CN1329626C - Well logging method and instrument based on HF array electromagnetic wave propagation - Google Patents

Abstract

The present invention discloses a well logging method and a logging instrument by HF array electromagnetic wave propagation. The logging instrument of the present invention comprises a coil array, a transmitter, a receiver, a measuring circuit, and an output and communication circuit, wherein 3 to 5 groups of coils are arranged in the coil array of the logging instrument; the operating frequency and the electrode spacing of each group of coil is set according to the condition of the monotonic variation of a resistivity curve of detection depth, and the condition is obtained by that detected phase difference signals and amplitude ratio signals are converted. In each period, the transmitter transmits high frequency electromagnetic waves in different work frequencies via a transmitting coil; the measuring circuit analyzes phase difference and amplitude ratio of received electromagnetic waves received by the receiver via a receiving coil to obtain 2 to 5 groups of phase difference signals and 1 to 3 groups of amplitude ratio signals, and the corresponding resistivity curve of the monotonic variation of detection depth is obtained bysolution. The present invention adopts a relative low frequency, and simultaneously increases the detection depth of the logging instrument while maintaining the longitudinal laminating capacity.

Description

The method and the logging instrument thereof of HF array electromagnetic wave propagation well logging

Technical field

The present invention relates in oil well logging, determine the method for the resistivity on stratum, relate in particular to the method that adopts HF array electromagnetic wave propagation to log well.

Background technology

Introduce the theoretical foundation of HF array electromagnetic wave propagation well logging earlier.In transmitting coil, pass to alternating current.When coil dimension is very little, can regard a point-like magnetic dipole as, its dipole moment changes by following rule in time:

M＝M ₀e ^-iωt (1)

In the formula: M ₀=I ₀S _tN _tI ₀Be current strength; S _tBe the transmitting coil area; N _tBe the transmitting coil number of turn.

The electromagnetic field that magnetic dipole forms can be described with the Maxwell equation:

$\▿\×\stackrel{\→}{H}=\mathrm{\σ}\stackrel{\→}{E}-\mathrm{i\ω\ϵ}\stackrel{\→}{E}$

$\▿\×\stackrel{\→}{E}=\mathrm{i\ω\μ}\stackrel{\→}{H}---\left(2\right)$

$\▿\·\stackrel{\→}{E}=0$

$\▿\·\stackrel{\→}{H}=0$

In the formula:

Magnetic field intensity;

Expression electric-field intensity; σ is the dielectric conductance rate; μ is a dielectric permeability; ε is the dielectric constant of medium.By the electrodynamics computing of knowing, can obtain on the axis of magnetic dipole apart from field source is the field at Z place:

E _φ＝0

H ₉＝0

$\mathrm{Hz}=\frac{{\mathrm{<figure-callout\; id="0"\; label="M"\; filenames="C20051010500900211.png,C20051010500900221.png"\; state="\{\{state\}\}">M</figure-callout>}}_0}{2\mathrm{\&pi;}{Z}^3}(1+\mathrm{ikz})\&CenterDot;e^{i(\mathrm{\&omega;t}-\mathrm{kz})}---\left(3\right)$

$=\frac{{\mathrm{<figure-callout\; id="0"\; label="M"\; filenames="C20051010500900211.png,C20051010500900221.png"\; state="\{\{state\}\}">M</figure-callout>}}_0}{2\mathrm{\&pi;}{Z}^3}(1+\mathrm{bz}+\mathrm{iaz})\&CenterDot;e^{-\mathrm{bz}}\&CenterDot;e^{i(\mathrm{\&omega;t}-\mathrm{az})}$

In the formula: k=a+ib is called the wave number of medium.

$a=\sqrt{\frac{\mathrm{\&mu;\&omega;\&sigma;}}{2}}{[\sqrt{1+{\left(\frac{\mathrm{\&omega;\&epsiv;}}{\mathrm{\&sigma;}}\right)}^2}+\frac{\mathrm{\&omega;\&epsiv;}}{\mathrm{\&sigma;}}]}^{\frac{1}{2}}---\left(4\right)$

$b=\sqrt{\frac{\mathrm{\&mu;\&omega;\&sigma;}}{2}}{[\sqrt{1+{\left(\frac{\mathrm{\&omega;\&epsiv;}}{\mathrm{\&sigma;}}\right)}^2}-\frac{\mathrm{\&omega;\&epsiv;}}{\mathrm{\&sigma;}}]}^{\frac{1}{2}}---\left(5\right)$

A is a phase constant, and b is an attenuation factor.

When ω ε/σ＞＞1, when promptly the displacement electric current is preponderated, have:

$a=\mathrm{\&omega;}\sqrt{\mathrm{\&mu;\&epsiv;}}---\left(6\right)$

In the formula: ε=ε ^*ε ₀, wherein: ε ^*Be relative dielectric constant; ε ₀=10 ^-9/ 36 π (farad/rice) are the dielectric constant of vacuum;

In non-magnetic conductive media, μ=μ ₀=4 π * 10 ^-7(Henry/rice) is the permeability in the vacuum.So, $a=\frac{\mathrm{\&omega;}}{c}\sqrt{{\mathrm{\&epsiv;}}^{*}}---\left(7\right)$

In the formula: c=3 * 10 ⁸Meter per second is the light velocity in the vacuum.

