SU1379452A1 - Pressure compensator for wells - Google Patents

Abstract

The invention relates to the field of drilling wells and allows to increase the reliability of the device by reducing the inertia of its operation, as well as the possibility of pressure compensation (D) during well cementing. The compensator includes a housing (K) 1 with an axial channel 2 and a compensation mechanism D. It is made in the form of a pipe 2, which forms an annular cavity 4 with K I, filled with gas and hydraulically connected in the lower part with channel 2 K I, B lower. An annular piston 5 is located there in the part of cavity 4, and in the upper one there is a check valve 6. When the device is lowered on the string of casing 9, fluid is directed from under the string into the gap between the well and the tubes 9 and in front of the lower part there is an increased D. It is transferred to the inside of the pipes 9 and is quenched by a compensator. The liquid is displaced from it by decreasing D after the column. At the same time, the D to the bottom is reduced. This shows the effect of compensation. 1 il. (L

Description

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IN9

The invention relates to the drilling of wells, in particular, devices for compensating the pressure in the wells during casing in the well and during the cementing of the well.

The purpose of the invention is to improve the reliability of the device by reducing the inertia of its operation, as well as the possibility of pressure compensation during well cementing.

The drawing shows the proposed compensator, a General view.

The pressure compensator for wells includes a housing 1 with an axial channel 2 and a pressure compensation mechanism, which is made in the form of a socket 3, which forms with the housing I an annular cavity 4 filled with air and hydraulically connected in the lower part with the axial channel 2 of housing 1. In this case The lower part of the cavity cavity 4 is equipped with a solid non-return valve 6. Case 1 and nozzle 3 are separated in the upper part with a metal ring 7. A centralizer 8 is provided for centering the nozzle. The device is connected to the casing 9 with coupling 10 and set under the check valve 6.

The compensator works as follows.

Before it is lowered into the annular cavity 4, compressed gas is pumped through the charging check valve 6. Under gas pressure, the annular piston 5 moves to the lower position, and the pressure in the annular cavity 4 is increased to the required value taking into account the depth of the well.

The compensator provides compensation in the well hydraulic shocks that occur in various technological processes. The casing string, provided with a check valve, is similar to a piston when it is lowered, which displaces fluid from the well. In this case, the liquid from under the column is directed into the gap between the borehole wall and the outer surface of the pipes. Depending on the rate of descent of the pipes, the viscosity of the solution, the size of the gap and the weight of the pipes in front of the bottom of the column, a zone of pressure is created. It can be extinguished by moving the displaced fluid.

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the volume of which depends on the diameter and length of the pipe.

Since the casing is considered a piston, the pressure is first transmitted to the inside of the pipe, i.e. where the compensator is installed and there it extinguishes. The other part of the fluid is directed along the gap and flows upwards. In the presence of a compensator, the flow time increases: the part of the liquid that goes inside the pipes, into the compensator, is displaced from there as the pressure decreases behind the column. Due to this, the pressure on the bottom is reduced. This is the effect of compensation.

Fluid pressure is transmitted directly to the annular piston 5, which holds the compressed gas. When the gas is compressed and the annular piston 5 moves, the pressure drops.

Thus, the compensator allows to reduce the force of hydraulic shocks that occur in the well during the descent of pipes, their rolling, and the injection of plugging solutions into the well. The resulting pressure impulses cannot have a large effect on the walls of the wellbore and bring to the formation hydraulic fracturing. Therefore, the descent rates of the columns can be increased, and the fastening time is shortened.

Borehole compensators, a warning of hydraulic fracturing, also improve the quality of separation of the formation, as the cement rises to the specified levels and does not clog up the formation.

Claims (1)

Invention A pressure compensator for wells, including a housing with an axial channel and a pressure compensation mechanism, is characterized in that, in order to increase the reliability of the device by reducing the inertia of its response, as well as the possibility of pressure compensation during well cementing pressure is made in the form of a branch pipe, which forms with the housing an annular cavity filled with gas and hydraulically connected in the lower part with the axial channel of the housing, and in the lower part of the annular strips and an annular piston placed and in the upper portion thereof is mounted a charging check valve.