CN101949973A - Method for measuring ground potential - Google Patents

Abstract

The invention relates to a method for measuring the ground potential. The method comprises the following steps of: arranging a rectangular or annular distributive parallel ground potential acquisition system measuring net in a measuring area; arranging more than one or even N acquisition units according to the range of the measuring area and the complexity of the geological condition, and connecting an upper computer and a master control unit with the acquisition units through data transmission cables; arranging a reference electrode outside the measuring net, wherein the reference electrode is connected with the master control unit through a lead to form a ground acquisition measuring net; selecting two wells in the measuring area as a power supply well and a convergence well; and connecting the power supply well and the convergence well with a high-power digital signal source to form an emission system. In the invention, the suppression of a free electric field interference source changing along with time is realized through a parallel acquisition mode, and a transmitter adopts a frequency encoding mode to realize the precise measurement of weak signals through digital signal processing under the condition of not increasing the transmitting power of the transmitter. The measurement mode effectively improves the precision of ground potential measurement data, improves the working efficiency and reduces the field construction cost.

Description

The earth potential measuring method

Technical field

The present invention relates to a kind of based on the earth potential measuring method in traditional geophysical method, the potential measurement method of the oil field remaining oil monitoring technology under the especially high background noise environment.

Background technology:

Oil is a kind of non-renewable energy, and oil recovery is not only petroleum industrial circle, and is the problem that entire society is concerned about.Oil exploitation is divided into three phases.Primary oil recovery is to rely on producing energy to carry out flow production, and its output accounts for contains 15%～20% of total amount.After producing energy discharges, augment the oil reservoir energy with the method for man-made injection or gas injection, make crude oil be able to continuous exploitation, this is called secondary oil recovery.The recovery ratio of secondary oil recovery is 15%～20%.After secondary oil recovery was carried out decades, remaining oil was caught in the oil reservoir sandstone pores by circle with the form of discontinuous oil clot, and this moment, extraction liquid water cut reached 85%～90%, have in addition up to 98%, exploitation has not at this moment had economic benefit.Therefore, have 60%～70% crude oil can only rely on other physics and chemical method to exploit approximately, such exploitation is called tertiary oil recovery, abroad also be referred to as to strengthen oil exploitation technology (Enhanced Oil Recovery, EOR).Usually adopt transfer drive technical measures such as some water fillings in reservoir, gas injection, the strong sulphur of notes, pressure break at present at tertiary phase, to improve the rate of extraction in former oil field.

Highly aqueous field remaining oil Dynamic Monitoring is important techniques means of implementing at tertiary phase, but migration rule by oil and water in this technology dynamic monitoring reservoir, understand water-oil interface and water logging and water string situation in the reservoir, this technology not only provides important directive significance to the enforcement of tertiary oil recovery technology scheme, and can also be for rationally, formulate highly aqueous field development plan and seek remaining oil distribution important scientific basis is provided economically.Along with the development of three the development approach technology in moisture oil field, the remaining oil real time monitoring has obtained significant progress, successively develops direct measuring method such as geophysical methods such as four-dimensional earthquake, well logging, potential measurement and tracer survey.Wherein potential measurement technology begins from late nineteen seventies, is being tested aspect the evaluation of waterfrac treatment orientation and extension by French scholar.Early eighties, U.S. Sang Diya experimental study center is beginning the test application aspect the coal-formed gas fracture evaluation.Late nineteen eighties, Japanese scholar is carrying out Preliminary Applications aspect the evaluating reservoir of geothermal well that sleeve pipe is arranged and production of hydrocarbons well.In the nineties later stage, the electrical survey technology has obtained widespread use in the formation evaluation of oil field, geothermal field, coalfield, underground water and the underground nuclear waste disposal field of (U.S., France, Japan, Germany, Indonesia etc.) a plurality of countries abroad.Domesticly also carried out a large amount of theories (He Yusheng etc., 1999) and field test research (Zhang Jincheng, 2001) from the end of the nineties, the electrical method measuring technology has obtained using widely at water injection well in oil fields water injection propelling orientation and fracturing fracture orientation, gas field, coal seam.

Present existing potential measurement method all is mise-a-la-masse methods of using in traditional geophysical method, promptly utilize boring or appearing of detected target body in the objective body that is detected, to set up a galvanic current field, utilize common DC electrical method instrument to carry out the measurement of a current potential or electric potential gradient again, can be finally inversed by the space distribution rule of the detection of a target according to the potential value of measuring in face of land pointwise.But this method directly used in the monitoring of oil field remaining oil have many problems, wherein be mainly reflected in the DC electric field of being set up and be subjected to the interference of the free electric field of test site easily, simultaneously because the reservoir depth of burial that is studied is bigger, effective potential value magnitude that the face of land is measured is very little, and this will directly cause measurement result bigger error to occur.At the problems referred to above, have both at home and abroad in recent years and also developed some special-purpose instrument and equipments, the for example IPRF-1 of Canada's development and domestic YL-841 drilling well fracturing fracture measurement of bearing, adopted multi-channel mode to measure and large power supply, but still fundamentally do not addressed the above problem.Therefore at the problems referred to above a kind of earth potential measuring method that is suitable for oil field remaining oil monitoring is proposed.

Summary of the invention:

Purpose of the present invention is exactly at above-mentioned the deficiencies in the prior art, and a kind of earth potential measuring method that is suitable for the remaining oil monitoring is provided.

The objective of the invention is to be achieved through the following technical solutions:

The earth potential measuring method comprises following method 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;

B, 1-2 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;

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:

$H_{\mathrm{\δ}}=503\sqrt{\frac{\mathrm{\ρ}}{f_b}}$

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 digital signal by the signal that acquisition system is collected and 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.

