Blowout preventer

Abstract

A blowout preventer includes a main housing containing a through bore. A first chamber is arranged transverse to the through bore. A second chamber is transverse to the through bore and is diametrically opposed to the first chamber. A first shearing device is located in the first chamber and a second shearing device located in the second chamber. The blowout preventer includes a charge that when activated propels each shearing device along its respective chamber and across the through bore into the opposing chamber, such that the first and second shearing devices are adjacent each other.

Claims

1. A blowout preventer comprising: a main housing containing a through bore; a first chamber transverse to the through bore; a second chamber transverse to the through bore, diametrically opposed to the first chamber; a first shearing device located in the first chamber, the first shearing device having an elongated planar body linked to a first piston; a second shearing device located in the second chamber, the second shearing device having an elongated planar body linked to a second piston; the first chamber and second chamber each comprising an arresting mechanism having an energy absorption mechanism configured with a resiliently deformable material; and a first charge and a second charge, each charge configured for activation to propel each respective shearing device along its respective chamber and across the through bore into the opposing chamber, such that the planar bodies of the first and second shearing devices are adjacent each other to inhibit fluid flow through the through bore.

2. The blowout preventer of claim 1 wherein the first and second shearing devices are immediately adjacent each other.

3. The blowout preventer of claim 1 wherein each shearing device has a housing arranged to block the through bore and substantially prevent passage of wellbore fluids through the through bore.

4. The blowout preventer of claim 1 wherein each shearing device has a cutting edge that can cut through tubular sections in the through bore.

5. The blowout preventer of claim 4 wherein the cutting edge is arcuate.

6. The blowout preventer of claim 1 further comprising at least one retaining device to retain each shearing device in a predetermined position in the respective chamber until a sufficient force is exerted on the shearing device caused by actuation of the charge.

7. The blowout preventer of claim 6 wherein the retaining device comprises a shear pin.

8. The blowout preventer of claim 1 wherein each charge comprises a chemical propellant.

9. The blowout preventer of claim 8 wherein the chemical propellant comprises at least one of a deflagrating charge and an explosive charge.

10. The blowout preventer of claim 8 wherein the chemical propellant comprises an initiator.

11. The blowout preventer of claim 10 wherein the initiator comprises a detonator.

12. The blowout preventer of claim 1 wherein each shearing device is configured with the piston at one end thereof and a cutting edge at an opposing end thereof.

13. The blowout preventer of claim 1 wherein each piston is disposed adjacent an end of the chamber.

14. The blowout preventer of claim 1 wherein each shearing device has at least one engagement member in an outer edge of the piston, the piston adapted to engage with the respective arresting mechanism.

15. The blowout preventer of claim 14 wherein, the engagement member comprises an annular ring located at or adjacent an outer edge of the piston.

16. The blowout preventer of claim 14 wherein the arresting mechanism comprises at least one corresponding recess to receive at least one protrusion of the engagement member.

17. The blowout preventer of claim 1 wherein the first shearing device is initially located in the first chamber on a first side of the through bore and the second shearing device is initially located in the second chamber on a second side of the through bore diametrically opposed and in the same plane with the first side.

18. The blowout preventer of claim 1 wherein each chamber comprises a space in a portion of the respective chamber between an initial location of the respective shearing device and the through bore wherein the space between the initial location of the respective shearing device and the through bore is between zero and a quarter of the length of the diameter of the through bore.

19. The blowout preventer of claim 1 wherein each chamber comprises a space in a portion of the respective chamber between an initial location of the respective shearing device and the through bore, wherein the space between the initial location of the respective shearing device and the through bore is longer than the diameter of the through bore.

20. The blowout preventer of claim 1 wherein the chambers are fluidly sealed from the through bore.

21. The blowout preventer of claim 1 wherein the second chamber further comprises a sled, the sled disposed adjacent to and covering a seal.

22. The blowout preventer of claim 1 wherein each arresting mechanism is located at an end of each chamber adjacent the through bore.