Correspondingly, $b=\frac{\mathrm{\&sigma;}}{2}\sqrt{\frac{\mathrm{\&mu;}}{\mathrm{\&epsiv;}}}=188\frac{\mathrm{\&sigma;}}{\sqrt{{\mathrm{\&epsiv;}}^{*}}}---\left(8\right)$

That is: when displacement current was preponderated, a and electricity were led irrelevant; B and field frequency are irrelevant.

When ω ε/σ＜＜1, when promptly conductive electric current is preponderated, have:

$a=b=\sqrt{\frac{\mathrm{\&omega;\&mu;\&sigma;}}{2}}=\sqrt{\mathrm{\&pi;f\&mu;\&sigma;}}---\left(9\right)$

Be that phase constant is all only relevant with electrical conductivity with attenuation factor, and irrelevant with dielectric constant.Notice that (3) formula is a plural form, can be write as the expression formula of amplitude and phase place:

$\left|\mathrm{Hz}\right|=\frac{{\mathrm{<figure-callout\; id="0"\; label="M"\; filenames="C20051010500900211.png,C20051010500900221.png"\; state="\{\{state\}\}">M</figure-callout>}}_0}{2\mathrm{\&pi;}{Z}^3}{e}^{-\mathrm{bz}}\sqrt{{(1+\mathrm{bz})}^2+{\left(\mathrm{az}\right)}^2}---\left(10\right)$

$\mathrm{\&phi;}=\mathrm{az}-\mathrm{arctg}\frac{\mathrm{az}}{1+\mathrm{bz}}---\left(11\right)$

The relative value of measuring amplitude or phase place is often more favourable in practice.Therefore in well logging, adopt the three-winding system of single transmit double reception more, or the single three-winding system that receives of two emission.In three-winding system, the amplitude ratio of two receiving coils:

$S=\left|\frac{{\mathrm{<figure-callout\; id="1"\; label="Hz"\; filenames="C20051010500900211.png,C20051010500900221.png"\; state="\{\{state\}\}">Hz</figure-callout>}}_1}{{\mathrm{<figure-callout\; id="2"\; label="Hz"\; filenames="C20051010500900191.png,C20051010500900211.png"\; state="\{\{state\}\}">Hz</figure-callout>}}_2}\right|={\left(\frac{z_2}{z_1}\right)}^3{e}^{-\mathrm{b\&Delta;z}}\sqrt{\frac{{(1+{\mathrm{bz}}_1)}^2+{\left({\mathrm{az}}_1\right)}^2}{{(1+{\mathrm{bz}}_2)}^2+{\left(a{z}_2\right)}^2}}---\left(12\right)$

Phase difference $\mathrm{\&Delta;\&phi;}=\mathrm{a\&Delta;z}-\mathrm{arctg}\frac{\mathrm{a\&Delta;<figure-callout\; id="1"\; label="z"\; filenames="C20051010500900211.png,C20051010500900221.png"\; state="\{\{state\}\}">z</figure-callout>}}{1+b(z_1+z_2)+(a^2+b^2)z_1*z_2}---\left(13\right)$

In the formula, z ₁And z ₂Be respectively reception far away and the near line circle spacing to transmitting coil, Δ z is two spacings between the receiving coil.

Above-mentioned (12), (13), (4), (5) formula are the fundamental formular of HF array electromagnetic wave logging method.

Therefore, electromagnetic wave is propagated in the stratum, and its amplitude and phase place can change, these variations relevant with ε with the electrical quantity σ on stratum (main relevant with σ below several megahertzes).By the variation of measuring amplitude and phase place, can find the solution the electrical conductivity and the dielectric constant on stratum.

Owing to electromagnetic investigation depth is along with the reduction of frequency and the increase of electrode spacing increase, by reasonable arrangement electrode spacing and frequency, can obtain the upwards investigation depth of monotone variation of footpath, thus the radial section of layer resistivity definitely.

For the survey meter that the reflects well formation properties of different depth upwards directly, generally adopt two or more operating frequencies.For f and two source frequencies of f ', as long as select z ₁, Δ z and z ₁', Δ z ₁' satisfy condition: a Δ z=a ' Δ z ', az ₁=a ' z ₁' (14)

Promptly $\frac{\sqrt{f}}{\sqrt{f^{\&prime;}}}=\frac{{\mathrm{\&Delta;z}}^{\&prime;}}{\mathrm{\&Delta;z}}=\frac{{z_1}^{\&prime;}}{z_1}---\left(15\right)$

At this moment, two source frequencies of f and f ' measured phase difference φ in uniform dielectric is identical.Parameter conditions such as Here it is.If a plurality of operating frequencies that we select all satisfy the condition of (15) formula, then many measured phase difference curves overlap mutually in even infinitely great medium.

