Ram blowout preventer stroke limiting and method

1. A blowout preventer for sealing a well, the blowout preventer comprising:

a body having first and second chambers, the first chamber extending substantially perpendicular to and intersecting the second chamber;

first and second ram blocks configured to move within the first chamber to seal a first region of the second chamber from a second region of the second chamber;

first and second rods connected to the first and second ram blocks, respectively, and configured to extend along the first chamber;

first and second bonnets partially covering first and second rods, respectively, the bonnets being detachably attached to the body; and

first and second stroke limiting devices configured to pierce through end parts of the first and second bonnets and to limit a stroke of the first and second rods by a predetermined amount.

2. The blowout preventer of claim 1 , wherein a length of the first and second stroke limiting devices inside the first and second bonnets is adjustable.

3. The blowout preventer of claim 2 , wherein the first and second stroke limiting devices are adjustable from outside the body.

4. The blowout preventer of claim 2 , wherein the first and second stroke limiting devices are manually adjustable from outside the body.

5. The blowout preventer of claim 2 , wherein the first and second stroke limiting devices are hydraulically adjustable.

6. The blowout preventer of claim 1 , further comprising:

a seal provided around each of the first and second stroke limiting devices such that a working fluid provided inside the body does not escape outside the body.

7. The blowout preventer of claim 1 , wherein the first and second stroke limiting devices, when limiting a stroke of the first and second ram blocks, prevent an opening of the first and second bonnets.

8. The blowout preventer of claim 1 , further comprising:

an opening chamber and a closing chamber in each of the first and second bonnets; and

a piston in each of the first and second bonnets separating corresponding opening and closing chambers and configured to be fixedly attached to a corresponding rod of the first and second rods such that when a differential pressure between the corresponding opening chamber and the corresponding closing chamber is positive the piston moves integrally with the corresponding rod to open the corresponding ram block and when the differential pressure is negative, the piston moves integrally with the corresponding rod to close the corresponding ram block,

wherein an opened functional position of the ram blocks is defined by the corresponding rod being in contact with the corresponding stroke limiting device.

9. The blowout preventer of claim 8 , wherein an opened maintenance position of the ram blocks, which is different from the opened functional position, is defined by the stroke limiting devices being further retracted from the first and second bonnets to permit the first and second ram blocks to be further opened.

10. The blowout preventer of claim 9 , wherein a difference between (i) the opened functional position of the ram blocks and (ii) the opened maintenance position of the ram blocks is between about 10% and 20% of the opened maintenance position of the ram blocks.

11. A blowout preventer for sealing a well, the blowout preventer comprising:

a body having first and second chambers, the first chamber extending substantially perpendicular to and intersecting the second chamber;

first and second ram blocks configured to move within the first chamber to seal a first region of the second chamber from a second region of the second chamber;

first and second rods connected to the first and second ram blocks, respectively, and configured to extend along the first chamber;

first and second bonnets partially covering the first and second rods, respectively, the first and second bonnets being detachably attached to the body;

first and second stroke limiting devices configured to pierce through end parts of the first and second bonnets and limit a stroke of the first and second rods by a predetermined amount;

an opening chamber and a closing chamber in each of the first and second bonnets; and

a piston in each of the first and second bonnets separating corresponding said opening and closing chambers and configured to be fixedly attached to a corresponding rod of the first and second rods such that when a differential pressure between the corresponding opening chamber and the corresponding closing chamber is positive the piston moves integrally with the corresponding rod to open the corresponding ram block and when the differential pressure is negative, the piston moves integrally with the corresponding rod to close the corresponding ram block,

wherein an opened functional position of the ram blocks is defined by the corresponding rod being in contact with the corresponding stroke limiting device.

12. The blowout preventer of claim 11 , wherein a length of the first and second stroke limiting devices inside the first and second bonnets is adjustable.

13. The blowout preventer of claim 12 , wherein the first and second stroke limiting devices are manually adjustable from outside the body.

14. The blowout preventer of claim 12 , wherein the first and second stroke limiting devices are hydraulically adjustable.

15. The blowout preventer of claim 11 , wherein an opened maintenance position of the ram blocks, which is different from the opened functional position, is defined by the stroke limiting devices being further retracted from the first and second bonnets to permit the first and second ram blocks to be further opened.

16. The blowout preventer of claim 15 , wherein a difference between (i) the opened functional position of the ram blocks and (ii) the opened maintenance position of the ram blocks is between about 10% and 20% of the opened maintenance position of the ram blocks.

17. The blowout preventer of claim 11 , wherein a pressure applied inside the first and second bonnets may be between 5,000 and 15,000 psi.

18. A method for reducing a stroke of a blowout preventer for sealing a well, the method comprising:

providing stroke limiting devices through end parts of bonnets of a body of the blowout preventer;

applying an opening pressure to move ram blocks from a closed position to an opened functional position inside the body; and

limiting a movement of rods attached to the ram blocks with the stroke limiting devices such that the ram blocks do not reach an opened maintenance position, which is used to open the bonnets of the blowout preventer for reaching the ram blocks.

19. The method of claim 18 , further comprising:

adjusting the stroke limiting devices to adjust an opened functional position of the ram blocks.

20. The method of claim 18 , further comprising:

further retracting the stroke limiting devices from the bonnets to permit the ram blocks to be further opened, which defines the opened maintenance position of the ram blocks, such that bonnets of the blowout preventer are allowed to be opened.