Patent Publication Number: US-7216717-B2

Title: Dual elevator system and method

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates generally to drilling equipment used particularly in the hydrocarbon production industry and specifically to an elevator system and method for running or raising tubulars in a well. 
   2. Description of the Prior Art 
   In the hydrocarbon production industry, tubular goods, including drill strings, casings and tubing and often referred to simply as tubulars, must at varying stages be run, i.e. lowered, into or raised from a well. Elevators are devices which support the tubular for the purpose of raising or lowering it. An elevator may clamp along the side of a tubular using slips and dies to exert a radial clamping force on the tubular wall, or an elevator may use a bushing to support the tubular at the lower lip of a box connector. The latter method is preferable for deep water production or when running heavy casings or landing strings, because a slip can exert damaging crushing forces on the tubular under high hook loads. 
     FIGS. 1 and 2  show one typical elevator setup of prior art where an elevator ( 10 ) is suspended from a top drive mechanism ( 9 ) by a pair of bails, or links ( 14 ), which have eyes ( 16 ,  18 ) at both ends. The top drive mechanism ( 9 ) is in turn suspended by a traveling block ( 12 ) and wire rope ( 19 ) rigged from a crown block (not shown) located in the top of the drilling rig. The upper eyes ( 16 ) of the pair of bails ( 14 ) are hooked to the link supports ( 20 ) of the top drive ( 9 ), and the lower eyes ( 18 ) of the pair of bails ( 14 ) are hooked to the ears ( 22 ) protruding from the elevator ( 10 ). The bails ( 14 ) are secured to the elevator ears ( 22 ) by locking mechanisms ( 25 ) to prevent the bails ( 14 ) from inadvertently becoming uncoupled from the elevator ( 10 ). The elevator ( 10 ) and the supported tubular ( 24 ) are thus raised and lowered by the traveling block ( 12 )/top drive ( 9 ) and bails ( 14 ). All the components in this series are designed to carry the expected loads. 
   The top drive ( 9 ) is used in place of a conventional rotary table and Kelly bushing to rotate the tubular during rotary drilling. Using hydraulic or electric motors ( 11 ) and a gear train ( 13 ) suspended above the drill string ( 24 ) enables the drill string to be rotated continuously while being lowered into or raised from a well. The top drive mechanism slides up and down along frame members ( 15 ) to check rotation of the top drive in reaction to the spinning of the tubular ( 24 ) while allowing free vertical movement of the device. 
   A spider, much like an elevator, is a device which supports a tubular to prevent it from descending into a well when it is not held by an elevator. Unlike an elevator, however, the spider is designed to remain on the drilling deck and is not moved vertically. When the elevator, suspended by the traveling block, nears its high limit of travel (when raising a tubular) or its low limit or travel (when running a tubular), or when a stand is required to be added or removed, the elevator must be repositioned in order to continue the operation. The spider supports the tubular prior to the elevator releasing the tubular. Thus, the tubular is held in place while the elevator is repositioned. Once the elevator carries the tubular at a new location, the spider is disengaged allowing the tubular to freely pass through the spider or for the spider to be moved completely clear of the tubular. 
   In some drilling platforms, particularly those used for deep water production, a large number of stands is required to be on hand. In such platforms, the derrick may become cluttered, hindering operations and increasing operation time. To simplify the operation, it has been known to use a first elevator as a temporary substitute for a spider to support a tubular and a second elevator, coupled to the traveling block, to lower the tubular string. Each elevator is preferably equipped with a door for side entry of a tubular. When the second traveling elevator is holding the tubular, the first spider elevator is moved clear of the tubular. The second elevator and tubular are lowered. When the second elevator has been lowered to the rig floor, the bails are removed from the second elevator and attached to the nearby first elevator. The second elevator now acts as the spider, holding the tubular while the first elevator is repositioned towards the top of the string where it supports the tubular or is used to move a new stand to the top of the string which is coupled thereto. The second elevator then releases the tubular and is moved clear of the tubular, and the first elevator lowers the tubular into the well. When the first elevator reaches the rig floor, the elevators are again swapped in a process sometimes referred to as circulating the elevators. The same process is used in a reverse sequence for raising a tubular. Because both elevators change their location continuously during this process, there is no need for elevator/spider differentiation. 
   A coordinated dual elevator system simplifies the process of circulating the elevators. A dual elevator system may incorporate features such as a shuttle table to receive the traveling elevator on deck for use as a spider, to readily move a spider elevator off of well center to prepare its use as a traveling elevator, and to vacate the landing table for receiving the next traveling elevator. In other words, the shuttle table is used to move the spider elevator into and out of engagement with a tubular at well center. 
   Many elevators and spiders used today employ power operated internal mechanisms, e.g., power doors and/or power slips. The powered elevators and spiders are commonly hydraulic, but can be pneumatic or electric. When circulating the elevators, power and control lines can interfere with deck operations, becoming entangled or snagging on objects. Additionally, uncoupling and re-coupling supply lines is also a burdensome manual process, particularly for hydraulic systems. Therefore, the process of circulating elevators has traditionally been limited to manually operated elevators. A method and apparatus which simplifies the supply of power to powered elevators when circulating the elevators is desirable. 
   3. Identification of Features of one or more Embodiments of the Invention 
   A primary object of the invention is to provide a method and apparatus for increasing the efficiency of drilling operations by automating the process of circulating elevators and by allowing for the use of powered elevators in the process of circulating elevators. 
   Another object of the invention is to provide a method and apparatus which prevents the need for riggers or other personnel to manually connect or disconnect power and control lines for an elevator or to manually move an elevator from well center to an offset standby position or vice versa. 
   Another object of the invention is to provide a method and apparatus for providing power and control to an elevator in a manner which does not cause power or control lines to hamper or otherwise interfere with deck operations. 
   Another object of the invention is to promote operator safety by providing for total hands-free operation of the elevator. 
   SUMMARY OF THE INVENTION 
   The objects identified above, as well as other features and advantages of the invention are incorporated in a dual elevator system and method comprising two elevators and a skid assembly or table for supporting one or both of the elevators thereon, for preferably hands-free shuttling an elevator between well center and offset standby positions, and for preferably hands-free coupling or uncoupling power and control to an elevator on the table by remote actuation. In a preferred embodiment, each of the two elevators is adapted for holding a tubular and being suspended by a pair of bails by elevator ears. Each elevator preferably has a rear power and control connector assembly for powering and controlling internal elevator systems. The rear power and control connector assembly is designed and arranged for coupling to a complementary second connector assembly by remote actuation. Each elevator also preferably has a hitch which is designed and arranged to push or pull said elevator along a table surface and for removable attachment to a complementary second hitch by remote actuation. The hitch and rear power and control connector assembly are preferably combined in a single block which is pivotally mounted to the elevator. Each elevator preferably has a door assembly designed and arranged to allow side entry of a tubular. 
   In a preferred embodiment, a skid assembly or table for supporting one or both of the elevators is characterized by a well center elevator position and a standby elevator position adjacent to said well center elevator position. The skid assembly includes a frame, a first skid surface located at the well center elevator position, and a second skid surface located at the standby elevator position, with the second skid surface positioned relative to said first skid surface to allow smooth sliding or rolling of an elevator between the standby position and the well center position, and vice versa. The skid assembly includes a shuttle mechanism which preferably moves along the skid surfaces and has a hitch and multi-coupling system connector assembly mounted thereto which attaches by remote actuation to elevator hitch and quick connectors at the rear power and control connector assembly. The shuttle mechanism is driven by an actuator, preferably a piston/cylinder arrangement, coupled between said shuttle mechanism and the skid assembly frame. The actuator is sized to move an elevator hitched to the shuttle mechanism between the well center and standby positions. 
   Preferably, the table may further include wheels coupled to said frame in movable relation characterized by engaged positions and disengaged positions such that when the wheels are in the disengaged positions, the skid assembly frame rests on the drilling deck, and when the wheels are in the engaged positions, the frame is carried by the wheels for free movement about the drilling deck. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is described in detail hereinafter on the basis of the embodiments represented in the accompanying figures, in which: 
       FIG. 1  is a side view of a prior art arrangement for lowering or raising a tubular including an elevator which holds the tubular, bails suspending the elevator by its protruding ears from a top drive mechanism, and a traveling block which carries the entire arrangement; 
       FIG. 2  is a front view of the prior art arrangement of  FIG. 1 , showing the manually operated locking tabs of the elevator ears; 
       FIG. 3  is a front perspective of an elevator according to one embodiment of the invention showing side-entry doors and an elevator ear equipped with quick connectors designed and arranged to mate with a bail-mounted multi-coupling system connector assembly (not shown); 
       FIG. 4  is a rear perspective of the elevator of  FIG. 3 , showing the elevator supporting a tubular and showing a rear power and control connector assembly which is designed and arranged to mate with a skid assembly multi-coupling system connector assembly ( FIG. 5 ); 
       FIG. 5  is a perspective view of a skid assembly according to one embodiment of the invention which is designed and arranged to support two elevators, e.g., of the type shown in  FIGS. 3–4  (not shown in  FIG. 5 ), showing a shuttle mechanism adapted to slide an elevator along the skid assembly and showing a multi-coupling system connector assembly mounted on the shuttle mechanism designed to mate with the elevator rear power and control connector assembly of  FIG. 4 ; 
       FIG. 6  is a perspective view of the skid assembly of  FIG. 5  showing the shuttle mechanism extended toward well center; 
       FIG. 7  is a side view of the skid assembly of  FIG. 5  with wheels engaged on a drill floor and positioned over a rotary table; 
       FIG. 8  is a simplified plan view showing the rotary table and skid assembly of  FIG. 7 ; 
       FIG. 9  is a perspective view of the skid assembly of  FIG. 5  carrying two elevators of  FIGS. 3–4 , with the elevator which is positioned at well center supporting a tubular; 
       FIG. 10  is a side view of the skid assembly and elevators of  FIG. 9  showing a cover over the control apparatus; 
       FIG. 11  is a top view of the skid assembly and elevators of  FIG. 10 ; 
       FIG. 12  is a top view explosion diagram showing the mating relationship of the elevator rear power and control connector assembly of  FIG. 4  and the skid assembly multi-coupling system connector assembly of  FIG. 5 ; 
       FIG. 13  is a perspective view of the elevator rear power and control connector assembly and the complementary skid assembly multi-coupling system connector assembly of  FIG. 12 ; 
       FIG. 14  is a rear view of the elevator rear power and control connector assembly taken along lines  14 — 14  of  FIG. 12 ; 
       FIG. 15  is a front view of the skid assembly multi-coupling system connector assembly taken along lines  15 — 15  of  FIG. 12 ; 
       FIG. 16  is a side cross-section of the elevator rear power and control connector assembly and the complementary skid assembly multi-coupling system connector assembly taken along lines  16 — 16  of  FIG. 12 ; 
       FIG. 17  is a top view of the elevator rear power and control connector assembly and the skid assembly multi-coupling system connector assembly of  FIG. 12  showing the two connectors in the mated and locked position; and 
       FIG. 18  is a side cross section of the elevator rear power and control connector assembly and the mated skid assembly multi-coupling system connector assembly taken along lines  18 — 18  of  FIG. 16 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION 
   The preferred embodiment of the invention includes two elevators.  FIG. 3  is a front perspective of one of the two elevators  30  according to one embodiment of the invention. Each elevator  30  preferably has a slip assembly for clamping a tubular  41  ( FIG. 4 ) or bushings  32  which support a tubular stand by the lower lip of a box connector at the upper end of the stand. Each elevator  30  also has a pair of elevator ears  34  for receiving bails or links (not shown) to lift the elevator  30 . Although other arrangements may be used, each elevator  30  preferably has quick-connect power and control connections  36  and guide sockets  38  in either one or both elevator ears  34 . The elevator ear power and control connections  36  and guide sockets  38  allow automatic coupling and uncoupling of hydraulic, pneumatic, or electric circuits to the elevator  30  when coupled to the bails. The power and control circuits provide power and control to various elevator systems, such as power doors  40  or power slips. Co-pending patent application Ser. No. 11/066,767, filed on Feb. 25, 2005 and entitled “Hands-Free Bail-Elevator Locking Device with Combined Power/Control Connector, Bail Spreader and Method for Use,” describes the operation and arrangement of the bail connections  36  and guide sockets  38  and is incorporated herein in its entirety by reference. 
   Each elevator  30  preferably has a front door assembly  40  which can open to accept side entry of a tubular into the elevator  30 . Preferably, a hydraulically operated double door design, as shown in  FIG. 3 , is used. The double door design, using two doors  40 A,  40 B each being generally one-half the size of the door in a single door elevator of similar capacity, allows the doors  40 A,  40 B to be opened and shut in relatively limited spaces. Elevator balance may also be improved in a double door design. Preferably, each elevator  30  is equipped with an interlock to prevent accidental door opening under load. 
     FIG. 4  is a rear perspective of an elevator  30  carrying a tubular  41 . Each elevator  30  preferably has a rear power and control connection assembly  42 . Like the elevator ear power and control connections  36 , the rear power and control connection assembly  42  is used to provide power and control to the elevator doors  40 A,  40 B and/or other powered elevator systems. The rear power and control connector assembly  42  is intended for use when the elevator  30  is not connected to the bails (not shown), i.e., when the elevator is in a standby position or acting as a spider on the drilling deck, and the elevator ear power and control connectors  36  are intended for use when the elevator  30  is coupled to the bails (not shown). 
   Referring to  FIG. 4 , the rear power and control connector assembly  42  preferably consists of a knob hitch  44 , which is adapted for remotely actuated coupling to a table shuttle mechanism, and a number of hydraulic, pneumatic, or electric quick-connectors  46  mounted in a block  48 . However, the hitch  44  and quick-connectors  46  may be contained in separate assemblies each individually mounted to the elevator. The hydraulic, pneumatic, or electric quick-connectors  46  are analogous in function to the elevator ear  34  power and control connections  36 . The rear connector block  48  is preferably pivotally mounted to the elevator  30  using integral gudgeons  49  which act as plain bearings and which are mounted in pillow block housings  50 . The rear quick-connect connectors  46  are preferably operatively connected to ports  52  located on a top surface of the block  48  and connected from there to ports on the elevator body  54  using flexible members  56 . Although a pivoting rear power and control connector assembly  42  is described, other arrangements may be used. Further, although the location of the rear power and control connector assembly  42  is illustrated generally midway between the elevator ears  34 , other suitable locations may be used. 
   As shown in  FIG. 5 , one or more embodiments also include an elevator table or skid assembly  60 . The table or skid assembly includes one or more skids or tracks  62 A,  62 B, mounted on frame  61 , for slideably supporting one or both of the elevators  30  (not shown). The skids  62 A,  62 B are preferably smooth and well greased to promote sliding of the elevators  30  on the skids. However, other arrangements may be used to promote moving an elevator  30  disposed thereon, e.g., clean Teflon tracks, rollers, wheels, etc. The skid assembly preferably has an aperture  64  for allowing a vertically oriented tubular to pass through. During use, the skid assembly  60  is generally positioned on the drilling deck such that the tubular aperture  64  is disposed at well center. Thus, the position of the skid assembly which contains the aperture  64  is referred to as the well center position  65 . The skids  62 A near the aperture  64  are preferably level, whereas the skids  62 B at a location offset from the aperture  64 , referred to as the standby position  66 , may have a gentle incline to promote the transfer of the bails (not shown) between an elevator located at well center  65  and the adjacent elevator located in the standby position  66 , because the bails, pivoting on the upper eyes (which are generally located near well center), will raise the lower eyes slightly when they are displaced from center to the offset location. 
   The skids  62 A,  62 B may also support a shuttle mechanism  68  which is designed and arranged to automatically couple to an elevator rear power and control connector assembly  42  and transfer the coupled elevator  30  between the well center position  65  and standby position  66 . The shuttle mechanism  68  preferably includes a sliding horizontal plate  70  and a vertical wall  72 . The vertical wall  72  in turn supports the multi-coupling system (MCS) connector assembly  74  which is designed to mate with the elevator rear power and control connector assembly  42 . 
   The MCS connector assembly  74  contains complementary hydraulic, pneumatic, or electric quick-connect connectors  76  ( FIGS. 10-11 ) to the elevator rear connector assembly  42  quick-connectors  46 . The elevator power and control circuits (via the MCS connector assembly  74 ) and a mechanism  77  for locking the elevator  30  to the shuttle mechanism  68  are coupled between the sliding shuttle mechanism  68  and the frame  61  by a number of flexible cables and/or hoses  78 . The flexible cables and/or hoses  78  are preferably wound on a number of spring-loaded reels or drums  80 , which allow the hoses or cables to be paid out as the shuttle mechanism  68  travels toward the well center position  65  and taken in as the shuttle mechanism  68  returns to the offset standby position  66 . However, other suitable means to operatively couple the shuttle mechanism  68  to the fixed skid assembly  60  may also be used. 
   As illustrated in  FIGS. 5–6 , the shuttle mechanism  68  is preferably driven by a hydraulic piston/cylinder arrangement  82 , although other means such as a rack and pinion or a lead screw may be used. Like the elevator rear connector block  48 , the drive piston  84  is preferably pivotally attached to the shuttle mechanism  68 , and the drive cylinder  86  is preferably pivotally mounted to the skid assembly frame  61  using plain bearings in a pillow block housing  88 . The pivot mounts for the drive piston/cylinder  82  and for the elevator rear connector assembly  42  allow the shuttle mechanism  68  to move an elevator  30  on both the level skids  62 A and the inclined skids  62 B.  FIG. 5  shows the drive piston fully retracted within the drive cylinder  86  and the shuttle mechanism  68  parked at the standby position  66 , and  FIG. 6  shows the drive piston  84  extended and the shuttle mechanism  68  near the well center position  65 . Thus, when an elevator  30  is coupled to the shuttle mechanism  68 , it may be pushed by the shuttle mechanism  68  from the standby position  66  to the well center position  65  or pulled by the shuttle mechanism  68  from the well center position  65  to the standby position  66 . 
   The skid assembly  60  includes wheels or casters  90  to allow the entire skid assembly  60  to be readily and easily moved about the platform deck. Thus, the skid assembly  60  may be quickly moved away from well center when its use is not required. The wheels  90  preferably can be moved to an enabled position, i.e., wheels down, or a disabled position, i.e., wheels up.  FIGS. 5–6  show the wheels  90  in the disabled or disengaged position. The disabled wheel position prevents the skid assembly  60  from inadvertently rolling on the deck during use. Due to the weight of the skid assembly (particularly when loaded with two elevators), the wheels are preferably power actuated between the up and down positions. As illustrated, each wheel may be mounted on one end of a bellcrank  92 . The opposite end of each bellcrank  92  is actuated by a piston/cylinder arrangement  94 . However, other means of engaging and disengaging the wheels  90 , e.g., gear drive or lead screws, may be employed. 
     FIG. 7  shows a side view of the skid assembly  60  with the wheels  90  in the enabled position. The skid assembly  60  is disposed over a rotary table  200  which is preferably recessed in a drill floor.  FIG. 8  is a simplified plan view of the skid assembly frame  61  disposed over the rotary table  200 . Referring to  FIGS. 7 and 8 , when the wheels  90  are in the disabled position (wheels up), the skid assembly  60  can be fixed to the rotary table  200  (or any other suitable surface) by using a number of clamping pins  204  disposed below the skid frame  61 . Rotary table  200  is shown including one or more adapters  210 , a bushing  212  and a bowl  214 , but other arrangements may be used. 
   In a preferred embodiment, the rotary table  200  has four holes  206  intervaled about well center  65  and a fifth hole  207  located near the standby position  66  for receiving and holding the clamping pins  204 . However, depending on the rotary table  200  used, other hole configurations may be employed. The skid assembly frame preferably includes an equal number and spacing of clamping pins  204  disposed such that the pins  204  align and mate with the rotary table holes  206 ,  207 . The clamping pins  204  can preferably be screwed from the top and clamp into the holes  206 ,  207  of the rotary table/drill floor. 
     FIG. 9  shows the skid assembly  60  of  FIG. 5  loaded with two elevators  30 A,  30 B. Elevator  30 A is disposed at the well center position  65  and supports a tubular  41  which passes through the tubular aperture  64  ( FIG. 5 ). Elevator  30 B is disposed at the offset standby position  66  and is disengaged from but ready for engagement with shuttle mechanism  68 .  FIGS. 10–11  show the skid assembly  60  and elevators  30 A,  30 B of  FIG. 9 , except a cover  98  protects a substantial portion of piston/cylinder  82 , drums  80 , hoses/cables  78  and associated control apparatus ( FIGS. 5–6 ). 
     FIG. 12  is an explosion diagram showing the elevator rear power and control connector assembly  42  and the table MCS connector assembly  74  in uncoupled relation.  FIG. 13  is a perspective view of  FIG. 12 ,  FIG. 14  is a view of the mating side of the elevator rear power and control connector assembly  42 ,  FIG. 15  illustrates the mating side of the skid assembly MCS connector assembly  74 , and  FIG. 16  is a cross section of  FIG. 12 . Likewise,  FIGS. 17 and 181  correspond to  FIGS. 12 and 16 , respectively, but show the two connector assemblies  42 ,  74  coupled together. Referring collectively to  FIGS. 12–18 , the knob hitch  44  of the rear connector assembly is designed to be received into a hole  100  in the shuttle mechanism wall  72  and locked in place to form a hitch assembly. The knob hitch  44  has a transverse hole  102  formed therein for receiving a locking pin  104  contained in the shuttle mechanism  68 . The locking pin  104  is moved into and out of engagement with the knob hitch  44  by an actuator  77 . Preferably, a hydraulic piston/cylinder arrangement is used to actuate the locking pin  104 , but other arrangements, e.g., a solenoid, may be used. Alternatively, other suitable hitch arrangements may be used in place of hitch knob  44 , actuator  77  and locking pin  104 , but the hitch assembly used preferably allows remotely actuated coupling and uncoupling. The skid assembly MCS connector assembly  74  preferably has male quick-connect connectors  76  which are designed and arranged to be received within complementary female quick-connect connectors  46  housed in the elevator rear power and control connector block  48 . The MCS quick-connectors  76  are operatively coupled to appropriate power and control systems via flexible cables and/or hoses  78  and rigid conduits mounted to frame  61  ( FIG. 5 ), and the rear power and control quick-connectors  46  are operatively routed through internal passages  103  in block  48  to ports  52  located on top of block  48  and in turn to elevator  30  through flexible members  56  ( FIG. 4 ). The rear power and control connector block  48  preferably has integral gudgeons  49  which pivot within pillow blocks  50  ( FIG. 4 ) to allow the connector assembly pair  74 ,  42  to function when the shuttle mechanism  68  is positioned on both the level skids  62 A and the inclined skids  62 B. However, other suitable means to pivot the connectors may be used. 
   The Abstract of the disclosure is written solely for providing the public at large with a means by which to determine quickly from a cursory inspection the nature and gist of the technical disclosure, and it represents solely a preferred embodiment and is not indicative of the nature of the invention as a whole. 
   While the preferred embodiments of the invention have been illustrated in detail, it is apparent that modifications and adaptations of the preferred embodiments will occur to those skilled in the art. Such modifications and adaptations are in the spirit and scope of the invention as set forth herein.