CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62/034,575, filed August 7, 2014, which is incorporated herein by reference.

BACKGROUND

[0002] The present disclosure relates generally to blowout preventers. More specifically, in certain embodiments the present disclosure relates to blowout preventers comprising kinetic shear rams and associated methods and systems.

[0003] Considerable safety measures are required when drilling for oil and gas on- shore and off-shore. One such safety measure is the use of blowout preventers (BOPs). BOPs are basically large valves that close, isolate, and seal the wellbore to prevent the discharge of pressurized oil and gas from the well during a kick or other event. One type of BOP used extensively is a ram-type BOP. This type of BOP uses two opposing rams that close by moving together to either close around the pipe or to cut through the pipe and seal the wellbore.

[0004] Conventional blowout preventers are typically operated using pressurized hydraulic fluid to control the position of the rams. Most BOPs are coupled to a fluid pump or another source of pressurized hydraulic fluid. In most applications, multiple BOPs are combined to form a BOP stack, and this may include the use of multiple types of BOPs. In some applications, several hundred gallons of pressurized hydraulic fluid may have to be stored in bottles at the BOP to be able to operate the BOP. Examples of conventional BOPs are described in U.S. Patent Nos. 4,602,794, 7,354,026, and 6,089,526, the entireties of which are hereby incorporated by reference.

[0005] Traditional BOPs may require large stored volumes of high pressure hydraulic fluids to drive the shear rams together at the required force necessary to shear a tubular. Friction losses in hydraulic systems may seriously impact the time to create enough pressure for the ram movement to sever the tubular. Also, the ability to store large volumes of high pressure hydraulic fluids is problematic.

[0006] Traditional BOPs may also be ineffective in sealing wellbores with heavyweight drill collars. These drill collars may be too thick for conventional hydraulic driven ram type BOPs to shear. Conventional rams may not have enough pressure and force to sever a drill collar or large diameter casing. As a result, the drill collar may not be sheared. In addition, traditional BOPs may also be ineffective in shearing large diameter casing.

[0007] It is desirable to develop a ram type blowout preventer that is capable of shearing heavy weight drill collars and does not rely upon a large amount of pressurized hydraulic fluid.

SUMMARY

[0008] The present disclosure relates generally to blowout preventers. More specifically, in certain embodiments the present disclosure relates to blowout preventers comprising kinetic shear rams and associated methods and systems.

[0009] In one embodiment, the present disclosure provides a blowout preventer comprising: a body and a kinetic shear ram disposed within the body.

[0010] In another embodiment, the present disclosure provides a blowout preventer system comprising: a tubular and a blowout preventer disposed around the tubular, wherein the blowout preventer comprises a body and a kinetic shear ram disposed within the body.

[0011] In another embodiment, the present disclosure provides a method of shearing a tubular comprising: providing blowout preventer system comprising a tubular and a blowout preventer disposed around the tubular, wherein the blowout preventer comprises a body and a kinetic shear ram disposed within the body and actuating the blowout preventer to sever the tubular.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] A more complete and thorough understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings.

[0013] Figure 1 illustrates a blowout preventer in accordance with certain embodiments of the present disclosure.

[0014] Figure 2 illustrates a blowout preventer system in accordance to certain embodiments of the present disclosure.

[0015] The features and advantages of the present disclosure will be readily apparent to those skilled in the art. While numerous changes may be made by those skilled in the art, such changes are within the spirit of the disclosure. DETAILED DESCRIPTION

[0016] The description that follows includes exemplary apparatuses, methods, techniques, and/or instruction sequences that embody techniques of the inventive subject matter. However, it is understood that the described embodiments may be practiced without these specific details.

[0017] The present disclosure relates generally to blowout preventers. More specifically, in certain embodiments the present disclosure relates to blowout preventers comprising kinetic shear rams and associated methods and systems.

[0018] One potential advantage of the blowout preventers discussed herein is that they may be capable of shearing tubulars that conventional blowout preventers may be unable to shear. Another potential advantage of the blowout preventers discussed herein is that they do not require the use of large stored volumes of high pressure hydraulic fluids.

[0019] Referring now to Figure 1, Figure 1 illustrates a blowout preventer 100 in accordance with certain embodiments of the present disclosure. In certain embodiments, blowout preventer 100 may comprise body 110, rams 120, and a propellant 130, such as a solid oxidant.

[0020] In certain embodiments, body 110 may be constructed of any conventional material used in subsea blowout preventers. In certain embodiments, inner surface 111 of body 110 may define a vertical bore 112. In certain embodiments, vertical bore 112 may be sized to house any conventional type of tubular. In certain embodiments, inner surfaces 113 of body 110 may define horizontal ram cavities 114. In certain embodiments, horizontal ram cavities 114 may be sized to house any conventional type of ram.

