SU960701A1 - Device for electromagnetic well-logging - Google Patents

Description

(54) DEVICE FOR ELECTROMAGNETIC CUTTING WELLS

The invention relates to geophysical field engineering, and more specifically to electromagnetic well logging equipment by field attenuation, and can be used to study the electrical resistivity distribution of rocks both in depth and in azimuthal directions in the perimeter, for example, to isolate fractured reservoirs.

Electromagnetic well logging by field attenuation consists in breaking up rocks in a well by the magnitude of the attenuation of the electromagnetic field in the area between the two measurement points by dividing the magnitudes of the electromagnetic field strengths at these points. The electromagnetic field with a frequency of 0.4-2.5 MHz is excited by the generator coil, and the attenuation measurement is carried out using two measuring coils located at the measuring points and the separating system, we. The magnetic moments of the generator and measuring coils are directed horizontally.

Electromagnetic logging on damping has a great depth, depending only on the distance between the master coils and the measuring coils, and a high resolution of the thickness of the layers, depending only on the distance between the coils. Due to the horizontal direction of the moment of the generator coil, the excited electromagnetic field acquires the properties of azimuthal orientation;

10 i.e. The current lines in the formation, against which the measuring coils are located, are directed along the bedding along a certain azimuth, depending on the position in the space of the axis of the helix coil.

In field geophysics, of great interest is the selection in the well section of permeable formations called reservoirs. Some

20 of the reservoirs, for example fracture ones, characterized mainly by vertical fracture directions, are azimuthally inhomogeneous media with respect to their specific

25 electrical resistance, i.e. The resistivity to be measured depends on the azimuth along which the current lines in this medium are directed.

