frequency is the integral multiple of transmission frequency.
The design of sampling length should be determined by following formula:
Wherein: L is the sampling length of acquisition system, and n is an integer, and satisfies L and can be divided exactly by 2,3 and 5.
The above-mentioned parameter design is provided with transmitter frequency and periodicity after finishing in high-power emissive source, parameters such as sampling rate and sampling length are set in the acquisition system, finishes the work that is provided with of parameter.Utilize the transmitter and the data collection system synchronizing work of radio or GPS time service synchro control transmitter, realize the collection of data.
The volume method of separating of image data is as described below:
Denoising
The signal of gathering is the f among Fig. 4
(t)With the n among Fig. 5
(t)Take advantage of and obtained a new signal r
(t):
r
t=f
(t)×n
(t)
Wherein: r
(t)Be the signal that collects, f
(t)Be signal source, n
(t)Be the place noise source, it is less and frequency shows as the wide spectrum characteristic that the place noise has amplitude, therefore needs to introduce wavelet transformation (Wavelet) instrument with its filtering.
r′
(t)=wden(r
(t))
Wherein: r '
(t)Be the signal after the denoising of process small echo, wden: be small echo denoising function.
Separate to compile and handle
In the signal after the above-mentioned denoising, have only the signal that has a same frequency with signal source to be only useful signal, utilize Fast Fourier Transform (FFT) (DFT) in the digital signal to realize decoding to useful signal for this reason.
Wherein: R
(ω)Be the Fourier spectrum of signal, get in this function with transmitting and have the signal of same frequency and calculate its amplitude spectrum, can obtain the voltage signal of actual measurement.
To obtain the potential value of each node in the test network at last, and show and data storage work with this one-tenth figure that carries out the current potential isoline.If test data does not satisfy test request, then can carry out the synchronous working of high-power signal source and acquisition system once more, carry out the repeated acquisition process of data.