Abstract:
A lockable swivel ( 4 ) for use in drilling applications which allows the operator to selectively engage and disengage the swivel ( 4 ). The lockable swivel ( 4 ) is comprised of a locking mandrel ( 7 ) carried in a body ( 3 ) which engages, upon actuation, splined surfaces ( 20, 21 ) within the swivel mandrel ( 5 ) thereby locking the two together. Various methods for the use of the lockable swivel ( 4 ) in wireline and other drilling operations are demonstrated.

Description:
This application claims the benefit of International Application No. PCT/US97/24043, filed Dec. 27, 1997, which claims the benefit of U.S. Provisional Application No. 60/034,799, filed Dec. 31, 1996. 
    
    
     DESCRIPTION 
     1. Technical Field 
     The present invention relates generally to a drill string apparatus for use in drilling operations, and more particularly to an apparatus and method for selectively locking an inline swivel to permit rotational movement of the drill string. 
     2. Background Art 
     In wireline operations, it is often desirable to selectively allow the drill string to rotate freely while the wireline operator manipulates the wireline. 
     Previously, if the operator desired to rotate the drill string during wireline operations, the wireline was pulled from the well bore and the entry devices were disengaged from the drill string. The removal of the wireline could be avoided if an inline swivel was placed in the drill string between the wireline device and the rotary table. This arrangement would permit rotation to be accomplished with a wireline in place, but effectively disengaged the top-drive unit from its preferred role of providing both lifting power and rotation to the drill string. 
     DISCLOSURE OF INVENTION 
     The invention disclosed herein provides an apparatus which would allow the connection of various wireline devices  106  to be placed in the drill string  100  between the top drive unit  102  and the rotary table  114  of a conventional drilling rig throughout wireline operations. Such devices  106  as the Boyd Borehole Drill Pipe Continuous Side Entry Or Exit Apparatus (such as described in U.S. Reissue Pat. No. 33,150) or applicant&#39;s Top Entry Sub Arrangement (as described in U.S. Pat. No. 5,284,210) may both be utilized for various wireline operations. 
     Referring to FIG. 4, the invention is a lockable in-line swivel device  110  which is selectively engaged by the operator to permit or inhibit rotational movement provided by a top drive unit  102  to be transmitted through the swivel  110  to the pipe string  112  and to allow disengagement of the locked swivel  110  so that rotation may be accomplished by the rotary table  114  simultaneously with the wireline operations. 
     Accordingly, it is the primary purpose of the invention disclosed herein to provide an apparatus and method which permits the wireline entry devices  106  described above to be left in the drill string  100  during all operations involving the wireline operation. This avoids the time consuming makeup and disengagement of the entry tools  106  required to safely permit entry of the wireline into the well bore. If rotation and longitudinal movement is desired with the invention disclosed herein, the wireline alone is removed from the wellbore, but the entry tool  106  remains in place and the swivel  110  is locked to provide transmission of all rotation through the swivel  110  into the pipe string  112 . 
     At other times, the operator using a top-drive unit  102  may desire to pick up the drill string  100  and yet maintain torque which has been put into the pipe string  112  in pipe recovery operations. This is best done by engaging the swivel  110  in locked position and picking up with the top drive unit  102 . As the torque is worked through the drill string  100 , additional wireline operations may be desired. In this eventuality, the operator would set the drill string  100  down, disengage the swivel  110 , continue to rotate with the rotary table  114  and continue the wireline operations. 
     Using prior conventional technology, the drill pipe was separated and raised high above the rig floor on each run in order to change out tools. Although the pipe can be rotated, the operator could not circulate or reciprocate the pipe during these periods. Circulation was achieved by adding a pump-in sub and another T.I.W. safety valve immediately above the existing T.I.W. valve; which, however, put the disconnect or break point between the upper T.I.W. valve and the swivel several feet above the rig floor creating a safety hazard while operating the rig tongs. 
