CN106593428B - Software focusing array lateral control method - Google Patents
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
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Abstract
The invention relates to a software focusing array lateral control method, which specifically comprises the following steps: 1) the method comprises the steps of constructing a high-resolution array lateral electrode system, wherein the high-resolution array lateral electrode system consists of 25 electrode arrays including 1 main electrode, 12 symmetrically-arranged monitoring electrodes and 12 symmetrically-arranged transmitting (receiving) electrodes, and solves the problems that the conventional lateral resolution is low and an invasion section cannot be clearly divided; 2) generating 7 working frequency and sine wave signal sources of 60Hz, 90Hz, 120Hz, 150Hz, 180Hz, 210Hz and 240Hz, wherein the signal output amplitude is 10VAC (effective value) sine signals, and loading the sine signals to corresponding electrodes on the array side; 3) the monitoring (sampling) electrode samples the formation potential difference signal and carries out differential amplification; 4) the differential amplification signal is subjected to program control gain amplification and A/D conversion; 5) and extracting the amplitude and the phase of each channel signal from the sampling signal through FIR and FFT.
Description
Technical Field
The invention relates to an FPGA (field programmable gate array) technology and a data synchronization technology under a distributed network architecture, in particular to a software focusing array lateral back control method.
Background
The software focusing array lateral logging instrument is a novel high-resolution and multi-detection-depth array instrument, is one of main devices of resistivity imaging logging, and is mainly applied to identification and evaluation of complex well conditions and complex hydrocarbon reservoirs. The method uses a main electrode and a series of symmetrically placed focusing electrodes to measure the stratum, can simultaneously provide 6 resistivity curves with different detection depths, and completes the apparent resistivity measurement from the stratum invaded zone resistivity to the original stratum resistivity at six different detection depths so as to research the change of the resistivity among the stratums; through a mathematical inversion technology and a two-dimensional stratum model capable of accurately reflecting the characteristics of the underground stratum, more accurate true resistivity Rt of the stratum can be obtained, and therefore the accuracy of calculating the oil saturation is improved.
In order to ensure that the software focusing array lateral one-time logging can simultaneously complete 6 resistivity measurements and complete fine formation information division, a software focusing array lateral electrode system and an independent working current field corresponding to the software focusing array lateral electrode system are designed. The early high-resolution array lateral current field control usually adopts a hardware focusing mode, realizes current field focusing control by controlling the ratio of main current (A0 electrode emission main current I0) to screen current (other shielding electrode emission screen current Ib), and is composed of a main focusing control circuit and a series of auxiliary focusing control circuits, thereby better completing formation resistivity measurement. However, the hardware focusing mode is not only complex in circuit realization, and difficult in debugging, fault judgment and maintenance, but also the current field control is realized by adopting a hardware circuit, once circuit parameters are set, the real-time adjustment can not be carried out according to the information state of the underground stratum during logging, when the change dynamic range of the stratum resistivity is large enough, the phenomenon of under-focusing or over-focusing is often generated, especially when the stratum resistivity (Rt) is far larger than the mud resistivity (Rm), namely Rt/Rm >100, the phenomenon of logging curve jumping is often generated due to the occurrence of a current negative value caused by over-focusing, and the measurement of the stratum resistivity can not be completed.
The high-resolution array lateral software focusing is based on an electric field superposition principle, the main focusing adopts a non-focusing resistivity measurement principle to respectively measure each sub-electric flow field, and the purpose of synthetic focusing is realized through mathematical operation; the auxiliary focusing is realized by measuring stratum signals sampled by each monitoring electrode (or sampling electrode), respectively extracting amplitude values and phase differences of each frequency component after differential amplification, program-controlled gain amplification, high-precision A/D sampling, FIR (finite impulse response) and FFT (fast Fourier transform) signal processing, and adjusting the magnitude of a screen flow output signal after processing by a certain back control algorithm. By adopting the software focusing implementation method, the circuit is simple to implement, the debugging and the maintenance are convenient, meanwhile, the focusing state of the instrument can be accurately judged according to the extracted phase, the parameters of the underground instrument can be adjusted in real time, and the phenomenon of under-focusing or over-focusing caused by electric field control is avoided.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a software focusing array lateral control method.
