RU2401383C1 - Method of analysing well casing inner surface - Google Patents

Abstract

FIELD: oil-and-gas production.

SUBSTANCE: main transducer output voltages are measured in every profilographed point on analysed profile, auxiliary transducer output voltages are subtracted therefrom and differential voltages are then recorded and processed. Note here that auxiliary transducer voltages are taken to be proportional to solution magnetic conductivity by shunting transducer pole tips with the help of ferromagnetic body so that there is a clearance between the latter and casing outer surface to allow free circulation of said solution. Ferromagnetic body is located at a distance from casing outer surface that does not exceed transducers operating ranges, while auxiliary transducer proper is arranged at one height with the main transducer. In analysis, transducer calibration curve is corrected with due allowance for solution magnetic conductivity variations. For this, short-term shunting of the main transducer pole tips is performed to produce reference differential voltage that corresponds to zero clearance between well casing inner surface and transducer case outer surface. Controlled clearances corresponding to each profilographed point of j-th profile are defined using mathematical relationship cited in this invention.

EFFECT: higher accuracy of determination well casing inner surface wear.

8 cl, 8 dwg

Description

The invention relates to the field of geophysical research of deep and superdeep oil and gas wells and is intended to control the technical condition of casing strings in wells.

There is a method of studying the profile of the inner surface of casing strings with drilling fluid in the well using a radial method for monitoring gaps between the inner surface of the string and the outer surface of the protective casing of the rotating sensor of the device with two main and auxiliary transformers with pole tips facing the measuring circuit that are identical and facing casing wall. This method was first used in the EPOK-1 profilograph (Shots MB Electromagnetic casing profilograph EPOK-1. Information leaflet (interindustry information) No. 43-76, series 08-12. VNIIOENG, 1976. Research and implementation of methods and tools for increasing reliability and durability of casing strings, Andrianov II, Kozyrev Yu.S., Pavlov AI, etc. - In the book: Drilling, testing and development of deep wells in the North Caucasus, Dagestan and Georgia, 1976, p. .63-68. Proceedings of SevKavNIPIneft) on autosvid. USSR No. 261318 (publ. 04.09.72) [patents: US No. 3727126, France No. 2108800 and Germany No. 2046733], intended primarily to determine the profile of the inner surface and groove wear of casing strings, provides for shunting of pole pieces in the process of monitoring the technical condition of cased holes auxiliary (or otherwise compensatory) transformer converter with a ferromagnetic body in the form of a plate placed inside the casing. Such an implementation of the method does not provide the necessary measurement accuracy in deep and ultra-deep wells due to the impossibility of taking into account the influence of external destabilizing factors (temperature, pressure, magnetic permeability of the drilling fluid, etc.) on the research results. This reduces the accuracy of determining crushing and critical internal pressures of worn casing pipes, and also leads to unreliable calculations of straining loads on worn coupling joints.

There is also a method of researching casing strings in a well by autosvid. USSR No. 1286758 (declared. 04.17.85), which provides the identification of trough-shaped workings and the degree of wear of the casing by a drilling tool by using an auxiliary transformer transducer of the sensor in the mode of a second measuring transducer, similar to the main one, when diametrically opposite to their installation inside the casing. This method also does not allow to obtain high measurement accuracy due to the instability of the parameters of the transducers when the ambient temperature changes. Another drawback is the introduction of additional errors in the results of determining the inner diameter of the casing strings in the presence of errors of the same sign for the transducers.

The main common drawback of these methods is the dependence of the results of the study of the technical condition of the casing strings from changes in the magnetic permeability of the working medium. This forces the calibration of the transducers to be carried out in the drilling fluid extracted from the well at the wellhead immediately before conducting its research. However, such an operation does not provide the necessary accuracy in determining the geometric characteristics of the inner surface of the casing strings, since the magnetic properties of the drilling fluid are not constant both in time and in the depth of the wellbore due to the influence of temperature, quantity, composition and deposition rate of impurities.

Closest to the proposed method is the study of the inner surface of the casing strings, which consists in measuring output voltages of the main transducer at each profiled point of the profile under investigation, subtracting the output voltages of the auxiliary transducer from them, followed by recording and processing the resulting current differential voltages (A. Abramov A., Izmailov LB, Klimov VV Development of a device for determining the wear of casing strings during well drilling. about research UDC 622.248.56.05, No. 0284.0056650, 1984, p. 55-64). This method involves placing the main and auxiliary transducers one above the other along the axis of the downhole tool with the orientation of the pole pieces in one direction and the radial displacement of their working surfaces relative to each other. In this case, the pole pieces of the main transducer serve to determine the gaps between them and the inner surface of the casing, being at the smallest distance from its generatrix compared to the pole pieces of the auxiliary transducer. Due to this, by differential extraction of the useful signal by calculation, not only the influence of the instability of the characteristics of the transducers and casing string structural elements when the temperature of the drilling fluid is changed, but also the influence of the change in the magnetic permeability of the latter on the measurement results is eliminated. However, with all the obvious advantages of this method, it also has a number of serious drawbacks that significantly limit its use from the metrological point of view in equipment for studying casing strings in deep and superdeep wells. On the one hand, this is due to the fact that under real conditions the generatrix of the inner surface of the casing, relative to which the gaps are measured at two points separated in depth most often because of the poor quality of centering of the downhole tool, is not strictly parallel to the planes of the working surfaces of the pole tips of the main and auxiliary converters. Most significantly, this factor manifests itself at the ends of the trough-like workings. For these reasons, an additional error will be introduced into the measurement results, directly proportional to the distance between the neutrals of the cores of the primary and secondary transducers. Obviously, to minimize this error, the neutrals of the cores of the transducers should be located in a single transverse plane of the downhole tool, and this contradicts the technical capabilities of the method under consideration. On the other hand, the radial displacement of the pole tips of the transducers relative to each other reduces the already small range of the sensor, usually not exceeding 30 ÷ 35 mm, by the magnitude of this displacement, and also reduces the sensitivity of the auxiliary transducer, which ultimately affects the quality of the study of the technical condition of the casing columns. Another disadvantage of this method is the need for simultaneous measurement of the output voltages of the transducers with a given perimeter scan step of the inner surface of the casing strings. This leads to the forced use of electronic circuits for intermediate signal transformations in a downhole tool, which limits its use in difficult thermobaric conditions of deep and superdeep wells. And, finally, placing the transducers one above the other along the axis of the downhole tool increases its axial dimension, which is undesirable for the end position of the sensor under the lower centralizer, since this reduces the passability of the device on the descent in sections of casing with patches in the case of an eccentricity of the sensor in the presence of an angle the inclination of the axis of its casing with respect to the investigated inner surface of the column.