From (15) formula as can be seen, the evolution and the spacing of frequency are inversely proportional to.We know that frequency is high more, and electrode spacing is more little, survey shallow more; Frequency is low more, and electrode spacing is big more, surveys just dark more.That is to say that when choosing different frequency and electrode spacing, each bar phase difference curve investigation depth diametrically is different.When the stratum had mud to invade, radially resistivity distribution was inhomogeneous, and the phase difference curve can separate.By the separation or the coincidence of phase difference curve, just can divide permeable formation and impervious bed intuitively, the identification reservoir.By two dimensional inversion interpretation software radially, can obtain the radially resistivity distribution of flushed zone-intermediate zone-undisturbed formation.

Based on above-mentioned theory, the parameter logging instrument VIKKKIZ such as high-frequency induction of Russia's development use 5 transmitting coils and 6 receiving coils, operating frequency is 0.875MHz, 1.75MHz, 3.5MHz, 7MHz and 14MHz, measure the phase difference that the electromagnetic wave of 5 kinds of frequencies is propagated in the stratum, obtain parameter phase difference curves such as 5.2.0 meters of its electrode system length; The maximum probe radius is 1.0 meters under the 5Ohm-m situation, be 1.6 meters under the 50Ohm-m situation; Its investigation depth has 30,50,75,115,5 kinds of 165cm, and vertical resolution is 30cm.

This instrument vertical resolution height can be discerned short lap and determine its actual thickness in section.Invade the stratum and can differentiate radially non-homogeneity and relevant parameter is provided having, can judge the low-resistance endless belt in forward position, invaded zone.But it has following limitation and deficiency:

1) investigation depth deficiency, on the whole, phase measurement has vertical resolution preferably, has relatively poor investigation depth simultaneously.Although it is not enough that the curve that VIKIZ can provide 5 footpaths to make progress different investigation depths, its investigation depth of all things considered are still disliked.

2) selection of instrument parameter is restricted, and owing to parameter designing such as employings, has limited the condition of choosing of operating frequency.Particularly instrument selection the such high frequency of 14MHz.And under high like this frequency, the influence of dielectric constant can not be ignored.

3) waste of information resources, instrument adopts 5 operating frequencies, only measures 5 phase difference curves, and many useful informations have been left in the basket.In addition, the amplitude of received signal or relative amplitude can provide more deep penetrating information, and it also is unfortunate that these information are left in the basket.

In addition, this method also has shortcomings such as the coil array design is restricted, electronic circuit is complicated.

Summary of the invention

The technical problem to be solved in the present invention provides a kind of method of HF array electromagnetic wave propagation well logging, adopts relatively low frequency, and can increase the investigation depth of instrument when keeping longitudinal layered ability.The present invention also will provide a kind of logging instrument of realizing this method.

In order to solve the problems of the technologies described above, the invention provides a kind of HF array electromagnetic wave propagation logging method, may further comprise the steps:

(a) 3～5 groups of single-emission and double-receivings or two bill take-up circle are set in the coil array of logging instrument, and, the operating frequency and the electrode spacing of every group of coil is set according to the condition of investigation depth monotone variation under various formation conditions of the resistivity curve that detected phase difference and amplitude are converted to than signal;

(b) in each cycle, emitter is launched the frequency electromagnetic waves of operating frequency separately by each transmitting coil, and receiver receives these electromagnetic waves by the receiving coil of correspondence;

(c) electromagnetic wave that receiving coil is received carries out phase difference analysis and amplitude than analyzing, and the amplitude that obtains 2～5 groups phase signal and 1～3 group is found the solution the resistivity curve that obtains corresponding investigation depth monotone variation again than signal.

Further, above-mentioned logging method also can have following characteristics: described step (a) is provided with four groups of coils, and first group of coil adopts first operating frequency, and electrode spacing is short; Second group of coil adopts first operating frequency, but electrode spacing is longer; The 3rd group of coil electrode apart from second group of difference less than 0.3m, but adopt second operating frequency lower than first operating frequency, the 4th group of coil adopts second operating frequency, and electrode spacing is the longest, in the described step (c), be to analyze the phase signal that obtains described four groups of coil received signals, and the amplitude of the received signal of the 3rd group and/or the 4th group coil compare signal.

Further, above-mentioned logging method also can have following characteristics: described first group of coil electrode is apart from being 0.4～0.6m, and second group of coil electrode is apart from being 0.9～1.1m, and the 3rd group of coil electrode is apart from being 1.0～1.3m, and the 4th group of coil electrode distance is 1.5～1.8m; Described first operating frequency is 0.2MHz～1.5MHz, and described second operating frequency is 1.5MHz～10MHz.

Further, above-mentioned logging method also can have following characteristics: described step (a) is provided with five groups of coils, and first group of coil adopts first operating frequency and first electrode spacing; Second group of coil adopts first operating frequency and greater than second electrode spacing of first electrode spacing; The 3rd group of coil electrode apart from second group of difference less than 0.3m, but adopt second operating frequency lower than first operating frequency, the 4th group of coil adopts second operating frequency and greater than the third electrode distance of second electrode spacing, the 5th group of coil adopts the 3rd operating frequency that is lower than second operating frequency, and greater than the third electrode distance of second electrode spacing; And, in the described step (c), be to analyze the phase signal that obtains described five groups of coil received signals, and the amplitude of the received signal of the 4th group and/or the 5th group coil compares signal.