The known low-frequency instrumentation of aerial prospecting using the rotating magnetic field method is designed to assess the degree of azimuthal inhomogeneity of the medium / state consisting of two mutually perpendicular oscillatory frames, powered by the generator of the same frequency and amplitude shifted by a single-sided phyo oscillator. each other in phase by 9Q, and two mutually perpen, dicular receiving frames, one of which is through an amplifier, and the second through an amplifier and an orthogonal (ninth-degree) phase shifter They are not equipped with two subtractive circuits that generate signals proportional to the amplitude and phase parameters, where Uj, Uv, are signals in the receiving frames; H f. - their phase shifts relative to the supply currents. Generator intersection axis: the framework coincides with the axis of the receiver intersection. - The field of the generating frame system has a circular polarization, i.e. The vector of field strength rotates around the axis of intersection of these frames in a plane perpendicular to it with a frequency equal to the current frequency within, not its change in Cl. The known apparatus, which operates at frequencies of 612.1225 and 2450 Hz, 2 However, this apparatus does not allow one to obtain information about the g specific resistance even of a homogeneous medium | Tsi, since in a uniform cpe-i de, regardless of its specific resistance, measured parameters: the difference amplitude A and the phase difference l are zero and can only serve to estimate the degree of heterogeneity of the studied medium. The use of electromagnetic frequency field. and c) rotating at the same frequency in space cannot be used to obtain information on the specific electrical resistance of azimuthally inhomogeneous media, since the frequency of the modulating effect due to the azimuthal inhomogeneity of the medium is at least twice with vertical fracturing) above the frequency of the probing floor. In addition, the use of a low-frequency field does not make it possible to use the effect of field attenuation to divide rocks, since at low frequencies the field attenuation is very small. The closest to the invention in technical essence is a device for electromagnetic well logging consisting of a high frequency generator, a generating coil, a first and a second receiving coil, a selective amplifier, a switching unit, an input switch key, a dividing system, and an output terminal; connected to the generator coil., the first and second receiving coils are connected to the controlled inputs of the switch key, the output of which is connected to the input of the selector th amplifier control input of commutator switch is connected to the first output switching unit selectively amplifier output is connected to the first input delitelnoy.sistemy second input pitch system coupled to a second output of the switching unit, and the output of the pitch system is the output terminal apparatus. This device allows the dissection of the cut of the well 1H by the attenuation value of the high-frequency electromagnetic field and obtain information on the specific electro-resistivity. breeds of NW. However, using this device, it is not possible to isolate azimuthally inhomogeneous media in the well section, such as vertical fractured reservoirs. Indications for output. This device in azimuthally inhomogeneous media depends on the position of the axis of the generator coil in space, which can be located in space randomly, again ...: The purpose of the invention is to expand the functionality by extracting and obtaining information on the specific resistivity of azimuthally inhomogeneous media. The goal is achieved in that a device for electromagnetic well logging, consisting of a high-frequency generator, a first generating coil, a first and a second receiving coils, a first input switch key, a selective amplifier, a dividing system, a switching unit and a first output terminal, the second receiving coils are connected to the controllable inputs of the first switch key, the control input of the first switch key is connected to the first output of the switching unit, the selective input of the The cable is connected to the first input of the dividing system, the second input