     Further, since the tool strings must be stripped in and out beneath the upper assembly, a lubricator or tool protection device could not be used and all tools and explosives were brought onto the rig floor unshielded and unconfined. In the event of an inadvertent detonation of the explosive string shot or perforators, all personnel on the rig floor were totally exposed to this unnecessary life-threatening hazard. 
     Once rigged-up and going in the hole using conventional technology such as the Boyd side-entry sub, the wireline passed through the acute angle in the side entry sub. This caused excessive wearing of the wireline and creates sever grooving in the sub. The single rubber pack-off, which is commonly used with this system, is very susceptible to leaking and/or line gripping and stoppage during pump-down operations. The system cannot be used when working under surface pressure and with the need to utilize a grease injector and wireline blow out preventers (BOPs). 
     During pipe recovery operations, both right and left-hand torque must be worked down-hole using the rig tongs. This is a procedure has long been recognized to be one of the greatest safety hazards to be encountered during pipe recovery operations. When using this prior technology, pipe tongs were attached to the drill string and secured to the rig to hold torque that had been put into the drill string from the rotary table or top drive unit. With the present invention, this torque can be maintained while continuing circulation and wireline operation. 
    
    
     These and other objects, features, and advantages of the present invention will become apparent from the drawing and the descriptions given herein. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an sectional view of the tool of the invention. 
     FIG. 2 is detailed view of the bearing arrangement of the invention encircled by ellipse of FIG.  1 . 
     FIG. 3A is a cross-sectional view of the upper spline engagement surfaces along line  3 A— 3 A of FIG.  1 . 
     FIG. 3B is a cross-sectional view of the lower spline engagement surfaces along line  3 B— 3 B of FIG.  1 . 
     FIG. 4 is a graphical representation of a drill string  100 . 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     In FIG. 1, the locking swivel apparatus  110  comprises a retainer sub  1  which is provided with means  10  for making a threaded connection with standard tubular members, and is threadably engaged with a lower body  3  to retain a locking mandrel  2 . The locking mandrel  2  is provided with splines  16  and splines  18  to engage splined surfaces  20  and  21  respectively formed both in the swivel mandrel  5  and in the lower body  3  for locking the swivel to the lower body to prevent rotation of the pipe string  112  (See FIG. 4) which would be connected to threads  10 ′. 
     The retainer sub  1 , locking mandrel  2 , and lower body  3  of the lockable swivel apparatus  110  engage the top sub  4  of an inline swivel. Brass packing rings  27  and washpipe packing  26  seal swivel mandrel  5  permitting fluid communication through the annulus of the inline swivel apparatus without leakage. Swivel mandrel  5  is secured to the circumferentially spaced brass wear ring  31 , bearing  29 , packing  28  and  30  by a bearing retainer nut  6 , which is threadably engaged on the top sub  4  by threads  33  and  33 ′. As shown in FIG. 2, the wear ring  31  has seal means  36 ,  37 , which contact the bearing retainer nut  6 . The lower body  3  is threadably engaged into the top sub  4  of the inline swivel. The swivel mandrel  5  of the inline swivel is provided with inner splines  21  to engage the outer splines  18  formed on the lower end of the locking mandrel  2  which extends through the lower body  3  and top sub  4 . 
     Hydraulic fitting ports  40  and  41  provided in the lower body  3  are disposed on either side of a dynamic seal means  17  in a chamber formed between exterior of the locking mandrel  2  and the interior wall  43  of the lower body  3  to move the locking mandrel  2  either up or down and thereby into or out of engagement with the splines  21  on the swivel mandrel  5  and the splines  20  in the lower body  3 . The locking mandrel  2  moves up or down as provided and is stopped by shoulder  15  from moving into retainer sub  1 . 
     Washpipe packer or seal means  45  and  46  are provided to make a hydraulic seal in chamber  43 ′ to enable an operator on the rig floor  116  to selectively move the locking mandrel  2  into and out of engagement with the swivel mandrel and to thereby control undesired rotation of the pipe string  112  by actuating a hydraulic pump. 