Purpose of the present invention can also realize in the following manner:

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, and the survey line angle is 5 °-30 °, and 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, form by 12 measuring points on the every survey line, 20～100 meters of measuring point spacings, the spacing of survey line are 50 meters.

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.

Beneficial effect: the present invention mainly realizes inhibition to time dependent free electric field interference source in the test environment by the distributed parallel potential measurement mode potential difference (PD) mode between all nodes and common reference electrode in the survey grid of gathering, transmitter adopts the frequency coding mode simultaneously, under the precondition that does not increase the transmitter emissive power, utilize the accurate measurement of Digital Signal Processing realization to weak signal.The design of this kind measuring method not only can improve the precision of earth potential measurement data, also makes simultaneously whole measuring system have characteristics such as operating efficiency height, equipment are light.

Description of drawings

Fig. 1 earth potential measuring method annular test network arrangenent diagram.

Fig. 2 earth potential measuring method test rectangle network arrangement figure.

Fig. 3 earth potential measuring method process flow diagram

Fig. 4 earth potential measuring method annular test earth potential cloud atlas

Fig. 5 earth potential measuring method test rectangle earth potential isogram

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:

$H_{\mathrm{\δ}}=503\sqrt{\frac{\mathrm{\ρ}}{f_b}}$

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:

$H_{\mathrm{\δ}}=503\sqrt{\frac{\mathrm{\ρ}}{f_b}}$

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:

$f_0=\frac{1}{\mathrm{\Δt}}$

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:

$L\≥=\frac{n}{\mathrm{\Δt}\×f_0}$

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.

$R_{\left(\mathrm{\ω}\right)}=\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{r}_{\left(t_n\right)}^{\′}{e}^{-i{\mathrm{\ωt}}_n}$

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:

$H_{\mathrm{\δ}}=503\sqrt{\frac{\mathrm{\ρ}}{f_b}}$

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:

$f_0=\frac{1}{\mathrm{\Δt}}$

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:

$L\≥=\frac{n}{\mathrm{\Δt}\×f_0}$

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.

$R_{\left(\mathrm{\ω}\right)}=\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{r}_{\left(t_n\right)}^{\′}{e}^{-i{\mathrm{\ωt}}_n}$

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:

$H_{\mathrm{\δ}}=503\sqrt{\frac{\mathrm{\ρ}}{f_b}}$

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:

$f_0=\frac{1}{\mathrm{\Δt}}$

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:

$L\≥=\frac{n}{\mathrm{\Δt}\×f_0}$

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.

$R_{\left(\mathrm{\ω}\right)}=\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{r}_{\left(t_n\right)}^{\′}{e}^{-i{\mathrm{\ωt}}_n}$

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:

$H_{\mathrm{\δ}}=503\sqrt{\frac{\mathrm{\ρ}}{f_b}}$

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:

$f_0=\frac{1}{\mathrm{\Δt}}$

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:

$L\≥=\frac{n}{\mathrm{\Δt}\×f_0}$

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.

$R_{\left(\mathrm{\ω}\right)}=\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{r}_{\left(t_n\right)}^{\′}{e}^{-i{\mathrm{\ωt}}_n}$

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:

$H_{\mathrm{\δ}}=503\sqrt{\frac{\mathrm{\ρ}}{f_b}}$

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:

$f_0=\frac{1}{\mathrm{\Δt}}$

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:

$L\≥=\frac{n}{\mathrm{\Δt}\×f_0}$

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.

$R_{\left(\mathrm{\ω}\right)}=\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{r}_{\left(t_n\right)}^{\′}{e}^{-i{\mathrm{\ωt}}_n}$

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:

$H_{\mathrm{\δ}}=503\sqrt{\frac{\mathrm{\ρ}}{f_b}}$

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:

$f_0=\frac{1}{\mathrm{\Δt}}$

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:

$L\≥=\frac{n}{\mathrm{\Δt}\×f_0}$

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.

$R_{\left(\mathrm{\ω}\right)}=\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{r}_{\left(t_n\right)}^{\′}{e}^{-i{\mathrm{\ωt}}_n}$

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.

Claims (4)

1. an earthy measuring method is characterized in that, comprises following order and step:

A, employing distributed parallel potential acquisition system arrange rectangle or annular spread survey grid in surveying the district, complexity according to coverage of survey area, geologic condition, survey grid is by arranging more than one and even N collecting unit, and host computer, main control unit and collecting unit are connected to form by data transmission cable;

B, 1-2 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 potential acquisition system;

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;

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:

$H_{\mathrm{\δ}}=503\sqrt{\frac{\mathrm{\ρ}}{f_b}}$

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, pick up the amplitude with emission coefficient same frequency signal, calculate the potential data between each node and reference electrode in the survey grid by the signal that acquisition system is collected.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.

2. according to the described earthy measuring method of claim 1, it is characterized in that, the annular survey grid be with the power supply well be the center of circle, with collecting unit be placed on the power supply Jing Chu, collecting unit is in the centre position of survey line, by more than 10 so that N collecting unit constitute, the survey line central point coincides with the center of circle of survey grid, and radially distributes, and the survey line angle is identical, the survey line angle is 5 °-30 °, and angle increases along with survey line quantity and reduces between survey line.

3. according to the described earthy measuring method of claim 1, it is characterized in that, the rectangle survey grid by more than 10 so that N collecting unit constitute equally spaced parallel survey line, form by 12 measuring points on the every survey line, 20～100 meters of measuring point spacings, the spacing of survey line are 50 meters.，

4. according to the described earthy measuring method of claim 1, it is characterized in that, the power supply well should be selected independently water injection well, then need to select one of them also to disconnect and the connecting line of other water injection well if group wells supplies water, junction box should be selected oil well or the water injection well outside the tested block.

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