of the dividing system is connected to the second output of the switching unit, a second generator coil, a balancing modulated oscillator, a third and a fourth receiving coils, a second input switch key, a reducing oscillator, an information separation unit are added and a second output terminal, with the second generator coil spatially aligned with the first, and their axes are mutually perpendicular, the high-frequency generator is connected to ode of the generator of balanced modulated oscillations, the first output of the former is connected to the first generating coil, the second to the second generating coil, the third to the first input of the carrier-carrying oscillation, the fourth to the second input of the carrier-carrying oscillation, a third receiving coil spatially aligned with the first receiving coil and their axes are mutually perpendicular, the fourth receiving coil is spatially aligned with the second receiving coil and their axes are mutually perpendicular, the third and fourth receiving to the carcasses are connected to the controlled inputs of the second input switch key, the control input of the second input switch key is connected to the third output of the switching unit, the output of the first input switch key is connected to the third input of the single-oscillation recuperator, and the output of the second - to its fourth input, output the carrier resilient is connected to the input of the selective amplifier, the output of the dividing system is connected to the input of the information separation unit, the first output of the information separation unit is connected to the first output terminal, and the second with the second output terminal, while the shaper of balanced-modulated oscillations consists of a low-frequency generator, an orthogonal phase shifter, the first and second balanced modulators, the first and second power amplifiers, and the output of the low-frequency generator is connected to the input of the orthogonal phase shifter, the first output of which is connected to the first input of the first balanced module, the same input is the third output of the balanced-modulated oscillator, in The output of the orthogonal phase shifter is connected to the first input of the second balanced modulator, which is the fourth output of the generator of a ball-modulated oscillation, the second inputs of the balanced modulators are interconnected and are the input of a generator of balanced modulated oscillations, the output of the first balanced modulator connected to the input of the first power amplifier, the output of which is the second output of a balanced-modulated oscillator, the output of the second balanced modulator is connected to the input the power amplifier, the output of which is the first output of a balancer-modulated oscillator, with the reduc- tor carrying oscillations. The scientific research institute consists of the first and second astro mixers and the adder, the first inputs of the frequency mixers being the first and second inputs of the carrier oscillator, respectively, and the second inputs of the third and fourth inputs, respectively, the outputs of the mixers are connected to the first and second inputs of the adder, the output which is the output of the carrier-reducing oscillator, while the information separation unit contains a low-pass filter (LPF), a high-pass filter

5 (high pass filter) and amplitude converter; moreover, the filter inputs are interconnected and are the input of the information separation unit, the output of the HPF is connected to the input of the amplitude converter, the output of which is the second output of the information separation unit, the output of the LPF is the first output of the information separation unit.

Figure 1 shows the structural

5 device diagram; 2 shows time diagrams of currents supplied by the first and second generator coils of the device.

The device contains a generator 1

0 HIGH frequency, first generating coil 2, first receiving coil 3, second receiving coil 4, first INPUT switch key 5, selective amplifier 6, dividing system 7, switching unit 8, first output terminal 9, second generating coil 10, driver 11 balanced-modulated oscillations, consisting of a generator 12 low-frequency.

