Abstract:
A bottom hole assembly (BHA) has a plug below a debris catcher and an optional telescoping joint. A cleaning tool is above the debris catcher with another cleaning tool further up the BHA that is designed to clean the riser that extends up from the BOP. The plug is spotted and released to commence the BOP cleaning and the riser cleaning. The cleaning tools can be reconfigured to allow through flow after the cleaning is done so that the rams can be closed around a drill collar and a pressure test take place. With the BHA above the BOP the rams can be closed against each other for another pressure test from above. In a variety of options for the method, the plug can be retrieved after released or left in the hole in the set position.

Description:
FIELD OF THE INVENTION 
       [0001]    The field of the invention is cleaning debris from a blowout preventer and conducting a pressure test in a single trip. 
       BACKGROUND OF THE INVENTION 
       [0002]    Blowout preventers (BOP) must be regularly pressure tested in order to ascertain their function. Prior methods took two separate trips for cleaning debris from the blowout preventer&#39;s internal components and capturing such debris either on a debris removal device that was part of a bottom hole assembly (BHA) or by circulation flow during the cleaning. When the cleaning process was done a separate trip with a packer set below the BOP was undertaken to pressure test the BOP. This additional trip created delay and additional cost and the objective of the present invention is to accomplish the cleaning of the BOP in the same trip as the pressure testing of the BOP. Variations are described where the plug used in the BHA is either left in the well or retrieved. Those skilled in the art will more readily appreciate various aspects of the present invention from a review of the detailed description of the preferred embodiment and the associated drawings. 
         [0003]    U.S. Pat. No. 7,031,840 generally describes methods for optimization of drilling time and makes reference to borehole cleaning as part of that process. 
       SUMMARY OF THE INVENTION 
       [0004]    A bottom hole assembly (BHA) has a plug below a debris catcher and an optional telescoping joint. A cleaning tool is above the debris catcher with another cleaning tool further up the BHA that is designed to clean the riser that extends up from the BOP. The plug is spotted and released to commence the BOP cleaning and the riser cleaning. The cleaning tools can be reconfigured to allow through flow after the cleaning is done so that the rams can be closed around a drill collar and a pressure test take place. With the BHA above the BOP the rams can be closed against each other for another pressure test from above. In a variety of options for the method, the plug can be retrieved after released or left in the hole in the set position. 
         [0005]    More specifically, the invention is a petroleum well BOP ( 10 ) cleaning and pressure testing method, comprising the steps of: 
         [0006]    tripping out a portion of a drilling string ( 42 ), 
         [0007]    arranging a borehole assembly ( 18 ) comprising a cleaning tool ( 36 ) and a disconnector ( 22 ) and a plug ( 21 ) on the remaining part of said drilling string ( 42 ) 
         [0008]    lowering said borehole assembly ( 18 ) on a string of drill pipes to below said BOP ( 10 ); 
         [0009]    setting said plug ( 21 ) which suspends said remaining part of said drilling string ( 42 ), 
         [0010]    disconnecting said disconnector ( 22 ), 
         [0011]    running said cleaning tool ( 36 ) in said BOP ( 10 ), 
         [0012]    pressure testing said BOP ( 10 ), 
         [0013]    reconnecting said disconnector to said plug ( 21 ), unsetting said plug ( 21 ), and retrieving said borehole assembly ( 18 ) and the top of said remaining part of said drilling string ( 42 ) to the surface, 
         [0014]    reassembling said drilling string ( 42 ) to the bottom of the hole and resuming drilling. 