     In the preferred embodiment, standard hydraulic lines are attached to hydraulic fitting ports  40  and  41  and connected by hydraulic lines to a pump controlled by the operator in a manner well known to those in the industry. The operator switches the flow of hydraulic fluid to port  40  if locking of the swivel is desired, and to port  41  if unlocking of the swivel is desired. 
     FIG. 2 of the drawings shows the detail of the bearing surfaces disposed around the swivel arrangement. FIGS. 3A and 3B are cross sectional views of the cooperating engagement surfaces or splines of the locking mandrel and the swivel mandrel. 
     When used in conjunction with wireline services on directional drilling operations, the magnetic or gyro-type tools have direct entry into the pipe string  112  through the top entry sub (a wireline access sub  106 ). Once the tools have been landed in the down-hole-guide sub, or in the wet-connect sub, the pipe string  112  can then be oriented using the rotary table  114 , while maintaining the swivel  110  in the unlocked position. Once the desired orientation has been attained, the pipe can then be held in position by locking the swivel and engaging the back-brake on the top drive unit  102 . 
     Should minor adjustments in the orientation be required, this can be easily accomplished since the locking mechanism in the swivel  110  incorporates a splined shaft which provides eighty three separate orientations per revolution. Utilization of this package enables drilling two or three joint per connection, depending on rig height, and eliminates holding the back-torque with the rig tongs. 
     In pipe recovery operations, once the downhole package has been assembled, the wireline tools always have direct entry into the pipe string  112  which eliminates having to separate and re-connect the pipe string  112  each run. Also, the tools can be fully lubricated which minimizes any bending, flexing or jarring of sensitive instrumentation. All explosive devices, such as string shots, cutters, severing tools and perforating guns are contained within the lubricator while in close proximity of the rig floor  116 . This minimizes exposure to potential injury in the event of an inadvertent detonation. The assembly enables operation under surface pressure, while performing pump-down operations, and while employing a grease injector system. Between wireline runs, the operator retains the ability to continue circulation and reciprocation of the pipe string  112 , thus preventing additional subsidence and sticking. During actual operations both make-up and reverse torque can be applied to the pipe string  112  and worked-down without utilizing the rig tongs. Prior to the ability to maintain the torque by setting the swivel  110  in the locked position, torque was maintained on the drill string by attaching pipe tongs to the string and cabling the end of the tong to the drilling structure while the operator reciprocates and manipulates the string. The disengagement of the pipe tong cabling while torque was being applied caused the tongs and cabling to dangerously rotate rapidly around the rig floor. 
     During pipe recovery operations, the wireline engineer must apply right hand, “make-up,” torque to the pipe string  112  and work it down in order to assure that the entire string is sufficiently tight before applying the left hand, “back off,” torque. With the pipe string  112  setting on the slips in the rotary table  114 , usually at neutral weight, the right hand torque is applied to the pipe string  112  in an amount less than the full make-up torque of the string and then releasing or relaxing the brake on the pipe string  112 . Non-absorbed torque will “come back.” This process is then repeated three to four times, with each iteration providing greater amounts of torque, until a predetermined amount based upon the recommended maximum torque load for the type of pipe and connections has been reached. The drilling engineer also uses the behavior of the pipe string  112  during this process to determine the amount of torque the hole is “trapping” or whether the torque is being distributed evenly through-out the pipe string  112  or encountering premature build up because of angle changes, dog legs, etc. 
     With the right hand torque being held securely with the rotary back-brake or the rotary lock, the operator switches the manual control valve on the hydraulic pump from the open/unlocked position to the closed/locked position to begin closing the locking mechanism in the swivel  110 . The operator should count the strokes and to observe the sudden pressure increase. If the number of strokes and the pressure change are consistent with the results experienced in the installation phase, the internal lock is completely closed. To assure that the swivel  110  remains in locked position, it is recommended that approximately 500 pounds of back pressure against the lock be maintained. 
     Referring to FIG. 4 after determining that the back-brake on the top drive unit  102  is securely locked, the operator commences releasing the rotary table  114  back-brake and slowly transfers the pipe torque to the top drive unit  102 . When the torque is being held with the rotary lock, engage the top drive and slowly increase the amperage until the torque is transferred and the rotary lock can be released. Once all the torque has been transferred to the top drive unit  102 , the wireline access port will become shifted approximately 10.8 degrees to the left of true alignment. However, in this procedure the port will not shift if using a single joint but will shift 10.8 degrees to the right if using a lubricator joint  108 . This is predicated on having one round per thousand in the drill pipe and the shifts are directly proportional to the amount of torque that is being transferred from the drill pipe into the assembly joint  104  between the top entry adapter sub (a wireline access sub  106 ) and the top drive unit, or the lubricator joint between the top entry sub and the swivel  110 . 
     Once satisfied that the pipe string  112  has been sufficiently tightened to the point of accepting left-hand torque without breaking pre-maturely, the pipe string  112  can be placed back on the slips in the rotary table  114 . The back-brake or the lock on the rotary table  114  should then be engaged. 
     With the weight of the pipe string  112  now resting on the rotary table  114 , the torque being held with the top drive unit  102  can be slowly transferred to the rotary table  114 . 
     With the torque transferred and the top drive unit  102  disengaged, the operator switches the controls on the hydraulic pump and opens or “unlocks” the swivel  110 . As before, the operator should count the strokes and watch the pressure to assure that the swivel  110  is totally open, or “unlocked.” Again, it is recommended that approximately 500 pounds of back pressure be maintained to assure that swivel  110  remains in the open or “unlocked” position. The wireline access sub  106  should then be realigned with the derrick sheave and the top drive unit  102  relocked. The torque can then be released with the rotary table  114 . At this point, the engineer may elect to reciprocate the pipe string  112  in order to work out any remaining trapped torque prior to running the free point or other services. 
     The invention also enables rotating, circulating and reciprocating the pipe while running and pumping-down various wireline tools and performing various services, i.e., end-of-hole gyros, “measure-while-drilling” (M-W-D) retrieval tools, pipe recovery service tools, gamma ray logging devices or total “vertical depth” (T.V.D.) devices and other logging or perforating service tools. 
     Since the package can be assembled in a variety of configurations, customer preference, operating conditions and job requirements, whether involving directional drilling, pump downs, grease injectors, MWD retrieval, coil tubing or pipe recovery, will strongly influence which configuration is most advantageous for the job to be performed. 
     Once the chosen packages described above have been installed and tightened, the hydraulic hoses should be attached to the locking swivel  110  and the hand pump. The hoses, the swivel and the hand pump have mated quick-connects which assures that the labeling on the hand pump, closed/locked and open/unlocked corresponds correctly with the direction of movement and position of the internal locking mechanism within the swivel  110 . 
     Lock the rotary table  114 , or attach the back-up rig tongs to the joint of pipe in the rotary table  114 , and the assembly can be tighten to maximum torque allowed using the top drive unit  102 . 
     Engage the top drive unit  102  and slowly increase the amperage until the maximum foot pounds of torque allowed for the particular drill pipe being used in the upper assembly has been reached. Reduce the amperage to zero and then increase back to maximum allowed amperage at least one or two more times. 
     Once the assembly has been properly tightened and the top drive amperage reduced to zero, unlock the rotary, or release the back-up tongs, and then open, “unlock”, the swivel. 
     Use the top drive unit  102  and slowly orient the upper assembly until the wireline access port in the top entry sub (a wireline access sub  106 ) is in perfect alignment with the wireline sheave in the derrick. The top drive unit  102  should then be locked in this alignment and secured so as to prevent inadvertent unlocking. 
     Upon making one final check and assuring that the top drive unit  102  is locked in the aligned position and the swivel  110  is in the unlocked position, the assembly will be ready to begin operations.