US20060278406A1 - Rod lock for ram blowout preventers - Google Patents
Rod lock for ram blowout preventers Download PDFInfo
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- US20060278406A1 US20060278406A1 US11/147,887 US14788705A US2006278406A1 US 20060278406 A1 US20060278406 A1 US 20060278406A1 US 14788705 A US14788705 A US 14788705A US 2006278406 A1 US2006278406 A1 US 2006278406A1
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- Prior art keywords
- rams
- spherical
- locking elements
- blowout preventer
- thrust
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/02—Surface sealing or packing
- E21B33/03—Well heads; Setting-up thereof
- E21B33/06—Blow-out preventers, i.e. apparatus closing around a drill pipe, e.g. annular blow-out preventers
- E21B33/061—Ram-type blow-out preventers, e.g. with pivoting rams
- E21B33/062—Ram-type blow-out preventers, e.g. with pivoting rams with sliding rams
Definitions
- the invention relates generally to locking mechanisms for a blowout preventer as deployed in the petroleum exploration and recovery industry. More particularly, the invention relates to a roller lock mechanism to prevent the undesirable reversal of a thrust rod for a ram-type blowout preventer.
- Wellbores are drilled deep into the earth's crust to recover oil and gas deposits trapped in the formations below.
- these wellbores are drilled by an apparatus that rotates a drill bit at the end of a long collection, or string, of threaded pipes known as a drillstring.
- a drilling fluid commonly referred to as drilling mud
- drilling mud is used to lubricate and cool the drill bit as it cuts the rock formations below.
- the drilling mud is capable of performing the secondary function of removing the drill cuttings from the bottom of the wellbore to the surface.
- drilling mud is delivered to the drill bit under high pressures through a central bore of the drillstring.
- nozzles on the drill bit direct the pressurized mud to the cutters on the drill bit where the pressurized mud cleans and cools the bit.
- the fluid As the fluid is delivered downhole through the central bore of the drillstring, the fluid returns to the surface in the annulus formed between the outside of the drillstring components and the cut wellbore. Therefore, a hydrostatic column of drilling mud typically extends from the surface to the bottom of the hole being cut.
- blowout preventers BOP's
- BOP's blowout preventers
- Blowout preventers are devices configured to seal the annular space that surrounds the drillstring.
- One of the most common types of blowout preventer is known as a ram-type blowout preventer.
- a ram-type blowout preventer includes a large housing mounted atop the wellhead that includes a large passageway through which the drillstring (and any components connected thereto) is able to pass.
- the housing also includes two or more rams located in a plane substantially normal to the axis of the drillstring and wellhead that are configured to move between retracted and extended positions. The ends of the rams are configured so that when extended, they provide a complete annular hydraulic seal around the drillstring disposed therethrough.
- Ram-type BOP 100 includes a main housing 102 , two or more piston ram housings 104 , and top 106 and bottom 108 bolting flanges for connection to other wellhead components (not shown).
- Ram-type blowout preventer 100 is preferably constructed such that a generally cylindrical through bore 110 allows oilfield tubulars 112 to unobstructedly pass through along a drillstring axis 114 .
- Oilfield tubulars 112 are typically components of a drillstring and may include, but are not limited to, drill pipe, drill collars, measurement tools, coiled tubing, or wirelines.
- Each ram assembly 118 includes a sealing ram 120 having a leading edge 122 connected to a hydraulic piston 124 through a thrust rod 126 .
- Leading edge 122 is preferably contoured such that it corresponds with an outer profile of oilfield tubular 112 so that a tight seal can be formed therebetween.
- hydraulic pistons are activated by an external hydraulic source (not shown) to engage leading edges 122 against tubular 112 and seal off annulus 116 .
- a ram-type BOP 100 may employ three or more ram assemblies 118 with corresponding circular portions for leading edges 122 to shut off and seal annulus 116 .
- pressurized fluids are applied to hydraulic port 128 in communication with a reservoir 130 of ram housing 104 .
- Increases in pressure in reservoir 130 urge back face 132 of piston 124 , causing piston 124 , rod, 126 , and ram 120 to be thrust toward tubular 112 .
- the higher the pressure in communication with reservoir 130 the higher the loads transmitted through rod 126 to ram 120 .
- pressure to port 128 is reduced and piston 124 is able to retract into reservoir 130 .
- Retraction of pistons 124 may be assisted through the use of retraction springs (not shown), hydraulic retraction, or through any other means known in the art.
