CN104453866B - The phase calibration method of induction logging current measurement - Google Patents
The phase calibration method of induction logging current measurement Download PDFInfo
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- CN104453866B CN104453866B CN201310426946.XA CN201310426946A CN104453866B CN 104453866 B CN104453866 B CN 104453866B CN 201310426946 A CN201310426946 A CN 201310426946A CN 104453866 B CN104453866 B CN 104453866B
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- 238000005259 measurement Methods 0.000 title claims abstract description 72
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- 238000004458 analytical method Methods 0.000 description 3
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Classifications
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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
-
- 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
- E21B47/00—Survey of boreholes or wells
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geophysics (AREA)
- Measurement Of Resistance Or Impedance (AREA)
Abstract
The present invention relates to a kind of phase calibration methods of induction logging current measurement.The vector of apparent conductivity in the case where by measuring different transmitting coils twice and receiving coil distance respectively, solve the current measurement phase error introduced by current transformer in current measurement circuit and non-linear element, to accurately know the error of current measurement link introducing, and eliminated in calculating, improve the scale and measurement accuracy of array induction logging instrument.
Description
Technical field
The present invention relates to a kind of induction well logging methods, particularly, are related to a kind of phase mark of induction logging current measurement
Determine method.
Background technique
Induction logging is the mutual inductance principle using alternating current, is felt in receiving coil using the alternating current in transmitting coil
Electromotive force should be gone out, since transmitting coil and receiving coil are all in well, the alternating current of transmitting coil it is inevitable pit shaft peripherally
Vortex is induced in layer, and the vortex has an impact the induced electromotive force of receiving coil, therefore the electromotive force and vortex
Intensity is related, i.e., related with the conductivity on stratum.
Induction logging instrument measures same stratum using a series of coil array of different coil spacings, then by hard
Part or software focus processing obtain the formation conductivity of different radials depth of investigetion, to efficiently identify oil-gas Layer.Such as attached drawing 1
Shown, array induction logging instrument passes through transmitting coil first, and to stratum transmission electromagnetic field, (1 topmost portion of attached drawing is emission lines
Circle), which generates induced current in stratigraphic unit ring, secondary field (1 middle section of attached drawing is stratigraphic unit ring) is excited,
Then it is received by each group receiving coil, secondary field generates secondary field induced electromotive force in receiving coil, the signal warp received
After downhole instrument processing, ground instrument (1 lowermost part of attached drawing is receiving coil) is transferred information to by the spread of the rumours system.
Attached drawing 2 is the relational graph of the current phase of transmitting coil, stratigraphic unit ring, receiving coil.As shown in Fig. 2, three
The receiving coil of dimension array induction logging instrument can receive straight coupling induced electromotive force from transmitting coil and from stratum
Secondary field induced electromotive force, in infinite uniform medium, the alternating electromagnetic field of transmitting coil is directly generated in receiving coil
Both induced electromotive forces phase difference be 90 degree, which is directly coupling signal, for garbage signal, and the alternating electromagnetism of transmitting coil
Secondary field phase difference of the field in receiving coil is 180 degree.
Coil array is located in uniform, isotropism stratum, magnetic conductivity, conductivityAnd dielectric constantIt is constant；Ground
Layer is around borehole axis rotational symmetry；WithRespectively transmitting and receiving coil, the number of turns areWith, coil radius is,For hair
Spacing between ray circle and receiving coil, coil work under certain frequency.
If loading an angular frequency on transmitting coil is ω, amplitude isAlternating current, it may be assumed that emission current time-domain signal
It is expressed asOr it is expressed as a vector.For uniform dielectric environment, in order to keep problem analysis simple
Change, do not consider skin effect and propagation effect, then in receiving coil induced electromotive force are as follows:
... (1)
... (2)
... (3)
WhereinFor magnetic conductivity (H/m), it is assumed that transmitting coil area is identical with receiving coil area, is expressed as,For ground
Layer conductivity, if coil supporter is ceramics, device is simultaneously placed in air, thenFor air permeability,Tend to be infinitely small,
In this case,=0, received signal is mutually perpendicular to emission current.In three-winding system,For composite received
The reception signal of coil, it is generally the case thatIt is not zero but insensitive for the variation of L；When L itself is smaller,To L's
Variation is very sensitive, then the variation for receiving voltage vector is vertical with current vector when L minor alteration.