The invention aims to complete the technical scheme that the software focusing array lateral control method specifically comprises the following steps:
1) a high-resolution array lateral electrode system is constructed, and consists of 25 electrode arrays including 1 main electrode, 12 symmetrically-arranged monitoring electrodes and 12 symmetrically-arranged transmitting or receiving electrodes, so that the problems that the conventional lateral resolution is low and the invasion section cannot be clearly divided are solved;
2) generating 7 working frequency and sine wave signal sources of 60Hz, 90Hz, 120Hz, 150Hz, 180Hz, 210Hz and 240Hz, wherein the signal output amplitude is 10VAC (effective value) sine signals, and loading the sine signals to corresponding electrodes on the lateral side of the array;
3) the monitoring or sampling electrode samples the formation potential difference signal and carries out differential amplification;
4) the differential amplification signal is subjected to program-controlled gain amplification and A/D conversion;
5) extracting the amplitude and phase of each channel signal from the sampled signal through FIR and FFT;
6) generating a feedback control signal through a feedback control algorithm according to the amplitude and the phase of the extracted formation signal, generating a feedback control signal through an iterative formula and corresponding operation, superposing the feedback control signal to the original 7 frequency signal sources to form a new transmitting signal source, and loading the new transmitting signal source to a corresponding electrode;
7) and repeating the steps 2) -6) until the potential difference of the monitoring or sampling electrode is lower than a set threshold value.
The invention has the beneficial effects that: the focusing state of the array lateral current field can be accurately judged, the parameters of the underground instrument can be adjusted in real time, the phenomenon of under-focusing or over-focusing caused by electric field control is solved, and more accurate true formation resistivity can be obtained.
Drawings
FIG. 1 is a schematic diagram of the current source loading of the present invention;
FIG. 2 is a schematic diagram of a differential amplifier circuit of the present invention;
FIG. 3 is a schematic diagram of the signal amplitude and phase difference extraction function of the present invention;
FIG. 4 is a schematic view of the auxiliary focus control of the present invention;
fig. 5 is a flow chart of the auxiliary focus control of the present invention.
Detailed Description
The invention will be described in detail below with reference to the following drawings:
1. and controllable multi-frequency signal loading. The main control signal processing board generates 7 frequency signals of 60Hz, 90Hz, 120Hz, 150Hz, 180Hz, 210Hz and 240Hz, the amplitude of the signals is +/-10 VAC, and the signals are simultaneously loaded to corresponding electrodes on the side of the array after being amplified by power push-pull. Among them, 240Hz constant current source was applied to the a0 electrode, 210Hz current source was applied to the A1A1 ' electrode, 180Hz current source was applied to the A1A2 and A1 ' A2 ' electrodes, 150Hz current source was applied to the A2A3 and A2 ' A3 ' electrodes, 120Hz current source was applied to the A3A4 and A3 ' A4 ' electrodes, 90Hz current source was applied to the A4A5 and A4 ' A5 ' electrodes, and 60Hz current source was applied to the A5A6 and A5 ' A6 ' electrodes, as shown in fig. 1.
2. The 11 paths of potential difference are amplified differentially. The 11-path potential difference differential amplification comprises a main preamplification part, an auxiliary preamplification part and a differential amplification part.
The main pre-amplification output comprises four groups of potential differences of VM0N, VMO 'N, VM0M1 and VM 0' M1 ', VM0N and VMO' N are used for formation resistivity calculation, and VM0M1 and VM0 'M1' are used for compound electric field focusing calculation, so that the balance of main flow electric fields of all frequency components is realized.
The auxiliary pre-amplification output comprises five groups of potential differences of VM2M3, VM4M5, VM2 'M3', VM4 'M5' and VA3A4, and the auxiliary pre-amplification output is mainly used for an auxiliary focusing back control algorithm to realize dynamic balance of an auxiliary focusing electric field.
The main preamplifier circuit and the auxiliary preamplifier circuit are directly placed in the main electrode in a pressure bearing design mode, so that the signal-to-noise ratio is improved, and the measurement accuracy of the instrument is ensured.
The differential amplification output comprises two groups of potential differences of VA4A5 and VA5A6, and is mainly used for an auxiliary focusing back control algorithm to realize dynamic balance of an auxiliary focusing electric field.
The 11-path differential amplification functional module is shown in fig. 2.
3. Multichannel signal program control amplification and sampling.
The 18 collected signals (including 7 current signals) are amplified by 1, 2, 4, 8, 16, 32, 64 and 128 times of program control gain, and are converted by 16-bit high-speed and high-precision A/D to form 18 x 16 bit data, and the 18 x 16 bit data are transmitted to the signal processing module under the control of a communication protocol.