- a retraction port 129 can be used to provide hydraulic access to a retraction reservoir 131 , such that an increase in hydraulic pressure displaces piston 124 to retract ram 120 .
- One former method to lock hydraulic rams 120 in place involves the tightening of mechanical screws to lock pistons 124 in place once displaced in reservoir 130 .
- Such screws were tightened either manually or through power devices and would effectively lock rams 120 , thrust rods 126 , and pistons 124 in place.
- accessibility concerns make such a solution less than optimal.
- these locking screws must be activated by remotely operated vehicles or through electrical actuators. As such, their reliability is suspect in depths of several hundred feet or more.
- the BOP 100 is typically located beneath the rig floor. As such, engaging and disengaging the locking screws takes considerable time, time that is not always available in the event of an emergency.
- a blowout preventer in one embodiment, includes a housing configured to be positioned above a wellhead and to surround a drillstring, a plurality of rams positioned perpendicular to an axis of the drillstring, and a roller lock positioned about a thrust rod of each ram.
- the rams may be configured to engage the drillstring and hydraulically isolate an annulus between the wellbore and the drillstring from components located above the housing when the rams are in a closed position.
- the roller locks may be configured to maintain the rams in the closed position.
- the present invention related to a locking apparatus to be used with a blowout preventer.
- the locking apparatus includes a plurality of spherical locking elements to engage and restrict movement of thrust rods connected to rams of the blowout preventer.
- the locking apparatus may also include a plurality of receptacles for the spherical locking elements, wherein each receptacle includes an inclined surface configured to thrust the spherical locking elements into compressive contact with the thrust rods when the operating rams are urged open.
- the locking apparatus may also include a release cage to retract and retain the spherical locking elements into the receptacles and to direct them out of compressive contact with the thrust rods when the operating rams are to be opened.
- the present invention relates to a method to lock rams of a blowout preventer.
- the method may include positioning spherical locking elements inside receptacles located adjacent to thrust rods of the rams, wherein the receptacles include inclined surfaces configured to engage the spherical locking elements into the thrust rods when the rams are urged open.
- the method may further include locking the thrust rods with compressive engagement of the spherical locking elements.
- the method may further include retracting the spherical locking elements into their respective receptacles with a release cage to unlock the rams.
- FIG. 1 is a schematic section-view drawing of a ram-type blowout preventer.
- FIG. 2 is a schematic drawing of a thrust rod retainer in accordance with an embodiment of the present invention.
- FIG. 3 is a schematic drawing of a thrust rod retainer in accordance with an embodiment of the present invention.
- thrust rod lock 250 is preferably located within a piston ram housing (e.g. 104 of FIG. 1 ) in a fixed position surrounding a thrust rod 226 .
- Thrust rod lock 250 is desirably configured to allow displacement of thrust rod 226 in a locking direction 252 , while disallowing displacement of thrust rod 226 in an unlocking direction 254 .
- Thrust rod lock 250 includes a main body 256 , into which one or more roller receptacles 258 are formed. Roller receptacle 258 is shown including a deep section 260 that extends to a shallow section 262 through an inclined surface 264 .
- each roller receptacle 258 is configured to retain and deploy a roller 266 within and from receptacle 258 when locking of thrust rod 226 is selectively desired.
- roller 266 when roller 266 is located within deep section 260 , substantially no contact occurs between roller and thrust rod 226 , but as roller 266 travels down inclined surface 264 , thrust rod 226 is increasingly locked into a bind by roller 266 and surface 264 .
- further increases in load upon thrust rod 226 in unlocking direction 254 tend to cause roller 266 in contact with inclined surface 264 to compress against thrust rod 226 even tighter, resulting in an even stronger locked position.
- Displacements of thrust rod 226 in locking direction 252 tend to roll roller 266 up inclined surface 264 toward deep section 260 of main body 256 , such that rod 226 is free to move in locking direction 252 .
- a retainer cage 268 of thrust rod lock 250 retains roller 266 within receptacle 258 and is configured to retrieve roller 266 into deep section 260 when thrust rod 226 is to be released.
- Retainer cage 268 preferably includes a slot (not shown) adjacent to roller 266 to allow retainer cage 268 to displace roller 266 without interfering with the roller's engagement with thrust rod 226 .
- slot can be a longitudinal slot or a spherical section to match the outer profile of roller 266 .
- the slot can be a transverse slot approximately the same width as roller 266 .
- retainer cage 268 is displaced in direction 270 to retrieve roller 266 up inclined surface 264 and into deep section 260 , away from the engagement with outer surface of thrust rod 226 .