0 tota, orthogonal phase shifter 13, first balanced modulator 14, second balanced modulator 15, first power amplifier 16, second power amplifier 17, third receiving coil 18, fourth receiving coil 19, second input switch key 20, reducing oscillator 21 consisting of First frequency mixer 22, second frequency mixer 23 and

0 adder 24, information sharing unit 25 consisting of low pass filter 26, high pass filter 27 and amplitude converter 28, second output terminal 29 of the device.

The first 3 and the second 4 receiving trunks are connected to the control inputs of the first input switch key 5, the control input of the first switch key 5 is connected to. the first output of the switching unit 8,

0 the output of the selective amplifier 6 is connected to the first input of the dividing system 7, the second input of the dividing system 7 is connected to the second output of the switching unit 8, the high frequency generator 1 is connected to the input of the driver 11 and is balanced by modulated signals, the first output of the driver 11 is connected to the first generator coil 2, the second with the second generator coil. 10 the third with the first input of the reducing agent 21 carrier oscillations, the fourth with the second input of the reducing carrier 21. carrier oscillations, the third 18 and the fourth 19 receiving coils Eny with the control inputs of the second input switch key 20, the control input of the second input switch key 20 is connected to the third ;: block 8 output of the com mutation, the output of the first input switch key 5 is connected to the third input of the regenerator 21 bearing oscillations, and the output the second input switch key 20 - With the fourth input of the resilient carrier 21 oscillations, the output of the carrier resilient 21 is connected to the input of the repeater amplifier b, the output of the separation system 7 is connected to the input of the separation unit 25 information, the first output of the information separation unit 25 is the middle one with the first output terminal 9 of the device, and the second with its second output terminal 29. In the generator 11 of the balanced-modulated vibration, the low frequency generator 12 is connected to the input of the orthogonal phase shifter 13 , the first output of which is connected to the first input of the first balanced modulator 14 This same input is the third output of a balanced modulated oscillator 11, the second output of the orthogonal phase shifter 13 is connected to the first input of the second balanced oscillator the modulator 15, simultaneously being the fourth output of the former .11, the second inputs of the balanced modulators are interconnected and are the input of the former 11 bilanna-modulated oscillations, the output of the first balanced modulator 14 is connected to the input of the first power amplifier 16, the output of which is the second output of the imaging unit 11, the output of the second balanced module of the switch. 15 is connected to the input of the second power amplifier 17, the output of which is the first output of the imaging unit 11 of the balance modulated oscillations. In the oscillator 21, the first input of the first frequency mixer 2.2 is the first input of the carrier 21 restorer 21, and the first input of the second frequency mixer 23 is the second input of the reducing agent 21, the second input of the first frequency mixer 22 is the ± input of the reducing agent 21, and the second the input of the second part-set mixer 23 is the fourth input of the reducing carrier 21, the oscillations, the outputs of the first and second frequency mixers 22 and 23 are connected to the first and second inputs of a sump 24, the output of which is output the reducing carrier 21, In the information separation block -25, the low and high pass filter inputs -26- and 27 are interconnected and are the input of the information separation block 25, the output of the HPF 27 is connected to the input of the amplitude converter 28, the output of which is the second output information sharing unit 25, the output of the low-pass filter 26 is the first output of information sharing unit 25. Figure 2 shows: 30 - form. in the first generating coil 2, 31 is the current form in the second generating coil 10, i is the axis of currents, t is the time axis. Device; in works as follows. . The high frequency generator 1 produces electrical sinusoidal oscillations with a frequency of 0.4-2.5 MHz. The analytical expression of these oscillations has the form coswt, where U is the instantaneous value of the voltage at the output of generator 1; UITI - oscillation amplitude j lo - circular oscillation frequency; , t is the current time. These oscillations are fed to the inputs of the balanced modulators 14 and 1.5 of the driver 11 of the balanced modulated oscillations. The low frequency generator 12 of this driver produces electrical oscillations at a frequency of 5-7 Hz. These oscillations are fed to the input of an orthogonal phase shifter 13, the outputs of which create two equal in amplitude and phase shifted by 90 ° voltage U and Uj, having the form U2 Umcos Yae,,. U3 UmCos (52) U sin52 t, (2) where Dm is the amplitude of low-frequency oscillations 1 I is the circular frequency of oscillations. The voltages U and Uj are supplied to the other inputs of the balanced modulators 14 and 15. The balanced modules of the tori 14 and 15 transform the oscillations of the high-frequency generator 1 into two balanced modulated signals, i.e. amplitude-modulated oscillations in which there is no oscillation of the carrier frequency UJ of the oscillator 1. When modulated with a single sinusoidal signal, the balanced modulated oscillation has the form ICt) E., .