Patent Publication Number: US-10767419-B2

Title: Apparatus and methods for handling drill string

Description:
TECHNICAL FIELD 
     The present disclosure relates to an apparatus and method for handling a drill string. The present disclosure relates to an apparatus and method for tripping a drill string—i.e. withdrawing a drill string out from a wellbore and lowering the drill string back into the wellbore. Particular embodiments permit tripping the drill string with minimal or no disassembly of the drill string. 
     BACKGROUND 
     In the oil and gas industry, drill strings are used to drill into the earth and form wellbores. A drill string is made up of pipe sections (often referred to as pipes) connected end to end. At times, the entire drill string needs to be pulled out from a wellbore, e.g. for servicing and/or repair. Such operations may require a large number of connected pipe sections to be disconnected as the drill string is withdrawn from the wellbore and re-connected when the drill string is re-inserted into the wellbore. The disconnection and subsequent connection of these pipe sections can be time consuming, expensive and dangerous. 
     There is a general desire for an improved apparatus and method for handling a drill string. There is a general desire for an apparatus and method for withdrawing a drill string out from a wellbore and lowering the drill string back into the wellbore. There is a general desire to withdraw a drill string from a wellbore and to reinsert the drill string into the wellbore with minimal or no drill string disassembly, except possibly to repair a portion of the drill string. 
     The foregoing examples of the related art and limitations related thereto are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings. 
     SUMMARY 
     The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above-described problems have been reduced or eliminated, while other embodiments are directed to other improvements. 
     One aspect of the present disclosure provides an apparatus for handling a drill string having an up-hole end, a mid-section and a down-hole end. The apparatus comprises: a first tension mechanism; a second tension mechanism; an up-hole cable operably connectable between the first tension mechanism and the up-hole end of the drill string; a down-hole cable operably connectable between the second tension mechanism and a connection location in the mid-section of the drill string; and a guide defining an elongated channel for receiving the drill string. The guide is located relative to the first tension mechanism, the second tension mechanism, the up-hole cable and the down-hole cable, so that force applied to the up-hole end of the drill string by the first tension mechanism via the up-hole cable pulls the drill string upwardly through the elongated channel and outwardly from a wellbore and force applied to the mid-section of the drill string by the second tension mechanism via the down-hole cable pulls the drill string downwardly through the elongated channel to facilitate at least partial re-insertion of the drill string into the wellbore. 
     The guide may be shaped to prevent the drill string from bending, as the drill string is pulled through the elongated channel, in a manner that is sharper a minimum threshold radius of curvature for the drill string. 
     Force applied to the mid-section of the drill string by the second tension mechanism via the down-hole cable pulls the drill string downwardly through the elongated channel to facilitate at least partial re-insertion of the drill string into the wellbore. During such reinsertion of the drill string into the wellbore: at a release configuration where at least an up-hole portion of the drill string is located in the guide and at least a down-hole portion of the drill string is located in the wellbore, at least one of: the second tension mechanism may be disconnected from the down-hole cable; and the down-hole cable may be disconnected from the drill string; and gravity may facilitate further downward withdrawal of the drill string through the elongated channel and further insertion of the drill string into the wellbore. 
     The release configuration may occur when a length of the down-hole cable between the second tension mechanism and the connection location is a minimum. The release configuration may occur when a force of gravity that tends to pull the drill string back into the wellbore becomes greater than frictional forces that tend to hold the drill string in the guide. The release configuration may occur immediately prior to the connection location entering the wellbore. 
     For at least a portion of the time during application of force to the mid-section of the drill string by the second tension mechanism via the down-hole cable to pull the drill string downwardly through the elongated channel to facilitate at least partial re-insertion of the drill string into the wellbore, the first tension mechanism via the up-hole cable may be operative to exert upwardly oriented force on the drill string which tends to prevent the drill string from falling back into the wellbore under the force of gravity. 
     After disconnection of at least one of: the second tension mechanism from the down-hole cable, and the down-hole cable from the drill string, the first tension mechanism via the up-hole cable may be operative to exert upwardly oriented force on the drill string, which tends to prevent the drill string from falling back into the wellbore under the force of gravity. An amount of upwardly oriented force exerted on the drill string by the first tension mechanism via the up-hole cable may be controlled to control a rate at which the drill string extends back into the wellbore. 
     The guide may comprise: a tail end through which the drill string enters the guide as the drill string is removed from the wellbore and pulled upwardly into the guide by the first tension mechanism via the up-hole cable; and a corresponding tail section that is relatively more proximate to the tail end than a remainder of the guide. The tail section may be moveable relative to the remainder of the guide between: a lowered configuration where the tail section and the remainder of the guide provide the elongated channel with a smooth shape; and a raised configuration where the tail end introduces a discontinuity into a shape of the elongated channel. 