- Retainer cage 268 may be biased so that roller 266 is biased in the direction opposite 270 and into thrust rod 226 .
- cage 268 may be unbiased allowing movement of thrust rod 226 to be the sole force in causing roller 266 to be engaged therewith.
- any means to displace or bias retainer cage known in the art may be employed, including, but not limited to, hydraulic lines, springs, and tension cables.
- retainer cage can be constructed to be displaced when hydraulic pressure is applied to a hydraulic actuator attached thereto.
- a control system (not shown) can be used to direct such hydraulic pressure to either the retainer cage actuator, the thrust rod retractor, or both.
- a hydraulic system to release thrust rod lock 250 can be distinct from a hydraulic system to displace thrust rod 226 in unlocking direction 254 .
- inclined surface 264 can be any of various types known in the art. Particularly, surface 264 can be a mere planar surface or can be profiled to fit the contours of spherical rollers 266 . Furthermore, while rollers 266 are described generically, it should be understood that they can be constructed as spherical or cylindrical devices and can be constructed with various hardness and friction values to facilitate contact and engagement between thrust rod 226 and inclined surface 264 .
- thrust rod lock 350 of FIG. 3 is preferably located within a piston ram housing 304 in a fixed position surrounding a thrust rod 326 . While a single thrust rod lock 350 is shown, it should be understood that a plurality of rod locks 350 can surround thrust rod 326 radially and axially.
- Thrust rod lock 350 is desirably configured to allow displacement of a thrust rod 326 in a locking direction 352 , while resisting displacement of thrust rod 326 in an unlocking direction 354 .
- Thrust rod lock 350 includes a main body 356 , into which two series of roller receptacles 358 A, 358 B are formed.
- inner roller receptacle 358 A is profiled to urge a roller 366 A into engagement with thrust rod 326 when thrust rod 326 is displaced in unlocking direction 354 .
- outer roller receptacle 358 B is profiled to urge a roller 366 B into engagement with an outer wear plate 380 when main body 356 is displaced in unlocking direction 354 . Therefore, for each location about and along thrust rod 326 , one roller 366 A bites with thrust rod 326 and another roller 366 B bites with wear plate 380 to resist displacement of thrust rod 326 in unlocking direction 354 . As such, for each incremental displacement in unlocking direction 354 , thrust rod 326 of FIG. 3 will experience double the radial compression as would be experienced by a thrust rod in a single roller configuration (e.g. FIG. 2 ).
- inner and outer retainer cages 368 A, 368 B retain rollers 366 A, 366 B inside receptacles 358 A, 358 B and allow for rod lock 350 to be released once retraction of thrust rod 326 is desired.
- retainer cages 368 A, 368 B allow rollers 366 A, 366 B to contact thrust rod 326 and wear place 380 through slots or other forms of apertures (not shown) therethrough.
- apertures in retainer cages 368 A, 368 B can take the form of longitudinal slots or spherical sections in the case where rollers 366 A, 366 B are spherical or can be transverse slots if rollers 366 A, 366 B are cylindrical.
- a pair of bias springs 382 , 384 is shown working in conjunction with main body 356 and retainer cages 368 A, 368 B to thrust rollers 366 A, 366 B into locking engagement with thrust rod 326 and wear plate 380 by default.
- spring 382 urges main body in the direction of arrow 352 such that inclined surface 364 A urges roller 366 A into contact with thrust rod 326 .
- spring 384 between main body 356 and outer retainer cage 368 B urges cage 368 B and roller 366 B in the direction of arrow 352 such that inclined surface 364 B urges roller 366 B into contact with wear plate 380 .
- Unlocking mechanism 386 can be constructed any number of ways, but is preferably configured to retract rollers 366 A, 366 B into their respective receptacles 358 A, 358 B so that thrust rod 326 can be retracted in unlocking direction 354 .
- Unlocking mechanism 386 of FIG. 3 is shown within a recess 388 of housing 304 .
- a hydraulic seal 390 surrounding mechanism 386 ensures that when hydraulic pressure is increased to a hydraulic port 392 , mechanism 386 is displaced in the direction of 354 such that a thrust face 394 engages a corresponding load shoulder 396 of outer retainer cage 368 B.
- Rod lock assemblies 250 and 350 of the present invention exhibit many advantages over locking mechanisms currently available.
- rod lock assemblies 250 , 350 are capable of securing thrust rods 226 , 326 almost instantaneously and with little or no backlash or slippage.
- rod lock assemblies 250 , 350 are disclosed as “fail safe” devices, in that they lock by default. No affirmative steps are necessary to lock thrust rods 226 , 326 in place once they are extended.
