SU43820A1 - An apparatus for measuring pressures, in particular in boreholes - Google Patents

Description

The proposed device is designed to measure pressures in oil wells. These measurements are very important both when calculating reserves in the new drilled areas and for the most efficient use of industrial oil sites (Baku, Grozny, etc.).

The proposed device is of the type of pressure measuring devices already known, consisting of a closed chamber membrane filled with liquid and connected to a gas tube of smaller diameter, the position of the liquid column to which determines the pressure value.

The invention consists in the fact that, in order to achieve with measurements by means of such an instrument of different pressures of the same accuracy, the tube connected to the chamber closed by the membrane has a variable diameter decreasing towards the upper end, for example, is stepped.

Shown schematically in the drawing, the device consists of a chamber 7 of a large volume, having a bottom, made in the form of a corrugated cylindrical membrane. On top of the chamber / is connected to the tube 2 of a smaller diameter, and this diameter gradually decreases towards the upper end of the tube. In the particular case shown in the drawing, the tube 2 is made stepwise in the form of a series of vessels of equal height placed one above another, the volume of each of which is a certain number of times larger than each previous vessel.

As in the already known devices, the chamber / is filled with liquid and according to the height of the liquid column in the tube 2, determined by the value of the external (measured) pressure on the membrane of the chamber /, the value of the measured pressure is judged.

The step shape of the tube 2, constituting the essence of the invention, makes it possible to measure different pressures with the same degree of accuracy.

The height of the liquid column in the tube 2 can be recorded by any of the known methods. It is possible, for example, to draw along the tube axis a wire of the greatest possible resistance included in the bridge circuit. With fluctuations in the level of the fluid in the tube, the working length of the wire changes, resulting in a change in the resistance of the circuit.

When the device is lowered into the well, it will undoubtedly be subjected to variable temperatures (by 10-15 °), which can give a distortion of the measurement result.

For automatic introduction of temperature correction when registering the height of a liquid column using the bridge method, the compensation method known in this method can be used.

In order to determine the magnitude of the increment of the liquid column due to the temperature, a second compensation device is used, similar to the main one, but not connected with the outside world by a membrane.

The main device is turned on in one shoulder of the Wheatstone bridge, and the potential difference device in the adjacent points of the bridge is measured in the adjacent shoulder of the bridge. The resulting change in resistance is determined solely by the change in pressure on the membrane of the main instrument, which is clear from the theory of the Wheatstone bridge.

The subject matter of the invention.

An apparatus for measuring pressure, in particular in boreholes, consisting of a membrane-filled chamber filled with liquid and connected to a gas-filled tube of smaller diameter, the position of the liquid column in which determines the pressure value, which is different pressure with the same accuracy, the tube connected to the chamber is made of alternating, decreasing to the upper end of the tube, the diameter, for example, stepped.