NO343814B1

NO343814B1 - Pressure Balanced Double Acting Shear Gate Valve

Info

Publication number: NO343814B1
Application number: NO20161775A
Authority: NO
Inventors: Vladimir Andreev
Original assignee: Vladimir Andreev
Priority date: 2016-11-09
Filing date: 2016-11-09
Publication date: 2019-06-11
Also published as: NO20161775A1; CN109923278B; GB2571664A; WO2018088911A1; CN109923278A; GB201907897D0; GB2571664B

Description

Technical Field

[0001] The present invention relates to the shear/seal ram for blowout preventers. The purpose of the shear/seal ram is to cut the drill string and seal the wellbore in case of blowout.

Background Art

[0002] 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:

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

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

[0003] Related prior art is disclosed in US 8,770,274 B2, GB 2352494 A, US 4523639 A and US 2012/0067563 A1. US 8,770,274 discloses a shear/ seal ram which provides a knife edge at a shearing edge and the knife edge is inclined to minimize the cutting force exerted on a wellbore pipe. A single cylinder, single piston system is used. The shear ram blade is a prolonged part of the piston rod. US 6,454,015 discloses a gate valve where the gate is a shear blade and the blade is arranged between two piston heads as part of the piston rods connecting the two piston heads, each piston head is associated with a cylinder house.

Disclosure of the Invention

[0004] It is an object according to the present invention to provide a shear/seal ram comprising a valve housing with two cylinder houses, two concentric double acting cylinders with pull-pistons moving inside a push-cylinder simultaneously exerting force on two gates via brackets.

[0005] In one aspect, the invention further includes: end closures for closing the ends of the valve housing, thus providing a pressure barrier between wellbore cavity and the cylinders housing.

[0006] In another aspect the shear/seal ram further includes a pressure seal against wellbore when the gates are closed, provided by a metal seal inserts, located in cavities between gate and valve housing.

[0007] In one embodiment of the invention it is disclosed a method for providing a shear/seal ram, comprising the steps of:

• providing a valve housing with two cylinder houses;

• providing two concentric double acting cylinders with pull-pistons moving inside a push-cylinder simultaneously exerting force on two gates via brackets.

[0008] In one aspect the method further includes the steps of:

• providing end closures for closing the ends of the valve housing, thus providing a pressure barrier between wellbore cavity and the cylinders housing.

[0009] In another aspect the method further includes the steps of:

• providing pressure seal against wellbore when the gates are closed, provided by a metal seal inserts, located in cavities between gate and valve housing.

[0010] Other advantageous embodiments, aspects and details according to the present invention will become apparent by the accompanying claims.

Brief Description of the Drawings

[0011] In order to make the invention more readily understandable, the discussion that follows will refer to the accompanying drawings, in which

[0012] Fig. 1, shows a shear/seal ram for blowout preventers;

[0013] Fig. 2 shows operating principle of the pressure balanced double acting shear gate valve;

[0014] Fig 3 shows an “inside piston” that exerts a pull action on to a gate via bracket; while an “outside piston” exerts a push action on to the gate via bracket;

[0015] Fig 4 shows a shear/seal ram with reactions from the well bore pressure applied to the gates 8, and;

[0016] Fig. 5 shows a shear/seal ram as shown in figure 4 in a closed configuration with reactions from the well bore pressure applied to the gates 8 and the pressure seal metal seal inserts 9.

Detailed description of the Invention

[0017] In the following, the present invention will be discussed by describing embodiments, and by referring to the accompanying drawings.

However, people skilled in the art will realize other applications and modifications within the scope of the invention as defined in the enclosed independent claims.

First embodiment

[0018] According to the first embodiment, it is provided a shear ram blowout preventer operating according to the principle shown in figures 3 - 5.

[0019] The pressure balanced double acting shear gate valve presented on Fig.1 operates as a gate valve. The gates 8 are sealing the wellbore and cutting the drill string, driven by the pistons 4,5 towards the wellbore. The pistons 4,5 exert a force onto the gates 8 via brackets 6,7. The force exerted by the pistons 4,5 is created by pressure from hydraulic fluid that is pumped simultaneously into the cylinder housings 3. End closures 2 are closing the ends of the valve housing 1, thus providing a pressure barrier between wellbore cavity and the cylinders housing 3. The end closures 2 also provides an axial fixture for the pistons 4,5. A pressure seal 9 against wellbore when the gates 8 are closed is provided by a pressure seal metal inserts 9, located in the cavities between gate 8 and valve housing 1.

[0020] 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.

[0021] An operating principle of the pressure balanced double acting shear gate valve is shown in Fig.2. When an emergency occurs, the hydraulic fluid is pumped into 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 in Fig. 3 an “inside piston” 4 exerts a pull action on to the gate 8 via bracket 7; while an “outside piston” 5 exerts a push action on to the gate 8 via bracket 6.

[0022] 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”.

[0023] The pressure balanced design is illustrated on the Fig. 4. The force produced by the wellbore pressure is exerted in both directions and therefore cancels each other out. Therefore, an effective force exerted onto the drill string by closing of the Gates 8 is independent of the wellbore pressure.

[0024] In order to establish seal that is reliable in all ranges of temperatures and fluid compositions, the pressure seal metal inserts 9 with double piston effect are utilized. The double piston effect principle is commonly used in heavy-duty valves. The double piston effect with pressure seal metal inserts 9 is illustrated on the Fig. 5. The pressure seal with double piston effect is increased with increased well bore pressure, and thus providing safe off pressure barriers in all operating conditions.

[0025]

Claims

1. A shear/seal ram

characterised in that it comprises a valve housing (1) with two cylinder houses, two concentric double acting cylinders with pull-pistons (4) moving inside a push-cylinder (5) simultaneously exerting force on two gates (8) via brackets (6, 7).

2. The shear/seal ram according to claim 1 further including end closures (2) for closing the ends of the valve housing (1), thus providing a pressure barrier between wellbore cavity and the cylinders housing (3).

3. The shear/seal ram according to claim 1 further including a pressure seal (9) against wellbore when the gates (8) are closed, provided by a metal seal inserts (9), located in cavities between gate (8) and valve housing (1).

4. A method for providing a shear/seal ram,

characterised in that it comprises the steps of:

providing a valve housing (1) with two cylinder houses;

providing two concentric double acting cylinders with pull-pistons (4) moving inside a push-cylinder (5) simultaneously exerting force on two gates (8) via brackets (6, 7).

5. The method according to claim 4, further including the steps of:

providing end closures (2) for closing the ends of the valve housing (1), thus providing a pressure barrier between wellbore cavity and the cylinders housing (3).

6. The method according to claim 4, further including the steps of:

providing pressure seal (9) against wellbore when the gates (8) are closed, provided by a metal seal inserts (9), located in cavities between gate (8) and valve housing (1).

Claims