- Rod lock assemblies 250 , 350 automatically engage and resist disengagement of thrust rods 226 , 326 .
- hydraulic (or other) power is only necessary to disengage rod locks 250 , 350 .
- rod locks 250 , 350 are configured to engage smooth outer profiles of thrust rods 226 , 326 , no obstructive features are necessary on thrust rods 226 , 326 .
- Former solutions required special profiles that could obstruct thrust rod 226 , 326 operation and engagement.
Abstract
Description
- 1. Field of the Invention
- The invention relates generally to locking mechanisms for a blowout preventer as deployed in the petroleum exploration and recovery industry. More particularly, the invention relates to a roller lock mechanism to prevent the undesirable reversal of a thrust rod for a ram-type blowout preventer.
- 2. Background Art
- Wellbores are drilled deep into the earth's crust to recover oil and gas deposits trapped in the formations below. Typically, these wellbores are drilled by an apparatus that rotates a drill bit at the end of a long collection, or string, of threaded pipes known as a drillstring. Because of the energy and friction involved in such an operation, a drilling fluid, commonly referred to as drilling mud, is used to lubricate and cool the drill bit as it cuts the rock formations below. Furthermore, the drilling mud is capable of performing the secondary function of removing the drill cuttings from the bottom of the wellbore to the surface. Typically, drilling mud is delivered to the drill bit under high pressures through a central bore of the drillstring. From there, nozzles on the drill bit direct the pressurized mud to the cutters on the drill bit where the pressurized mud cleans and cools the bit. As the fluid is delivered downhole through the central bore of the drillstring, the fluid returns to the surface in the annulus formed between the outside of the drillstring components and the cut wellbore. Therefore, a hydrostatic column of drilling mud typically extends from the surface to the bottom of the hole being cut.
- As wellbores are drilled several thousand feet below the surface, the hydrostatic column of drilling mud serves to help prevent blowout of the wellbore as well. Often, hydrocarbons and other fluids trapped in subterranean formations exist under significant pressures. Absent any flow control schemes, fluids from such ruptured formations can blow out of the wellbore like a geyser and spew hydrocarbons and other undesirable fluids into the atmosphere. Several thousand feet of hydraulic head from the drilling mud column helps to prevent the wellbore from blowing out under normal conditions. However, under certain unforeseen circumstances, the drill bit will encounter pockets of pressurized formations and will cause the wellbore to “kick” or experience a rapid increase in pressure. Because formation kicks are unpredictable and would otherwise result in disaster, flow control devices known as blowout preventers (“BOP's”), are mandatory on most drilling rigs in use today.
- Blowout preventers are devices configured to seal the annular space that surrounds the drillstring. One of the most common types of blowout preventer is known as a ram-type blowout preventer. A ram-type blowout preventer includes a large housing mounted atop the wellhead that includes a large passageway through which the drillstring (and any components connected thereto) is able to pass. The housing also includes two or more rams located in a plane substantially normal to the axis of the drillstring and wellhead that are configured to move between retracted and extended positions. The ends of the rams are configured so that when extended, they provide a complete annular hydraulic seal around the drillstring disposed therethrough.
