NO20161775A1

NO20161775A1 - Pressure Balanced Double Acting Shear Gate Valve

Info

Publication number: NO20161775A1
Application number: NO20161775A
Authority: NO
Inventors: Vladimir Andreev
Original assignee: Vladimir Andreev
Priority date: 2016-11-09
Filing date: 2016-11-09
Publication date: 2018-05-10
Also published as: CN109923278B; WO2018088911A1; GB201907897D0; CN109923278A; GB2571664A; GB2571664B; NO343814B1

Abstract

The present invention relates to the shear/seal ram for blowoutpreventers. The purpose of the shear/seal ram is to cut the drill string and seal the wellbore in case of blowout.The present invention relates to the shear / seal ram for blowout preventer. The purpose of the shear / seal ram is to cut the drill string and seal the wellbore in case of blowout.

Description

The invention relates to the shear/seal ram of the Blowout Preventers. Purpose of the shear/seal ram is to cut the drill string and seal the well bore in case of blowout.

Although there is a requirement for shear/seal ram to be able to cut the heaviest drill string, the majority of the shear/seal ram designs share several inherent features that, in some cases make it impossible to safely cut the drill string and seal the well. Those features are:

1. The rams are working against well pressure and therefore at high pressures their effectiveness is impaired.

2. The shape of the blades is such that it cannot always effectively move drill string into the center of the BOP, for example when the drill string is buckled under high well bore pressure.

3. There is only one cylinder that applies force to the ram blade, thus only limited amount of force can be applied.

4. The seals in the shear/seal ram are made of polymers and for some well fluid compositions combined with high temperatures the seals effectiveness is impaired

The invented Pressure Balanced Double Acting Shear Gate Valve addresses all these shortcomings in a single concept.

The Pressure Balanced Double Acting Shear Gate Valve presented on the Fig.1 operates in the same way as Gate Valve; the Gates (8) are sealing the well and cutting the drill string, driven by the Pistons (4)(5) towards well bore. The Pistons (4)(5) exert the force onto the Gates (8) via brackets (6)(7). The force exerted by the Pistons (4)(5) is created by the pressure from the hydraulic fluid that is pumped simultaneously into the Cylinder Housings (3). The End Closures (2) are closing the ends of the Valve Housing (1), thus providing a pressure barrier between Well Bore cavity and the Cylinders Housing (3). The End Closures (2) also providing an axial fixture for the Pistons (4)(5). The pressure seal against well bore when the Gates (8) are closed is provided by the Metal Seal Inserts (9), located in the cavities between Gate (8) and Valve Housing (1).

The employment of the “gate valve” principle ensures that the drill string is always inside the gate opening and therefore regardless of the drill string location and shape it will always be kept in optimal position against the cutting blade during gate closing. It also ensures a reliable seal against well bore pressure.

Operating principle of the Pressure Balanced Double Acting Shear Gate Valve presented on the Fig.2. When the emergency occurs, the hydraulic fluid is pumped into the both cylinders simultaneously, thus applying a pressure in the space between pistons and forcing the pistons in opposite directions; the pistons are exerting force on to the Gates. The pistons are concentric where one piston is moving inside the other one. As it is illustrated on the Fig.3 the “inside piston” (4) exerts a Pull action on to the Gate (8) via Bracket (7); while the “outside piston” (5) exerts a Push action on to the Gate (8) via Bracket (6).

Due to the dual action the hydraulic cylinders, consisting of Pull Pistons (4), Push Pistons (5), Cylinder Housings (3) and End Closures (2), are named as “Double Acting Cylinders”.

The Pressure Balanced Design is illustrated on the Fig.4. The force produced by the Well Bore Pressure is exerted in both directions and therefore canceling each other. Therefore, the effective force exerted onto the drill string by closing of the Gates (8) is independent of the Well Bore Pressure.

In order to establish seal that is reliable in all ranges of temperatures and fluid compositions, the metal seals with double piston effect, that is commonly used in heavy duty valves. The double piston effect seal is illustrated on the Fig.5. The Double Piston Effect seal is increased with increased well bore pressure, and thus providing safe 2 off pressure barriers in all operating conditions.

There are several patents from NOV, Enovate and some others which employ Gate Valve principle also with metal seal and double seal, however none them provide fully pressure balanced design with effective force on the blades exerted via “push-pull” action from double acting hydraulic cylinders.

Claims

Claims I claim:

1. The principle of the exerting simultaneous “Push” and “Pull” action on the Gate (8) by the Push-piston (5) and Pull-piston (4)

2. The principle of two concentric double acting cylinders with Pull-pistons (4) moving inside the Push-cylinders (5) simultaneously exerting force on two Gates (8) via brackets (6)(7)

3. The concept of the Pressure Balanced Double Acting Shear Gate Valve with Double Piston Effect metal seal.