23. The blowout preventer of claim 1 wherein each energy absorption mechanism comprises a honeycomb core.

24. The blowout preventer of claim 23 wherein the honeycomb core comprises one of high density aluminum, stainless steel, titanium and carbon fiber.

25. The blowout preventer of claim 1 further comprising a through bore sealing arrangement adapted to seal between the through bore and each shearing device when each shearing device is located across the through bore.

26. The blowout preventer of claim 25 wherein each through bore sealing arrangement comprises a sealing ring that is adapted to be pressed onto a sealing face of each shearing device.

27. The blowout preventer of claim 26 wherein each sealing ring is located concentrically with the through bore and has a larger diameter than the through bore.

28. The blowout preventer of claim 1 wherein each of the first and second shearing devices is linked to the respective piston by a coupling junction.

29. The blowout preventer of claim 28 wherein the coupling junction on each of the first and second shearing devices comprises a T-shaped end on each shearing device and a corresponding T-shaped opening in each piston.

30. A method of closing a through bore located within a main housing of a blowout preventer, the method comprising: activating two charges, each charge to propel a respective first and second shearing device, the first and second shearing devices each having an elongated planar body respectively linked to a piston located in a respective one of two opposing chambers disposed in opposite directions along the chambers transverse to the through bore, such that the first and second shearing devices each travel across the through bore with the planar bodies of the devices adjacent each other to inhibit the flow of wellbore fluids through the through bore, wherein each of the two opposing chambers comprises an arresting mechanism having an energy absorption mechanism configured with a resiliently deformable material.

31. A blowout preventer comprising: a housing containing a through bore; a first chamber transverse to the through bore; a second chamber transverse to the through bore, diametrically opposed to the first chamber: a first shearing device located in the first chamber and linked to a first piston; a second shearing device located in the second chamber and linked to a second piston; a first charge and a second charge, each charge configured for activation to propel each respective shearing device along its respective chamber and across the through bore; and an arresting mechanism located in each of the chambers configured to bring the shearing device in the respective chamber to rest, the arresting mechanism having an energy absorption mechanism configured with a resiliently deformable material.

32. The blowout preventer of claim 31 wherein the first and second shearing devices are respectively linked to the first and second pistons via a coupling junction comprising a T-shaped end on each shearing device and a corresponding T-shaped opening in each piston.

33. The blowout preventer of claim 31 wherein each arresting mechanism is disposed at an end of the chamber opposed to the charge.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a sectioned view of an example embodiment of a blowout preventer according the present disclosure

(2) FIG. 2 shows a cross section view of a blowout preventer prior to being activated.

(3) FIG. 3 shows a cross section view of a blowout preventer that has been activated.

(4) FIG. 4 shows a cross section view of a blowout preventer in a minimum arrest state with the shearing device having sheared the wellbore.

(5) FIG. 5 shows a cross section view of a blowout preventer in a maximum arrest state with the shearing device having sheared the wellbore.

(6) FIG. 6 shows a cross section view of a blowout preventer with the shearing device being pulled clear of the wellbore.

(7) FIG. 7 shows an exploded view of the blowout preventer.

(8) FIG. 8 shows a top down view of the blowout preventer prior to being activated.

DETAILED DESCRIPTION

(9) FIG. 1 shows a sectioned view of an example embodiment of a blowout preventer 100 according to the present disclosure. The blowout preventer 100 has a main housing 110 having a through bore 112. The example embodiment of the blowout preventer 100 also has a first chamber 114 and a second chamber 116 that are opposing and located transverse to the through bore 112. It will be appreciated that the blowout preventer 100 may be coupled to a wellbore proximate an upper end of the wellbore, for example on a casing flange, or on top of or within other well closure devices associated with a plurality of blowout preventer elements constituting a BOP “stack.”

