The present invention relates to a multi-window lateral well locating/reentry apparatus and method, and more particularly to an apparatus and method for locating multiple windows in a main well and reinstalling a guide for reentry through the windows and into lateral wells.
In the exploration for oil and gas, a main well bore is drilled and cased. The well bore may be a vertical or horizontal well. It is often necessary to drill one or more lateral wells off of the main well bore. These lateral wells are usually drilled to increase production from the producing zone or enter new zones which may contain a hydrocarbon reservoir. To drill a lateral well, a whip stock is run into the main well bore on a work string and anchored at a location where the lateral well is to be drilled. The upper end of the whip stock has an inclined face. A milling bit on a tubular is diverted by the whip stock's inclined face into the casing wall where a window or opening in the casing is made for a lateral exit from the main well bore. The whip stock may be removed from the well bore after the lateral has been completed.
After removal of the whip stock, the need may arise to reenter a lateral well to clean it out or conduct remedial work. The present invention provides a reliable, cost-effective means to locate and reenter a lateral well bore after the whip stock has been removed from the main well bore.
The need may also arise to reenter multiple lateral wells from a single main well to clean such lateral wells or conduct remedial work therein. The present invention provides a reliable, cost-effective means to locate and reenter multiple lateral well bores after the whip stock has been removed from the main well bore.
It is an object of the present invention to provide a down-hole assembly and method capable of locating a window in a well bore.
It is a further object of the present invention to provide a down-hole assembly and method capable of determining the dimension and shape of a window in a well bore.
It is a further object of the present invention to provide a down-hole assembly and method capable of reinstalling a guide for reentry through a window into a lateral well bore.
It is a further object of the present invention to provide a down-hole assembly and method capable of the combined procedure of locating a window and guiding reentry of a down-hole tool through the window into a lateral well bore after a whip stock has been removed.
It is an object of the present invention to provide a down-hole assembly and method capable of locating multiple windows in a well bore.
It is a further object of the present invention to provide a down-hole assembly and method capable of determining the dimension and shape of multiple windows in a well bore.
It is a further object of the present invention to provide a down-hole assembly and method capable of reinstalling a guide for reentry through multiple lateral-well-bore windows.
It is a further object of the present invention to provide a down-hole assembly and method capable of the combined procedure of locating multiple lateral-well-bore windows and guiding reentry of a down-hole tool through each of the windows into a lateral well bore after a whip stock has been removed.
These and other objects and advantages of the present invention are achieved by a novel down-hole assembly for locating a window and reentering a lateral well bore in a main well bore after removal of a whip stock. The down-hole assembly may include a running tool having an upper section, a middle section and a lower section. The running tool may include a window locator for locating the window in the main well bore which leads to the lateral well bore. The assembly may also include a guide member having an upper section, a middle section and a lower section. The guide member may have a wedged-shaped outer surface for diverting a down-hole tool through the window and into the lateral well bore. The lower section of the running tool and the upper section of the guide member may each be shaped to receive the other in mating relationship. The lower section of the running tool and the upper section of the guide member may be capable of being detachably connected. When detachably connected, the running tool and the guide member may be in fluid communication.
The window locator in the running tool may include a pivoting arm and a window locating head. The running tool may also have biasing means operatively associated with the window locator. The biasing means may exert a force on the pivoting arm of the window locator to bias the window locating head in a direction external of the running tool. The window locating head may have a run-in position, a retracted position, and a window locating position. In the run-in position, the window locating head is positioned between the retracted and window locating positions and held stationary. The running tool may include one or more shear pins affixed to the window locator. The shear pins maintain the window locating head in the stationary position until sheared. In the retracted position, the window locating head is positioned substantially within the running tool. The window locating head may be held in the retracted position by the main well bore. In the window locating position, the window locating head may be biased in a direction external of the running tool with a portion of the window locating head positioned within the window.
The running tool may include a block means for restricting a maximum outward pivoting angle of the window locating head. The block means may have a shoulder capable of receiving an outer edge surface of the window locating head.
The running tool may include a stop means for preventing retraction of the window locating head from the window locating position. The stop means may comprise one or more spring-loaded shear pins. The one or more spring loaded shear pins may be actuated by displacement of the window locating head from the retracted position to the window locating position and deactivated by a shearing force. The deactivation may result in the window locating head returning to the retracted position.
The upper section of the running tool may have a first internal fluid passage bore and the lower section of the running tool may have a second internal fluid passage bore. The first and second internal fluid passage bores may be fluidly connected by a conduit. The conduit may by-pass the window locator.