     The guide may comprise: a tail end through which the drill string enters the guide as the drill string is removed from the wellbore and pulled upwardly into the guide by the first tension mechanism via the up-hole cable; and a corresponding tail section that is relatively more proximate to the tail end than a remainder of the guide. At least a portion of the tail section may be shaped to provide the elongated channel with an enclosed shape, the enclosed shape surrounding a transverse cross-section of the drill string located in the elongated channel at the at least a portion of the tail section. At least a portion of the remainder of the guide may be shaped to provide the elongated channel with an open shape, the open shape surrounding only a portion of a transverse cross-section of the drill string located in the elongated channel at the at least a portion of the remainder of the guide. 
     The at least a portion of the tail section may comprise a moveable cover that may be moveable between a closed configuration that provides the at least a portion of the tail section with the enclosed shape and an open configuration that provides the at least a portion of the tail section with an open shape which surrounds only a portion of the transverse cross-section of the drill string located in the elongated channel at the at least a portion of the tail section. 
     Another aspect of the invention provides a method for handling a drill string having an up-hole end, a mid-section and a down-hole end. The method comprises pulling a drill string out from a wellbore. Pulling the drill string out from the wellbore comprises: releasably connecting an up-hole cable between a first tension mechanism and the up-hole end of the drill string; and pulling the up-hole cable and the drill string upwardly into a guide. The method comprises lowering the drill string from the guide back into the wellbore. Lowering the drill string from the guide back into the wellbore comprises: releasably connecting a down-hole cable between a second tension mechanism and a connection location in the mid-section of the drill string; pulling the down-hole cable and the drill string downwardly out from the guide to facilitate at least partially re-inserting the drill string into the wellbore; at a release configuration, where at least an up-hole portion of the drill string is located in the guide and at least a down-hole portion of the drill string is located in the wellbore, disconnecting at least one of: the second tension mechanism from the down-hole cable; and the down-hole cable from the drill string; and after the disconnecting, permitting gravity to pull the drill string further downwardly out from the guide to facilitate further re-inserting the drill string into the wellbore. 
     Pulling the up-hole cable and the drill string upwardly into the guide may comprise pulling at least a portion of the drill string through an elongated channel defined by the guide. The guide may be shaped to prevent the drill string from bending, as the drill string is pulled through the elongated channel, in a manner that is sharper than a minimum threshold radius of curvature for the drill string. 
     The release configuration may occur when a length of the down-hole cable between the second tension mechanism and the connection location is a minimum. The release configuration may occur when a force of gravity that tends to pull the drill string back into the wellbore becomes greater than frictional forces that tend to hold the drill string in the guide. The release configuration may occur immediately prior to the connection location entering the wellbore. 
     For at least a portion of the time during lowering the drill string from the guide back into the wellbore, the method may involve applying upward force to the up-hole end of the drill string using the first tension mechanism via the up-hole cable wherein the upward force tends to prevent the drill string from falling back into the wellbore under the force of gravity. 
     After disconnecting at least one of: the second tension mechanism from the down-hole cable, and the down-hole cable from the drill string, the method may involve applying upward force to the up-hole end of the drill string using the first tension mechanism via the up-hole cable wherein the upward force tends to prevent the drill string from falling back into the wellbore under the force of gravity. The method may comprise controlling an amount of the upward force exerted on the drill string by the first tension mechanism via the up-hole cable to control a rate at which the drill string extends back into the wellbore. 
     The guide may comprise: a tail end through which the drill string enters the guide as the drill string is pulled upwardly into the guide; and a corresponding tail section that is relatively more proximate to the tail end than a remainder of the guide. The method may further comprise moving the tail section relative to the remainder of the guide between: a lowered configuration where the tail section and the remainder of the guide provide an elongated drill-string receiving channel of the guide with a smooth shape; and a raised configuration where the tail end introduces a discontinuity into a shape of the elongated channel. 
     At least a portion of the tail section may be shaped to provide the elongated channel with an enclosed shape, the enclosed shape surrounding a transverse cross-section of the drill string located in the elongated channel at the at least a portion of the tail section. At least a portion of the remainder of the guide may be shaped to provide the elongated channel with an open shape, the open shape surrounding only a portion of a transverse cross-section of the drill string located in the elongated channel at the at least a portion of the remainder of the guide. The at least a portion of the tail section may comprise a moveable cover and the method may comprise moving the moveable cover between a closed configuration that provides the at least a portion of the tail section with the enclosed shape and an open configuration that provides the at least a portion of the tail section with an open shape which surrounds only a portion of the transverse cross-section of the drill string located in the elongated channel at the at least a portion of the tail section. 
     In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following detailed descriptions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments are illustrated in referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive. 
         FIG. 1  shows a schematic view of a drilling operation using an apparatus for handling a drill string according to an example embodiment. 
         FIG. 2  shows a schematic view of a drilling operation using an apparatus for handling a drill string according to a second example embodiment. 
         FIG. 3  shows a cross sectional view of a guide according to an example embodiment, wherein the guide is used to support a drill string. 
         FIG. 4A  shows a side elevation view of a guide according to a second example embodiment wherein the guide is in a lowered configuration. 
         FIG. 4B  shows a side elevation view of the embodiment of  FIG. 4A  wherein the guide is in an raised configuration. 
         FIG. 5A  shows a cross sectional view of a head end of a guide according to a third example embodiment. 