(10) A shearing device 118 having a piston 120 and a cutting edge 122 is located in each chamber 114, 116 on first and second opposing sides 124, 126 of the through bore 112. The piston 120 has an engagement member 121 in the form of an annular ring at an outer edge of the piston 120, which is adapted to engage with an arresting mechanism.

(11) Each chamber 114, 116 comprises a space in the portion of the chamber 114, 116 between the initial location of the shearing device 118 and the through bore 112.

(12) A charge, which in the present example embodiment may be in the form of a chemical propellant 128 is located between the piston 120 of each shearing device 118 and an ignition port 130. The chemical propellant 128 is adapted to propel each shearing device 118 along its respective chamber 114, 116 and across the through bore 112 into the opposing chamber 114, 116, as will be described in greater detail below.

(13) A seal in the form of a cylinder 132 fluidly seals each chamber 114, 116 from the through bore 112.

(14) An arresting mechanism in the form of an energy absorption mechanism 134 is located at the end of each chamber 114, 116 closest to the through bore 112. Each energy absorption mechanism 134 has a front portion 136 having an annular slot 138 at an outer edge of the energy absorption mechanism 134 facing towards the respective piston 120 of the shearing device 118. The annular slot 138 is of a complementary shape to the engagement member 121 of the piston and receives the engagement member 121 once the shearing device 118 has traveled along the length of the chamber 114, 116.

(15) The energy absorption mechanism 134 is configured to absorb the kinetic energy of each shearing device 118, as will be described in greater detail below.

(16) The operation of the blowout preventer 100 will now be explained with reference to FIGS. 2-6. FIG. 2 shows a cross section view of the example embodiment of the blowout preventer 100 prior to being activated. As can be observed in FIG. 2, the charge (e.g., chemical propellant) 128 and shearing device 118 are located in the chambers 114, 116 on opposing sides 124, 126 of the through bore 112.

(17) FIG. 2 also shows the cylinder 132 fluidly sealing the chambers 114, 116 from the through bore 112.

(18) A through bore sealing arrangement 140 is disposed round the through bore 112 which will be explained in more detail below. The energy absorption mechanism 134 is located within each chamber 114, 116 on each side 124, 126 of the through bore 112. As can be observed, each energy absorption mechanism 134 is located in the same chamber 114, 116 as the shearing device 118 that the energy absorption mechanism 134 will arrest.

(19) FIG. 3 shows a cross section view of the example embodiment of the blowout preventer 100 where the chemical propellant 128 has been activated by the ignition port 120. The shearing devices 118 are held in place by a shear pin (not shown) until a sufficient expansion of hot gases has occurred after activation of the chemical propellant 128.

(20) Once a sufficient expansion of hot gases has occurred after activation of the chemical propellant 128 to cause pressure to shear the shear pin (not shown), the shearing devices 118 accelerate along the chambers 114, 116 towards the cylinder 132 and through bore 112.

(21) As the shearing devices 118 accelerate along the chambers 114, 116 and begin to shear the cylinder 120, the shearing devices 118 will also shear any wellbore tubulars, tools, drill strings or the like which are present in the through bore 112. The shearing devices 118 pass one another in the through bore 112.

(22) FIG. 4 shows a cross section view of the blowout preventer 100 where the first shearing device 118 has connected with the sled 142 and the piston 120 has engaged with the energy absorption mechanism 134 in a minimum arrest state. The sled 142 covers and protects the through bore sealing arrangement 140. As shown, the shearing devices 118 are immediately adjacent to one another and sit in close contact with a small clearance between shearing devices 118. In operation, the shearing devices 118 will likely be in intimate contact once pressure is applied from the below from the wellbore.

(23) The pistons 120 of the shearing devices 118 have engaged with and have started to be arrested by the energy absorption mechanism 134 without significantly deforming the energy absorption mechanism 134.

(24) FIG. 5 shows a cross section view of the blowout preventer 100 in a maximum arrest state. The shearing devices 118 have connected with the sled 142 of the energy absorption mechanism 134. In the figure shown, the shearing devices 118 have not had to shear any heavy materials contained in the through bore 112 and therefore require maximum arresting. As a result, the pistons 120 have engaged and deformed the energy absorption mechanism 134 to arrest the acceleration of the shearing devices 118.