[0021] In certain embodiments, rams 120 may comprise shear rams. In certain embodiments, rams 120 may comprise kinetic shear rams. As used herein, the term "kinetic shear ram" refers to a shear ram whose kinetic energy achieved before contacting the tubular is sufficient to shear the tubular. Such kinetic shear rams achieve a peak velocity before contacting the drill collar. The kinetic energy of the shear ram at that velocity is sufficient alone to shear the drill collar. The term kinetic shear ram excludes other rams that do not achieve a sufficient velocity before contacting a tubular to generate enough kinetic energy to shear the tubular without requiring the use of additional force. As used herein, the term "kinetic shearing" refers to the shearing a tubular by the use of a kinetic shear ram. In certain embodiments, rams 120 may comprise kinetic shear-seal rams. [0022] In certain embodiments, rams 120 may have a mass in the range of from 50 to 100 kg a piece. In certain embodiments, rams may have a mass in the range of from 100 to 500 kg a piece. In certain embodiments, rams may have a mass in the range of from 300 to 400 kg a piece.

[0023] In certain embodiments, rams 120 may be partially or wholly disposed within horizontal ram cavities 114. For example, as shown in Figure 1, a first ram 120 may be disposed within a first ram cavity 114 and a second ram 120 may be disposed within a second ram cavity 114. In certain embodiments, rams 120 may be positioned within ram cavities 114 so that they can sever a tubular disposed within vertical bore 114 when activated.

[0024] In certain embodiments, rams 120 may comprise shear blades 121 and piston 122. In certain embodiments, shear blades 121 may be constructed of any conventional shear blade materials. In certain embodiments, shear blades 121 may be constructed out of any material stiff and heavy enough to deliver the required shear force to the tubular. In certain embodiments, the shear blade material is capable of cutting through a drill collar material without excessive blunting or burring.

[0025] In certain embodiments, shear blades 121 may be elliptically shaped. In certain embodiments, shear blades 121 may have a geometry that comprises a V-angle and a rake angle. In certain embodiments, the V-angle of shear blades 121 may be in the range of from 0 to 60 degrees. In other embodiments, the V-angle of the shear blades 121 may be in the range of from 0 to 45 degrees. In other embodiments, the V angel of the shear blades 121 may be in the range of from 15 to 30 degrees. In certain embodiments, the rake angle of shear blades 121 may be in the range of from 30 to 90 degrees. In other embodiments, the rake angle of the shear blades 121 may be in the range of from 30 to 60 degrees. In other embodiments, the rake angle of the shear blades 121 may be in the range of from 45 to 60 degrees.

[0026] In certain embodiments, shear blades 121 may be attached to a first end 123 of pistons 122. In certain embodiments, pistons 122 may be constructed of any conventional ram piston material. In certain embodiments, pistons 122 may comprise a first end 123 a second end 124 and a rod 126. In certain embodiments, pistons 122 may be a single piece. In certain embodiments, second end 124 of piston 122 may provide sealing contact with inner surface 113. In certain embodiments, one or more seals 127 may provide the sealing contact between inner surface 113 and piston 122. Inner surface 113 of body 110 and second end 124 of piston 122 may define a propellant cavity 115 and a gas cavity 116. In certain embodiments, gas cavity 116 may be filled with pressure nitrogen or other gases. In certain embodiments, a gas valve or inlet/outlet 117 may permit the flow of gas in and out of gas cavity 116.

[0027] In certain embodiments, shear pins 125 may be disposed within ram cavity

112. In certain embodiments, shear pins 125 may be design to contact rams 120 preventing the closure of the blowout preventer. In certain embodiments, shear pins 125 may be designed to shear when the pressure inside propellant cavity 115 reaches a pressure sufficient to allow the kinetic shearing of a tubular disposed within the blowout preventer, thus allowing the blowout preventer to be actuated. In certain embodiments, shear pins 125 may be designed to fail at a pressure in the range of from 5,000 to 20,000 psi. In other embodiments, shear pins 125 may be designed to fail at a pressure in the range of from 5,000 to 10,000 psi. In other embodiments, shear pins 125 may be designed to fail at a pressure in the range of from 7,500 to 10,000 psi. In certain embodiments, shear pins 125 may each be designed to fail simultaneously. For example, in certain embodiments each ram 120 may be linked with a solid bar that fails when one of shear pins 125 fails. In certain embodiments, shear pins 125 may be designed not to fail unit the amount of pressure generated by the propellant 130 is sufficient to ensure kinetic shearing of the tubular.

[0028] In certain embodiments, propellant 130 may comprise any propellant capable of generating gas when ignited, such as solid oxidant. In certain embodiments, propellant 130 may be an explosive. An example of a suitable propellant is MK90 propellant manufactured by Alliant Techsystems. In certain embodiments, propellant 130 may comprise one or more rods. In other embodiments, propellant 130 may comprise a sheet explosive, layers of sheet explosive, disks, or cartridges.

[0029] In certain embodiments, propellant 130 may be disposed in a propellant cavity 115. In other embodiments, propellant 130 may be attached to ram 120. For example, in certain embodiments, propellant 130 may be attached to second end 124 of ram 120.