The invention solves the problem of increasing the accuracy of the study of casing strings in deep and superdeep oil and gas wells.

To achieve the named technical result in the proposed method for studying the profile of the inner surface of casing strings with drilling fluid in the borehole by the radial method for checking the gaps between the inner surface of the casing and the outer surface of the protective casing of the rotary sensor of the device with two main and auxiliary transformer connected to the measuring circuit, identical in parameters transducers with pole tips facing the wall of the casing, namely, that at each profiled point of the profile under study, the output voltages of the main transducer are measured, the output voltages of the auxiliary transducer are subtracted from them, followed by registration and processing of the obtained current differential voltages, the output voltages of the auxiliary transducer are formed proportional to the magnetic permeability of the solution by shunting its pole tips with a ferromagnetic body with a gap with respect to to the outer surface of the casing, providing freedom dnuyu circulation solution, wherein the ferromagnetic body is arranged on the outer surface of the housing at a distance not exceeding the range of the transducers, and the auxiliary drive is mounted on a level with the main altitude.

In addition, in the proposed method, when conducting studies, the calibration of the sensor is adjusted taking into account changes in the magnetic permeability of the solution, for which a short-term magnetic shunting of the pole pieces of the main transducer is made and the reference differential voltage is formed between the inner surface of the column and the outer surface of the casing, while the controlled the gaps corresponding to each profiled i-th point of the studied j-th profile, determined by the formula

where a is the distance from the pole pieces of the transducers to the outer surface of the casing;

in - the distance from the outer surface of the casing to the opposite surface of the ferromagnetic body, shunting the pole pieces of the auxiliary transducer;

- опорное разностное напряжение, постоянное по величине, при данном составе бурового раствора на заданной глубине для j-го исследуемого профиля;

- reference differential voltage, constant in magnitude, for a given composition of the drilling fluid at a given depth for the j-th studied profile;

- выходное напряжение основного преобразователя, соответствующее нулевому зазору между внутренней поверхностью колонны и наружной поверхностью кожуха, для j-го исследуемого профиля;

- the output voltage of the main Converter, corresponding to a zero gap between the inner surface of the column and the outer surface of the casing, for the j-th studied profile;

- выходное напряжение вспомогательного преобразователя для j-го исследуемого профиля;

- output voltage of the auxiliary converter for the j-th studied profile;

j = 1, 2, 3, ..., No. - serial number of the studied profile;

No. - the number of profiles studied;

- текущее разностное напряжение для j-го исследуемого профиля в i-ой профилографируемой точке;

- the current differential voltage for the j-th profile under study at the i-th profiled point;

- текущее выходное напряжение основного преобразователя для j-го исследуемого профиля в i-й профилографируемой точке;

- the current output voltage of the main converter for the j-th studied profile at the i-th profiled point;

i = 1, 2, 3, ..., k is the serial number of the profiled point of the profile under study;

k is the number of profiled points of the studied profile.

Moreover, in the proposed method, magnetic shunting of the main transducer can be carried out by pressing the casing to the unworn internal surface of the investigated section of the column.

In addition, magnetic shunting of the main converter can be carried out using a ferromagnetic shutter installed on the device.

In addition, the formation of the reference differential voltage can be carried out using an additional converter placed in the device, similar in parameters to the first two, which is periodically connected to the measuring circuit instead of the main converter with pole tips, shunted by an additional ferromagnetic body with a fixed gap equal to the distance from the pole tips main and auxiliary converters to the outer surface of the casing.

Moreover, it is advisable to install the additional converter inside the casing at the same height level with the main and auxiliary converters, and the orientation plane of its pole pieces should be positioned at an angle of 90-135 ° relative to the orientation planes of the pole pieces of the other two transducers.

In addition, it is advisable to separate the current and reference differential voltages from the output voltages of the converters obtained by their half-wave rectification.

Moreover, it is advisable to half-wave rectify the output voltages of the converters alternately using one rectifier.

The distinguishing features of the proposed method for studying the inner surface of the casing from the above known closest to it are the formation of output voltages of the auxiliary transducer, proportional to the magnetic permeability of the drilling fluid by shunting its pole tips with a ferromagnetic body with a gap relative to the outer surface of the protective casing, providing free circulation of the solution placing a ferromagnetic body from the outer surface of the casing at a distance not exceeding the operating range of the transducers and installing an auxiliary transducer at the same altitude level as the main one, as well as adjusting the calibration characteristics of the sensor under borehole conditions taking into account changes in the magnetic permeability of the solution by means of short-term magnetic shunting of the pole pieces of the main transducer and the formation of the corresponding zero clearance between the inner surface of the casing and the outer surface of the skin ha of the reference differential voltage with the subsequent determination of controlled gaps according to the algorithm (1). Other distinctive features are the possible options for the formation of the reference differential voltage, carried out by pressing the casing to the unworn internal surface of the investigated section of the column or using a ferromagnetic shutter installed on the borehole device, or using an additional converter placed in the device, similar in parameters to the first two, which are periodically connected to the measuring circuit instead of the main converter with pole tips shunted additional a solid ferromagnetic body with a fixed gap equal to the distance from the pole pieces of the main and auxiliary transducers to the outer surface of the casing. In addition, the hallmark is the ability to install an additional transducer inside the casing at the same height level with the main and auxiliary transducers with the orientation of its pole pieces relative to the orientation planes of the pole pieces of the latter two at an angle of 90 ÷ 135 °. Distinctive features, in addition, are the separation of the current and reference differential voltages from the output voltages of the converters obtained by their half-wave rectification, as well as the implementation of two-half-wave rectification of the output voltage of the converters in turn using one rectifier.

The proposed method is illustrated by the drawings shown in figures 1-8.

Figure 1 shows the electrokinematic diagram of the measuring part of the downhole profilograph to study the inner surface of the casing strings.

Figure 2 is a graph of the profiler readings on the size of the controlled gaps between the inner surface of the casing and the outer surface of the protective casing of the sensor.

Figure 3 presents one of the options for downhole profilograph, a General view with a partial longitudinal section.

Figure 4 is a second possible embodiment of a downhole profilograph, a fragment of a General view with a partial longitudinal section.

Figure 5 is a section aa in figure 4.

In Fig.6 is a view of B in Fig.4.

7 is an electrokinematic diagram of a third possible embodiment of a downhole profilograph.

On Fig shows a possible installation diagram of the transducers of the sensor for the third embodiment of the downhole profilograph.

The essence of the method is as follows.

Before conducting a cased well survey, a profilograph made in accordance with the electro-kinematic diagram of FIG. 1 is connected via a unified cable lug through a three-core geophysical armored cable to a typical computerized logging station. Then, in terrestrial conditions, they check the operability of the device, remove the calibration dependence and enter the data into the station computer. In this case, the profiler, as usual, contains a compensated security case, centralizers, control and monitoring elements, a measuring circuit, a non-contact sensor of a mutually inductive (transformer) type, enclosed in a thin-walled magneto-transparent protective casing with a rotation drive. Moreover, in the considered method, the sensor is a sensitive module, composed of two rigidly connected to the casing 1 (see Fig. 1), identical in parameters and electrically interconnected transformer converters, one of which is the main 2 for the purpose and the other is auxiliary 3. Converters 2 and 3 contain U-shaped cores made of charged electrical steel with low hysteresis losses and are installed in the casing 1 along its generators at the same height level, i.e. when placing the neutrals of said cores in one transverse plane. The pole tips of the cores of the transducers 2 and 3 are turned in different directions and are located from the outer surface of the casing 1 at the same distances, usually not exceeding a = 2 ÷ 3.5 mm, and thus form open magnetic circuits, i.e. containing conditionally aerial initial gaps a = const, which, as a rule, have a greater magnetic resistance compared to other parts of the chains. In order to eliminate the influence of destabilizing factors on the operation of converters 2 and 3, their field windings have the same number of turns W ₁ = W ' ₁ and are connected in series to a stabilized alternating current supply source I ₁ with a stabilized frequency. Secondary (or otherwise signal) windings of transducers 2 and 3 also have an equal number of turns W ₂ = W ' ₂ and are connected to a measuring circuit that provides alternating transmission of their output voltages, for example, along one of the conductors (LC) and the braid (armor) of the geophysical cable to the input of the logging station with subsequent measurement, registration and primary processing of the received information, which consists in extracting the differential voltages by subtracting the output voltages of the auxiliary transducer 3 from the output voltages of the main 2. To carry out the forming process of the measuring circuit comprises a two-position switch K. In order to avoid phase distortion and eliminate problems connected with the influence of changes in the electrical characteristics of the logging cable, isolation of difference voltages is advantageously carried out at a constant current. For this, a half-wave diode rectifier D is introduced into the measuring circuit of the profilograph. In this case, the main transducer 2 serves to determine the gaps δ _i between the inner surface of the casing 4 (when a closed magnetic circuit is formed with it) and the outer surface of the casing 1. Auxiliary transducer 3 is shunted by a ferromagnetic body in the form of a plate screen 5 of soft magnetic steel with a gap of = const relative to the outer surface of the casing 1 and is intended to obtain an output voltage proportionally the magnetic permeability of the working medium in the aforementioned gap, which, for obvious reasons, cannot exceed the operating range of converters 2 and 3, and from a structural and technological point of view, its choice is preferable in the range of = 7 ÷ 15 mm. Moreover, the cores of the transducers 2 and 3 have a common-mode (unidirectional) flow of magnetic fluxes, which ensures mutual repulsion of their magnetic fields from each other, respectively, towards the inner surface of the column 4 and the screen 5. This allows you to install the transducers 2 and 3 at a fairly close distance from each other without shielding and improve the radiation pattern of the sensor during its rotation.