- Referring initially to
FIG. 1 , a typical ram-type BOP 100 is shown schematically. Ram-type BOP 100 shown includes amain housing 102, two or morepiston ram housings 104, andtop 106 andbottom 108 bolting flanges for connection to other wellhead components (not shown). Ram-type blowout preventer 100 is preferably constructed such that a generally cylindrical throughbore 110 allowsoilfield tubulars 112 to unobstructedly pass through along adrillstring axis 114.Oilfield tubulars 112 are typically components of a drillstring and may include, but are not limited to, drill pipe, drill collars, measurement tools, coiled tubing, or wirelines. Under normal conditions, throughbore 110 is open and not obstructed such that fluids pass through anannulus 116 formed between the outer profile oftubulars 112 and the inner profile of throughbore 110. When the wellbore below is to be shut off such that fluids belowBOP 100 can no longer communicate with the wellbore aboveBOP 100,ram assemblies 118 are activated to provide a 360° seal ofannulus 116 betweenbore 110 andtubulars 112. - Each
ram assembly 118 includes asealing ram 120 having a leadingedge 122 connected to ahydraulic piston 124 through athrust rod 126.Leading edge 122 is preferably contoured such that it corresponds with an outer profile of oilfield tubular 112 so that a tight seal can be formed therebetween. Connected to sealingrams 120 throughthrust rods 126, hydraulic pistons are activated by an external hydraulic source (not shown) to engage leadingedges 122 against tubular 112 and seal offannulus 116. While it may be typical for there to be tworam assemblies 118, each with a corresponding semi-circular profile for leadingedges 122, it should be understood that a ram-type BOP 100 may employ three ormore ram assemblies 118 with corresponding circular portions for leadingedges 122 to shut off and sealannulus 116. - To seal off
annulus 116, pressurized fluids are applied tohydraulic port 128 in communication with areservoir 130 ofram housing 104. Increases in pressure inreservoir 130urge back face 132 ofpiston 124, causingpiston 124, rod, 126, andram 120 to be thrust toward tubular 112. The higher the pressure in communication withreservoir 130, the higher the loads transmitted throughrod 126 toram 120. To retractrams 120 out ofannulus 116, pressure toport 128 is reduced andpiston 124 is able to retract intoreservoir 130. Retraction ofpistons 124 may be assisted through the use of retraction springs (not shown), hydraulic retraction, or through any other means known in the art. Particularly, aretraction port 129 can be used to provide hydraulic access to aretraction reservoir 131, such that an increase in hydraulicpressure displaces piston 124 to retractram 120. - With
rams 120 extended and leadingedges 122 engaging oilfield tubular 112, a strong hydraulic seal prevents fluid from escaping the wellbore throughannulus 116. As long as hydraulic pressure is maintained inreservoir 130,rams 120 will continue to sealannulus 116. However, there are circumstances where it is desired to maintain the annular seal regardless of the operational abilities of ram-type BOP 100. For example, it is desirable to maintain seal integrity in the event of a power failure at the rigsite. Furthermore, if wellbore is to be shut-in for an extended period of time, maintaining hydraulic pressure over that time period is not always reliable or prudent. Therefore, systems and mechanisms to “lock”hydraulic rams 120 in place once activated are highly desirable in the oilfield. - One former method to lock
hydraulic rams 120 in place involves the tightening of mechanical screws to lockpistons 124 in place once displaced inreservoir 130. Such screws were tightened either manually or through power devices and would effectively lockrams 120,thrust rods 126, andpistons 124 in place. However, accessibility concerns make such a solution less than optimal. Particularly, in deep-sea installations, these locking screws must be activated by remotely operated vehicles or through electrical actuators. As such, their reliability is suspect in depths of several hundred feet or more. Furthermore, on land-based rigs, theBOP 100 is typically located beneath the rig floor. As such, engaging and disengaging the locking screws takes considerable time, time that is not always available in the event of an emergency. - Additional solutions to lock hydraulic rams are available to lock
thrust rods 126 in place. Formerly, ratchet profiles (e.g. U.S. Pat. No. 3,941,141 to Robert, hereby incorporated by reference herein) have been used upon the outer profiles ofthrust rods 126 in conjunction with matching locking members to retainthrust rods 126 in place. Furthermore, various internal threaded mechanisms (e.g U.S. Pat. No. 4,052,995 to Ellison and U.S. Pat. No. 4,076,208 to Olson, both hereby incorporated by reference herein) have been employed to securethrust rods 126 in place using wherebythrust rods 126 are threaded and corresponding jam-nut devices lockthrust rods 126 in place. Finally, various wedging solutions (e.g. U.S. Pat. Nos. 4,305,565 to Abbe and U.S. Pat. No. 4,969,390 to Williams, both hereby incorporated by reference herein) have been proposed to lockthrust rods 126 in place. While promising, each of these solutions are considered by many to be less than optimal in that they exhibit a slight amount of slip or “play” in the reverse direction known as backlash before they engage and lock thethrust rods 126 in place. In the event of a high pressure “kick” to a wellbore, even infinitesimal displacements inrams 120 connected to thrustrods 126 can result in a catastrophic release of wellbore fluids. - Therefore, there is a long-felt need in the industry for an apparatus to quickly, positively, and solidly lock ram-type blowout preventers in an engaged position with minimal operator interaction and with minimal backlash of the rams before locking occurs.
- In one embodiment, a blowout preventer includes a housing configured to be positioned above a wellhead and to surround a drillstring, a plurality of rams positioned perpendicular to an axis of the drillstring, and a roller lock positioned about a thrust rod of each ram. The rams may be configured to engage the drillstring and hydraulically isolate an annulus between the wellbore and the drillstring from components located above the housing when the rams are in a closed position. The roller locks may be configured to maintain the rams in the closed position.
