SU1717806A1 - Inclination and sight angle sensor - Google Patents

Abstract

The invention relates to field geophysics and is intended to determine the spatial position of a well trajectory. The purpose of the invention is to improve the measurement accuracy of the zenith angle and noise immunity. The sensor contains a cylindrical body 1 of conductor material, four rod p CO with 4 00 O O

Description

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electrode 2 located parallel to the axis of the housing 1 at equal distances from each other and from the housing and intersecting the interface between the immiscible dielectric 4 and electrically conductive 5 fluids. Along the axis of the housing 1, a hollow cylinder 3 of conductor material is installed, insulated from the housing 1, electrodes 2 and liquids 4.5 using dielectric bushings 6-9. In addition, the sensor contains a fifth electrode 10, has a cylindrical shape and is completely immersed in a conductive liquid 5. When the sensor is rotated, the interface of liquids 4.5 is displaced along the rod electrodes 2, as a result of which the conductivities between the electrodes 2 and the housing 1 change. the fifth electrode 10 and the housing 1 remains unchanged. The values of these conductivities are used to calculate the zenith and target angles. 2 Il.

This invention relates to field geophysics and can be used in inclinometers as primary transducers of zenith and target angles.

A known zenith angle transducer for measuring the curvature of a borehole, comprising a body mounted coaxially with the body in rotational bearings, a movable frame and a toroidal cavity with electrodes, which is mounted on the movable frame, communicates with a cylindrical spiral tube and is filled with two immiscible liquids.

The disadvantages of the converter are the difficulty of manufacturing a toroidal cavity with electrodes due to its specific configuration and low reliability when operating under vibration conditions due to the use of a solid-state moving frame, rotational supports, and also due to the necessity of using a collector to remove signals from the moving frame . In addition, the disadvantage of the transducer is the low accuracy of angle measurements due to the change in the ratio of the volumes of liquids in the electrode area and the change in the physical properties of the liquids (electrical permeability and resistivity) under the action of temperature. The latter factors are largely due to the toroidal shape of the working cavity of the device, the use of which places the measured values of the zenith angle directly dependent on the location of the interface between the fluids and the center of symmetry of the toroidal cavity.

Also known is a zenith and target angle sensor, comprising a cylindrical housing, inside which are placed three cylindrical spiral tubes, joined by their upper and lower ends and filled with two immiscible liquids. Upper ends of the tubes

They have straight sections, installed vertically close to the walls of the housing and provided with coaxial electrodes crossing the interface of the fluids. The angles between the planes passing through the axes of the rectilinear sections of the tubes and the axis of the body are 120 °.

The sensor is simpler and more accurate to manufacture, more reliable, because it has no movable mechanical connections. In addition, the sensor has a greater accuracy of measurement, independent of the ratio of the volumes of the liquids being poured, since a change in the ratio of the volumes of liquids, including a temperature change, leads to the same displacement of the interface between liquids along each of the parallel rod electrodes and does not affect angle measurement result.

The disadvantage of the sensor is the error in measuring the zenith angle caused by temperature changes in the physical properties of liquids such as resistivity and electrical conductivity.

Closest to the present invention is a device for measuring tilt and rotation (zenith and sight angles), containing a hollow cylinder of dielectric,

filled with two immiscible liquids, one of which is dielectric and one conductor, several rod electrodes located along the inner wall of the cylinder, and a central electrode located along the axis of the cylinder. All electrodes cross the interface of liquids. Moving the latter leads to a change in electrical conductivities between the electrodes. Measurement

conductivities provide information for determining zenith and target angles by calculation.

The disadvantage of this device is a significant measurement error

zenith angle caused by temperature variation of the electrical resistivity of the working fluid.

The aim of the invention is to improve the measurement accuracy of the zenith angle and increase the noise immunity.

This goal is achieved by that the sensor of the zenith and target angle contains a cylindrical body filled with two immiscible liquids, one of which has dielectric properties, and another conductor parallel to the axis of the body, rod electrodes located at equal distances from each other and from the axis bodies and crossing the interface of liquids, provided with an additional cylindrical electrode, located completely in the volume of the conducting liquid, do not overlap the rod electrodes in the radial direction, and the cylinder matic body is made of conductive material. In addition, the sensor is equipped with a hollow cylinder mounted along the axis of the housing and made of conductive material, as well as with dielectric bushings that isolate the hollow cylinder from the housing, the electrode, and liquids.

