Patent Publication Number: US-8122960-B2

Title: Spoolable coiled tubing spear for use in wellbores and methods of using same

Description:
BACKGROUND 
     1. Field of Invention 
     The invention is directed to fishing devices for retrieving coiled tubing disposed in oil and gas wells and, in particular, to spoolable coiled tubing spears for retrieving coiled tubing within the wellbores of oil and gas wells. 
     2. Description of Art 
     In certain oil and gas drilling and production operations, coiled tubing is disposed in a wellbore for carrying out the operations. As used herein, the term “wellbore” includes cased and uncased boreholes as well as risers that may be connected or in fluid communication with a subsea “Christmas tree,” blowout preventer, or other component of a subsea oil or gas well. One advantage to using coiled tubing is that it can be spooled so that long lengths of tubing are more easily and efficiently delivered to and stored at the wellbore or at the off-shore floating platform or vessel from which the oil or gas operations are managed. In certain situations, the coiled tubing must be cut at or near the bottom of the wellbore, or riser. For example, in deep water oil and gas operations, a oil and gas production or drilling floating platform or vessel on the surface of the water may need to be disconnected from a subsea blowout preventer such as when a hurricane or other inclement weather is approaching. In these situations, the coiled tubing is cut at the blow-out preventer, leaving only the blowout preventer located at or near the seafloor and a short length of coiled tubing. The platform or vessel, and riser, can then either be moved as necessary, or be permitted to move with the wave-action without placing undo stresses on the coiled tubing or other structures normally connected between the platform and the blowout preventer. 
     After being cut, it is normally desirable to reconnect with the cut coiled tubing. To do so, however, requires the operators of the wellbore to “fish” the cut coiled tubing from the wellbore so that it can be brought to the surface of the wellbore, e.g., the floating platform or vessel, where it can be reconnected to the spooled coiled tubing. The spoolable coiled tubing spears described here achieve the function of fishing the cut coiled tubing from the wellbore. 
     SUMMARY OF INVENTION 
     Broadly, the coiled tubing spears disclosed herein include a mandrel having a spear disposed at a first or lower end, a centralizer disposed around the mandrel, and an attachment member at a second or upper end of the mandrel for securing the mandrel to a spooled length of coiled tubing. During run-in and run-out, the centralizer(s) maintain the coiled tubing in the proper alignment within the wellbore, or riser, to facilitate insertion of the spear into the bore of the cut coiled tubing as discussed in greater detail below. 
     The spear is designed to secure to coiled tubing left down a wellbore. In one particular embodiment, the spear comprises a grapple disposed on a spear body. The grapple is designed to be inserted into a cut end of coiled tubing for securing the grapple to an inner wall surface of the coiled tubing. As a result of this connection between the spear and the coiled tubing, retraction of the spear out of the wellbore will result in the coiled tubing also being retrieved. 
     In certain embodiments, the centralizer is operatively associated with a releasable member such as a collet so that the centralizer is prevented from movement along the outer wall surface of the mandrel by the releasable member. Upon reaching the surface of the wellbore, or the platform or vessel deck, the releasable member can be actuated to allow it and the centralizer to move along an outer wall surface of the mandrel so that both the collet and the centralizer slide off of the mandrel. As a result, during spooling of the coiled tubing, the coiled tubing spear, and the recovered coiled tubing, the spear and mandrel can pass through an injector head and be spooled onto a spool containing the coiled tubing. 
     In other particular embodiments, the coiled tubing spear comprises two spears, one at each end of the mandrel, two centralizers, and two releasable members, e.g., collets, one operatively associated with a corresponding centralizer, so that both centralizers can be released from, and slid off, the outer wall surface of the mandrel along with the releasable members. 
     In still other certain embodiments, the mandrel is a flex tube to facilitate the mandrel being spooled during retrieval of the cut coiled tubing. 
     In operation, the coiled tubing spear is attached to an end of coiled tubing disposed at the surface of the wellbore. The spear is then lowered into the wellbore by unspooling the coiled tubing from a spool. In general, before entering the wellbore, the coiled tubing passes through an injection head, through which a centralizer located on the coiled tubing spear cannot pass. Therefore, the coiled tubing spear is secured to the coiled tubing after the coiled tubing has been unspooled and passed through the injector head. 
     The coiled tubing spear is lowered into the wellbore until it engages the cut coiled tubing disposed within a well, or at the subsea blow-out preventer of a well. The grapple of the spear is then inserted into the bore of the cut coiled tubing so that the grapple can engage and secure the spear to an inner wall surface of the cut coiled tubing. The coiled tubing, coiled tubing spear, and, therefore, the cut coiled tubing previously disposed within the well, are retrieved by pulling, and spooling, the coiled tubing. 