Further, above-mentioned logging method also can have following characteristics: described first electrode spacing is 0.35～0.55m, and described second electrode spacing is 0.75～0.95m; Described third electrode is apart from being 0.85～1.15m, and described the 4th electrode spacing is 1.45～1.75m, and described the 5th electrode spacing is 1.85～2.15m; Described first operating frequency is 3MHz～10MHz, and described second operating frequency is 1MHz～3MHz, and described the 3rd operating frequency is 0.2MHz～1MHz.

HF array electromagnetic wave propagation logging instrument provided by the invention comprises coil array, emitter, receiver, measuring circuit, and output and communicating circuit, it is characterized in that, described coil array comprises 3～5 groups of single-emission and double-receivings or two bill take-up circle, described emitter produces the frequency electromagnetic waves of 2～3 different frequencies by described coil array, the high-frequency signal analysis that described measuring circuit receives for each group coil array obtains 2～5 groups of phase signals and 1～3 group of amplitude compares signal, described output and communicating circuit are used to export to be analyzed the phase signal and the amplitude that obtain and compares signal, and, the investigation depth monotone variation under various formation conditions that is arranged so that the resistivity curve that detected phase difference and amplitude are converted to than signal of the operating frequency of described every group of coil and electrode spacing.

Further, above-mentioned logging instrument also can have following characteristics: described coil array comprises four groups of coils: first group of coil adopts first operating frequency, and electrode spacing is short; Second group of coil adopts first operating frequency, but electrode spacing is longer; The 3rd group of coil electrode apart from second group of difference less than 0.3m, but adopt second operating frequency lower than first operating frequency, the 4th group of coil adopts second operating frequency, and electrode spacing is the longest, and, described measuring circuit is not only measured the phase difference of these four groups of coil received signals, and the received signal of the 3rd group and the 4th group coil is wherein also measured its amplitude ratio.

Further, above-mentioned logging instrument also can have following characteristics: described first operating frequency is 1.5MHz～10MHz, and described second operating frequency is 0.2MHz～1.5MHz.

Further, above-mentioned logging instrument also can have following characteristics: described first group of coil electrode distance is 0.4～0.6m; Second group of coil electrode distance is 0.9～1.1m; The 3rd group of coil electrode is apart from being 1.0～1.3m, and the 4th group of coil electrode distance is 1.5～1.8m.

Further, above-mentioned logging instrument also can have following characteristics: described coil array comprises five groups of coils: first group of coil adopts first operating frequency and first electrode spacing; Second group of coil adopts first operating frequency and greater than second electrode spacing of first electrode spacing; The 3rd group of coil electrode apart from second group of difference less than 0.3m, but adopt second operating frequency lower than first operating frequency, the 4th group of coil adopts second operating frequency and greater than the third electrode distance of second electrode spacing, the 5th group of coil adopts the 3rd operating frequency that is lower than second operating frequency, and greater than the third electrode distance of second electrode spacing, and, described measuring circuit is not only measured the phase difference of these five groups of coil received signals, and the received signal of the 4th group and the 5th group coil is wherein also measured its amplitude ratio.

Further, above-mentioned logging instrument also can have following characteristics: described first operating frequency is 3MHz-10MHz, and described second operating frequency is 1MHz～3MHz, and described the 3rd operating frequency is 0.2MHz～1MHz.

Further, above-mentioned logging instrument also can have following characteristics: described first electrode spacing is 0.35～0.55m, and described second electrode spacing is 0.75～0.95m; Described third electrode is apart from being 0.85～1.15m, and described the 4th electrode spacing is 1.45～1.75m, and described the 5th electrode spacing is 1.85～2.15m.

Further, above-mentioned logging instrument also can have following characteristics: described respectively the group in the coil, the distance between two receiving coils or two transmitting coils is 0.05～0.4m.

As from the foregoing, adopt the inventive method, keeping the very strong longitudinal layered ability of VIKIZ instrument, increased the investigation depth of instrument simultaneously, this point is especially meaningful for the low-resistance stratum.Simultaneously, because only adopt two operating frequencies to measure four phase difference curves and two amplitudes, simplified the circuit design of apparatus structure and instrument greatly than curve.

Description of drawings

Figure 1A is the schematic diagram that first embodiment of the invention adopts the logging instrument of 2 operating frequencies.

Figure 1B is the schematic diagram that second embodiment of the invention adopts the logging instrument of 3 operating frequencies.

Fig. 2 is the vertical characteristics curve map of 6 resistivity curves obtaining of the first embodiment method.

Fig. 3 is the radially derivative characteristic curve map of 6 resistivity curves obtaining of the first embodiment method.

Fig. 4 is the radially integral characteristic curve map of 6 resistivity curves obtaining of the first embodiment method.

Fig. 5 A～Fig. 5 C is respectively that second embodiment adopts 7 resistivity curves that 3 operating frequencies obtain at vertical feature on 5 Ω .M stratum, the radially derivative characteristic and the curve map of integral characteristic radially.

Fig. 6 A～Fig. 6 C is to be respectively that second embodiment adopts 7 resistivity curves that 3 operating frequencies obtain at vertical feature on 50 Ω .M stratum, the radially derivative characteristic and the curve map of integral characteristic radially.