Based on the difference method of extracting the useful signal, the characteristic of the considered profilograph sensor can be represented in the following general form:

- коэффициент пропорциональности;Where

- coefficient of proportionality;

ω = 2πf is the circular frequency of the supply current;

f is the current frequency;

I ₁ - the magnitude of the current in the field windings of the converters;

W ₁ - the number of turns in the field windings of the converters;

W ₂ - the number of turns in the signal windings of the converters;

µ _o - magnetic permeability of air;

µ _p - magnetic permeability of the working fluid (drilling fluid);

S _B is the cross-sectional area of the air gap at the pole tips of the converters.

, получаемую в процессе градуировки профилографа на устье скважины в изъятом из нее буровом растворе (фиг.2). Для получения этой зависимости используют градуировочное приспособление, например, в виде имитирующей участок колонны ферромагнитной желобообразной пластины, оснащаемой электронным штангенциркулем и устанавливаемой на корпусе прибора с возможностью радиального перемещения относительно полюсных наконечников основного преобразователя 2 от точки соприкосновения с поверхностью кожуха 1 на расстояние, не превышающее диапазона его работы. Результаты градуировки заносятся в память компьютера каротажной станции и в дальнейшем используются при исследовании внутренней поверхности обсадной колонны. Причем в условиях нормальной среды (на воздухе) с µ_р=µ_о характеристика (2) примет вид:Characteristic (2) is a relationship

obtained in the process of calibrating the profilograph at the wellhead in the drilling fluid withdrawn from it (figure 2). To obtain this dependence, a calibration device is used, for example, in the form of a ferromagnetic gutter plate imitating a column section equipped with an electronic vernier caliper and mounted on the device’s body with the possibility of radial movement relative to the pole tips of the main transducer 2 from a point of contact with the surface of the casing 1 by a distance not exceeding the range his works. The calibration results are recorded in the memory of the computer logging station and are subsequently used in the study of the inner surface of the casing. Moreover, in a normal environment (in air) with µ _p = µ _о characteristic (2) will take the form:

.Where

.

, отражающая характеристику (3), будет являться исходной и по форме совпадать с рабочей кривой, представленной на фиг.2, а также пересекать ось абсцисс в прежней точке, т.е. на расстоянии в от начала координат, обеспечивая при этом получение

и переход к его отрицательным значениям при δ_i>в. Опорная точка исходной кривой, находящаяся на оси ординат при δ_i=0, будет располагаться ниже опорной точки рабочей кривой, а нижняя ветвь исходной кривой в области отрицательных значений

займет верхнее положение по отношению к нижней ветви рабочей кривой. Отсюда следует, что по показаниям профилографа, полученным в процессе его градуировки в рабочей среде с отличающейся магнитной проницаемостью можно построить семейство кривых, пересекающихся в одной точке на оси абсцисс и характеризующихся разным местоположением опорных точек на оси ординат с соответствующими им опорными разностными напряжениями. Очевидно, что определение этих напряжений в скважинных условиях позволит, как это показано ниже, переходить вследствие изменения магнитной проницаемости рабочей среды от одной градуировочной зависимости к другой.In this case, the curve (shown in phantom in the drawing), the dependencies

, reflecting characteristic (3), will be initial and coincide in shape with the working curve shown in figure 2, and also cross the abscissa axis at the previous point, i.e. at a distance from the origin, while providing

and the transition to its negative values for δ _i > in. The reference point of the original curve, located on the ordinate axis with δ _i = 0, will be located below the reference point of the working curve, and the lower branch of the original curve in the region of negative values

will occupy the upper position in relation to the lower branch of the working curve. It follows that according to the profilograph readings obtained during its calibration in a working medium with different magnetic permeability, it is possible to construct a family of curves intersecting at one point on the abscissa axis and characterized by different locations of the reference points on the ordinate axis with the corresponding reference differential voltages. Obviously, the determination of these stresses in downhole conditions will allow, as shown below, to pass due to changes in the magnetic permeability of the working medium from one calibration dependence to another.

Undoubtedly, the implementation of the proposed method with preliminary calibration of the profilograph at the wellhead in the working medium due to the difference in the selection of useful signals and the presence of a solution in the working gaps of the transducers 2 and 3 provides a sufficiently high accuracy of the study of the inner surface of the casing strings with solutions containing barite , siderite, hematite. However, for the study of cased wells with heavier drilling fluids containing magnetite additives and other ferromagnetic inclusions, this use of the method is irrational due to the deposition of ferromagnetic particles and their different concentrations in the solution at different depths. In addition, the calibration of the profilograph in the drilling fluid at the wellhead before lowering into the well reduces the usability and research productivity.

Obviously, the most preferable from both a metrological and operational point of view is such a form of implementation of the proposed method, which provides for the possibility of graduating a profilograph at predetermined depths in a cased well immediately before measurements. This possibility arises when finding the algorithm for determining δ _ij , which allows to exclude the proportionality coefficient A. From the measurement results, it is enough to make a short-term magnetic shunting of the pole pieces of the main transducer 2 and obtain the corresponding zero clearance (δ _i = 0) between the inner surface of the column 4 and the outer surface casing 1 reference differential voltage in the form:

Considering that for a profilograph at least an insignificant time in an unchanged working medium, the proportionality coefficient A within this time is a constant value, from expressions (2) and (4) we will have

Hence, after the transformations, we obtain the desired algorithm (1) for determining controlled gaps δ _ij corresponding to each profiled i-th point of the investigated j-th profile of the inner surface of the casing, intended for secondary computer processing of useful information transmitted from the cased well.