     After the coiled tubing spear reaches the surface, the releasable member(s) are actuated, such as by either the centralizer(s) or the releasable member(s) being pulled against the injector head as the coiled tubing enters the injector head, causing the releasable member(s) to release from the mandrel or the spear body so that the releasable member(s) and the centralizer(s) can slide down the coiled tubing and the coiled tubing, mandrel, and spear(s), can pass through the injector head and be spooled onto the spool. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of one particular embodiment of the coiled tubing spear disposed herein. 
         FIG. 2  is a cross-sectional view of the embodiment of the coiled tubing shown in  FIG. 1 . 
         FIG. 3  is a partial cross-sectional view of the embodiment of the coiled tubing shown in  FIG. 1 . 
     
    
    
     While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF INVENTION 
     Referring now to  FIGS. 1-3 , one specific embodiment of coiled tubing spear  20  comprises mandrel  30  having first or lower end  32 , second or upper end  34 , and bore  36  defined by inner wall surface  37  and outer wall surface  38 . Although mandrel  30  can be formed out of any material desired or necessary to facilitate connection of a spear (discussed in greater detail below) to mandrel  30  so that cut coiled tubing can be retrieved, in one particular embodiment, mandrel  30  is a flex tube formed out of  41 / 40  steel or other metal or composite material have similar characteristics to  41 / 40  steel. 
     Mandrel  30  includes attached to both lower end  32  and upper end  34  an attachment member. The attachment member at lower end  32  secures the coiled tubing spear to the section of cut coiled tubing disposed in the wellbore. The attachment member at upper end  34  secures the coiled tubing spear to the section of spooled coiled tubing located at the surface of the wellbore. As used herein, the term “cut coiled tubing” refers to the section of coiled tubing disposed in the wellbore that is to be retrieved and the term “spooled coiled tubing” is the section of coiled tubing that is initially disposed on a spool located at the surface of the wellbore, e.g., on the offshore platform or on the deck of the vessel, that is unspooled and lowered down the wellbore to retrieve the cut coiled tubing. As shown in the Figures, the two attachment members are shown as spears  40 ,  50 ; however, it is to be understood that any attachment member known in the art can be used. 
     As shown in  FIGS. 1 and 2 , mandrel  30  includes spear  40  secured to lower end  32  of mandrel  30  and spear  50  secured to upper end  34 . As discussed in greater detail below, in this particular embodiment, spear  50  is used to attach coiled tubing spear  20  to spooled coiled tubing located at the surface of a wellbore, or at the surface of the water. As a result, coiled tubing spear  20  can be lowered down to the section of cut coiled tubing within the wellbore or at the subsea blow-out preventer, or at any other location in which coiled tubing is used in wellbores, by unspooling the spooled coiled tubing. 
     In the embodiment shown in the Figures, both spears  40 ,  50  comprise spear bodies  42 ,  52 , grapples  44 ,  54 , release rings  46 ,  56 , and retainer nut  48 ,  58 . Grapples  44 ,  54 , include profiles  45 ,  55  to facilitate attachment to an inner wall surface of a section of cut coiled tubing (not shown) when grapples  44 ,  54  are inserted into the bore of the section of cut coiled tubing so that the section of cut coiled tubing can be retrieved. 
     Centralizers  60 ,  70  are releasably secured to, and in some embodiments, when released, are in sliding engagement with, outer wall surface  38  of mandrel  30 . Centralizers  60 ,  70  are each releasable secured to outer wall surface  38  by one or more releasable members, such as shear screws  69 ,  79 . Upon retrieval of the section of cut coiled tubing from the wellbore, shear screws  69 ,  79  can be broken to release centralizers  60 ,  70  from their initial, secured position to outer wall surface  38  of mandrel  30  so that centralizers  60 ,  70  can be removed and mandrel  30  and spears  40 ,  50  can pass through an injector head located at the surface of the wellbore. In one particular embodiment, shear screws  69 ,  79  are broken by pulling the spooled coiled tubing through the injector head causing centralizers  60 ,  70 , in series, to engage a surface of the injector head which applies an axial force along the length of mandrel  30 . The pulling force through the injector is countered by the force being exerted on centralizers  60 ,  70  by the injector head causing shear screws  69 ,  79  to break. This allows mandrel  30  and spears  40 ,  50  to travel through the injector head. 