The specific embodiment

In the present invention, adopt phase difference and amplitude to do data interpretation than the resistivity curve that curve is converted to, thereby the parameter condition such as can satisfy, as long as the resistivity curve radial depth of investigetion after the conversion is a monotone variation, and cover suitable scope, just can pass through radially two dimensional inversion interpretation software, obtain the radially resistivity distribution of flushed zone-intermediate zone-undisturbed formation.

The present invention is described further below in conjunction with drawings and Examples.

First embodiment

The mid portion of the double frequency array electromagnetic wave logging instrument of present embodiment is mounted in the coil array on the glass fiber reinforced plastic skeleton, and there is the glass reinforced plastic pipe pressure-bearing outside, goes to allow electromagnetic wave to be transmitted in the stratum through glass reinforced plastic pipe.The two ends of coil array are outer steel shell, in emitter, receiver, measuring circuit, output and communicating circuit etc. are housed.

Fig. 1 shows the structure of present embodiment coil array, as shown in the figure, comprises 2 transmitting coil T1, T2 and 8 receiving coil R1～R8 of arranging point-blank, has formed the coil of four groups of single-emission and double-receivings, and the electrode system length of whole probe is 1.8 meters.Wherein:

First group of coil is made up of transmitting coil T2 and receiving coil R7, R8, operating frequency is 6.4MHz, electrode spacing is 0.5 meter (distance that all refers to transmitting coil to two a receiving coil mid point, when adopting two bills to receive structure, then refer to the distance of two transmitting coil mid points) to receiving coil, the receiving coil spacing is 0.1 meter, and this group coil is used to measure the phase difference F05 of frequency electromagnetic waves.

Second group of coil is made up of transmitting coil T2 and receiving coil R3, R4, and operating frequency is 6.4MHz, and electrode spacing is 1.0 meters, and the receiving coil spacing is 0.1 meter, and this group coil is used to measure the phase difference F10 of frequency electromagnetic waves.

The 3rd group of coil is made up of transmitting coil T1 and receiving coil R5, R6, and operating frequency is 0.8MHz, and electrode spacing is 1.1 meters, and the receiving coil spacing is 0.3 meter, and this group coil is gone back measuring amplitude and compared S11 except that the phase difference F11 that measures frequency electromagnetic waves.

The 4th group of coil is made up of transmitting coil T1 and receiving coil R1, R2, and operating frequency is 0.8MHz, and electrode spacing is 1.65 meters, and the receiving coil spacing is 0.3 meter, and this group coil is gone back measuring amplitude and compared S16 except that the phase difference F16 that measures frequency electromagnetic waves.

Emitter can excite the high-frequency electromagnetic vibration successively in one group of transmitting coil T1, T2, frequency of oscillation is respectively 0.8MHz and 6.4MHz.Each emission of T1 and T2 once is an one-period, and one-period is 0.1 second.

Receiver and measuring circuit are used to receive the signal that 8 group of received coil R1-R8 receive, it is converted to intermediate-freuqncy signal, measure the phase signal of 4 group of received coil R1-R2, R3-R4, R5-R6, R7-R8 and wherein the amplitude of two group of received coil R1-R2, R5-R6 then these signals of representing formation resistivity are transferred to output and communicating circuit than signal.

Output and communicating circuit are used to receive the control command on ground, and measurement result is transported to floor treatment in certain sequence.

Correspondingly, the flow process of present embodiment logging method may further comprise the steps:

Step 1 is provided with 4 groups of coils in the coil array of survey meter, adopt 2 operating frequencies, measures 4 groups of phase signals respectively, and two groups of coils are measured 2 groups of amplitudes than signal therein, and by the agency of above the concrete configuration of coil array no longer repeats here;

Step 2, in each cycle, emitter is launched the electromagnetic wave that a secondary frequencies is 0.8MHz and 6.4MHz respectively by coil T1 and T2, receiver is by coil R1 and R2, R5 and R6 receive the electromagnetic wave of 0.8MHz, coil R3 and R4, and R7 and R8 receive the electromagnetic wave of 6.4MHz;

Step 3, the electromagnetic wave that every group of received coil is received carries out phase analysis, and the electromagnetic wave that two groups of coils of R1-R2, R5-R6 are received also carries out amplitude analysis, obtains the phase signal of 4 group of received coils and the amplitude of two group of received coils and compares signal;

Step 4 is found the solution the resistivity curve that obtain 6 corresponding different investigation depths according to formula (12) with (13) than signal with 2 groups of amplitudes to 4 groups of phase differences that obtain, and carries out subsequent analysis again.

When floor treatment, to 6 resistivity curves, further inverting obtains vertical multilayer, the resistivity distribution image of 4 picture dots (being divided into well mud, flushed zone, intermediate zone and undisturbed formation) radially, inversion result can provide with the form of tables of data or curve map, also can provide with the cutaway perspective form based on the data fields imaging technique.