Figure 1 shows the block diagram of the sensor; figure 2 - section aa in figure 1.

The sensor contains a cylindrical case A filled with two immiscible liquids, the bottom of which has electrical conductivity and is working, as well as three parallel rod electrodes B, C, D, of which C is central, i.e. located along the axis of the hull. All three electrodes are in the same plane, this plane coincides with the plane of the drawing, and the sensor measures the angle of inclination of the body relative to the gravitational vertical.

Two main variants of the sensor construction are analyzed: 1 - case A is made of dielectric; 2 - case A is made of conductor material and the Electrode is present. In the first version of the sensor, when the housing is tilted, the electrical conductivities between the electrodes B, O and the central electrode C change:

AYBc YBc (t /) -YBc (0),

AYDcfy) -YDc (0), (1)

where Y ($) is the conductivity at a tilt angle if Y (0) is the conductivity at gr 0. Due to the fact that the electrodes are parallel, the measurement of conductivities occurs solely by changing the average area

sections of conductors formed by a conductive fluid between the electrodes, i.e.

AYBC, AYDC, (2)

rd is the electrical resistivity of the fluid; And is the average length of the conductor formed by the conductive fluid between the electrodes, which is equivalent to the distance between the electrodes.

The required angle is determined by the dependence

t / arctg KI (D YDC - AYec)

. arctg 1 (D5os-D SBC), (3)

where KI is a constant coefficient determined by control measurements.

In the second version of the sensor, when the case is tilted, the electrical conductivities between the electrodes B.D and case A change, therefore the measured angle is

V arctg K (D YDA - D YBA)

K2

(four)

 arctg (D SDA - A SBA),

where Ka is a constant empirical coefficient; 2 - the average length of the conductors formed by the liquid between the electrodes and the housing, which is equivalent to the distance between the electrodes and the housing; Azod. A SB A is the average cross-sectional area of the respective conductors.

The average displacement of the interface between the considered pairs of electrodes at the same angle of inclination 1p in the first variant (nij is much smaller than in the second variant (n2). These mixes are proportional to the change in the average cross section of the conductors between the corresponding pairs of electrodes. In the proposed sensor, the housing is made of conductive material. When the ambient temperature changes, the liquids expand volumetrically and the electrical resistivity of the conductive fluid changes. The first factor leads to a displacement of the interface between the fluids along the electrodes and a corresponding increment in the cross-sectional areas of the liquid conductors. If for the second variant of the sensor, we present the change in areas A SDA. A SBA in the form

ASDA SDA (V) -S (0),

A SBA SBA ($ -S (0), (5)

where 5 (0} is the cross-sectional area of the conductors at 0 is the same for both pairs of electrodes, it is easy to see that the calculation of the difference D SDA - D SBA when determining the angle by the formula (4) completely eliminates the effect

parallel displacement of the interface of liquids to the measurement result.

Therefore, if there is a temperature shift in the interface between fluids along parallel electrodes, then it does not affect the result and the measurement accuracy. This is the phenomenological advantage of sensors with straight parallel electrodes compared with other liquid sensors. However, the Ytbroy factor, i.e. temperature change of the fluid resistivity () (t °) causes an error in the angle measurement. In order to take into account the temperature drift of the resistivity, in the proposed device an additional electrode is used that does not cross the interface between the fluids. Therefore, the temperature change in conductivity between this electrode and the housing is caused only by the change in the resistivity of the fluid.

In Fig. 1, an additional electrode is conventionally designated with the letter F, the corresponding conductivity is determined as

SFA

YFA

(6)

f arctg:

(7)

where SFA, IFA are constant values that characterize the cross-section and length of the liquid conductor between the additional electrode and the housing, and determine the desired angle as follows:

Kz (AURA-AUVA)

YFA

where Cs is the new empirical constant coefficient. Then, after transformations, taking into account (4) and (6),

for arctg (ASDA-ASBA) FA. hSFA

 K4 arctg (A SDA - A SBA). (8)

where "4 is a new constant coefficient taking into account only the structural dimensions of the sensor.

Thus, the use of an additional electrode eliminates a significant disadvantage of a sensor with straight parallel electrodes.

The anti-aircraft and target angle sensor (Fig. 2) contains a cylindrical body 1 of conductive material, four rod electrodes 2. parallel to the axis of the body 1, a hollow metal cylinder 3, which is insulated from the internal cavity filled with liquids 4.5 by means of dielectric bushings 6- 9, an additional electrode 10 of a cylindrical shape, mounted on the sleeve 9. In this case, the cylinder 3 performs the role of a chassis on which it is assembled and fixed with nuts

5 0 5 0

five

11 remaining sensor details. The output 12 serves to ensure the electrical contact of the electrode 10 with the electronic circuit, and the screw 13 performs the function of a plug. For the fluid to flow through the sleeve 8, holes 14 are provided in the latter.

The sensor works as follows.

When the case is tilted relative to the gravitational vertical, the interface between the fluids moves along the electrodes 2, resulting in a change in the conductivities formed by the conductive fluid 5 between the electrodes 2 and the case 1. The conductivities change due to a change in the average cross-sectional area of the respective conductors. The change in conductivity occurs both due to the inclination of the sensor to the zenith angle in and due to its rotation around the axis, i.e. when you change the target angle p. These angles are determined by the following ratios

U (U1-Oz) 2+ () 2.

31 Y5

P arctg. (9)

0

five

0

five

0

0 arctg

Yi-Uz

where Y1 ... Y4 is the conductivity between the electrodes 2 and the housing 1;

Y5 is the conductivity between the additional electrode 10 and the housing 1; ai is the empirical coefficient. which is determined by reference measurements. Electrode numbers 1-4 are counted counterclockwise when viewed from above the sensor. In this case, the first electrode is chosen from the condition YI - Uz 0 for Y4 - - Y2 0. Since the conductivity between each of the electrodes 2, including the additional electrode 10, is proportional to the ratio Si / p, where Si is the average cross-sectional area of the corresponding liquid conductor; /) -specific electrical resistance of the fluid 5. The electrodes 2 are parallel, the formula (9) is invariant to the same changes in the cross-sectional area of the conductors between the electrodes 2 and the housing 1 dB and to the value of the specific resistance of the fluid 5, i.e. The displacement of the interface of liquids due to their temperature expansion and change does not affect the measurement result.

If we assume the absence of an additional electrode 10, then in the formula for in the subfunctional expression would be proportional to Mp, i.e. The measured zenith angle would depend on / and its changes. But since in the sensor an additional electrode 10 is applied, completely

immersed in liquid 5, and the corresponding conductivity YS is proportional to 1 / p, then taking into account in the formula the magnitude of this conductivity eliminates the dependence of the bot specific electrical resistance of the fluid, which achieves the effect of increasing the measurement accuracy of the zenith angle. When calculating the sighting angle f, information from the additional electrode 10 is not required. The measurement of conductivities is performed by any of the known transducer circuits, and the processing of information is carried out using computers.

The proposed sensor provides greater measurement accuracy due to the use of an additional electrode fully immersed in the working fluid, as well as greater sensitivity with the same internal diameters of the co-pus due to the manufacture of the housing from conductive material and using the housing as a common electrode. In addition, it provides the possibility of laying transit wires from adjacent blocks through hollow cylinder 3, has greater noise immunity, since the housing 1 and cylinder 3, made of conductive materials, can be connected to the common wire of the circuit and thereby shield the liquid conductors from electromagnetic fields. currents flowing in the transit wires and the protective casing of the sensor.

The maximum value of the systematic error of measurement of the zenith angle is 0.12 ° in the range of 0-80 °, the maximum value of the systematic error of the sight angle is 2 ° at 0 0.5 ° and 0.3 ° at 3-80 °, and the additional The temperature error is practically absent in the range of temperature changes from 0.1 to 20-150 ° C. The sensor used organosilicate fluid as the working conductive fluid 5, and transformer oil as the fluid 4 with dielectric properties.

Claims (1)

Claims of the Zenith and Target Angle Sensor, comprising a cylindrical body filled with non-interchangeable dielectric and electrically conductive liquids, located at equal distances from each other and from the body axis, four rod electrodes intersecting the interface of fluids and the fifth Electrode, characterized in that. in order to improve the measurement accuracy of the zenith angle and noise immunity, it is provided with an axially mounted housing made of conductor material with a hollow cylinder with dielectric sleeves designed to isolate the hollow cylinder from the housing, electrodes and liquids, while the cylindrical housing is made of conductive material and The fifth electrode has a cylindrical shape and is located entirely in the volume of an electrically conductive fluid displaced relative to the rod electrodes in the radial section. / V Shig.2