         [0015]    The invention is also a petroleum well BOP ( 10 ) cleaning and testing assembly ( 18 ) comprising 
         [0016]    a plug ( 21 ) arranged for being set in a well and for holding a borehole tool such as a drilling string ( 42 ), 
         [0017]    a disconnector/connector ( 22 ) arranged above said plug ( 21 ) and below 
         [0018]    a BOP ( 10 ) cleaner tool ( 36 ) arranged for being suspended in a drill pipe string ( 40 ) from a drilling vessel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a first option of the method showing the running-in position. In this first option there is a string ( 42 ) hanging under the plug; 
           [0020]      FIG. 2  is the view of  FIG. 1  showing the plug set with the string suspended in the plug; 
           [0021]      FIG. 3  is the view of  FIG. 2  showing the BOP being cleaned internally; 
           [0022]      FIG. 4  is the view of  FIG. 3  showing the BOP being tested. It may be tested by leaving a pipe of the toolstring through the BOP and setting pressure through the string to establish pressure below the BOP and above the plug, or pulling the toolstring entirely above the BOP and setting pressure from above; 
           [0023]      FIG. 5  is the view of  FIG. 4  showing the BHA being pulled out of the hole (POOH) with the plug left set in the hole; 
           [0024]      FIG. 6  is a second option of the method showing the running-in position. Below the plug is a magnetic tool for cleaning the casing wall before the plug is set, instead of a string (drillstring etc.) suspended below the plug; 
           [0025]      FIG. 7  is the view of  FIG. 6  showing the plug being set and released from the BHA; 
           [0026]      FIG. 8  is the view of  FIG. 7  showing the BOP being cleaned; 
           [0027]      FIG. 9  is the view of  FIG. 8  showing the BOP being tested either having a pipe string through the BOP for setting pressure below BOP or the pipe string pulled above the BOP and closing the BOP for testing the BOP setting pressure above; 
           [0028]      FIG. 10  is the view of  FIG. 9  showing the BHA moving through the BOP to unset the plug and retain the plug; 
           [0029]      FIG. 11  is the view of  FIG. 10  with the BHA being POOH with the plug; 
           [0030]      FIG. 12  is a third option of the method showing the BHA being run in; 
           [0031]      FIG. 13  is the view of  FIG. 12  showing the plug not set; 
           [0032]      FIG. 14  is the view of  FIG. 13  showing the plug set and the BOP being cleaned; 
           [0033]      FIG. 15  is the view of  FIG. 14  showing the BOP being pressure tested; 
           [0034]      FIG. 16  is the view of  FIG. 15  showing the BHA going through the BOP to release the plug; 
           [0035]      FIG. 17  is the view of  FIG. 16  showing the BHA being POOH with the plug; 
           [0036]      FIG. 18  is a fourth option of the method in the run in position; 
           [0037]      FIG. 19  is the view of  FIG. 18  showing the plug set; 
           [0038]      FIG. 20  is the view of  FIG. 19  showing the cleaning of the BOP; 
           [0039]      FIG. 21  is the view of  FIG. 20  showing the BOP being pressure tested; 
           [0040]      FIG. 22  is the view of  FIG. 21  with the BHA being POOH while leaving the plug in the hole. 
           [0041]      FIG. 23  is a series of steps showing the use of the invention wherein a drilling string is hung off suspended in the plug while the BOP is being cleaned, until the entire drilling string is reestablished in the well 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0042]      FIGS. 1-6  illustrate a first option of the method where the BOP  10  is situated below a marine riser  12  with the casing strings  14  supporting the BOP  10 . A flex joint  16  is placed between the BOP  10  and the riser  12 . The BHA  18  is run in on a string  40  from a vessel or a platform in an offshore application and will be described going from the bottom up. A magnetic drift  20  is on the bottom. It guides the BHA  18  and picks up magnetic debris that may be in the borehole ahead of the plug  21 . Plug  21  has a disconnect  22  so that when the plug  21  is set the BHA  18  above the disconnect  22  can be moved up for the cleaning of the BOP  10 . Drill collars  24  weigh down the BHA for ease of running in. A junk basket or some other type of debris catcher  26  is used to catch any debris that manages to go further downhole during the cleaning of the BOP  10  with the cleaning tool  36 . The debris catcher  26  is a known design and can have a plurality of biased fingers that trap debris between the fingers. 