In induction logging, signal measured directly is voltage signal, i.e. induced electromotive force.In practical applications, usually
A measurement conductivity is defined to indicate measuring signal.Due to stratum be it is heterogeneous, measurement conductivity simultaneously be not equal to true conductance
Rate, therefore it is called apparent conductivity, apparent conductivity is defined as:
... (4)
Wherein
... (5)
Referred to as instrumental constant.For frequency give coil array,It is constant.
Wherein apparent conductivity can use formulaIt acquires,For the induced voltage of the receiving coil of actual measurement
Vector,For the emission current vector of actual measurement, K is instrumental constant,For apparent conductivity.
Such as previous analysis, for the short space coil close to transmitting coil, L itself very little, when L minor change
When, receive signalTheoretically withVertically.
If real current is, and the electric current measured is, actually measured induced voltage is, then
... (6)
It can be seen that due to there are error, therefore actually measured apparent conductivity intercoupling for real part and imaginary part will occur, and empty
Portion is usually not sufficiently stable, then will seriously affect the real part of the apparent conductivity of actual measurement.Although this coupling can be carved by instrument
Degree is eliminated, but in the instrument manufacturing stage, be will be unable to the source for positioning this error, brought difficulty to case study.
Summary of the invention
The present invention is to propose based on the above issues, and its purpose is to provide a kind of phases of induction logging current measurement
Position scaling method can accurately know the error that current measurement link introduces, and give in calculating after current measurement is demarcated
To eliminate.
The present invention provides a kind of phase calibration method of induction logging current measurement, to using array induction logging instrument
The error of current measurement caused by the minor change of the distance of transmitting coil and receiving coil carries out during progress induction logging
Calibration, the array induction logging instrument includes pre-amplifier unit, D/A conversion unit, which is characterized in that
The phase difference between current vector that the difference of apparent conductivity vector that measurement obtains and actual measurement are obtained as
The correction amount of current measurement phase is modified the electric current of actual measurement, thus to obtain the apparent conductivity of actual measurement (reality), comprising:
(1) the step of setting the initial distance between receiving coil and transmitting coil；
(2) current vector and voltage vector extraction step, the acquisition signal from current measurement channel and receiving coil channel
Two vectors of middle extraction, are denoted as current vector and voltage vector respectively；
(3) adjust the distance between the receiving coil and the transmitting coil, and repeat the current vector with
The step of voltage vector extraction step, the extraction of progress current vector and voltage vector；
(4) electric current correction amount determines step, according to current vector and voltage vector acquired in step (3), determines electricity
The correction amount of flow valuve；
(5) it according to the correction amount of identified current value in above-mentioned steps (4), is surveyed according to following formula (7) (real
Border) apparent conductivity,
... (7)
WhereinFor the induced voltage vector of the receiving coil of actual measurement, K is instrumental constant, ItFor real current,For view
Conductivity, IaFor measured current,For the vector angle of measured current and real current,For the real part of apparent conductivity,For
The imaginary part of apparent conductivity.
Preferably, in the phase calibration method of induction logging current measurement of the invention, the current vector and electricity
The amount of pressing to extraction step includes the following steps: the emission current for emitting single-frequency in transmitting coil；To the pre-amplifier unit
Gain with the D/A conversion unit is demarcated, so that the gain phase in current measurement channel and the channel of the receiving coil
Together；In measurement mode after record current Measurement channel and the acquisition signal in receiving coil channel, the method for Fourier transform is utilized
Two vectors are extracted, and are denoted as current vector and voltage vector respectively.