(25) The energy absorption mechanism 134 will retain the shearing devices 118 in such a position that a sealing face (not shown) of each shearing device 118 is sufficiently aligned with the through bore sealing arrangement 140. Once the shearing device 118 is sufficiently aligned with the through bore sealing arrangement 140, the sealing arrangement 140 will firmly press a sealing ring (not shown) against the sealing face (not shown) of the shearing device 118, to stop the flow of wellbore fluids through the through bore 112, thereby securing the well. Once the well is secured, well control operations (for example choke and kill operations) can commence. In some embodiments, the energy absorption mechanism 134 may comprise a honeycomb or cores. In some embodiments, the honeycomb or cores comprise one or more of high density aluminum, stainless steel, titanium and carbon fiber.

(26) Once well control has been re-established, the blowout preventer 100 can be de-activated as seen in FIG. 6. As shown in FIG. 6, the sealing arrangement 144 retracts the sealing ring (not shown) from the sealing face (not shown) of the shearing devices 118 and the shearing devices 118 are pulled clear of the through bore 112.

(27) FIG. 7 shows an exploded view of the example embodiment of the blowout preventer 100.

(28) FIG. 8 shows a top down view of the blowout preventer 100 prior to being activated. FIG. 8 more clearly illustrates the arcuate shape of the cutting edge 122 of the shearing device 118.

(29) A possible advantage of a blowout preventer made according to the present disclosure is that the blowout preventer can be actuated without having to produce hydraulic forces to hydraulically push rams across the through bore to close off the through bore. Instead, the energy required to close the through bore is contained in the charge in the blowout preventer where it is required.

(30) A possible advantage of holding the shearing device 118 in place by a shear pin is that this assists in the rapid acceleration of the shearing device 118 along the chambers 114, 116 once sufficient force has been generated by the expanding gases of the chemical propellant 128.

(31) A possible advantage of having the cylinder 130 fluidly sealing the chambers 114, 116 from the through bore 112 is that the shearing devices 118 can accelerate along the chambers 114, 116 unhindered by wellbore fluids or other liquids until the shearing devices 118 starts to shear the cylinder 130.

(32) A possible advantage of having a space between the initial location of the shearing device 118 and the through bore 112 is that the shearing device 118 reaches sufficient velocity to shear any device disposed within the through bore 112.

(33) A possible advantage of using an energy absorption mechanism 134 is that excess kinetic energy of the shearing devices 118 is not directly transferred into a structural portion of the blowout preventer 100.

(34) A possible advantage of pulling the shearing devices 118 clear of the through bore 112 is that the shearing devices 118 do not have to be drilled through for wellbore operations to recommence.

(35) A possible advantage of a blowout preventer according to the present disclosure is that the use of two adjacent shearing devices may provide two opposing forces that minimize, and effectively cancel recoil.

(36) A further possible advantage is that the bending moments imparted on the wellhead are reduced by the use of a second shearing device acting from an opposite side to the first shearing device. In effect, the two shearing devices ‘scissor’ the through bore

(37) Another possible advantage is that the sled 142 covers and protects the through bore sealing arrangement 140 from debris and damage during the shearing phase and then opens up during the arresting phase to ensure a seal can be actuated.

(38) Another possible advantage is that the larger circumference of the piston and energy absorption mechanism provide a more effective arresting system.

(39) The foregoing embodiments are illustrative only of the principles of a blowout preventer according to the present disclosure, and various modifications and changes will readily occur to those skilled in the art. The blowout preventer as described herein is capable of being made and used in various ways and in other embodiments. For example, individual features from one embodiment may be combined with another embodiment. It is also to be understood that the terminology employed herein is for the purpose of description and should not be regarded as limiting. Although only a few examples have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the examples. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims.