SU996856A1 - Device for measuring deformation - Google Patents

Description

The invention relates to measuring equipment, in particular to devices for measuring rock deformations.

A device for measuring radial deformation of a well is known, comprising a cylindrical body, cantilever beams with strain gauges and measuring supports in contact with the walls of the well during measurements (1].

However, such a device allows only radial displacements of the well walls to be measured, which are not enough to calculate the total stress tensor.

Closest to the invention in technical essence is a device for measuring strain, comprising a cylindrical body with. cantilever beams placed along its perimeter parallel to the generatrix, and strain gauge sockets of three sensors mounted on each beam. Two beams are placed at an angle of 90 ° to each other, and the third at an angle of 135 ° to each of the first two, and the sensors on them, respectively, at an angle of 90 °, 45 °, 0 ° to the generatrix of the housing [2].

However, the known arrangement of sensors and cantilever beams does not provide the most informative 5 measured strains to calculate the effective stresses in the well. In addition, in the known construction, three longitudinal sensors actually duplicate each other, while of the remaining six sensors, the lie is the only control. This circumstance also reduces the reliability of the experiment as a whole, since in the event of failure of any two non-longitudinal DAFs during the “experiment • 5 experiment, the calculation of the stress tensor becomes impossible due to insufficient independent measurements.

The aim of the invention is to increase the accuracy of measurements.

This goal is achieved by the fact that in the device for measuring strains, containing a cylindrical body with cantilever beams placed along its perimeter parallel to the generatrix, and installed on each beam tensometric sockets from. of three sensors, the beams are placed at an angle of 120 ° to each other, and the sensors on them, respectively, at an angle of 30 ± 2® 30 77 ± 2 °, 117 + 4 ° to the cylinder generatrix.

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This arrangement of cantilever beams and sensors provides a minimum of generalized variance of the estimates of the components of the stress tensor.

In FIG. 1 shows a device for measuring strain, longitudinal section; in FIG. 2 - section AA on. FIG. 1; in FIG. 3 is a view B in FIG. 2.

The device comprises a cylindrical housing 1, cantilever beams 2, placed along the perimeter of the housing 1 parallel to the generatrix, and strain gauge sockets 3 of three sensors mounted on each beam 2. Cantilever beams 2 are placed at an angle of 120 ° to each other (Fig. 2), and sensors on them, respectively, at an angle of 30 ± 2 °, 77 ± 2 °, 117 ± 4 ° to the generatrix of the cylinder (Fig. 3).

Strain gauge sockets 3 are placed on the rubber plates 5, pre-glued on the cantilever beams 2.

The device also contains a cap 6, a rod 7 and a tension nut 8. The sealing of strain gauge sockets 3 in the well (not shown in the drawing) is carried out using rubber rings 9 and 10. Electrical connection with the sensors 4 is carried out using cable 11..

The device operates as follows.

Before installing the device in the well, the cantilever beams 2 are precompressed using the cap b, the rod 7 and the tension nut 8. After installing the device in the well, the tension; the nut 8 is unscrewed from the rod 7, the cap b releases the cantilever beams 2, which

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VNIIIPI Order 917/58 J Circulation 600 Subscription The pressure of sensors 4 to the walls of the well is injected. From each sensor 4 readings are taken, based on which the deformation of the well is determined.

Thus, the optimal placement of sensors on the surface of the well. Zhina allows increasing the accuracy of measurements of the deformation of the surface of the well the generalized variance of the estimates of the desired stresses decreases by a factor of compared with the known design, the reliability of the experiment as a whole increases, since the calculation of stresses is possible even with poor-quality operation or the breakdown of three sensors.

Claims (1)

Claim A device for measuring deformations, comprising a cylindrical body with cantilever beams placed along its perimeter parallel to the generatrix, and strain gauge sockets of three sensors mounted on each beam, characterized in that, in order to improve the measurement accuracy, the beams are placed at an angle of 120 ° to each other , and the sensors on them, respectively, at an angle of 30 ± 2®, 7712®, 117 ± 4 ° to the cylinder generatrix.