     In certain specific embodiments, the releasable members comprise collets  80 ,  90  which include collet fingers  82 ,  92  that are initially secured to one or both of mandrel  30  or spears  40 ,  50 . In the embodiment of  FIGS. 1-3 , the tips of collet fingers  82 ,  92  include inner flanges  83 ,  93 , that are disposed within recess or grooves  49 ,  59  of spears  40 ,  50 , respectively (shown best in  FIG. 3  with respect to spear  40 ). Thus, in the particular embodiment of  FIGS. 1-3 , collets  80 ,  90  are initially connected along outer wall surface  38  and to spear bodies  42 ,  52 . Collet fingers  82 ,  92  can be biased outwardly such that a releasable member, such as shear screws  102  disposed in holes  100  (shown best in  FIG. 3 ), secure collet fingers  82 ,  92  within grooves  49 ,  59  of spears  40 ,  50 , respectively (shown best in  FIG. 3  with respect to spear  40 ). Alternatively, collet fingers  82 ,  92  are not biased outwardly and shear screws  102  are absent so that after retrieving coiled tubing spear  20  with the cut portion of coiled tubing, pins or other devices (not shown) can be inserted into holes  100  to force each collet finger  82 ,  92  outwardly to release collets  80 ,  90  from mandrel  30  and/or spears  40 ,  50 . 
     Centralizers  60 ,  70  are operatively associated with collets  80 ,  90  so that sliding movement of collets  80 ,  90  along outer wall surface  38  causes sliding movement of centralizers  60 ,  70  along outer wall surface  38 ; and so that no sliding movement of collets  80 ,  90  along outer wall surface  38  prevents sliding movement of centralizers  60 ,  70  along outer wall surface  38 . In the embodiment shown in  FIGS. 1-3 , collet outer flanges  84 ,  94  of collets  80 ,  90 , respectively, are disposed at a first end of collets  80 ,  90  and within centralizer recess or grooves  62 ,  72  of centralizers  60 ,  70 , respectively, so that centralizers  60 ,  70  are operatively associated with collets  80 ,  90 . These features are shown best in  FIG. 3  with respect to centralizer  60  and collet  80 . 
     When it is desired to release collets  80 ,  90 , and centralizers  60 ,  70  from mandrel  30  or spear bodies  42 ,  52 , pressure can be applied axially along the length of collets  80 ,  90  to break shear screws  102  (and, if present, shear screws  69 ,  79 ), thereby permitting collet fingers  82 ,  92  to radially expand and, therefore, release collets  80 ,  90  and centralizers  60 ,  70  so that they can slide along outer wall surface  38  and ultimately off of coiled tubing spear  20 . In one particular embodiment, the pressure applied axially along the length of mandrel  30  is due to either centralizers  60 ,  70  or collets  80 ,  90  being forced into a surface disposed on an injector head so that mandrel  30  and spears  40 ,  50  can continue to travel through the injector head while centralizers  60 ,  70  and collets  80 ,  90  are slide down the section of cut coiled tubing and ultimately removed. 
     Alternatively, as discussed above, shear screws  102  may be absent so that a pin or other device is inserted into holes  100  to force collet fingers  82 ,  92  away from outer wall surface  38  of mandrel  30 , grooves  49 ,  59 , and/or spear bodies  42 ,  52 . In so doing, collets  80 ,  90  are free to move, thereby freeing centralizers  60 ,  70  to move and ultimately be removed from coiled tubing spear  20  in the same manner as described above. 
     It is to be understood that the invention is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. For example, spear  40  does not have to be identical in construction to spear  50 . Spears  40 ,  50  may be any attachment member known in the art for securing the coiled tubing spear to the section of cut coiled tubing and spooled coiled tubing, respectively. Further, the coiled tubing spear can include only one centralizer, and, therefore, only one releasable member. Additionally, the collet(s) can be replaced by an other release member that is capable of releasing the centralizer(s) so the centralizer(s) can slide along the outer wall surface of the mandrel. Moreover, the collet(s) can be secured solely to the outer wall surface of the mandrel instead of as shown in  FIGS. 1-3  as being also connected to the spear bodies. In addition, the grooves or recesses in the spear bodies are not required and release members other than shear screws can be used to maintain the collet fingers in connection with the mandrel or spear body. Moreover, the releasable member may be secured to either the mandrel, the spear body, or both the mandrel and the spear body. Further, the releasable member may be secured through any method or device known in the art. And, the collet(s) and may be operatively associated with the centralizer(s) through any method or device known in the art. Similarly, the collet(s) may be secured to the mandrel or spears through any method or device known in the art. Accordingly, the invention is therefore to be limited only by the scope of the appended claims.