[0030] In certain embodiments, the propellant 130 in each propellant cavity 115 may be activated by an ignition system 140. In certain embodiments, the propellant 130 in each propellant cavity 115 may be activated simultaneously. In certain embodiments, ignition system 140 may comprise any ignition system that can be remotely activated to ignite the propellant 130. In certain embodiments, ignition system 140 may be capable of igniting the propellant 130 automatically. In certain embodiments, propellant 130 may be activated manually.

[0031] In certain embodiments, the amount of propellant 130 disposed within propellant cavity 115 may be sufficient to generate enough gas pressure to accelerate rams 120 to a velocity in the range of from 50 to 250 m/s. In certain embodiments, the amount of propellant 130 disposed within propellant cavity 115 may be sufficient to generate enough gas pressure to accelerate rams 120 to a velocity in the range of from 75 to 180 m/s. In certain embodiments, the amount of propellant 130 disposed within propellant cavity 115 may be sufficient to generate enough gas pressure to accelerate rams 120 to a velocity in the range of from 100 and 120 m/s.

[0032] In certain embodiments, propellant 130 may have a thickness in the range of from 12 to 65 mm. In certain embodiments, the amount of propellant 130 disposed within propellant cavity 115 may be sufficient to generate a pressure of 7000 psig or more within propellant cavity 115. In certain embodiments, the amount of propellant 130 disposed within the propellant cavity 115 may be sufficient to generate a pressure in the range of from 5,000 to 25,000 psi within propellant cavity 115. In other embodiments, the amount of propellant 130 disposed within the propellant cavity 115 may be sufficient to generate a pressure in the range of from 5,000 to 20,000 psi within propellant cavity 115. In other embodiments, the amount of propellant 130 disposed within the propellant cavity 115 may be sufficient to generate a pressure in the range of from 10,000 to 20,000 psi within propellant cavity 115.

[0033] Referring now to Figure, 2, Figure 2 depicts an embodiment of a blowout preventer system according to the invention. As can be seen in Figure 2, blowout preventer system 200 may comprise blowout preventer 300 and tubular 400.

[0034] In certain embodiments, blowout preventer 300 may comprise any combination of features discussed above with respect to blowout preventer 100. In certain embodiments, tubular 400 may comprise any type of tubular. In certain embodiments, tubular 400 may comprise a drill collar. In certain embodiments, tubular 400 may comprise a heavyweight drill collar with a 9-1/2" OD and 3" bore. In certain embodiments, tubular 400 may comprise large diameter casing. In certain embodiments, tubular 400 may be constructed from 4140 material. In certain embodiments, tubular 400 may pass through the vertical bore of blowout preventer 300 and extend to a bottom hole assembly 900. In certain embodiments, blowout preventer 300 may be attached to a wellhead 500 on top of wellbore 600 on sea floor 700. In certain embodiments, a riser 800 may extend from blowout preventer 300.

[0035] In certain embodiments, the present disclosure provides a method of shearing a tubular comprising: providing blowout preventer system comprising a tubular and a blowout preventer disposed around the tubular, wherein the blowout preventer comprises a body and a kinetic shear ram disposed within the body and actuating the blowout preventer to sever the tubular.

[0036] In certain embodiments, providing the blowout preventer system comprising a tubular and a blowout preventer disposed around the tubular may comprise passing a tubular through a blowout preventer. In certain embodiments, the tubular may comprise any tubular discussed above with respect to tubular 400. In certain embodiments, the blowout preventer may comprise any blowout preventer discussed above with respect to blowout preventers 100 and 300. In certain embodiments, the blowout preventer system may comprise any combination of features discussed above with respect to blowout preventer system 200.

[0037] In certain embodiments, actuating the blowout preventer to sever the tubular comprises igniting the propellant. In certain embodiments, igniting the propellant comprises igniting the propellant with an ignition system.

[0038] In certain embodiments, once ignited, the propellant may rapidly develop a high pressure gas. In certain embodiments, the pressure may rapidly build up in the propellant cavity of the blowout preventer in a few milliseconds. In certain embodiments, once a preset pressure is reached within the propellant cavity, the shear pins may shear will allow the rams to accelerate rapidly to a high velocity before impacting the tubular. In certain embodiments, ram achieves a sufficient amount of kinetic energy to sever the tubular before contacting the tubular. In certain embodiments, the method further comprises kinetically shearing the tubular.

[0039] In certain embodiments, after the blowout preventer has been actuated, the blowout preventer may be deactivated. In certain embodiments, the blowout preventer may be deactivated by injecting gas into the gas chamber, thereby allowing the rams to be retracted.

[0040] While the embodiments are described with reference to various implementations and exploitations, it will be understood that these embodiments are illustrative and that the scope of the inventive subject matter is not limited to them. Many variations, modifications, additions and improvements are possible.

[0041] Plural instances may be provided for components, operations or structures described herein as a single instance. In general, structures and functionality presented as separate components in the exemplary configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements may fall within the scope of the inventive subject matter.