Preferably, in the phase calibration method of induction logging current measurement of the invention, which is characterized in that described
Electric current correction amount determines in step, after system is stablized, determines measured current according to acquired current vector and voltage vector
With the vector angle of real current, thus actually measured current value is modified.
Preferably, in the phase calibration method of induction logging current measurement of the invention, the transmitting electricity of the single-frequency
The frequency of stream is 40kHz.
Preferably, in the phase calibration method of induction logging current measurement of the invention, which is characterized in that described to connect
Initial distance between take-up circle and transmitting coil is 0.4 inch, and distance adjusted is 0.42 inch.
After the above method demarcates phase, the phase of current measurement has degree of precision, to instrument response and
Deviation positioning between theoretical response is of great significance.
Detailed description of the invention
Attached drawing 1 is the schematic diagram of cubical array induction logging instrument measuring signal.
Attached drawing 2 is the relational graph of the current phase of transmitting coil, stratigraphic unit ring, receiving coil.
Attached drawing 3 is the block diagram of the current measurement system of cubical array induction logging instrument.
Attached drawing 4 is the structural block diagram of the coil array of cubical array induction logging instrument.
Attached drawing 5 is the vectogram of induced voltage and emission current.
Specific embodiment
The phase calibration method of current measurement of the invention assumes the minor change of the distance of transmitting coil and receiving coil
The imaginary part of apparent conductivity is only influenced, and the influence to real part can be ignored, through the difference for measuring obtained apparent conductivity vector
It is vertical with current vector, and the phase difference between actually measured current vector can serve as the amendment of current measurement phase
Amount.
Hereinafter, the phase calibration method for current measurement of the invention is specifically illustrated.
Attached drawing 3 is the system block diagram of the current measurement of cubical array induction logging instrument.As shown in Fig. 3, cubical array
Induction logging instrument generates transmitting letter using direct digital frequency synthesis technology by digital signal processing unit (being abbreviated as DSP)
Number, which drives transmitting coil, in certain space underexcitation multifrequency variation magnetic field after power drive unit amplifies.It adopts
Current Transformer directly measures emission current, after current-voltage is converted, is sent to the input terminal of pre-amplifier unit,
It is amplified together with the induced voltage of receiving coil, finally obtains induction coil by AD conversion unit (being abbreviated as ADC)
Induced voltage signal and emission current signal, digital signal processing unit obtains the time domain waveform of signal first, in digital signal
The width for the signal for obtaining each channel using associated extraction technology in processing unit is mutually worth, i.e., each subarrayWith transmitting electricity
Stream。
Current Voltage converting unit mainly includes sampling resistor, linear drive circuit, signal transformer and resistance decrement net
Network.And current transformer (TC), linear transform circuit, pre-amplifier unit connector, signal transformer are in current measurement channel
Signal condition part, pre-amplifier unit and AD conversion unit can realize the circuit gain in each channel by interior carving method
All the same, the phase error which introduces can not consider.And current transformer (TC), linear transform circuit, preposition amplification
The introduced measurement error in unit connector, signal transformer part can not be eliminated by interior quarter, in this way, actually measured hair
Radio stream just has differences between true emission current.The difference will lead to the directly coupling signal measured and current vector not just
It hands over, makes to generate larger deviation between calibration factor and 1.In order to eliminate the error that conversion section is introduced in current measurement channel,
It needs to demarcate current measurement, referred to as be carved in current measurement.It carves to incude by cubical array in current measurement and survey
The record data of well instrument are realized compared between the practical measurement of current value measured using other equipment, and three-dimensional battle array can also be used
The characteristics of column induction instrument aratus itself, demarcates current measurement.
The scale phase error of cubical array induction logging instrument is analyzed below.
As it was noted above, set real current as, and the electric current measured is, surveying induced voltage is, then
... (6)
It can be seen that having the presence of error, and in the instrument manufacturing stage, the source for positioning this error will be unable to, it is right
Case study brings difficulty.But the above problem can be eliminated by demarcating to the phase error of current measurement.
Specifically, attached drawing 4 is the structural block diagram of the coil array of cubical array induction logging instrument.As shown in Fig. 4, if connecing
Initial distance between take-up circle (Coil0) and transmitting coil Tx is L, and above-mentioned distance is made to increase △ L1, distance after change
Measurement voltage is recorded when L1=L+ △ L1, when making above-mentioned distance continue to increase △ L2, make distance L2=L+ △ L2 after changing
When, record measurement voltage。
Attached drawing 5 is the vectogram of induced voltage and emission current, and as shown in Fig. 5, the variation of voltage vector and electric current hang down
Directly.In Fig. 5,Measured inductive voltage value when distance is L1 between transmitting coil Tx and receiving coil (Coil0), to
AmountMeasured inductive voltage value, vector when distance is L2 between transmitting coil Tx and receiving coil (Coil0)For institute
The vector differentials of two induced voltages measured.Current vector is, and and voltage vectorVertically, actually measured electric current
VectorWith real current vectorBetween there are vector differences, i.e.,, then, according to
The formula can be in the hope of, then basis, actually measured current value can be modified, and according to following public affairs
Formula (7) is surveyed the apparent conductivity of (reality):
... (7)
WhereinFor the induced voltage vector of actually measured receiving coil, K is instrumental constant, ItFor real current,
For apparent conductivity, IaFor measured current,For the vector angle of measured current and real current,For the real part of apparent conductivity,For the imaginary part of apparent conductivity.
Specific amendment step is as follows:
A. in the present embodiment, if the initial distance between receiving coil (Coil0) and transmitting coil Tx is L1, herein
If L1=0.4 inch；
B. the transmitting signal from digital signal processing unit amplifies through power drive unit and after current transformer,
Emit the emission current of single-frequency, frequency 40kHz in transmitting coil；
C. the gain of pre-amplifier unit, AD conversion unit is demarcated, the purpose is to make current measurement channel
It is identical with the gain in channel of receiving coil (Coil0)；
D. the acquisition signal of record current Measurement channel and the channel receiving coil (Coil0) in measurement mode, it is then sharp
Two vectors are extracted with the method for Fourier transform, are denoted as current vector respectivelyAnd voltage vector；
E. the distance between receiving coil (Coil0) and transmitting coil are adjusted to L2, set L2=0.42 inch herein；
F. the work of b, c, d are repeated, and acquired current vector and voltage vector are denoted asWith；
G. after system is stablized, ordinary circumstance experimental record twiceWithVery little is differed, can be neglected in analysis；
H. it calculates separately, then using obtaining+ = It obtains(as shown in Fig. 5), thus to reality
The current value that border measures is modified, and the apparent conductivity of (reality) is surveyed according to above-mentioned formula (7).
After the above method is to current measurement calibration, the introduced error of current measurement link is eliminated, to make electricity
Flow measurement phase has degree of precision, is of great significance to the deviation positioning between instrument response and theoretical response.
By the description of embodiment of above, those skilled in the art are it is understood that without departing from the present invention
Spirit and scope in the case where, various changes and replacement can also be made to a specific embodiment of the invention.These change and
Replacement is all fallen within the scope of the invention as defined in the claims.