Fig. 2 shows the vertical characteristics of 6 resistivity curves that detection obtains under 5 Ω-m situation, the vertical resolution that can reflect curve, in measurement, in order to determine the border on stratum, a curve that vertical resolution is good will be arranged at least, and the curve of other vertical resolution difference can obtain the longitudinal frame coupling by iterating.As can be seen from Figure, it is sensitive to locate response corresponding to the resistivity curve of phase difference F05 that measures and F10 at survey mark (i.e. 0 point), has good vertical resolution, is 0.3 meter.

Fig. 3 shows the radially derivative characteristic of 6 resistivity curves that detection obtains under 50 Ω-m situation, this curve is as can be seen on the sagittal plane of well, each cell rings is to the contribution of measuring-signal, as can be seen, for F05, cell rings contribution nearby is bigger, and for S16, cell rings contribution nearby is less.

Fig. 4 shows the radially integral characteristic of 6 resistivity curves that detection obtains under 50 Ω-m situation, in general, is 0.5 with ordinate on the curve, and promptly the pairing abscissa of point of half range value promptly apart from the distance radially of well, is defined as its investigation depth.As can be seen from the figure, corresponding to phase difference F05, F10, F11, F16 and amplitude investigation depth monotone variation, be respectively 30,60,100,150,250,300cm than 6 resistivity curves of S11, S16.

The radius of investigation of the logger of present embodiment is 1.6 meters (the darkest curves) under the 5Ohm-m situation, under the 50Ohm-m situation is 3.0 meters.And investigation depth can be divided into 30,60,100,150,250, and 300cm6 kind, vertical resolution are 30cm.KIZ compares with VI, under the situation on same stratum, has bigger investigation depth, and electrode spacing is also little.

As can be seen from the above analysis, present embodiment is when the design of coil array, owing to made full use of the useful information of amplitude ratio, adopt 4 groups of coils just to obtain the resistivity curve of 6 investigation depth monotone variation, and its investigation depth (when 50 Ω-m is 300cm, when 5 Ω-m is 160cm) the logging instrument VI KIZ (165cm) of 5 phase difference curves of measurement of mentioning in greater than background technology, particularly to the low-resistance stratum, investigation depth can be significantly increased when introducing amplitude measurement.Simultaneously, this logging instrument also has less electrode spacing (1.8m) and good vertical resolution (30cm).In addition, because operating frequency is less and the parameter condition such as need not to satisfy, relatively low (6.4MHz) that its high frequency and VIKIZ (14MHz) relatively can be provided with avoided the adverse effect of dielectric constant to measurement.

The present invention is not limited to the configuration parameter of the foregoing description coil array, but when the frequency of coil and electrode spacing are respectively organized in design, under different formation conditions, each investigation depth of organizing coil needs monotone variation, can be effectively there be the stratum of intrusion to differentiate radially non-homogeneity and relevant parameter is being provided, and the low-resistance endless belt etc. of judging the forward position, invaded zone.In order to satisfy this condition, being provided with of coil array of the present invention need be satisfied certain condition.

The analysis showed that coil array frequency, electrode spacing and its investigation depth, vertical resolution have substantial connection, operating frequency is high more, surveys shallowly more, and layering is good more; Electrode spacing is short more, surveys shallow more; And under same electrode spacing and frequency condition, the investigation depth of amplitude ratio is darker than phase difference.Therefore, the present invention can be provided with when four groups of coils are set by the following method, first group of operating frequency height, and electrode spacing is short, the preferable 0.4～0.6m that gets; Second group of operating frequency is identical with first group, but electrode spacing is longer, the preferable 0.9～1.1m that gets; The 3rd group of electrode spacing similar to second group (difference is less than 0.3 meter), the preferable 1.0～1.3m that gets, but operating frequency is low, and the 4th group of operating frequency is the same with the 3rd group, and electrode spacing is the longest, the preferable 1.5～1.8m that gets.These four groups of coils are measure phase difference all, the 3rd group and fourth stage measuring amplitude ratio also wherein, and each spacing of organizing between the coil receiving coil is 0.05～0.4 meter.Like this, just can guarantee that first group to the 4th group phase difference, the 3rd group of amplitude are monotone variation than, the 4th group of amplitude than the investigation depth of the resistivity curve that obtains.

Being provided with of frequency, require frequency enough high, not so amplitude is very littler than, phase difference value, detection difficult, and frequency when too high dielectric constant measurement result is had adverse effect, investigation depth also can descend.In general, when present embodiment was provided with 2 frequencies, the range of choice of low frequency can be 0.2MHz～1.5MHz, and the range of choice of high frequency can be 1.5MHz～10MHz.

Second embodiment

According to top analysis, in Figure 1B, provided the coil array structure of another embodiment logging instrument that adopts 3 operating frequencies, comprise point-blank 3 transmitting coil T1, T2 and T3 and 10 receiving coil R1～R10 of arranging, the coil of having formed 5 groups of single-emission and double-receivings, the electrode system length of whole probe is 2.15 meters.Wherein:

First group of coil is made up of transmitting coil T3 and receiving coil R9, R10, and operating frequency is 6.4MHz, and electrode spacing is 0.45 meter, and the receiving coil spacing is 0.1 meter, and this group coil is used to measure the phase difference Y1 of frequency electromagnetic waves.

