RU2131029C1 - Method of determination of azimuth, zenith angle and angle of dip - Google Patents

Abstract

FIELD: well logging; applicable in control of complex parameters of space orientation of well bore and well objects. SUBSTANCE: method includes measurement of signals from flux-gate meters α, θ and ν of three-component geomagnetometer, measurement of signals from devices specified by invention description proportional to sine T_x and cosine T_y of angle of sight. On the basis of mathematical dependence, reduced values of the given signals T_z, U_s and U_c are found. Intermediate parameters T $\genfrac{}{}{0ex}{}{\text{*}}{\text{x}}$ , T $\genfrac{}{}{0ex}{}{\text{*}}{\text{y}}$ and T $\genfrac{}{}{0ex}{}{\text{*}}{\text{z}}$ are determined. Ranges of variation of determined angles t $\genfrac{}{}{0ex}{}{\text{*}}{\text{y}}$ , t $\genfrac{}{}{0ex}{}{\text{*}}{\text{x}}$ and t $\genfrac{}{}{0ex}{}{\text{*}}{\text{z}}$ are preset. Cycles of successive variation by angles α, θ and ν with uniform step of quantization are preset. Determined for each value of preset angles α, θ and ν in point of variation cycles are theoretical values α_i. Modules of difference θ_i are found. Numerical value of parameter E is preset with which all three Modules of difference are compared. If even one of Modules of differences has value larger than parameter E, successive cycles of variation are continued. If all three Modules of difference simultaneously have values less or equal to parameter E, cycles of variation are discontinued. Current values of angles ν_i, t_xi,t_yi,t_zi and

are considered as sought ones. EFFECT: higher accuracy and simplification of determination of azimuth α_i,, zenith angle θ_i, and angle of dip ν_i. 2 cl, 2 dwg

Description

 The invention relates to the field of field geophysics and can be used to control a set of parameters of the spatial orientation of the well trajectory and well objects.

 A known method of controlling the complexes of parameters of the well trajectory implemented in the device [1], including measuring three orthogonal components of the Earth’s magnetic field vector using a three-component flux-probe azimuth sensor, measuring the sines and cosines of respectively zenith and sighting angles using a pendulum converter according to the kinematic scheme of the gimbal , on the axis of rotation of which sine-cosine rotary transformers are installed, and determination by measured signal m azimuth, and the determination of the measured signals azimuth, anti-aircraft and sighting angles [1].

 There is also a method of controlling the complex of parameters of the well’s trajectory, implemented in the device [2], which includes measuring three non-orthogonal components of the Earth’s magnetic field vector using a flux-probe azimuth sensor, measuring sines and cosines of the zenith angle, sighting angle, and non-orthogonal installation angle of the first and second flux probes in the azimuth sensor and the determination of the measured azimuth signals, anti-aircraft and sighting angles [2].

 The disadvantages of the analogues are as follows. The complexity of the design and low accuracy due to the presence of mechanical rotating parts of the zenith angle converter in the gimbal, characterized by the moment of frictional forces in the suspension supports, causing the error in determining the desired angular parameters.

 The closest in technical essence and the achieved result is a method of measuring the angular parameters of the spatial orientation of well objects, including the installation of a three-component flux-gate magnetometer and a sighting angle transducer in the body of the downhole tool, made in the form of a relative pendulum with a sine-cosine rotary transformer mounted on its axis of rotation (SKVT ), and the sensitivity axes of the fluxgates are oriented orthogonally to each other, and the axis of the third fluxgate and the axis of rotation of the pendulum coincide with the longitudinal axis of the body of the downhole tool, measuring signals from flux-gates proportional to the projections of the total vector of the geomagnetic field strength on the axis of their sensitivity and signals from SECS proportional to the sine and cosine of the viewing angle, and determining the zenith angle, the angle of magnetic inclination and azimuth according to the measured signals [3].

 The disadvantages of the prototype. The complexity of determining the angle of magnetic inclination, zenith angle and azimuth, due to the cumbersome dependences of the measured signals with the desired angular parameters, as well as the use of ground-based measurements and low accuracy, due to the fact that the angle of magnetic inclination is determined on the Earth's surface, and is not taken into account when processing the measurement results its change in depth of the trajectory of the well.