4. And (4) extracting amplitude phase difference of the 18 paths of signals.
The extraction of the amplitude and the phase difference of the 18 paths of signals is mainly realized by 2 pieces of FPGA and DSP, and the extraction method mainly comprises the following 4 functions:
1) filtering an input set of time domain signals;
2) transforming the input time domain data (1024 points) into frequency domain signals through FFT;
3) selecting a specific frequency domain point from the obtained group of frequency domain data;
4) and calculating the amplitude and the phase of a specific frequency domain point and outputting the two results.
The block diagram of the amplitude and phase difference extraction function is shown in fig. 3.
5. And (5) realizing a back control algorithm.
The extracted voltages and corresponding phase differences of VM2M3, VM4M5, VM2 'M3', VM4 'M5', VA3a4, VA4a5 and VA5a6 are respectively used for controlling the output magnitude of the focusing current source. The current source control schematic diagram is shown in fig. 4, and the implementation process is as follows:
the working of the instrument comprises 7 channels which are respectively marked as a channel I to a channel VII, each channel respectively generates 7 working frequency and sine wave signals of 60Hz, 90Hz, 120Hz, 150Hz, 180Hz, 210Hz and 240Hz, the signal output amplitude is 10VAC (effective value) sine signals, and the sine signals are respectively loaded on each electrode in the step 1;
the electrode system array is put down into the stratum, the current source loaded on the electrode system divergently flows in the stratum, a potential difference is generated through a stratum resistor, a monitoring electrode or a sampling electrode on the electrode samples a stratum potential difference signal, and the stratum potential difference is differentially amplified through a preamplification circuit in the electrode;
after the formation potential difference signal is subjected to 1/2/4/8/16/32/64/128 times of range control gain amplification and A/D sampling, under the control of a communication protocol, sampling data are transmitted to a signal control processing circuit, and the formation potential difference amplitude and phase value are extracted through descending sampling, FIR filtering, FFT conversion and phase/amplitude calculation;
according to the amplitude dv and phase of the formation potential difference, a feedback control signal Vf is generated, dv is multiplied by an original signal Vi with a corresponding frequency to generate the amplitude of the feedback control signal, the phase difference determines whether the feedback control signal and the original signal are added or subtracted, dv>Addition of 0, dv<0 is subtracted by the following formula: Δ Vf (+/-) dv Vi;
the generated back control signal passes through an iterative formula: vf (n +1) ═ Vf (n) +/-dv Vi is superimposed on the original signal, generating a new transmissionThe injection signal Vout, Vout is Vi + Vf (n +1), and when dv is 0, the back control process is ended.
It should be understood that equivalent substitutions and changes to the technical solution and the inventive concept of the present invention should be made by those skilled in the art to the protection scope of the appended claims.
Claims (4)
1. A software focusing array lateral control method is characterized in that: the method comprises the following steps:
1) constructing a high-resolution array lateral electrode system, which consists of 25 electrode arrays of 1 main electrode, 12 symmetrically-arranged monitoring electrodes and 12 symmetrically-arranged transmitting or receiving electrodes;
2) generating 7 working frequency and sine wave signal sources of 60Hz, 90Hz, 120Hz, 150Hz, 180Hz, 210Hz and 240Hz, wherein the signal output amplitude is 10VAC sine signals, and loading the sine signals to corresponding electrodes on the lateral side of the array;
3) the monitoring or sampling electrode samples the formation potential difference signal and carries out differential amplification;
4) the differential amplification signal is subjected to program-controlled gain amplification and A/D conversion;
5) the sampled signals are subjected to FIR filtering and FFT conversion, and the amplitude and the phase of each channel signal are extracted;
6) generating a feedback control signal through a feedback control algorithm according to the amplitude and the phase of the extracted formation signal, generating a feedback control signal through an iterative formula and corresponding operation, superposing the feedback control signal to the original 7 frequency signal sources to form a new transmitting signal source, and loading the new transmitting signal source to a corresponding electrode;
and repeating the steps 2) -6) until the potential difference of the monitoring or sampling electrode is lower than a set threshold value.
2. The software focus array lateral steering method of claim 1, wherein: controllable multi-frequency signal loading in step 2): the main control signal processing board generates 7 frequency signals of 60Hz, 90Hz, 120Hz, 150Hz, 180Hz, 210Hz and 240Hz, the signal amplitude is +/-10 VAC, and the signals are simultaneously loaded to corresponding electrodes on the side of the array after being amplified by power push-pull; wherein 240Hz constant current source is applied to the A0 electrode, 210Hz current source is applied to the A1A1 ' electrode, 180Hz current source is applied to the A1A2 and A1 ' A2 ' electrodes, 150Hz current source is applied to the A2A3 and A2 ' A3 ' electrodes, 120Hz current source is applied to the A3A4 and A3 ' A4 ' electrodes, 90Hz current source is applied to the A4A5 and A4 ' A5 ' electrodes, and 60Hz current source is applied to the A5A6 and A5 ' A6 ' electrodes.
3. The software focus array lateral steering method of claim 1, wherein: differential amplification of 11 paths of potential differences in step 3): the 11 paths of potential difference differential amplification comprise a main preposed amplification part, an auxiliary preposed amplification part and a differential amplification part; the main pre-amplification output comprises four groups of potential differences of VM0N, VMO 'N, VM0M1 and VM 0' M1 ', wherein VM0N and VMO' N are used for formation resistivity calculation, and VM0M1 and VM0 'M1' are used for composite electric field focusing calculation, so that the balance of main electric fields of all frequency components is realized; the auxiliary pre-amplification output comprises five groups of potential differences of VM2M3, VM4M5, VM2 'M3', VM4 'M5' and VA3A4, and is mainly used for an auxiliary focusing back control algorithm to realize dynamic balance of an auxiliary focusing electric field; the main preamplifier circuit and the auxiliary preamplifier circuit are directly placed in the main electrode in a pressure-bearing design mode, so that the signal-to-noise ratio is improved, and the measurement accuracy of an instrument is ensured; the differential amplification output comprises two groups of potential differences of VA4A5 and VA5A6, and is mainly used for an auxiliary focusing back control algorithm to realize dynamic balance of an auxiliary focusing electric field.
4. The software focus array lateral steering method of claim 1, wherein: the back control algorithm in the step 6) comprises the following steps: the extracted voltages and corresponding phase differences of VM2M3, VM4M5, VM2 'M3', VM4 'M5', VA3A4, VA4A5 and VA5A6 are respectively used for controlling the output size of the focusing current source;
1) the instrument work comprises 7 channels which are respectively marked as a channel I to a channel VII, each channel respectively generates 7 working frequency and sine wave signals of 60Hz, 90Hz, 120Hz, 150Hz, 180Hz, 210Hz and 240Hz, the signal output amplitude is 10VAC sine signals, and the signals are respectively loaded on each electrode in the step 1);
2) the electrode system array is put into the stratum, a current source loaded on the electrode system divergently flows in the stratum, a potential difference is generated through a stratum resistor, a monitoring electrode or a sampling electrode on the electrode samples a stratum potential difference signal, and the stratum potential difference is differentially amplified through a preamplifier circuit in the electrode;
3) after the formation potential difference signal is subjected to 1/2/4/8/16/32/64/128 times of gain control amplification and A/D sampling, under the control of a communication protocol, sampling data are transmitted to a signal control processing circuit, and the formation potential difference amplitude and phase value are extracted through descending sampling, FIR filtering, FFT conversion and phase/amplitude calculation;
4) according to the amplitude dv and the phase of the formation potential difference, generating a feedback control signal Vf, multiplying the dv by an original signal Vi with a corresponding frequency to generate the amplitude of the feedback control signal, determining whether the feedback control signal and the original signal are added or subtracted by the phase difference, adding dv >0, subtracting dv <0, and adopting the specific formula: Δ Vf (+/-) dv Vi; the delta Vf is a feedback control signal amplitude value;
5) and the generated back control signal each time passes through an iterative formula: vf (n +1) ═ Vf (n) +/-dv Vi is superimposed on the original signal, generating a new transmitted signal Vout, Vout ═ Vi + Vf (n +1), when dv is 0, the back control process ends.
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| CN107907912A (en) * | 2017-12-07 | 2018-04-13 | 中石化石油工程技术服务有限公司 | High-resolution oil-base mud Electrical imaging pole plate |
| CN111350494B (en) * | 2020-03-16 | 2023-06-30 | 中国石油天然气集团有限公司 | Lateral self-adaptive constant power control method for hardware focusing array |
| CN111474591B (en) * | 2020-04-01 | 2022-11-04 | 中国石油天然气集团有限公司 | Method for testing residual potential difference and main screen flow ratio of homogeneous stratum for azimuth array lateral direction |
| CN112081585B (en) * | 2020-09-29 | 2024-03-26 | 中国石油天然气集团有限公司 | Autonomous focusing circuit of array lateral logging instrument and control method |
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