As follows from the expression (1), it is acceptable for the implementation of the proposed method in any really existing downhole environment, since it is well known that the magnetic permeability of a solid body (columns, transducer cores) is always less than the permeability of a substance (drilling fluid). Thus, the proposed method by definition becomes universal and, depending on the method of magnetic shunting of the main transducer at δ _i = 0, can be implemented in three versions.

Option 1. To implement the proposed method, a profilograph can be used that uses the principles of building known devices for monitoring the technical condition of cased wells, providing the possibility of radial movement of the sensor in the well [see, for example, auto review. USSR No. 787627 (publ. 15.12.80) and autosvid. USSR No. 863849 (publ. 15.09.81)]. Such a profilograph (Fig. 3) includes a measuring part, made in accordance with the electrokinematic circuit shown in Fig. 1, and contains a sensor rigidly connected to the protective casing 1 and consisting of identical main and auxiliary transformer transducers 2 and 3 in terms of parameters the first of which is designed to interact with the inner surface of the studied casing 4, and the second is to interact with a gutter-shaped ferromagnetic screen 5, rigidly connected to the casing 1 and installed with a fixed th e gap in respect to its outer surface. U-shaped cores of converters 2 and 3 carry excitation windings 6 and 7, respectively, fed by stabilized alternating current with a stabilized frequency, and also signal windings 8 and 9. Moreover, the pole tips of converters 2 and 3 are located at equal distances from the outer surface of the casing 1 equal to the value of a. Moreover, the casing 1 is made of a heat-resistant solid dielectric or non-magnetic metal with a high electrical resistivity (manganin, steel, titanium) and together with the screen 5 is rigidly attached to the parallelogram mechanism, closed in the drawing with a flexible sleeve 10 and mounted on the end of the rotor 11 with the possibility radial movement of the sensor under the action of the drive 12 mounted inside the rotor 11. Other typical structural elements of the profilograph, providing the implementation of the proposed method, are mustache 13, filled with dielectric fluid, pressure compensator 14, upper and lower centralizers 15 and 16, electrical unit 17 located in a pressure-resistant chamber with electric input 18 and connected through a unified cable lug 19 with a three-core geophysical armored cable 20 connected to the input of a computerized logging station (not shown), a rotary drive 21 of the rotor 11 carrying the measuring part, and a protective casing 22 of this part of the device.

Before lowering the considered profilograph into a cased hole, under normal conditions using a calibration device, the calibration dependence is removed in accordance with the characteristics of the device (3). When the gap δ _i = 0 receive the reference voltage in the form:

The magnitude of this voltage is recorded in the memory of the logging station computer and, using algorithm (1), a profilograph is tested to determine its accuracy characteristics and readiness to conduct a study of the technical condition of casing strings in wells. Moreover, it is advisable to carry out this preparatory operation at the base before going to the well.

After entering the profilograph into the test column 4 with the drilling fluid, it is stopped. Using drive 12, the measuring part of the device is radially moved in the direction of the sensitivity zone of the main transducer 2 until a working gap of the order of δ _p = 6 ÷ 10 mm is determined, determined by the difference between the nominal radius of the inner surface of the studied column 4 and the distance from the center of rotation of the sensor to the maximum distance from forming the outer surface of the casing 1. Then, using the drive 21, the sensor scans the inner surface of the column 4, determine the profile column an unworn portion of this surface, the sensor is stopped opposite it, and then, using the drive 12, the outer surface of the casing 1 is brought into contact with this surface and, in the case μ _p ≠ μ _{о, the} reference differential voltage is measured in the form (4). The magnitude of this voltage is stored in the computer logging station to ensure subsequent measurement of the gaps δ _ij at each profiled i-th point of the studied j-th profile of the column 4. The metrological control performed in this way allows automatic correction in case of a change in the magnetic permeability of the working medium the calibration dependence of the device and with high accuracy, according to algorithm (1), determine the current values of the gaps δ _ij . After the casing 1 with the sensor is withdrawn from the inner surface of the column 4 to a distance δ _{p, the} sensor rotation drive 21 is turned on and the profilograph is launched to a predetermined depth at a speed that provides a step size (usually h _c = 0.2 ÷ 0.3 m) of screw scanning, excluding the loss of information about the presence of defects on the inner surface of the investigated column 4. The main task to be solved is to identify zones of trough-like wear and their length on the inner surface of the studied column 4.

. После чего с шагом h_c при остановках прибора для получения более качественной (детальной) информации в интересующих оператора интервалах желобного износа выполняют профилографирование поперечных профилей внутренней поверхности исследуемой колонны. Эту операцию повторяют по мере протяженности и количества зон износа, а получаемую в ходе исследования информацию используют в дальнейшем для определения расчетным путем фактических прочностных характеристик исследованной обсадной колонны.At the end of the cased well borehole sounding performed in this way, the profilograph is stopped at a predetermined depth, then it is raised to the identified wear zone of the inner surface of the column and, in accordance with the method described above, the next control metrological operation is performed to refine the value of the previously measured reference differential voltage

. Then, in increments of h _c, when the device stops, to obtain better (detailed) information in the intervals of groove wear of interest to the operator, profiling of the transverse profiles of the inner surface of the column under study is performed. This operation is repeated as the length and number of wear zones are used, and the information obtained during the study is used in the future to determine by actual calculation the actual strength characteristics of the studied casing string.