Claims (6)
1. a kind of phase calibration method of induction logging current measurement carries out induction logging to using array induction logging instrument
The error of current measurement caused by the minor change of the distance of transmitting coil and receiving coil is demarcated in the process, the battle array
Column induction logging instrument includes pre-amplifier unit, D/A conversion unit, which is characterized in that
The phase difference between current vector that the difference for the apparent conductivity vector that measurement obtains and actual measurement are obtained is as electric current
The correction amount of measurement phase is modified measured current, thus to obtain the apparent conductivity of actual measurement, comprising:
(1) the step of setting the initial distance between receiving coil and transmitting coil；
(2) current vector and voltage vector extraction step, from being mentioned in the acquisition signal in current measurement channel and receiving coil channel
Two vectors are taken, are denoted as current vector and voltage vector respectively；
(3) the distance between the receiving coil and the transmitting coil are adjusted, and repeats the current vector and voltage
The step of vector extraction step, the extraction of progress current vector and voltage vector；
(4) electric current correction amount determines step, according to current vector and voltage vector acquired in step (3), determines current value
Correction amount；
(5) according to the correction amount of identified current value in step (4), the apparent conductivity of actual measurement is obtained according to following formula (7),
……(7)
WhereinFor the induced voltage vector of the receiving coil of actual measurement, K is instrumental constant, ItFor real current,To regard conductance
Rate, IaFor measured current,For the vector angle of measured current and real current,For the real part of apparent conductivity,For view electricity
The imaginary part of conductance.
2. the phase calibration method of induction logging current measurement as described in claim 1, which is characterized in that the electric current to
Amount and voltage vector extraction step include the following steps:
Emit the emission current of single-frequency in transmitting coil；
The gain of the pre-amplifier unit and the D/A conversion unit is demarcated, so that current measurement channel and described
The gain in the channel of receiving coil is identical；
In measurement mode after record current Measurement channel and the acquisition signal in receiving coil channel, the method for Fourier transform is utilized
Two vectors are extracted, and are denoted as current vector and voltage vector respectively.
3. the phase calibration method of induction logging current measurement as claimed in claim 1 or 2, which is characterized in that described
Electric current correction amount determines in step, after system is stablized, determines measured current according to acquired current vector and voltage vector
With the vector angle of real current, thus actually measured current value is modified.
4. the phase calibration method of induction logging current measurement as claimed in claim 2, which is characterized in that the single-frequency
The frequency of emission current is 40kHz.
5. the phase calibration method of induction logging current measurement as claimed in claim 2, which is characterized in that the single-frequency
The frequency of emission current is 40kHz.
6. the phase calibration method of induction logging current measurement as claimed in claim 1 or 2, which is characterized in that described to connect
Initial distance between take-up circle and transmitting coil is 0.4 inch, and distance adjusted is 0.42 inch.
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| CN106646636A (en) * | 2016-12-26 | 2017-05-10 | 中国石油天然气集团公司 | Method of calculating stratum true conductivity by using well axis electric field distribution |
| CN109581517B (en) * | 2018-12-11 | 2020-09-18 | 中国石油化工股份有限公司 | Method and device for calculating array induction apparent conductivity weight coefficient |
| CN109779621B (en) * | 2019-01-30 | 2022-05-13 | 北京工业大学 | Method and device for responding to logging of induction logging instrument |
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| US5781436A (en) * | 1996-07-26 | 1998-07-14 | Western Atlas International, Inc. | Method and apparatus for transverse electromagnetic induction well logging |
| US5884227A (en) * | 1997-04-01 | 1999-03-16 | Western Atlas International, Inc. | Method for interpreting induction logs in high resistivity contrast earth formations |
| US6044325A (en) * | 1998-03-17 | 2000-03-28 | Western Atlas International, Inc. | Conductivity anisotropy estimation method for inversion processing of measurements made by a transverse electromagnetic induction logging instrument |
| CN1185508C (en) * | 2000-07-07 | 2005-01-19 | 石油大学(北京) | Electromagnetic wave logging method without skin effect |
| CN101231267B (en) * | 2008-01-31 | 2010-12-22 | 华南理工大学 | Polyphase eddy detection system |
| CN101397907B (en) * | 2008-10-20 | 2012-12-26 | 中国海洋石油总公司 | Method and apparatus for eliminating directly coupling signal of induction logging tool |
| CN102678106B (en) * | 2012-05-02 | 2015-04-01 | 中国电子科技集团公司第二十二研究所 | Data processing method for LWD (Logging While Drilling) electromagnetic wave resistivity logging instrument |
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