Second group of coil is made up of transmitting coil T3 and receiving coil R5, R6, and operating frequency is 6.4MHz, and electrode spacing is 0.85 meter, and the receiving coil spacing is 0.1 meter, and this group coil is used to measure the phase difference Y2 of frequency electromagnetic waves.

The 3rd group of coil is made up of transmitting coil T2 and receiving coil R7, R8, and operating frequency is 1.6MHz, and electrode spacing is 1.0 meters, and the receiving coil spacing is 0.2 meter, and this group coil is used to measure the phase difference Y3 of frequency electromagnetic waves.

The 4th group of coil is made up of transmitting coil T2 and receiving coil R3, R4, and operating frequency is 1.6MHz, and electrode spacing is 1.6 meters, and the receiving coil spacing is 0.2 meter, and this group coil is gone back measuring amplitude and compared Y4S except that the phase difference Y4 that measures frequency electromagnetic waves.

The 5th group of coil is made up of transmitting coil T1 and receiving coil R1, R2, and operating frequency is 0.8MHz, and electrode spacing is 2 meters, and the receiving coil spacing is 0.3 meter, and this group coil is gone back measuring amplitude and compared Y5S except that the phase difference Y5 that measures frequency electromagnetic waves.

Logging instrument 5 phase difference curves of measurement of 3 operating frequencies of present embodiment employing and 2 amplitudes are convertible into the resistivity curve of 7 different investigation depths then than curve.Fig. 5 A～Fig. 5 C has provided 7 resistivity curves at vertical feature on 5 Ω .M stratum, the radially derivative characteristic and the curve map of integral characteristic radially.Fig. 6 A～Fig. 6 C has provided 7 resistivity curves at vertical feature on 50 Ω .M stratum, the radially derivative characteristic and the curve map of integral characteristic radially.As can be seen from the figure, the logging instrument of present embodiment is by introducing amplitude measurement, and investigation depth obviously increases, and also has good vertical resolution now.

According to the analysis same with first embodiment, the present invention can be provided with when five groups of coils are set by the following method, first group of operating frequency height, and electrode spacing is short, the preferable 0.35～0.55m that gets; Second group of operating frequency is identical with first group, but electrode spacing is longer, the preferable 0.75～0.95m that gets; The 3rd group of electrode spacing similar to second group (difference is less than 0.3 meter), the preferable 0.85～1.15m that gets, but operating frequency is low; The 4th group of operating frequency is the same with the 3rd group, and electrode spacing is longer, the preferable 1.45～1.75m that gets; The 5th group of operating frequency is minimum, and electrode spacing is the longest, the preferable 1.85～2.15m that gets.These five groups of coils are measure phase difference all, the 4th group and the 5th group measuring amplitude ratio also wherein, and each spacing of organizing between the coil receiving coil is 0.05～0.4 meter.Like this, just can guarantee that first group to the 5th group phase difference, the 4th group of amplitude are monotone variation than, the 5th group of amplitude than the investigation depth of the resistivity curve that signal is converted to.

When 3 frequencies were set, low frequency can be selected 0.2Hz～1MHz, and intermediate frequency can be selected 1MHz～3MHz, and high frequency can be selected 3MHz～10MHz.

In sum, the parameter designing such as a kind of new non-of the present invention by coil array is proposed makes survey meter have better investigation depth, good vertical resolution, structure is simple relatively simultaneously, and electrode spacing is little, is specially adapted to determine in the oil well logging of open hole well the resistivity on stratum.

Should be noted that the present invention can also have many conversion scheme, at other embodiment, can detect 5～7 resistivity curves, wherein 1～3 can obtain by the measuring amplitude ratio, and other obtains with phase difference.And, preferable 3～5 groups of coils are set being provided with of coil array, detect required phase difference or amplitude ratio.In addition, coil array of the present invention also can change two bills into by single-emission and double-receiving and receive, and both are reciprocal, and other design all is the same.

Claims (13)

1, a kind of HF array electromagnetic wave propagation logging instrument, comprise coil array, emitter, receiver, measuring circuit, and output and communicating circuit, it is characterized in that, described coil array comprises 3～5 groups of single-emission and double-receivings or two bill take-up circle, described emitter produces the frequency electromagnetic waves of 2～3 different frequencies by described coil array, the high-frequency signal analysis that described measuring circuit receives for each group coil array obtains 2～5 groups of phase signals and 1～3 group of amplitude compares signal, described output and communicating circuit are used to export to be analyzed the phase signal and the amplitude that obtain and compares signal, and, the investigation depth monotone variation under various formation conditions that is arranged so that the resistivity curve that detected phase difference and amplitude are converted to than signal of the operating frequency of described every group of coil and electrode spacing.

2, logging instrument as claimed in claim 1 is characterized in that, described coil array comprises four groups of coils: first group of coil adopts first operating frequency, and electrode spacing is short; Second group of coil adopts first operating frequency, but electrode spacing is longer; The 3rd group of coil electrode apart from second group of difference less than 0.3m, but adopt second operating frequency lower than first operating frequency, the 4th group of coil adopts second operating frequency, and electrode spacing is the longest, and, described measuring circuit is not only measured the phase difference of these four groups of coil received signals, and the received signal of the 3rd group and the 4th group coil is wherein also measured its amplitude ratio.