- m-cos lotcos (u) -S2; i +. + (og + ftH I where E (t) is the instantaneous value of the balanced modulated signal; m is the modulation coefficient, E is the amplitude of the modulated oscillation / YuI are the angular frequencies of the modulating and modulating oscillations, respectively. Thus, at the output of the balanced modulator 14 a balanced modulated oscillation will be obtained, having the form .m (t) Urn m-cosuot .c; osS2t,) a at the output of the balanced modulator 15 oscillations of the form PI (t) Umv-cosiut-s i nflt. five),. The balance modulators-14 and 15 should have equal modulation factors t. From the outputs of the modulators 14 and 15, the oscillations E (t) and ti (t} are fed to power amplifiers 16 and 17 having the same gain factors. The amplified oscillations from the outputs of the amplifiers 16 and 17 are supplied to the first and second generator coils 2 and 10, the axes of which are perpendicular to each other and the axes of the well. The shape of the currents flowing in the coils and representing balanced-modulated oscillations is depicted in Fig. 2. Each of the currents will create pulsing with frequency The electromagnetic field, the intensity vector, the magnetic component of which is directed along the axis of its coil. The resulting vector, the intensity of such a system of coils, will rotate at a frequency equal to the frequency of change of the envelope of the balanced-modulated oscillation around the line of intersection of these in a plane perpendicular to this line and the amplitude of the voltage of the resulting field remains unchanged in magnitude. In the area of the receiving coils Zi18, 4 and 19 an electromagnetic field will be created, the vector of The bones of the magnetic component of which rotates in the plane perpendicular to the axis of the well with a frequency S, and the magnitude of this vector depends on the electrical properties of the rocks in the vicinity of the receiving wells, which, in turn, are generally functions of the well depth and azimuth. Thus, H; ((h, e) f (h, e), (6), where Hx (h, 0) is the amplitude of the horizontal component of the magnetic component of the field; is the vertical and azimuthal coordinates of the measuring point in the well Receiving coils 3, 18 and 4, 19 transform the magnitudes of the tension of the polycio 3, the wildfire so it was having / where to go to the bl of cm to see some 21 years and you can see the electrical signals proportional to them. Because The axes of the coils 18 and 4.19 are pairwise mutually perpendicular, then the signals in these coils are shifted from each other by 90 ° and also represent the assembled bs-measured oscillations. Ala in coils 3 and 18 will be of the form kH (1i, 6) sinw4-to5Slt, (1i, 0) sinuot-sinSlt, is the proportionality coefficient that is the same for all coils, since their parameters are the same; Hx (b) is the intensity the horizontal component of the magnetic component of the field at the location of the first 3 and third 18 receiving coils, and the signals in the first 3, and the third 18 kag carcasses, respectively. Signals in the coils 4 and 19 will be e .. l, e) sinu3i- COSSZt, 1 (c) (ii, 0) sina t-Sin t, 1.4 signals, respectively, in the second 4th and quarterly 19 KaTytiKax; ((11, в) is the intensity of the horizontal component of the magnetic component of the field at the location of the second 4 and fourth 19 receiving coils. The signals of the receiving coils received the inputs of the first 5 and second 20 mutator switches controlled by the switching unit 8. In the first clock cycle, the unit 8, the switching coil 3 is connected via the first key 5 to the second input of the first frequency power supply 22, and the coil 18 through the swarm key 20 to the second input of the time mixer 23 of the carrier oscillator. On the first frequency mixers 22 and 23 pots equal in amplitude and offset Inu phase out of 90 vibrations from the pen and the second output of the orthogonal phasing of the generator 13 of the balance modulated signals. The frequency mixers 22 and 23 must have a square characteristic Uftbix the voltage at the mixer output; Ugx is the input voltage; c is the proportionality coefficient. The output at the exit of the first mixer 22 will have the form CM (, 0) si JU: C05ftt + U with osIlf c) (ti, 0} s4n w) i-cos 2t + 1c1cU Hx - x {ti, e) sinwt-cos "T -cUJ cos fll, (10) and at the output of the second mixer 23 and gGGKN (1i, e) sinujt-S n5it + U Sinai a (1i, 0) sin flt + 2c1 yrrt-Hx x (-h, G) sinioi..l. (11) From the outputs of frequency mixers 22 and 23, these voltages are fed to the input of the adder 24, in which the UCM voltages are summed. The total voltage will have the form- - JCM, H, e) + lckU Hj ((Vi, e) 5inu) t-f-cU. (l1) This voltage consists of the constant component c, and the first harmonic 2ckUrr, H d (h, b) S i nuJt of the carrier oscillator of generator 1 and its second harmonic (| - c, d) S. These voltages are fed to the input of a selective amplifier 6 tuned to the first harmonic of the carrier wave. The amplified and transformed carrier frequency oscillations, proportional to the field strength of the field H x- | (h, 6), are fed to the input of the divider system 7 of the time-pulse type. In the second measurement cycle, the switching unit 8 disconnects the coils 3 and 18 from the frequency mixers 22, 23 and connects to the first mixer 22 through the first key 5 the second receiving coil 4, and to the second mixer 23 through the second, key 20 - the fourth receiving coil 19. Above the signals of t. and ст in a carrier 21, the carrier carries the same transformations as on signals 6 and Eg, which result in the sum of the oscillations and SCN (h, 0) sin at the output of the 24 ut 2c1tW; ((, e) sitiwt 2.l Ll, i