- In one aspect, the present invention related to a locking apparatus to be used with a blowout preventer. In one embodiment, the locking apparatus includes a plurality of spherical locking elements to engage and restrict movement of thrust rods connected to rams of the blowout preventer. The locking apparatus may also include a plurality of receptacles for the spherical locking elements, wherein each receptacle includes an inclined surface configured to thrust the spherical locking elements into compressive contact with the thrust rods when the operating rams are urged open. Furthermore, the locking apparatus may also include a release cage to retract and retain the spherical locking elements into the receptacles and to direct them out of compressive contact with the thrust rods when the operating rams are to be opened.
- In one aspect, the present invention relates to a method to lock rams of a blowout preventer. The method may include positioning spherical locking elements inside receptacles located adjacent to thrust rods of the rams, wherein the receptacles include inclined surfaces configured to engage the spherical locking elements into the thrust rods when the rams are urged open. The method may further include locking the thrust rods with compressive engagement of the spherical locking elements. The method may further include retracting the spherical locking elements into their respective receptacles with a release cage to unlock the rams.
- Other aspects and advantages of the invention will be apparent from the following description and the appended claims.
-
FIG. 1 is a schematic section-view drawing of a ram-type blowout preventer. -
FIG. 2 is a schematic drawing of a thrust rod retainer in accordance with an embodiment of the present invention. -
FIG. 3 is a schematic drawing of a thrust rod retainer in accordance with an embodiment of the present invention. - Referring now to
FIG. 2 , a schematic representation of athrust rod lock 250 in accordance with an embodiment of the present invention is shown. In this embodiment, thrustrod lock 250 is preferably located within a piston ram housing (e.g. 104 ofFIG. 1 ) in a fixed position surrounding athrust rod 226.Thrust rod lock 250 is desirably configured to allow displacement ofthrust rod 226 in alocking direction 252, while disallowing displacement ofthrust rod 226 in an unlockingdirection 254.Thrust rod lock 250 includes amain body 256, into which one ormore roller receptacles 258 are formed.Roller receptacle 258 is shown including adeep section 260 that extends to ashallow section 262 through aninclined surface 264. - As such, each
roller receptacle 258 is configured to retain and deploy aroller 266 within and fromreceptacle 258 when locking ofthrust rod 226 is selectively desired. Particularly, whenroller 266 is located withindeep section 260, substantially no contact occurs between roller and thrustrod 226, but asroller 266 travels downinclined surface 264, thrustrod 226 is increasingly locked into a bind byroller 266 andsurface 264. Furthermore, once so locked, further increases in load uponthrust rod 226 in unlockingdirection 254 tend to causeroller 266 in contact withinclined surface 264 to compress againstthrust rod 226 even tighter, resulting in an even stronger locked position. Displacements ofthrust rod 226 in lockingdirection 252 tend to rollroller 266 upinclined surface 264 towarddeep section 260 ofmain body 256, such thatrod 226 is free to move in lockingdirection 252. - Furthermore, a
retainer cage 268 ofthrust rod lock 250 retainsroller 266 withinreceptacle 258 and is configured to retrieveroller 266 intodeep section 260 when thrustrod 226 is to be released.Retainer cage 268 preferably includes a slot (not shown) adjacent toroller 266 to allowretainer cage 268 to displaceroller 266 without interfering with the roller's engagement withthrust rod 226. In the case whereroller 266 is a spherical roller, slot can be a longitudinal slot or a spherical section to match the outer profile ofroller 266. Alternatively, in the case whereroller 266 is cylindrical, the slot can be a transverse slot approximately the same width asroller 266. Regardless of configuration, when thrustrod 226 is to be displaced in unlockingdirection 254,retainer cage 268 is displaced indirection 270 to retrieveroller 266 upinclined surface 264 and intodeep section 260, away from the engagement with outer surface ofthrust rod 226.Retainer cage 268 may be biased so thatroller 266 is biased in the direction opposite 270 and intothrust rod 226. Alternatively,cage 268 may be unbiased allowing movement ofthrust rod 226 to be the sole force in causingroller 266 to be engaged therewith. - It should be understood that any means to displace or bias retainer cage known in the art may be employed, including, but not limited to, hydraulic lines, springs, and tension cables. Particularly, retainer cage can be constructed to be displaced when hydraulic pressure is applied to a hydraulic actuator attached thereto. Furthermore, if a hydraulic device is employed to retract