         [0043]    Above the debris catcher  26  there are several stands of pipe  28  for spacing purposes for the plug  21  when the cleaning tool  36  is at the position just below the BOP  10 . A long stroke bumper sub  30  is used to compensate for vessel or platform movement due to wave action and can be optionally omitted where such movement compensation is not an issue. More tubular stands  32  are above the bumper sub  30  followed by a magnet  34  that catches debris from the cleaning tool  36 . The cleaning tool  36  is a known design that has spiral flow passages and circulation ports for jetting action as well as brushes on the raised portions that define the spiral paths. The tool  36  can be configured to direct flow straight through instead of out laterally through the cleaning jets by dropping an object such as a dart and shifting a sleeve to allow the dart or object to release for a flow through central bore. As seen in  FIG. 1  the magnet and riser brush assembly  38  is spaced to be at the riser  12  bottom when the cleaning tool  36  is at the bottom of the BOP  10 . Optionally, the BHA  18  can continue beyond the magnetic drift  20  with a string such as a drilling string and other tools that are schematically represented as  42 . If the plug  21  stays in the hole after the pressure testing of the BOP  10  then the portion of the BHA  18  below the set plug  21  would clearly also remain in the hole. (In this case the BHA here illustrated could rather be called a “borehole assembly” than a “bottomhole assembly”.) 
         [0044]    With the major components described, the various options for the method can now be explained. As states,  FIG. 1  is the position after running in to the desired location. In  FIG. 2  the plug  21  is set and the disconnect  22  is released so that the remainder of the BHA  18  can be pulled up to put the cleaning device  36  in position just below the BOP  10 . In  FIG. 3  circulation is initiated through the jet ports in the cleaning device  36  as represented by the arrow  50 . Most of the debris is circulated out of the well through the annulus  52  in the riser  12 . Should any magnetic debris fall down the hole the magnet  34  can get it. If the falling debris is not magnetic or for some reason does not adhere to the magnet  34  then the debris catcher  26  can collect such debris and bring it to the surface when the BHA  18  is removed from the well. The cleaning step can also involve rotation or reciprocation of the string  40  to aid the scrubbing process. At the same time the magnet/brush  38  is scraping the riser  12  and capturing some of the debris with the magnet that is part of that assembly. At the end of the cleaning, the cleaning device  36  can be reconfigured for through flow as opposed to lateral flow out the cleaning nozzles by dropping an object or a dart (not shown) to move a sleeve to close the lateral port and open the through port when the dart or object exit the cleaning tool  36 . 
         [0045]    As seen in  FIG. 4  the BHA  18  is pulled above the BOP  10  except for the plug  21  and what is below it which remains behind with the plug  21  still set. Pressure is applied through the BHA  18  and down to the set plug  21  to test the integrity of the BOP  10 . Alternatively the rams, of which three are shown can close on tubulars  32  or  28  and the test can be conducted for the BOP  10  clamped onto the BHA  18  with the plug  21  serving as the bottom pressure retaining device.  FIG. 5  shows that at the conclusion of the pressure test the BHA  18  is pulled out of the hole (POOH) while leaving the plug  21  and anything it supports below remaining in the well. 
         [0046]      FIGS. 6-11  represent another order for the method using the same parts.  FIGS. 6-9  correspond to  FIGS. 1-4  and the method thus far is unchanged. In  FIG. 10  the BHA  18  is lowered to release plug  21  after re-latching into it. In  FIG. 11  the BHA  18  is POOH with the released plug  21  and any other components that it supports. 
         [0047]    In the third option, the BHA  18  is run in as before but this time the plug  21  is not set before the cleaning with the cleaning device  26  starts. In  FIG. 13  the cleaning commences with the cleaning device  26  as previously described and then in  FIG. 14  the plug  21  is set and released at the disconnect  22 . In  FIG. 15  the BHA  18  is pulled above the BOP  10  for the pressure test as described before. In  FIG. 16  the plug  21  is about to be engaged to be grasped and then released so that in  FIG. 17  it is removed with the BHA  18 . 
