SU600289A1 - Device for locking preventer packing members - Google Patents

Description

one

The invention relates to the oil and gas industry, in particular for use in universal preventers designed to seal the subsea or surface wellbore of oil and gas wells and allow for the possibility of opening and pulling the pipe string at a sealed wellhead.

Devices are known for automatically fixing sealing elements when closing prepeptor 1.

These devices do not allow, after fixing the closed position of the sealing elements, to reduce the pressure value of the sealing elements on the pipe string when it is pushed and pulled.

A shutter preventer is also known for fixing pilot elements in the closed position, including controllable check valves with drain and pressure lines and a safety valve that allows the pipes to open and drag when the sealed wellhead 2.

Its disadvantage is an increase in the degree of unevenness in maintaining the design pressure in the hydraulic cylinder during the tool pulling process with an increase in the length of the discharge pipeline, which reduces the reliability of the sealing.

The aim of the invention is to increase the reliability of fixing the sealing elements of the pipe string through the seal preventer a by eliminating the influence of the resistance of the pressure pipe.

This is achieved by the fact that the safety valve of the proposed device has a control cascade and an overflow cascade with a spool, the overflow cascade is connected to the drain line of one non-return valve, and the control cascade is connected to the pressure line of another non-return valve.

On the circuit presented the proposed device.

The device for fixing the sealing elements of the pre-filter includes controlled check valves 1 and 2, a safety valve 3 consisting of the control cascade 4 and the overflow cascade 5 with the spool 6, which is retained in the closed position by the spring 7. Chambers A, B p C overflow cascade 5 with the help of drossel 8 and the holes 9 are interconnected. The rotary valve 10 cuts off the chamber G of control cascade 4 from chamber B of the overflow cascade 5.

Pipeline 11 connects cameras D and D between them; the control stage chamber E is connected to the pressure pipe 12; pipe 13 connects the control chamber

a check valve 1 with a hydraulic control unit, a pipe 14 connects with each other and with a hydraulic control unit a spacer cavity of the preventer hydraulic cylinder, a control chamber of the check valve 2 and a pipeline 11.

The sub valve valve of the check valve cavity 1 is connected by means of the drain pipe 15 to the chamber B of the overflow stage 5 of the safety valve 3; the subvalvular cavity of the check valve 2 is connected by means of an inlet pipe 12 to a hydraulic control unit.

The device works as follows.

When closing the preventer fluid under pressure is fed into the pipeline 12, the pipeline 14 is connected to the drain. The fluid entering the controlled check valve 2 pushes the valve over the saddle and passes into the shut-off cavity of the hydraulic cylinder, displaces its piston, thereby closing the preveitor. After closing the preventer, the valve 2 under the action of the spring sits in its socket, blocking the pressurized fluid in the shut-off cavity of the preventer hydraulic actuator and thereby fixing the sealing element in the closed position.

In order to pull the pipe string through the preventer sealant, pressurized fluid is supplied through pipeline 13 to the control chamber of the check valve 1.

The piston with the pusher of the check valve 1 under the action of pressure moves upwards, opening and blocking the valve 1 in the open position.

Liquid under pressure from line 12 enters chamber E of control stage 4 and through valve 2, forcibly open valve 1, pipe 15, hole 9 and throttle 8 fills chambers A, B, B of overflow stage 5 of safety valve 3. Chamber D of overflow stage 5 and the chamber G of the control cascade 4 are connected via a conduit 14 to a drain.

After filling all the chambers with liquid, the individual elements of the proposed device are in the following position: valve 2 is closed, valve 1 is forcibly opened, chambers A, B, C and the locking cavity of the hydraulic actuator are under operating pressure, valve 6 is in closed position under the action of a spring 7, since the pressure in chambers A and B is the same. The valve 10 is also closed, since the forces acting on the valve 10 from the pressure in the chambers B and E are equal to each other. The pipeline 14 is connected to the drain.

Then, in the pipeline 12, the pressure is reduced to the design pressure using the control valve of the hydraulic control unit. In chamber E, pressure is also reduced to the calculated value, since it is connected to pipeline 12. In this chamber, as well as in chambers A, B, and the stop cavity of the hydraulic cylinder, at this time there is liquid under working pressure. The valve 10 of the control cascade under the action of the force from the differential pressure (working and calculated) opens, and the liquid from chamber B flows into chamber D and then into pipeline I connected to the drain. After establishing the design pressure in chamber B, as well as in the associated chambers A, B and the cage of the cylinder, the valve 10 sits on its saddle under the action of a spring.

When pulling the drill pipe coupling through the universal preventer seal, it pushes the seal, which

in turn, the piston of the hydraulic actuator moves downward, displacing fluid from the locking cavity through the check valve 1, forcibly opened, into chambers B, A, B, in which the pressure begins to rise (more than the calculated value). When the pressure rises (above calculated) in chamber B, valve 10 opens and excess liquid flows through pipe 11 into pipe 14 connected to a drain.

Since a sufficiently large volume of fluid is displaced during a relatively short period of time when the clutch is pulled from the closure chamber, this leads to a large flow through the throttle 8. As a result of throttling the fluid flow through the throttle 8, a differential pressure is applied to the spool 6. Under the action of this differential force, the spool 6 moves upwards and connects chamber B with chamber D connected to the drain.

When the coupling moves in the seal, the fluid from the stop cavity stops, the pressures in chambers A, B and E are equalized, as a result of which the valve 10 is closed, and the valve 6 moves downward under the action of spring 7, chamber B from chamber D.

When the coupling leaves the seal, the hydraulic piston begins to move upward under the action of pressure, compressing the seal around the pipe, as a result of which the pressure in the hydraulic shut-off chamber begins to decrease (lower than the calculated one). On the non-return valve 2, the differential pressure starts to operate, the valve 2 opens, and the fluid under the design pressure from the pipeline 12 enters the barrier cavity, raising the pressure there to the design one. After equalization of pressures in the locking cavity and the pipeline

12 valve 2 is closed.

To open the preventer, pressurized fluid is supplied to conduit 14, conduit 12 is connected to a drain. By means of the conduit 14, the fluid flows simultaneously to the spacer cavity of the preventer hydraulic cylinder and to the control chamber of the check valve 2.

Under pressure from fluid pressure piston with a pusher check valve

2 forcibly opens valve 2, connect