 The problem to which the invention is directed is to increase the accuracy and simplify the determination of azimuth α, zenith angle θ and angle of magnetic inclination ν by cyclically varying the theoretical values of the desired angles α, θ and ν, performing intermediate calculations and comparing the moduli of the difference of the theoretical values of the intermediate parameters and parameters determined by measuring signals from flux gates and SLE and at each point of change along the well path.

задают диапазоны варьирования определяемых углов α, θ и υ, задают циклы последовательного варьирования по углам α, θ и ν, с равномерным шагом квантования, для каждого значения заданного угла α_i, θ_i и υ_i, в точке циклов варьирования определяют теоретические значения
t_Xi= cosυ_icosθ_icosα_i-sinυ_isinθ_i,
t_Yi= -cosυ_isinα_i,
t_Zi= cosυ_icosα_isinθ_i+sinυ_icosθ_i,
находят модули разностей

задают численное значение параметра E, с которым осуществляют сравнение всех трех модулей разности так, что если хотя бы один из модулей разностей имеет величину, большую, чем параметр E, то продолжают последовательные циклы варьирования, а если все три модуля разностей одновременно имеют величины, меньшие или равные параметру E, то циклы варьирования прекращают, а текучие значения углов α_i, θ_i и υ_i, принимают как искомые угол магнитного наклонения υ, азимут α и зенитный угол θ, причем приведенные значения сигналов с феррозондов и СКВТ определяют следующим образом:

где T_X, T_Y, T_Z - измерительные сигналы с феррозондов, U_S и U_C - сигналы с синусной и косинусной обмоток СКВТ; шаги квантования по углам α, θ и υ задают равными требуемой точности определения соответственно угла магнитного наклонения, азимута и зенитного угла, а значение параметра E принимают меньшим или равным наименьшему значению из заданных шагов квантования.This object is achieved in that in the method [3] for determining the angle of magnetic inclination ν, zenith angle θ and azimuth α, which includes installing a three-component flux-gate magnetometer and a sighting angle transducer in the downhole tool housing, made in the form of a single-stage pendulum with an SCVT mounted on its axis of rotation moreover, the sensitivity axes of the fluxgates are oriented orthogonally to each other, and the axis of the third fluxgate and the axis of rotation of the pendulum coincide with the longitudinal axis of the body of the downhole tool, measured signals from flux gates T _X , T _Y , T _Z proportional to the projections of the full vector of the geomagnetic field intensity on the axis of their sensitivity and signals from SECS proportional to the sine and cosine of the viewing angle φ, determine the reduced values of signals from flux gates and SEC, according to which

specify the ranges of variation of the determined angles α, θ and υ, set cycles of sequential variation in the angles α, θ and ν, with a uniform quantization step, for each value of the given angle α _i , θ _i and υ _i , at the point of the variation cycles determine the theoretical values
t _Xi = cosυ _i cosθ _i cosα _i -sinυ _i sinθ _i ,
t _Yi = -cosυ _i sinα _i ,
t _Zi = cosυ _i cosα _i sinθ _i + sinυ _i cosθ _i ,
find difference modules

set the numerical value of the parameter E, with which all three difference modules are compared so that if at least one of the difference modules has a value greater than the parameter E, sequential cycles of variation are continued, and if all three difference modules simultaneously have values smaller or equal to the parameter E, the cycles of variation cease, and the flowing values of the angles α _i , θ _i and υ _i are taken as the desired angle of magnetic inclination υ, azimuth α and zenith angle θ, and the values of signals from flux gates and SECS are determined Pour as follows:

where T _X , T _Y , T _Z - measuring signals from flux gates, U _S and U _C - signals from the sine and cosine windings of an SCR; the quantization steps along the angles α, θ, and υ are set equal to the required accuracy of determining respectively the angle of magnetic inclination, azimuth, and zenith angle, and the value of the parameter E is taken to be less than or equal to the smallest value from the given quantization steps.