         [0048]    In  FIGS. 18-22  the BHA  18  is run in in  FIG. 18  to the desired location as shown in  FIG. 19 . The cleaning commences in  FIG. 20  with the cleaning device  26  with the plug  21  unset. The plug  21  is then set and released as in  FIG. 22  and the BHA  18  is raised above the BOP  10  for the pressure test. The plug  21  is then left in the hole and the BHA is removed through the riser  12  as shown in  FIG. 22 . 
         [0049]    Those skilled in the art will appreciate that what is described is a one trip technique for running in and cleaning a BOP with a plug set or unset and either leaving the plug in the hole after the pressure test or removing the plug after the pressure test by re-latching onto it and releasing it for ultimate removal. The plug in all these options can have further tools secured to itself. What was previously done in discrete trips now can be done in a single trip. 
         [0050]    A significant advantage of the invention is that a major part drill string may be hung off below a plug in the well instead of tripping out the entire drill string before plugging the well and pressure testing the BOP. This may also prove to save much time in case using the plug as a storm lock plug in order to hang off the drill string in the hole and pressure testing the BOP before having to disconnect. After reconnecting the same tool is used to pressure test the BOP and remove the plug and resume the drilling operation. One may conduct pressure testing above the plug and below the BOP because the plug is able to hold the drill string which may be several kilometers long. 
         [0051]      FIG. 23  is a series of steps showing the use of the invention wherein a drilling string is hung off suspended in the plug while the BOP is being cleaned, until the entire drilling string is reestablished in the well. 
         [0052]      FIG. 23 a    illustrates a drill string ( 42 ) in a drilling position in a well and suspended from the drilling rig at the sea. The drill string extends through a riser ( 12 ) and further through a BOP ( 10 ) into the well. The drill string ( 42 ) is, according to the method, tripped out by a length of drill pipes corresponding to deeper than the BOP ( 10 ), then a borehole assembly ( 18 ) according to the invention comprising at least a plug ( 21 ), a disconnector/connector ( 22 ), and a cleaning tool ( 26 ) is inserted onto the remaining drilling string and lowered using drill pipes with the plug ( 21 ) into the casing and with the cleaning tool ( 36 ) below the BOP ( 10 ). Then the plug ( 21 ) is set in  FIG. 23 b   . In  FIG. 23 c    the borehole assembly ( 18 ) is disconnected from the set plug, which suspends the drilling string ( 42 ) in the borehole, and the cleaning tool ( 36 ) is run through the BOP ( 10 ). Flushing fluid may be supplied to the cleaning tool ( 36 ) through the drill pipes suspending the cleaning tool ( 36 ). The BOP ( 10 ) may in the situation illustrated in  FIG. 23 d    be closed entirely and pressure tested from above or below, and/or closed about a lower portion of drill pipe and pressure tested through establishing pressure through the drill pipes holding the cleaning tool ( 36 ), and the plug. Then the drill pipes with the assembly ( 18 ) is lowered and reconnected with the plug ( 21 ), the plug unset, and the assembly ( 18 ) with the plug ( 21 ) and the cleaning tool may be retrieved to the surface as illustrated in  FIG. 23 e   .  FIG. 23 f    illustrates drilling ready to be resumed. 
         [0053]    Variations of the sequence of cleaning, disconnecting, pressure testing and re-latching/reconnecting are possible. 
         [0054]    Another variation of the method is that after the plug ( 21 ) has been set and the BOP ( 10 ) preferably has been pressure tested, the riser should be ready for being emergency disconnected in order to ride off a storm. After the storm, with or without having disconnected the riser, one is back to the situation illustrated in  FIG. 23 d   , wherein one may conduct pressure testing, reconnecting and retrieving the plug, and lower the drilling string to resume drilling as shown in  FIG. 23   f.