Option 2. To implement the proposed method without radial movement of the sensor, a profilograph can be used, which, as in the first embodiment, includes a measuring part, made in accordance with the electrokinematic circuit shown in figure 1, and contains (figure 4) similar elements designs: protective cover 1 of the sensor, the main and auxiliary transformer transducers 2 and 3, the first of which is designed to interact with the inner surface of the studied casing 4, and the second for interactions with a gutter-shaped ferromagnetic screen 5, field windings 6 and 7 and signal windings 8 and 9, placed on the U-shaped cores of transducers 2 and 3, as well as centralizers not shown in the drawing, pressure compensator and other auxiliary elements characteristic of this type of equipment. New and structurally different elements are: the rotor 23, rigidly connected with the casing 1 and the screen 5, bearing the finger 24 fixed therein, a reversible rotor drive 25 of the rotor 23, housed in the housing 26, as well as an abutment 27 in the form of an annular sector (Fig. 5), rigidly mounted on the shutter 28, which is coaxially mounted on the housing 26 with the possibility of rotation relative to its surface. In this case, the shutter 28 has an upper end made in the form of a cylindrical glass with a bottom hole covering the annular groove provided on the surface of the lower part of the housing 26 and excluding, for example, due to frictional forces, spontaneous rotation of the shutter 28 on the body of the housing 26. Moreover, the inner surface the lower part of the curtain 28 has the ability to gapless (to ensure δ _i = 0) to come into contact with the outer surface of the casing 1 in the area of the main transducer 2.

обеспечивают с помощью шторки 28, шунтирующей полюсные наконечники основного преобразователя 2. Причем измерение этого напряжения может производиться при вращении ротора 23 с датчиком, например, против направления вращения часовой стрелки (см. фиг.5). В этом случае палец 24, находясь в контакте с правым концом упора 27, будет обеспечивать принудительное вращение шторки с сохранением исходного положения относительно полюсных наконечников основного преобразователя 2, необходимого для проведения контрольной метрологической операции. После завершения этой операции с помощью реверсивного привода 25 изменяют направление вращения ротора 23 на противоположное. В этом случае палец 24, выходя из соприкосновения с правым концом упора 27, совершает свободное перемещение на 180° до вхождения в контакт с его левым концом. После чего, шторка 28 захватывается этим пальцем 24 и вращается совместно с ротором 23 по направлению вращения часовой стрелки. При этом нижняя (шунтирующая) часть шторки 28 располагается за экраном 5, а полюсные наконечники основного преобразователя 2 открываются для обеспечения возможности сканирования внутренней поверхности колонны с определением геометрических характеристик как винтового, так и поперечных ее профилей по алгоритму (1).Implementation of the proposed method using a profilograph of the described design involves performing similar operations in the same sequence as in the first embodiment. However, in contrast to the profilograph with radial movement of the sensor in the device depicted in figure 4 in the initial state, obtaining the reference differential voltage

provide with the help of a shutter 28, shunting the pole pieces of the main converter 2. Moreover, the measurement of this voltage can be performed by rotating the rotor 23 with a sensor, for example, counterclockwise (see FIG. 5). In this case, the finger 24, being in contact with the right end of the abutment 27, will provide forced rotation of the shutter while maintaining the initial position relative to the pole pieces of the main transducer 2, which is necessary for the control metrological operation. After completing this operation, using the reversing drive 25, the direction of rotation of the rotor 23 is reversed. In this case, the finger 24, coming out of contact with the right end of the stop 27, makes a free movement of 180 ° until it comes into contact with its left end. After that, the shutter 28 is captured by this finger 24 and rotates together with the rotor 23 in the clockwise rotation direction. In this case, the lower (shunting) part of the shutter 28 is located behind the screen 5, and the pole tips of the main transducer 2 are opened to enable scanning of the inner surface of the column with determination of the geometric characteristics of both its screw and transverse profiles according to algorithm (1).

The considered embodiment of the proposed method does not exclude the use of shunt shutters and other types of triggering mechanisms.

. Сигнальная обмотка дополнительного преобразователя 29 также имеет равное с двумя другими количество витков

и подсоединена к ним с возможностью их поочередного подключения с помощью коммутатора К к измерительной схеме профилографа. Коммутатор К в наипростейшем виде позволяет подключать к геофизическому кабелю через выпрямитель Д сигнальную обмотку основного преобразователя 2 в течение промежутка времени, обеспечиваемого поворотом поводка на 180° при скольжении его щетки по поверхности контактной пластины 31. Две другие контактные пластины 32 и 33 обеспечивают контактирование с щеткой при перемещении поводка 34 на угол, меньший 90°. Причем контактная пластина 32 подключена к сигнальной обмотке вспомогательного преобразователя 3, а контактная пластина 33 к сигнальной обмотке дополнительного преобразователя 29. При этом зазоры между всеми контактными пластинами 31, 32 и 33 используются для получения всплеск-меток, позволяющих определять очередность подключения к каротажной станции (на схеме не показана) преобразователей 2, 3 и 29. Причем полюсные наконечники дополнительного преобразователя 29 зашунтированы ферромагнитным телом 30 с зазором а, равным соответствующим зазорам основного и вспомогательного преобразователей 2 и 3, а сам преобразователь 29 предназначен для имитации беззазорного по отношению к кожуху 1 шунтирования полюсных наконечников основного преобразователя 2 с целью получения при периодическом проведении контрольных метрологических операций опорных разностных напряжений

. Для обеспечения возможности проведения исследования обсаженных скважин профилографом, выполненным в соответствии с описанной схемой (см. фиг.7), необходимо, чтобы угловая скорость поводка 34 коммутатора К была вдвое меньше угловой скорости вращения датчика. Эта задача легко решается с помощью одного электродвигателя с двумя редукторами (на схеме не показаны), имеющими отличающиеся передаточные отношения. Что же касается местоположения дополнительного преобразователя 29 с шунтирующим его полюсные наконечники ферромагнитным телом 30, то оно может быть любым в зависимости от конструкции профилографа, однако наиболее предпочтительной для минимизации погрешностей, вызванных изменением температуры окружающей среды, является его установка внутри кожуха 1 на одном высотном уровне с основным и вспомогательным преобразователями 2 и 3, т.е. при расположении нейтралей их сердечников в одной поперечной плоскости. Причем для уменьшения взаимного влияния электромагнитных полей преобразователей 2, 3 и 29 плоскости ориентации их полюсных наконечников целесообразно располагать под углом 90÷135° одна относительно другой. На фиг.9 при поперечном сечении кожуха 1 и виде снизу изображена возможная схема установки преобразователей 2, 3 и 29. При этом кожух 1 с целью повышения компактности измерительной части профилографа выполнен в поперечном сечении профилированным, благодаря чему экран 5 и ферромагнитное тело 30 оказываются вписанными по наружной поверхности с кожухом 1 в окружность одного диаметра. Причем в данном случае плоскость ориентации полюсных наконечников основного преобразователя 2 расположена под углом 120° к плоскости ориентации полюсных наконечников вспомогательного преобразователя 3 и под углом 105° к плоскости ориентации полюсных наконечников дополнительного преобразователя 29. При необходимости в кожухе 1 между преобразователями 2, 3 и 29 на хвостовике 35 могут быть установлены три одинаковые экранирующие пластины 36, изготовленные из магнитомягкой стали.Option 3. In contrast to the above, the present embodiment of the proposed method eliminates the need for the use in the used profiler of the operations of forced magnetic shunting of the sensor element of the sensor to obtain the reference differential voltage. To ensure this, the electrokinematic diagram of the profilograph shown in Fig. 7 differs from the circuit in Fig. 1 by the presence of an additional transformer transducer 29 with shunting pole pieces by an additional ferromagnetic body 30 in the form of a plate made of soft magnetic steel, as well as the implementation of the switch K three-position in the form of an electrical insulation board with three contact plates 31, 32 and 33, having the form of annular sectors, and a leash 34, carrying a flycatcher type electric brush. The additional Converter 29 is made similar to the parameters of the main and auxiliary converters 2 and 3. Moreover, its U-shaped core carries an excitation winding connected in series to the excitation windings of the first two converters 2 and 3 and has a number of turns

. The signal winding of the additional converter 29 also has an equal number of turns with two other

and connected to them with the possibility of their alternate connection using the switch K to the measuring circuit of the profiler. The switch K in its simplest form allows you to connect to the geophysical cable through the rectifier D the signal winding of the main transducer 2 for a period of time provided by turning the leash 180 ° while sliding its brush on the surface of the contact plate 31. Two other contact plates 32 and 33 provide contact with the brush when moving the leash 34 at an angle less than 90 °. Moreover, the contact plate 32 is connected to the signal winding of the auxiliary transducer 3, and the contact plate 33 is connected to the signal winding of the additional transducer 29. In this case, the gaps between all contact plates 31, 32 and 33 are used to obtain burst marks that allow determining the sequence of connection to the logging station ( the diagram does not show) converters 2, 3 and 29. Moreover, the pole pieces of the additional converter 29 are shunted by the ferromagnetic body 30 with a gap a equal to the corresponding gaps SIC and auxiliary converters 2 and 3, and the inverter 29 is intended to simulate a backlash with respect to the casing 1 shunt pole pieces of the main converter 2 in order to obtain the periodic conducting control operations metrological reference of difference voltages

. To enable the study of cased wells with a profilograph made in accordance with the described scheme (see Fig. 7), it is necessary that the angular velocity of the lead 34 of switch K be half the angular velocity of rotation of the sensor. This problem can be easily solved with the help of a single electric motor with two gearboxes (not shown in the diagram) having different gear ratios. As for the location of the additional transducer 29 with the ferromagnetic body 30 shunting its pole pieces, it can be any depending on the design of the profilograph, however, it is most preferable to minimize errors caused by changes in the ambient temperature inside the casing 1 at the same height level with main and auxiliary converters 2 and 3, i.e. with the arrangement of the neutrals of their cores in one transverse plane. Moreover, to reduce the mutual influence of the electromagnetic fields of the transducers 2, 3 and 29 of the orientation plane of their pole pieces, it is advisable to place them at an angle of 90 ÷ 135 ° relative to each other. In Fig. 9, with a cross-section of the casing 1 and a bottom view, a possible installation diagram of the transducers 2, 3 and 29 is shown. In this case, the casing 1 is made profiled in cross-section in order to increase the compactness of the measuring part of the profilograph, so that the screen 5 and the ferromagnetic body 30 are inscribed on the outer surface with a casing 1 in a circle of one diameter. Moreover, in this case, the orientation plane of the pole pieces of the main converter 2 is located at an angle of 120 ° to the orientation plane of the pole pieces of the auxiliary converter 3 and at an angle of 105 ° to the orientation plane of the pole pieces of the auxiliary converter 29. If necessary, in the casing 1 between the transducers 2, 3 and 29 three identical shielding plates 36 made of soft magnetic steel can be mounted on the shank 35.

и определения зазоров δ_ij по алгоритму (1). Этот процесс может повторяться до тех пор, пока не будет прекращено вращение датчика. Здесь следует отметить, что при увеличении длины контактной пластины 31, соответствующем уменьшении длин контактных пластин 32 и 33 и изменении передаточных отношений вышеупомянутых редукторов можно существенно повысить производительность исследования профилографом обсаженной скважины за счет увеличения числа непрерывно следующих один за другим оборотов датчика с подключенным к каротажной станции основным преобразователем 2 в промежутках между одинарными оборотами, используемыми для съема информации с дополнительного и вспомогательного преобразователей 29 и 3.The process of implementing the proposed method in this embodiment is basically similar to the processes in the first two variants. However, in contrast to them, carrying out control metrological operations in the process of studying the inner surface of the column under consideration does not require stops of the profilograph at given depths. This is because when the sensor rotates in one revolution, the readings of the additional transducer 29 and then the auxiliary transducer 3 are recorded alternately (see Fig. 7). The obtained stress values are stored in the logging computer computer and, during the next rotation of the sensor, which provides scanning of the inner surface of the test column while the lead brush 34 is on the contact plate 31, they participate in the operations of isolating the current differential voltages

and determining the gaps δ _ij according to algorithm (1). This process can be repeated until the rotation of the sensor is stopped. It should be noted here that with an increase in the length of the contact plate 31, a corresponding decrease in the lengths of the contact plates 32 and 33 and a change in the gear ratios of the aforementioned gearboxes, it is possible to significantly increase the productivity of the cased hole profilograph study by increasing the number of sensor turns continuously connected one after the other with the logging station the main Converter 2 in the intervals between single revolutions, used to extract information from the auxiliary and auxiliary interface converter 29 and 3.

The use of the invention will significantly improve the accuracy of determining the profile of the inner surface and the groove wear of the inner surface of the casing strings in deep and superdeep oil and gas wells.

Claims (8)

1. A method for studying the profile of the inner surface of casing strings with drilling fluid in the borehole with the radial method for checking the gaps between the inner surface of the casing and the outer surface of the protective casing of the rotary sensor of the device with two main and auxiliary transformers with pole tips facing identical to the measuring circuit, facing to the wall of the casing, which consists in the fact that at each profiled point of the studied profile producing t is the measurement of the output voltages of the main converter, the output voltages of the auxiliary converter are subtracted from them with subsequent registration and processing of the obtained current differential voltages, characterized in that the output voltages of the auxiliary converter are formed proportional to the magnetic permeability of the solution by shunting its pole tips with a ferromagnetic body with a gap with respect to the outer the surface of the casing, providing free circulation of the solution, while the ferromagnet the total body is placed from the outer surface of the casing at a distance not exceeding the operating range of the transducers, and the auxiliary transducer itself is installed at the same height level with the main one. 2. The method according to claim 1, characterized in that during the studies, the calibration of the sensor is adjusted taking into account the change in the magnetic permeability of the solution, for which a short-term magnetic shunting of the pole pieces of the main transducer is performed and a corresponding zero clearance is formed between the inner surface of the column and the outer surface of the casing reference differential voltage, and controlled gaps corresponding to each profiled i-th point of the studied 7th profile I, determined by the formula

,
where a is the distance from the pole pieces of the transducers to the outer surface of the casing;
in - the distance from the outer surface of the casing to the opposite surface of the ferromagnetic body, shunting the pole pieces of the auxiliary transducer;
U _{support j} = U _OPj -U _VPj - reference differential voltage constant in magnitude for a given composition of the drilling fluid at a given depth for the j-th studied profile;
U _OPj - the output voltage of the main Converter, corresponding to zero clearance between the inner surface of the column and the outer surface of the casing, for the j-th studied profile;
U _VPj is the output voltage of the auxiliary converter for the j-th studied profile;
j = 1, 2, 3, ..., No. - serial number of the studied profile;
No. - the number of profiles studied;
U _resij = U _δij -U _VPj - current differential voltage for the j-th profile under study at the i-th profiled point;
U _δij is the current output voltage of the main converter for the j-th studied profile at the i-th profiled point;
i = 1, 2, 3, ..., k is the serial number of the profiled point of the profile under study;
k is the number of profiled points of the studied profile. 3. The method according to claim 2, characterized in that the magnetic bypass of the main Converter is produced by pressing the casing to the unworn internal surface of the investigated section of the column. 4. The method according to claim 2, characterized in that the magnetic shunting of the main Converter is carried out using a ferromagnetic curtain installed on the device. 5. The method according to claim 2, characterized in that the formation of the reference differential voltage is carried out using an additional transducer located in the device, similar in parameters to the first two, which are periodically connected to the measuring circuit instead of the main transducer with pole pieces, shunted by an additional ferromagnetic body with a fixed a gap equal to the distance from the pole pieces of the main and auxiliary transducers to the outer surface of the casing. 6. The method according to claim 5, characterized in that the additional converter is installed inside the casing at the same height level with the main and auxiliary converters, and the orientation plane of its pole pieces is positioned at an angle of 90 ÷ 135 ° relative to the orientation planes of the pole pieces of the other two transducers. 7. The method according to one of claims 1 to 6, characterized in that the separation of current and reference differential voltages is carried out from the output voltages of the converters obtained by their half-wave rectification. 8. The method according to claim 7, characterized in that the half-wave rectification of the output voltage of the converters is carried out alternately using one rectifier.

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