The shape of the lower end of the running tool (or a portion thereof) may be substantially convex. The shape of the upper end of the guide member (or a portion thereof) may be substantially concave. The lower section of the running tool and the upper section of the guide member may be detachably connected by a shear bolt. The lower section of the running tool and the upper end of the guide member may be further detachably connected by a dovetail joint.
The guide member may include an internal fluid passage bore. The running tool may include a stinger pipe fluidly connected to the second internal fluid passage bore. The stinger pipe may be sealingly connected to the internal fluid passage bore of the guide member when the running tool and the guide member are detachably connected.
The guide member may also include a retrieval means. The retrieval means may provide a point of operative attachment for a retrieval or fishing tool for retrieval of the guide member.
In an alternative embodiment, the down-hole assembly may include a diverter sub having an upper end and a lower end. The upper end of the diverter sub may be operatively connected to a tubular. The assembly may also include a running tool having an upper section, a middle section and a lower section. The upper section of the running tool may be operatively connected to the lower end of the diverter sub. The running tool may have a window locator for locating a window in a main cased well bore. The upper section of the running tool may include a first internal fluid passage bore. The lower section of the running tool may include a second internal fluid passage bore. The running tool may also have a conduit fluidly connecting the first and second internal fluid passage bores. The assembly may also include a guide member having an upper section, a middle section and a lower section. The lower section of the running tool and the upper section of the guide member may each be shaped to receive the other in mating relationship. The guide member may have an internal fluid passage bore. The upper section of the guide member may be detachably connected to the lower section of the running tool. The guide member may have a wedged-shaped outer surface for diverting a down-hole tool through the window and into the lateral well bore. The assembly may also have a stinger pipe with an upper end and a lower end. The upper end of the stinger pipe may be sealingly connected to the second internal fluid passage bore in the lower end of the running tool. The lower end of the stinger pipe may be sealingly connected to the internal fluid passage bore of the guide member. The assembly may also include a debris sub having an upper end and a lower end. The upper end of the debris sub may be operatively connected to the lower section of the guide member. The debris sub may include an internal fluid passage bore in fluid communication with the internal fluid passage bore of the guide member. The assembly may also include an anchor sub having an upper end and a lower end. The upper end of the anchor sub may be operatively connected to the lower end of the debris sub. The anchor sub may include an internal fluid passage bore fluidly connected to the internal fluid passage bore of the debris sub. The anchor sub may have anchor means for detachably affixing the anchor sub to the main cased well bore.
The tubular may be a work string, drill pipe or coiled tubing. If the tubular is coiled tubing, the down-hole assembly may further comprise an indexing tool.
In the alternative embodiment, the window locator may comprise a pivoting arm and a window locating head. The running tool may include a biasing means operatively associated with the window locator. The biasing means may exert a force on the pivoting arm of the window locator to bias the window locating head in a direction external of the running tool. The window locating head may have a run-in position, a retracted position, and a window locating position. In the run-in position, the window locating head may be positioned between the retracted and the window locating positions and held stationary. In the run-in position, the window locating head may be partially positioned external of the running tool for engagement with the main cased well bore or a smaller internal diameter section of the main cased well bore.
In the alternative embodiment, the shape of the lower end of the running tool (or a portion thereof) may be convex. The shape of the upper end of the guide member (or a portion thereof) may be concave. The lower section of the running tool and the upper section of the guide member may be detachably connected by a shear bolt. The lower section of the running tool and the upper end of the guide member may be further detachably connected by a dovetail joint. The running tool may include one or more shear pins affixed to the window locator. The shear pins maintain the window locating head in the stationary position until sheared. In the retracted position, the window locating head is positioned substantially within the running tool. The window locating head may be held in the retracted position by the main cased well bore or more particularly, the inner wall of the main cased well bore. In the window locating position, the window locating head may be biased in a direction external of the running tool with a portion of the window locating head positioned within the window.
The running tool of the alternative embodiment may also include a block means for restricting a maximum outward pivoting angle of the window locating head. The block means may be L-shaped and have a shoulder capable of receiving an outer edge surface of the window locating head.
The running tool of the alternative embodiment may also include stop means for preventing retraction of the window locating head from the window locating position. The stop means may comprise one or more spring-loaded shear pins. The one or more spring loaded shear pins may be actuated by displacement of the window locating head from the retracted position to the window locating position and deactivated by a shearing force. The deactivation may result in the window locating head returning to the retracted position.