 In FIG. 1 is a kinematic diagram, and FIG. 2 is a functional diagram of a device that implements the proposed method, comprising installing three orthogonally oriented flux probes 2, 3, and 4 in the housing 1 of a downhole tool and a sighting angle transducer made in the form of a single-stage pendulum 5 with an SCVT 6 mounted on its axis of rotation, the axis of sensitivity of the third the flux gate 4 and the axis of rotation of the pendulum 5 coincide with the longitudinal axis of the housing 1. The functional diagram (Fig. 2) of the device also contains excitation generators of the flux gates 7 and SKVT 11, analog switches 8, 12 14, a selective amplifier 9, phase-sensitive detectors 10 and 13, integrator 15, analog-converter (ADC) 16, a data transmission unit 17, a computer 18 and a control unit 19.

The operation of the device is as follows. The excitation generator 7 provides the voltage of the required amplitude and frequency to the series-connected excitation windings of the flux gates 2, 3 and 4. The signals T _X , T _Y and T _Z proportional to the projections of the geomagnetic field on the sensitivity axis of the flux gates 2, 3 and 4, sequentially through the analog the switch 8 is fed to the input of the selective amplifier 9. A double-frequency sinusoidal voltage from the output of the selective amplifier 9 is detected in the phase-sensitive detector 10 and through the third analog switch 14 is fed to the input of the integrator 15, in which the constant voltage level is converted, which is proportional to the signals T _X , T _Y, and T _Z , respectively. The field winding of the SCRT 6 is supplied from the generator 11, and the output signals U _S and U _C , proportional to the sine and cosine of the viewing angle φ, respectively, through the second analog switch 12, the second phase-sensitive detector 13 and the third analog switch 14 are sequentially fed to the input of the integrator 15, which is also converted to a constant voltage level proportional to the signals U _S and U _C , respectively. Next, the signals T _X , T _Y , T _Z , U _S and U _{C are} converted in the ADC 16 into digital codes, which are transmitted to the computer 18 by means of the data transmission unit 17.

 The control unit 19 fulfills the necessary control commands to the analog switches 8, 12 and 14, phase-sensitive detectors 10 and 13, the integrator 15, the ADC 16, the data transfer unit 17, and also provides the arrival of clock pulses to the generators 7 and 11.

T_Z = T[cosυcosαsinθ+sinυcosθ].
Способ определения азимута α, зенитного угла θ и угла магнитного наклонения υ по измеренным сигналам с феррозондов T_X, T_Y, T_Z и сигналам с СКВТ U_S и U_C заключается в следующем. Определяют приведенные значения сигналов

Затем определяют промежуточные параметры:

Задают диапазоны варьирования определяемых углов α, θ и υ, задают циклы последовательного варьирования по углам α, θ и υ , с равномерным шагом квантования, после чего для каждого значения заданного угла α_i, θ_i и υ_i в точке циклов варьирования определяют теоретические значения:

находят модули разностей

задают численное значение параметра E, с которым осуществляют сравнение всех трех модулей разностей так, что если хотя бы один из модулей разностей имеет величину, большую, чем параметр E, то есть

то продолжают последовательные циклы варьирования, а если все три модуля разностей одновременно имеют величины, меньшие или равные параметру E, то есть

то циклы варьирования прекращают, а текущие значения углов α_i, θ_i и υ_i принимают как искомые угол магнитного наклонения υ, азимут α и зенитный угол θ, причем шаги квантования по углам α, θ и υ задают равными требуемой точности определения данных углов, а значение параметра E принимают меньшим или равным наименьшему значению из заданных шагов квантования.Thus, at each measurement point along the well path in the computer 18, codes are generated corresponding to the measured signals T _X , T _Y , T _Z , U _S and U _C , with U _S corresponding to the sine of the line of sight, U _C to the cosine of the line of sight, and signals from flux gates are associated with azimuth α, zenith angle θ, sighting angle φ, angle of magnetic inclination υ and the magnitude of the total geomagnetic field intensity vector T by the following equations:

T _Z = T [cosυcosαsinθ + sinυcosθ].
The method for determining the azimuth α, zenith angle θ, and magnetic inclination angle υ from the measured signals from flux gates T _X , T _Y , T _Z and signals from SECS U _S and U _C is as follows. Determined signal values

Then determine the intermediate parameters:

The ranges of variation of the determined angles α, θ and υ are set, the cycles of sequential variation in the angles α, θ and υ are set, with a uniform quantization step, after which theoretical values are determined for each value of the given angle α _i , θ _i and υ _i at the point of the variation cycles :

find difference modules

set the numerical value of the parameter E with which all three difference modules are compared so that if at least one of the difference modules has a value greater than the parameter E, i.e.

then sequential cycles of variation continue, and if all three modules of differences at the same time have values less than or equal to the parameter E, i.e.

then the cycles of variation are stopped, and the current values of the angles α _i , θ _i and υ _i are taken as the desired angle of magnetic inclination υ, azimuth α and zenith angle θ, and the quantization steps at angles α, θ and υ are set equal to the required accuracy of determining these angles, and the value of the parameter E is taken to be less than or equal to the smallest value from the given quantization steps.

 So, the claimed invention allows to increase the accuracy and simplify the determination of the desired angles α, θ and υ by cyclically varying the theoretical values of these angles, performing intermediate calculations and comparing the modules of the differences of the theoretical values of the intermediate parameters and parameters determined by measuring signals from flux gates and SECS.

Sources of information
1. USSR author's certificate N 1078041, M. cl. E 21 B 47/02, 1984

 2. Copyright certificate of the USSR N 1208208, M. cl. E 21 B 47/02, 1986

 3. Copyright certificate of the USSR N 1543060, M. cl. E 21 B 47/02, 1987 (prototype).

Claims (1)

1. The method of determining the azimuth, zenith angle and angle of magnetic inclination, including the installation in the body of a downhole tool of a three-component flux-gate magnetometer and a transducer of the viewing angle, made in the form of a single-stage pendulum with a sine-cosine rotary transformer (SCRT) mounted on its axis of rotation, and the sensitivity axis fluxgates are oriented orthogonally to each other, and the axis of the third fluxgate and the axis of rotation of the pendulum coincide with the longitudinal axis of the body of the downhole tool, as measured s signals ferroprobes _{T x, T y, T z} , proportionate projections of the total vector of the geomagnetic field on-axis sensitivity, and the signals from resolver proportional to the sine and cosine of the sight angle φ, and the determination of the zenith angle θ, the angle of magnetic inclination υ and azimuth α from the measured signals, characterized in that the reduced values of the signals from the flux gates -T $\genfrac{}{}{0ex}{}{\text{*}}{\text{x}}$ , T $\genfrac{}{}{0ex}{}{\text{*}}{\text{y}}$ , T $\genfrac{}{}{0ex}{}{\text{*}}{\text{z}}$ and SKVT - sinφ and cosφ, by which we find the relations

specify the ranges of variation of the determined angles α, θ and υ, set the cycles of sequential variation in the angles α, θ and υ with a uniform quantization step for each value of the given angles α _i , θ _i and υ _i , at the point of the variation cycles determine the theoretical values

find difference modules

set the numerical value of the parameter E, with which all three difference modules are compared so that if at least one of the difference modules has a value greater than the parameter E, sequential cycles of variation continue, and if all three difference modules simultaneously have values smaller or equal to the parameter E, the cycles of variation cease, and the current values of the angles α _i , θ _i and υ _i take as the desired angle of magnetic inclination υ, azimuth α and zenith angle θ.
2. The method according to claim 1, characterized in that the values of the signals from the flux gates and SLE are determined as follows:

where T _x , T _y , T _z are the measured signals from flux gates: U _s and U _c are the signals from the sine and cosine windings of an SCR, the quantization steps at angles α, θ, and υ are set equal to the required accuracy of determining, respectively, the angle of magnetic inclination υ, azimuth α and zenith angle θ, and the value of the parameter E is taken to be less than or equal to the smallest value from the specified quantization steps.

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