(13)

+ cU

Fri

From these oscillations by a selective amplifier b, the first harmonics of the carrier oscillation are allocated. Proportional to the amplitude of the field strength) - This oscillation is also fed to the input of the dividing system 7. The dividing system 7, controlled by the switching unit 8, performs x proportional to the amplitude of the intensity field Hx / 2. (h, 0) by an amount proportional to the amplitude of the intensity

Claims (3)

1. Electromagnetic well logging tool consisting of a high-frequency generator, a first generating coil, a first and second receiving coils, a first KoiviMyTaTopHOro input key, a selective amplifier, a dividing system, a switching unit and a first output terminal, with the first and second receiving coils connected with controllable Hx (h, 0). At the output of the dividing system 7, a voltage is formed that is proportional to the value of .S-Trf characterizing the attenuation of the field in the section between two pairs of receiving coils 3, 18 and 4, 19. The value of P (h, e) is a function of both the depth of the well h and and the azimuth of the vector of the intensity of the rotating field. The frequency spectrum of P (b, b) consists of two frequency regions: the first region, due to the dependence of the attenuation of the field on the depth of the well, occupies the region from zero to 2-3 Hz, depending on the differentiation of the section, the second frequency region, due to the dependence of the attenuation of the field on azimuthal inhomogeneity of the medium, occupies the frequency range from 2SJ and above, i.e. from 10–14 Hz and higher, depending on the nature of the heterogeneity. This circumstance allows one to single out its azimuthal P (Q) from P (h, 0) and the components related to the depth P (h). This function is performed by the information sharing unit 25, the low-pass filter 26 selects the frequency range from zero to 3 Hz, i.e. component P (h), and high pass filter 27. a range of frequencies from 10 Hz and above, i.e. component P (0), which is further converted into a DC voltage proportional to amplitude P (9), characterizing the degree of azimuthal heterogeneity of the studied medium. The components P (h) and P (9) are fed to the output terminals 9 and 29 of the device. In the logging process, the borehole is centered, so that the axis of rotation of the electromagnetic field coincides with the axis of the well. The proposed device allows to isolate azimuthally inhomogeneous media in well sections (for example, fractured reservoirs), to determine the electrical resistivity of these media in different directions, at the same time providing information about the distribution of specific electrical resistances across the depth of the well. With the first switch key, the control input of the first switch key is connected to the first output of the switching unit, the output of the selective amplifier is connected to the first input of the dividing system, the second input of the dividing system is connected to the second output of the switching unit, characterized in that capabilities of the device due to the separation and acquisition of information on the electrical resistivity of azimuthally inhomogeneous media, additionally introduced, the second generator coil, driver alanna-modulated oscillations, one-third and even-fourth receiving coils, a second input switch key, a carrier-carrier restorer, an information separation unit and a second output terminal, the second generator / coil being spatially aligned with the first, and the LER axis and the second generator axis Katu: EC is mutually perpendicular, the high-frequency generator is connected to the input of the driver, a balance-modulator, ovarian oscillations, the first output of the driver, is connected to the first generating coil, the second from the second generating cable oh, the third — with the first input of the carrier-carrying oscillator, the fourth — with the second input of the carrier-carrying oscillator, a third receiving coil is spatially aligned with the first receiving coil and their axes are mutually perpendicular, the fourth receiving coil is spatially aligned with the second receiving coil and their axes are perpendicular The third, third, and fourth receiving coils are connected to the control inputs of the second switch key, whose control input is connected to the third output of the switching unit, the input of the first input The second switch is connected to the third input of the Hecyiiuix oscillation recuperator, and the second switch is connected to the fourth input, the output of the carrier oscillator is connected to the input of the selective amplifier, the output of the separation system is connected to the input of the information separation unit, the first output of the information separation unit is connected to the first output terminal of the device, and the second output - with the second output terminal .. 2. The device according to claim 1, .o tl and -; Chayu1ees the fact that the driver of balanced-modulated oscillations consists of a generator izkoy frequency orthogonal phase shifter, the first and second balanced modulators, the first and second power amplifiers, the low frequency oscillator output is connected to the input of the orthogonal phase shifter, a first output connected to a first input of the first balanced modulator ztot same input is the third; the output of a balancer-modulated oscillator, the second output of the orthogonal phase shifter is connected to the first input of the second balanced modulator, which is the even-sided output of the bi-modulated oscillator, the second inputs of the balanced modulators are interconnected and serve as the input of the balancer modulated oscillators , the output of the first balanced modulator is connected to the input of the first power amplifier, the output of which is the second output of a generator balanced with oscillations, the output of the second balanced modulator connected to the input of the second power amplifier whose output is the output of the first -sluzhit balansnomodulirovannyh oscillations. 3. The device according to claim 1, which is based on the fact that the reductant of the carrier oscillations consists of. the first and second frequency mixers and the adder, the first inputs of the frequency mixers being the first AND second inputs of the carrier-carrying oscillator, respectively, and the second inputs are. respectively, the third and fourth inputs thereof, the outputs of the mixers are connected to the first and second inputs of the adder, the output of which is the output of the reducing carrier. oscillations. 4.-device according to claim 1, characterized in that the information separation unit comprises a low-pass filter, a high-pass filter and an amplitude converter, the filter inputs being interconnected and serving as the input of the information-separation block, the output of the upper-frequency filter. It is connected to an amplitude input, a converter, the output of which is the second output of the information separation unit, and the output of the low-pass filter serves as its first output. Sources of information taken into account in the examination 1. Bobrovnikov L.Z. and others. Electrical prospecting apparatus and equipment. M., Nedra, 1979, pp.280-282. 2. Yakubovsky Yu. V. Electrointelligence. M., Nedra, 1980, p.363. 3. Authors certificate of the USSR 313966, cl. E 27 B 47/00, 1970 (prototype). ffia.1 L.