thrust rod 226 into unlockingdirection 254, a control system (not shown) can be used to direct such hydraulic pressure to either the retainer cage actuator, the thrust rod retractor, or both. Alternatively, a hydraulic system to release thrustrod lock 250 can be distinct from a hydraulic system to displacethrust rod 226 in unlockingdirection 254. - Furthermore, it should be understood that
inclined surface 264 can be any of various types known in the art. Particularly,surface 264 can be a mere planar surface or can be profiled to fit the contours ofspherical rollers 266. Furthermore, whilerollers 266 are described generically, it should be understood that they can be constructed as spherical or cylindrical devices and can be constructed with various hardness and friction values to facilitate contact and engagement betweenthrust rod 226 andinclined surface 264. - Referring now to
FIG. 3 , a schematic of athrust rod lock 350 in accordance with an embodiment of the present invention is shown. Likethrust rod lock 250 ofFIG. 2 , thrustrod lock 350 ofFIG. 3 is preferably located within apiston ram housing 304 in a fixed position surrounding athrust rod 326. While a singlethrust rod lock 350 is shown, it should be understood that a plurality ofrod locks 350 can surround thrustrod 326 radially and axially. -
Thrust rod lock 350 is desirably configured to allow displacement of athrust rod 326 in alocking direction 352, while resisting displacement ofthrust rod 326 in an unlockingdirection 354.Thrust rod lock 350 includes amain body 356, into which two series ofroller receptacles receptacles 258 ofFIG. 2 ,inner roller receptacle 358A is profiled to urge aroller 366A into engagement withthrust rod 326 when thrustrod 326 is displaced in unlockingdirection 354. At the same time,outer roller receptacle 358B is profiled to urge aroller 366B into engagement with anouter wear plate 380 whenmain body 356 is displaced in unlockingdirection 354. Therefore, for each location about and alongthrust rod 326, oneroller 366A bites withthrust rod 326 and anotherroller 366B bites withwear plate 380 to resist displacement ofthrust rod 326 in unlockingdirection 354. As such, for each incremental displacement in unlockingdirection 354, thrustrod 326 ofFIG. 3 will experience double the radial compression as would be experienced by a thrust rod in a single roller configuration (e.g.FIG. 2 ). - Furthermore, inner and
outer retainer cages rollers receptacles rod lock 350 to be released once retraction ofthrust rod 326 is desired. As withretainer cage 268 ofFIG. 2 ,retainer cages rollers thrust rod 326 and wearplace 380 through slots or other forms of apertures (not shown) therethrough. As before, such apertures inretainer cages rollers rollers main body 356 andretainer cages rollers thrust rod 326 and wearplate 380 by default. Asinner retainer cage 368A is fixed relative tohousing 304,spring 382 urges main body in the direction ofarrow 352 such that inclinedsurface 364A urgesroller 366A into contact withthrust rod 326. Likewise,spring 384 betweenmain body 356 andouter retainer cage 368B urgescage 368B androller 366B in the direction ofarrow 352 such thatinclined surface 364B urgesroller 366B into contact withwear plate 380. - To release
rollers thrust rod 326 and wearplate 380, an unlockingmechanism 386 is employed. Unlockingmechanism 386 can be constructed any number of ways, but is preferably configured to retractrollers respective receptacles thrust rod 326 can be retracted in unlockingdirection 354. Unlockingmechanism 386 ofFIG. 3 is shown within arecess 388 ofhousing 304. Ahydraulic seal 390surrounding mechanism 386 ensures that when hydraulic pressure is increased to ahydraulic port 392,mechanism 386 is displaced in the direction of 354 such that athrust face 394 engages acorresponding load shoulder 396 ofouter retainer cage 368B. When pressure toport 392 is sufficiently elevated, springs 384 and 382 are compressed such thatrollers recesses thrust rod 326 to be retracted. Oncethrust rod 326 is retracted, pressure to port 392 can be released so thatthrust rod 326 can be quickly engaged and held in place without any secondary locking step necessary. In its ordinary, equilibrium state,rod lock assembly 350 resists disengagement ofthrust rod 326 without any supplemental steps, even in the event of total loss of hydraulic power. -
