SU651126A1 - Seam pressure measuring device - Google Patents

Description

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The invention relates to well testing and is intended for piezo-measurements in underground leaching processes associated with the movement of solutions of varying density through productive formations.

A device for measuring reservoir pressure is known, consisting of an observation well and a hydrostatic level meter, the transducer of which is placed at pressure control point 1.

The drawbacks of the device are low reliability, especially with aggressive solutions, and the laboriousness of the measurement process associated with the need to remove the device from the well to determine reservoir pressure.

It is also known a device for measuring formation pressure in a hydro-observational piezometric well, comprising a level transducer and a measuring unit 2.

This device is closest to the invention by its technical essence and the achieved result.

The drawback of the device is a large measurement error in the event of a change in the density of the solution in the well.

The purpose of the invention is to improve the accuracy of formation pressure measurements by reducing the effect of changes in the density of the solution in the well.

The goal is achieved by the fact that the device is equipped with a piezometric tube placed in a well and filled with a liquid whose density is less than the density of the solution, the level converter being installed in the tube.

The pipe may have a choke.

The drawing shows the proposed device in section.

The device contains a hydron-observation well — a piezometer 1 with a solution, an additional piezometer 2 — a pipe filled with a constant density fluid, insoluble in the reservoir solution and lighter than it. In the additional piezometer 2, a choke 3 and a level converter 4 are installed, which is connected to the measuring unit 5.

An additional piezometer 2 may have a chamber 6 below, in which the interface 7 of the formation

jc solution of a fluid of constant density.

The device works as follows.

In the initial state, the pressure of the solution in the reservoir 8 is balanced by the pressure of the solution column in well 1 and is equal to the pressure of the height of the liquid column filling the additional piezometer. A change in pressure in the reservoir causes a change in the levels of the solution in the well and the fluid in the additional piezometer. But in a well, this change in the level of H depends not only on the pressure in the reservoir, but also on the density of the solution in the well, which varies both in time and in the height of the well.

In the additional piezometer 2, the fluid level Hj, due to the fact that it has a constant density, is linearly related to the pressure in the reservoir and is measured by a level gauge consisting of a level transducer 4 and a measuring unit 5.

The error in measuring the pressure of the solution in the formation without the use of an additional piezometer is

.du

where H is the value of the level of solution in the well at the minimum pressure in the reservoir

A is the magnitude of the change in solution density in the well.

The proposed device provides a measurement of the pressure of the solution in the reservoir with a lower error, which is

AP Hi.iy

where H is the value of the level of the reservoir solution in the additional piezometer; Hj H

, is the difference between the densities of the reservoir solution and the fluid of constant density.

As the pressure in the reservoir increases, the value of H increases, IHO this increase, and accordingly;

and the error is inversely proportional to the square of the diameters of the chamber 6 and the pipe 2.

Short-term changes in pressure in the formation are smoothed by the choke 3.

Thus, the proposed device is a system of two piezometers combined by a certain 06-7 time, one of which is the actual hydro-observation well (piezometer), the other placed in it is a special additional piezometer. The reservoir pressure is measured by the position of the level, in the latter, which is independent of the change in density of the reservoir solution.

Since the liquid in the additional piezometer can be chosen non-corrosive with respect to the level transmitter, the reliability of the proposed device will be higher.

Claims (2)

1. A device for measuring formation pressure in a hydroaboard a piezometric borehole containing a level transducer and a gauge {Ny unit, characterized in that, in order to improve the accuracy measurements by reducing the effect of changes in the density of the solution in the well, it is equipped with a piezometric tube placed in the well and filled with a liquid whose density is less than the density of the solution, the level converter being installed in the pipe. 2. The device according to claim 1, characterized in that the pipe has throttle. Sources of information taken into account in the examination 1. USSR author's certificate number 72608, cl. E 21 B 47/06, 1944. 2. USSR author's certificate No. 258994, cl. E 21 B 47/06, 1967. " .J Have one