3, logging instrument as claimed in claim 2 is characterized in that, described first operating frequency is 1.5MHz～10MHz, and described second operating frequency is 0.2MHz～1.5MHz.

4, logging instrument as claimed in claim 2 is characterized in that, described first group of coil electrode distance is 0.4～0.6m; Second group of coil electrode distance is 0.9～1.1m; The 3rd group of coil electrode is apart from being 1.0～1.3m, and the 4th group of coil electrode distance is 1.5～1.8m.

5, logging instrument as claimed in claim 1 is characterized in that, described coil array comprises five groups of coils: first group of coil adopts first operating frequency and first electrode spacing; Second group of coil adopts first operating frequency and greater than second electrode spacing of first electrode spacing; The 3rd group of coil electrode apart from second group of difference less than 0.3m, but adopt second operating frequency lower than first operating frequency, the 4th group of coil adopts second operating frequency and greater than the third electrode distance of second electrode spacing, the 5th group of coil adopts the 3rd operating frequency that is lower than second operating frequency, and greater than the third electrode distance of second electrode spacing, and, described measuring circuit is not only measured the phase difference of these five groups of coil received signals, and the received signal of the 4th group and the 5th group coil is wherein also measured its amplitude ratio.

6, logging instrument as claimed in claim 5 is characterized in that, described first operating frequency is 3MHz～10MHz, and described second operating frequency is 1MHz～3MHz, and described the 3rd operating frequency is 0.2MHz～1MHz.

7, logging instrument as claimed in claim 5 is characterized in that, described first electrode spacing is 0.35～0.55m, and described second electrode spacing is 0.75～0.95m; Described third electrode is apart from being 0.85～1.15m, and described the 4th electrode spacing is 1.45～1.75m, and described the 5th electrode spacing is 1.85～2.15m.

8, as claim 4 or 7 described logging instruments, it is characterized in that, described respectively the group in the coil, the distance between two receiving coils or two transmitting coils is 0.05～0.4m.

9, a kind of HF array electromagnetic wave propagation logging method may further comprise the steps:

(a) 3～5 groups of single-emission and double-receivings or two bill take-up circle are set in the coil array of logging instrument, and, the operating frequency and the electrode spacing of every group of coil is set according to the condition of investigation depth monotone variation under various formation conditions of the resistivity curve that detected phase difference and amplitude are converted to than signal;

(b) in each cycle, emitter is launched the frequency electromagnetic waves of operating frequency separately by each transmitting coil, and receiver receives these electromagnetic waves by the receiving coil of correspondence;

(c) electromagnetic wave that receiving coil is received carries out phase difference analysis and amplitude than analyzing, and the amplitude that obtains 2～5 groups phase signal and 1～3 group is found the solution the resistivity curve that obtains corresponding investigation depth monotone variation again than signal.

10, logging method as claimed in claim 9 is characterized in that, described step (a) is provided with four groups of coils, and first group of coil adopts first operating frequency, and electrode spacing is short; Second group of coil adopts first operating frequency, but electrode spacing is longer; The 3rd group of coil electrode apart from second group of difference less than 0.3m, but adopt second operating frequency lower than first operating frequency, the 4th group of coil adopts second operating frequency, and electrode spacing is the longest, in the described step (c), be to analyze the phase signal that obtains described four groups of coil received signals, and the amplitude of the received signal of the 3rd group and/or the 4th group coil compare signal.

11, logging method as claimed in claim 10 is characterized in that, described first group of coil electrode is apart from being 0.4～0.6m, and second group of coil electrode is apart from being 0.9～1.1m, and the 3rd group of coil electrode is apart from being 1.0～1.3m, and the 4th group of coil electrode distance is 1.5～1.8m; Described first operating frequency is 0.2MHz～1.5MHz, and described second operating frequency is 1.5MHz～10MHz.

12, logging method as claimed in claim 9 is characterized in that, described step (a) is provided with five groups of coils, and first group of coil adopts first operating frequency and first electrode spacing; Second group of coil adopts first operating frequency and greater than second electrode spacing of first electrode spacing; The 3rd group of coil electrode apart from second group of difference less than 0.3m, but adopt second operating frequency lower than first operating frequency, the 4th group of coil adopts second operating frequency and greater than the third electrode distance of second electrode spacing, the 5th group of coil adopts the 3rd operating frequency that is lower than second operating frequency, and greater than the third electrode distance of second electrode spacing; And, in the described step (c), be to analyze the phase signal that obtains described five groups of coil received signals, and the amplitude of the received signal of the 4th group and/or the 5th group coil compares signal.

13, logging method as claimed in claim 12 is characterized in that, described first electrode spacing is 0.35～0.55m, and described second electrode spacing is 0.75～0.95m; Described third electrode is apart from being 0.85～1.15m, and described the 4th electrode spacing is 1.45～1.75m, and described the 5th electrode spacing is 1.85～2.15m; Described first operating frequency is 3MHz～10MHz, and described second operating frequency is 1MHz～3MHz, and described the 3rd operating frequency is 0.2MHz～1MHz.

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