Rod lock assemblies rod lock assemblies rods rod lock assemblies rods Rod lock assemblies thrust rods rod locks rod locks thrust rods thrust rods rod - While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
Claims (21)
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US (1) | US20060278406A1 (en) |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20090127482A1 (en) * | 2004-11-04 | 2009-05-21 | Anthony Stephen Bamford | Hydraulic rams |
WO2012012192A1 (en) * | 2010-07-19 | 2012-01-26 | National Oilwell Varco, L.P. | System and method for sealing a wellbore |
WO2012012193A1 (en) * | 2010-07-19 | 2012-01-26 | National Oilwell Varco, L.P. | Method and system for sealing a wellbore |
WO2013151527A1 (en) * | 2012-04-02 | 2013-10-10 | Halliburton Energy Services, Inc. | Method and apparatus for pressure-actuated tool connection and disconnection |
US8844898B2 (en) | 2009-03-31 | 2014-09-30 | National Oilwell Varco, L.P. | Blowout preventer with ram socketing |
US8978751B2 (en) | 2011-03-09 | 2015-03-17 | National Oilwell Varco, L.P. | Method and apparatus for sealing a wellbore |
CN104632127A (en) * | 2013-11-15 | 2015-05-20 | 中国石油天然气股份有限公司 | Oil production wellhead integrating device |
WO2015103217A1 (en) * | 2013-12-30 | 2015-07-09 | Longyear Tm, Inc. | Diverter assemblies and systems for forming seals around pipe elements and methods of using same |
CN106246140A (en) * | 2016-07-26 | 2016-12-21 | 陕西恒合石油科技有限公司 | Coiled tubing trips out alarm controller |
WO2017120338A1 (en) * | 2016-01-07 | 2017-07-13 | Ensco International Incorporated | Subsea casing tieback |
US10018009B2 (en) * | 2015-02-26 | 2018-07-10 | Cameron International Corporation | Locking apparatus |
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Cited By (20)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20090127482A1 (en) * | 2004-11-04 | 2009-05-21 | Anthony Stephen Bamford | Hydraulic rams |
US8844898B2 (en) | 2009-03-31 | 2014-09-30 | National Oilwell Varco, L.P. | Blowout preventer with ram socketing |
WO2012012192A1 (en) * | 2010-07-19 | 2012-01-26 | National Oilwell Varco, L.P. | System and method for sealing a wellbore |
WO2012012193A1 (en) * | 2010-07-19 | 2012-01-26 | National Oilwell Varco, L.P. | Method and system for sealing a wellbore |
GB2495254A (en) * | 2010-07-19 | 2013-04-03 | Nat Oilwell Varco Lp | System and method for sealing a wellbore |
US8540017B2 (en) | 2010-07-19 | 2013-09-24 | National Oilwell Varco, L.P. | Method and system for sealing a wellbore |
US8544538B2 (en) | 2010-07-19 | 2013-10-01 | National Oilwell Varco, L.P. | System and method for sealing a wellbore |
GB2495254B (en) * | 2010-07-19 | 2017-04-12 | Nat Oilwell Varco Lp | Seal assembly for a blowout preventer |
US8978751B2 (en) | 2011-03-09 | 2015-03-17 | National Oilwell Varco, L.P. | Method and apparatus for sealing a wellbore |
GB2514937A (en) * | 2012-04-02 | 2014-12-10 | Halliburton Energy Serv Inc | Method and apparatus for pressure-actuated tool connection and disconnection |
US8893801B2 (en) | 2012-04-02 | 2014-11-25 | Halliburton Energy Services, Inc. | Method and apparatus for pressure-actuated tool connection and disconnection |
WO2013151527A1 (en) * | 2012-04-02 | 2013-10-10 | Halliburton Energy Services, Inc. | Method and apparatus for pressure-actuated tool connection and disconnection |
GB2514937B (en) * | 2012-04-02 | 2019-02-27 | Halliburton Energy Services Inc | Method for pressure-actuated tool disconnection |
CN104632127A (en) * | 2013-11-15 | 2015-05-20 | 中国石油天然气股份有限公司 | Oil production wellhead integrating device |
WO2015103217A1 (en) * | 2013-12-30 | 2015-07-09 | Longyear Tm, Inc. | Diverter assemblies and systems for forming seals around pipe elements and methods of using same |
US10087699B2 (en) | 2013-12-30 | 2018-10-02 | Longyear Tm, Inc. | Diverter assemblies and systems for forming seals around pipe elements and methods of using same |
US10018009B2 (en) * | 2015-02-26 | 2018-07-10 | Cameron International Corporation | Locking apparatus |
WO2017120338A1 (en) * | 2016-01-07 | 2017-07-13 | Ensco International Incorporated | Subsea casing tieback |
US10081986B2 (en) | 2016-01-07 | 2018-09-25 | Ensco International Incorporated | Subsea casing tieback |
CN106246140A (en) * | 2016-07-26 | 2016-12-21 | 陕西恒合石油科技有限公司 | Coiled tubing trips out alarm controller |
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