The guide member of the alternative embodiment may include a retrieval means. The retrieval means may provide a point of operative attachment for a fishing tool.
The present invention is also directed to a method of locating a window and reentering a lateral well bore in a main well bore from which a whip stock has been removed. The main well bore may be a cased well. The method may include the step of deploying a tubular down the main well bore. The tubular may be a work string such as drill pipe or coiled tubing. The tubular may contain a down-hole assembly. The down-hole assembly may include a running tool having an upper section, a middle section and a lower section. The running tool may include a window locator for locating the window. The assembly may also have a guide member with an upper section, a middle section and a lower section. The guide member may have a wedged-shaped outer surface for diverting a down-hole tool through the window and into the lateral well bore. The lower section of the running tool and the upper section of the guide member may each be shaped to receive the other in mating relationship. The lower section of the running tool and the upper section of the guide member may be capable of being detachably connected. When detachably connected, the running tool and the guide member are in fluid communication.
The method may also includes the step of activating the window locator so that the window locator is able to reposition to a window locating position external of the running tool when the running tool is placed adjacent the window. The method may further include the step of causing the window locator to reposition to the window locating position by placing the running tool adjacent the window. The method may involve the step of maintaining the window locator in the window locating position. The method may include the steps of determining the dimensions of the window (e.g., determining an upper edge of the window and a lower edge of said window) and positioning the guide member, and more particularly the wedge-shaped portion of the guide member, adjacent the window. The method may further include the step of anchoring the guide member in the main cased well bore. The method may also involve detaching the running tool from the guide member and pulling the running tool out of the main cased well bore. The method may then proceed with the steps of deploying a second tubular containing a down-hole tool down the main cased well bore, through the window, and into the lateral well bore. The wedged-shaped outer surface of the guide member may act to divert the down-hole tool from the main cased well bore, through the window, and into the lateral well bore.
The method of the present involve may further comprise the step of causing the down-hole tool to perform remedial work on the lateral well bore. The method may additionally include the steps of deploying a third tubular containing a fishing tool down the main cased well bore, connecting the fishing tool to the guide member, disengaging the guide member from the main cased well bore, and pulling the guide member out of the main cased well bore.
The down-hole assembly and method of the present invention eliminate the need for running a caliper log to determine the position and shape of the window. Once the down-hole assembly, is set in place about the window, the well is restored to the same configuration that the well had before the whip stock was removed. The down-hole assembly permits drill bits, mill bits, work strings, and even tools with shoulders to be run in and out of the window without fear of dislodging the concave member (i.e., the guide member). The down-hole assembly also allows the window to be reamed out with one or more mills without causing the concave member to drop down-hole. Once work on the lateral well bore is completed, the down-hole assembly may be easily removed from the well bore with a retrieving tool.
The down-hole assembly is a reliable, cost-effective tool to locate and reenter an existing window in a cased well. The down-hole assembly may be used to clean-out a lateral well bore such as a horizontal leg, to restore production. The down-hole assembly may also be used to re-drill a lateral well. It could also be used to install a liner in an existing lateral. The down-hole assembly may be used for any type of remedial work where a reliable guide in and out of an existing window is required.
In an alternative embodiment, the down-hole assembly is capable of locating a plurality of lateral well bore windows in a main well bore. The running tool may have an upper section, a middle section, a lower section and an internal cavity section with a cavity floor. The running tool may include a window locator assembly for locating the plurality of lateral well bore windows. The window locator assembly may be pivotally positioned within the cavity of the running tool and may include a window locator and a stop/shear block. The window locator may include a selectively reciprocating shear rod operatively associated with the stop/shear block. The shear rod may have a proximal end, a distal end, and an outer surface including a plurality of shoulders. The outer surface of the shear rod may also have a plurality of shear grooves. The stop/shear block may include a shear rod engaging surface, a tapered surface, a shear surface, and a stop shoulder. The alternative down-hole assembly may also contain a guide member having an upper section, a middle section and a lower section. The guide member may have a wedged-shaped outer surface for diverting a down-hole tool through one of the plurality of windows and into the lateral well bore for the window. The lower section of the running tool and the upper section of the guide member may each be shaped to receive the other in mating relationship. The lower section of the running tool and the upper section of the guide member may be capable of being detachably connected. When detachably connected, the running tool and the guide member may be in fluid communication.
In the alternative down-hole assembly, the window locator may include a first spring means operatively connected to the shear rod. The first spring means may bias the shear rod in a direction towards the stop/shear block. The first spring means may be operatively connected to the proximal end of the shear rod.
The window locator in the alternative assembly may further include a spring-loaded bushing surrounding a first portion of the shear rod. The spring-loaded bushing may include a second spring means.
The window locator in the alternative assembly may also include a dog assembly having an upper section, a lower section and an internal section containing a dog. The lower section may be positioned external of the window locator. The internal section may be operatively associated with a second portion of the shear rod. The dog may selectively engage a shoulder of the shear rod to prevent the shear rod from being reciprocated in the direction of the stop/shear block by the first spring means. The dog assembly may be movably positioned within a recess in the window locator. The second spring means of the spring-loaded bushing biases the spring-loaded bushing into operative engagement with the dog assembly.
In the alternative assembly, the window locator may further include a floating plate and a plurality of spring means. The floating plate and the plurality of spring means may each be contained within the recess of the window locator. The plurality of spring means may bias the floating plate into operative engagement with the upper section of the dog assembly.
The window locator may also include a shear bushing surrounding a third portion of the shear rod. The shear bushing may be positioned adjacent to the stop/shear block. The stop/shear block may further include an inspection window for viewing the alignment of the shear bushing with the shear grooves on the surface of the shear rod.
The shear rod engaging surface of the stop/shear block may include an adjustable calibration plate. The calibration plate may be used to calibrate the point at which the dog selectively engages one of the shoulders of the shear rod. The running tool may further include a calibration hole directly over the dog such that a user may view the point at which the dog selectively engages one of the shoulders of the shear rod.
The stop/shear block may include a U-shaped catcher for receiving the distal end of the shear rod. The catcher may also retain the distal end of the shear rod or the sheared piece of the shear rod after the distal end is sheared. The catcher may be positioned between the stop shoulder and the shear surface of the stop/shear block. The catcher may include a V-shaped surface capable of allowing the sheared piece of the shear rod to travel in only one direction.
In the alternative assembly, the running tool may have a pocket operatively connected to the stop/shear block for storing the sheared piece or pieces of the shear rod.
In another embodiment of the alternative down-hole assembly, the running tool may have an upper section, a middle section, a lower section, and an internal cavity section with a cavity floor. The running tool may include a window locator assembly for locating the plurality of lateral well bore windows. The window locator assembly may be pivotally positioned within the cavity of the running tool and include a window locator and a stop/shear block. The window locator may comprise a pivoting arm, a window locating head, and a selectively reciprocating shear rod operatively associated with the stop/shear block. The shear rod may have a proximal end, a distal end, and an outer surface including a plurality of shoulders. The outer surface of the shear rod may also include a plurality of shear grooves. The stop/shear block may include a shear rod engaging surface, a tapered surface, a shear surface, and a stop shoulder. The running tool further may include a biasing means operatively associated with the window locator. The biasing means may exert a force on the pivoting arm of the window locator to bias the window locator head in a direction external of the running tool. The assembly may also include a guide member having an upper section, a middle section, and a lower section. The guide member may have a wedge-shaped outer surface for diverting a down-hole tool through one of the plurality of lateral well windows and into the lateral well bore for the window. The lower section of the running tool and the upper section of the guide member may each be shaped to receive the other in mating relationship. The lower section of the running tool and the upper section of the guide member may be capable of being detachably connected. When detachably connected, the running tool and the guide member may be in fluid communication.
In this embodiment, the window locator may include: a first spring means operatively connected to the shear rod, the spring means biasing the shear rod in a direction towards the stop/shear block; a spring-loaded bushing surrounding a first portion of the shear rod, the spring-loaded bushing including a second spring means; a recess in the window locating head; a dog assembly movably positioned within the recess of the window locating head, the dog assembly may have an upper section, a lower section, and an internal section containing a dog, the lower section may be positioned external of the window locator, the internal section may be operatively associated with a second portion of the shear rod, the dog may selectively engage a shoulder of the shear rod to prevent the shear rod from being reciprocated in the direction of the stop/shear block by the first spring means; a floating plate and a plurality of spring means, the floating plate and the plurality of spring means may each be contained within the recess of the window locating head, the plurality of spring means may bias the floating plate into operative engagement with the upper section of the dog assembly; and a shear bushing surrounding a third portion of the shear rod, the shear bushing positioned adjacent to the stop/shear block. The stop/shear block may further include an inspection window for viewing the alignment of the shear bushing with the shear grooves on the surface of the shear rod.
The first spring means may be operatively connected to the proximal end of the shear rod. The second spring means of the spring-loaded bushing may bias the spring-loaded bushing into operative engagement with the dog assembly.
The shear rod engaging surface of the stop/shear block may include an adjustable calibration plate. The calibration plate may be used to calibrate the point at which the dog selectively engages a shoulder of the shear rod. The running tool may further include a calibration hole directly over the dog such that a user may view the point at which the dog selectively engages a shoulder of the shear rod.
The stop/shear block may further include a catcher for receiving the distal end of the sheared rod. The catcher may also retain the distal end of the shear rod or the sheared piece of the shear rod after shearing. The catcher may be positioned between the stop shoulder and the shear surface of the stop/shear block. The catcher may include a V-shaped surface capable of allowing the sheared piece of the shear rod to travel in only one direction.
The running tool may also include a pocket for storing the sheared piece of the shear rod. The pocket may be operatively connected to the stop/shear block for passage of the sheared piece from the catcher to the pocket.
The present invention is also drawn to a method of locating a plurality of lateral well bore windows in a main well bore. The method involves deploying a tubular down the main well bore. The tubular may contain a down-hole assembly. The down-hole assembly may include a running tool having an upper section, a middle section, a lower section, and an internal cavity section with a cavity floor. The running tool may include a window locator assembly for locating the plurality of lateral well bore windows. The window locator assembly may be pivotally positioned within the cavity of the running tool and include a window locator and a stop/shear block. The window locator may include a pivoting arm, a window locating head, and a selectively reciprocating shear rod operatively associated with the stop/shear block. The shear rod may have a proximal end, a first distal end, and an outer surface including a plurality of shoulders. The stop/shear block may include a shear rod engaging surface, a tapered surface, a shear surface, and a stop shoulder. The assembly may have a guide member with an upper section, a middle section, and a lower section. The guide member may have a wedge-shaped outer surface for diverting a down-hole tool through one of the plurality of lateral well bore windows and into the lateral well bore. The lower section of the running tool and the upper section of the guide member may each be shaped to receive the other in mating relationship. The lower section of the running tool and the upper section of the guide member may be capable of being detachably connected. When detachably connected, the running tool and the guide member may be in fluid communication. At deployment, the reciprocating shear rod is maintained in a non-reciprocating position so that the first distal end of the shear rod does not engage the engaging surface of the stop/shear block.
The method also includes the step of running the down-hole assembly to a first area in the main well bore having a first internal diameter that causes the window locating head to move inward relative to the cavity of the running tool releasing the shear rod from the non-reciprocating position to a reciprocating position wherein the first distal end of the shear rod engages the engaging surface of the stop/shear block. The method also includes the step of running the down-hole assembly to a second area in the main well bore having a second internal diameter that causes the window locating head to move further inward relative to the cavity of the running tool. The method then involves running the down-hole assembly to a first lateral well window in the main well bore that causes the window locating head to move outward relative to the cavity of the running tool to a first window locating position wherein the first distal end of the shear rod upwardly traverses the engaging surface of the stop/shear block, the tapered surface of the stop/shear block, and engages the stop shoulder. The method continues with the step of determining an upper edge or a lower edge of the first lateral well bore window. The method then includes the step of positioning the down-hole assembly to a third area in the main well bore having a third internal diameter that causes the window locating head to move inward relative to the cavity of the running tool wherein the first distal end of the shear rod is sheared by the shear surface of the stop/shear block resulting in a second distal end of the shear rod, the second distal end of the shear rod downwardly traverses the tapered surface of the stop/shear block and the engaging surface of the stop/shear block. The method includes the step of running the down-hole assembly to a second lateral well bore window in the main well bore that causes the window locating head to move outward relative to the cavity of the running tool to a second window locating position wherein the second distal end of the shear rod upwardly traverses the engaging surface of the stop/shear block, the tapered surface of the stop/shear block, and engages the stop shoulder. The method includes determining an upper edge or a lower edge of the second lateral well bore window.
If the stop/shear block includes a catcher for receiving the first distal end of the shear rod. The catcher may also retain the sheared first distal end of the shear rod, the method may include the step of retaining the sheared first distal end of the shear rod in the catcher. The catcher may include a V-shaped surface capable of allowing the sheared first distal end of the shear rod to travel in only one direction.
The method may also further comprise the steps of repeating the prior steps one to five additional times to locate a third, fourth, fifth, sixth, or seventh lateral well bore window in the main well bore.
If the running tool includes a pocket for storing the sheared distal ends of the shear rod, the method may include the step of causing the sheared first distal end of the shear rod retained by the catcher to be deposited in the pocket for storage.
If the outer surface of the stop/shear block also includes a plurality of shear grooves, the first distal end of the shear rod is sheared at one of the plurality of shear grooves by the shear surface of the stop/shear block.
If the shear rod engaging surface includes an adjustable calibration plate and the running tool further includes a calibration hole disposed above the plurality of shoulders on the shear rod, the method may also include a calibration step involving calibrating the reciprocating position of the shear rod by replacing the calibration plate with a second calibration plate having a different diameter than the calibration plate or by inserting one or more shims behind the calibration plate, observing through the calibration hole the position of the shoulders in the reciprocating position, and repeating as necessary to achieve the desired reciprocating position of the shear rod.
If the stop/shear block further includes an inspection window and the window locator further includes a shear bushing surrounding a portion of the outer surface of the shear rod, the method may further include the steps of observing through the inspection window the position of the shear bushing in relation to the first distal end and one of the plurality of shear grooves, and aligning the shear bushing with the shear groove by adjusting the position of the shear bushing.
The method may also include the steps of positioning the guide member adjacent to one of the first and second (or third) lateral well bore windows, anchoring the guide member in the main well bore, detaching the running tool from the guide member, pulling the running tool out of the main well bore, and deploying a second tubular containing a down-hole tool down the main well bore, through the one of the first or second lateral well bore windows, and into a lateral well bore, the wedge-shaped outer surface of the guide member acting to divert the down-hole tool from the main well bore, through the first or second lateral well bore window, and into the lateral well bore. The method may also comprise the step of causing the down-hole tool to perform remedial work on the lateral well bore.
The method may also involve deploying a third tubular containing a fishing tool down the main well bore, connecting the fishing tool to the guide member, disengaging the guide member from the main well bore, and pulling the guide member out of the main well bore. The main well bore may be a cased well bore. The tubular may be a work string, drill pipe, or coiled tubing. If the tubular is coiled tubing, the down-hole assembly may further include an indexing tool.
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After completion of the work, the assembly of guide member 14, debris sub 122 and anchor sub 124 may be removed from well bore 60. A retrieval or fishing tool may be sent down well bore 60 to retrieve the assembly. Such retrieval tools are commercially available from Knight Fishing Services under model name 7″STANDARDWHSTK-RETHK.
The fishing tool may have a retrieving device such as a hook that connects to retrieval slot 116 in guide member 114. Once connected, the fishing tool, together with the assembly of guide member 14, debris sub 122 and anchor sub 124, would be extracted or pulled out of well bore 60. Slips 128 would disengage from the inner wall of the casing in well bore 60 due to sufficient pulling force being applied to anchor sub 124.
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In a preferred embodiment, rod 204 is approximately 9.587 inches in length having a diameter of approximately 0.625 inches. In this embodiment, shoulders 218 have lengths of approximately 0.125 inches each, and the portions of rod 204 between shoulders 218 are approximately 0.250 inches in length each with diameters of 0.425 inches. Shear grooves 221 are each composed of an angular surface and a perpendicular surface which intersect at a 30 degree angle. The diameter of rod 204 at this intersection in each groove 221 is approximately 0.545 inches. The perpendicular surfaces of grooves 221 are approximately 0.375 inches apart. In this embodiment, proximal end 212 of rod 204 includes an end section having a length of approximately 0.25 inches and a diameter of approximately 0.35 inches. The remainder of proximal end 212 is approximately 0.662 inches in length. The portion of rod 204 between shoulders 218 and shear grooves 221 is approximately 3.175 in length.
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While preferred embodiments of the present invention have been described, it is to be understood that the embodiments described are illustrative only and that the scope of the invention is to be defined solely by the appended claims when accorded a full range of equivalents, many variations and modifications naturally occurring to those skilled in the art from a perusal hereof.
This application is a continuation-in-part of and claims priority to U.S. patent application Ser. No. 12/417,170, filed Apr. 2, 2009, which is incorporated herein by reference.
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Number | Date | Country | |
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20100252257 A1 | Oct 2010 | US |
Number | Date | Country | |
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Parent | 12417170 | Apr 2009 | US |
Child | 12796965 | US |