         FIG. 5B  shows a cross sectional view of a tail end of the  FIG. 5A  guide. 
         FIG. 6A  shows a schematic side elevation view of an apparatus for handling a drill string according to another example embodiment. 
         FIG. 6B  shows a cross sectional view of the  FIG. 6A  apparatus. 
         FIGS. 7A-7E  show a schematic view of the drill operation wherein the  FIG. 1  drill string handling apparatus is used for withdrawing the drill string out from a wellbore and lowering the drill string back into the wellbore. 
         FIG. 8  shows an example path along which the  FIG. 1  drill string handling apparatus can guide a drill string. 
     
    
    
     DESCRIPTION 
     Throughout the following description specific details are set forth in order to provide a more thorough understanding to persons skilled in the art. However, well known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure. Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense. 
       FIG. 1  shows an example embodiment of an apparatus  10  for handling a drill string. Drill string  18  has an up-hole end  18 A, a mid-section  18 B and a down-hole end  18 C. As is known in the art, drill string  18  may comprise a plurality of pipe sections (pipes) connected end to end. Mid-section  18 B of drill string  18  may be proximate to the effective centre of gravity of drill string  18 . 
     Apparatus  10  comprises a first tension mechanism  13 A, such as a winch  13 , a second tension mechanism  12 A, such as a winch  12 , one or more up-hole cable(s)  14  (e.g. one up-hole cable  14  in the illustrated embodiment), one or more down-hole cable(s)  16  (e.g. one down-hole cable  16  in the illustrated embodiment) and a guide  20 . For simplicity, the embodiments described herein with one up-hole cable  14  and one down-hole cable  16 , it being understood that there may be a plurality of such cables. 
     The first tension mechanism  13 A and the second tension mechanism  12 A are winches  12 ,  13  in the  FIG. 1  embodiment, but these tension mechanisms  12 A,  13 A can be any suitable force-providing mechanisms which can apply tension to drill string  18  via cables  14 ,  16 . Winches  12 ,  13  may be controlled automatically using tension controls that set a constant or variable tension at the winch. 
     Up-hole cable  14  is releasably connected to up-hole end  18 A of drill string  18  via any suitable releasable connection/attachment mechanism. Winch  13  is operatively connected to up-hole cable  14  to pull drill string  18  up and out from wellbore  19  through guide  20 . 
     Down-hole cable  16  is releasably connected to a connection location  27  in mid-section  18 B of drill string  18  via any suitable releasable connection/attachment mechanism. Additionally or alternatively, as shown in  FIG. 2 , down-hole cable  16  can also be releasably connected to the up-hole end  18 A of drill string  18 . Winch  12  is operatively connected to down-hole cable  16  to pull drill string  18  back from guide  20 , where drill string  18  can be re-inserted back down into wellbore  19 . 
     Referring to  FIGS. 1-3 , guide  20  defines an open channel  28  for receiving drill string  18 . Drill string  18  may be pulled upwardly out of wellbore  19  into guide  20  via winch  13  and up-hole cable  14 , and may be pulled out of guide  20  for downward reinsertion back into wellbore  19  via winch  12  and down-hole cable  16 . Guide  20  has a head end  23  and a tail end  21 . Drill string  18  is fed upwardly out of wellbore  19  and into guide  20  through tail end  21  and, as drill string  18  continues to be pulled upwardly out of wellbore  19 , drill string  18  may exit guide  20  through head end  23 . Guide  20  may be dimensioned to prevent drill string  18  from bending in a manner that is sharper its minimum threshold radius of curvature. 
     As used in this disclosure and in the accompanying claims, the term “upwardly”, unless context dictates otherwise, refers to a direction through guide  20  from tail end  21  toward head end  23 . “Upward” movement of drill string  18  through guide  20  corresponds with movement of drill string  18  outwardly from wellbore  19  (i.e. extraction of drill string  18  from wellbore  19 ). The term “downwardly”, unless context dictates otherwise, refers to a direction through guide  20  from head end  23  toward tail end  21 . “Downward” movement of drill string  18  through guide  20  corresponds with movement of drill string  18  into wellbore  19  (i.e. insertion of drill string  18  into wellbore  19 ). 
     As shown in  FIG. 3 , guide  20  of the illustrated embodiment comprises a base  22  and two side walls  24 ,  26 . Base  22  and side walls  24 ,  26  define an open channel  28  (e.g. upwardly opening) for receiving drill string  18 . When received in open channel  28 , drill string  18  may rest on base  22  (due to gravity) and may be stabilized or otherwise prevented from undesirable transverse movement by side walls  24 ,  26 . Guide  20  may be curved but is shaped to prevent drill string  18  from bending with a radius of curvature that is less than (tighter bend than) a threshold radius of curvature. Controlling this threshold radius of curvature prevents drill string  18  from being damaged when it is supported by guide  20 . A person skilled in the art will appreciate that guide  20  can have any number of suitable configurations, as long as guide  20  defines channel  28  through which drill string  18  may be pulled and, optionally, supported and/or constrained. 
     In some embodiments, base  22  may be equipped with a conveyor system, such as a conveyor belt, a moving floor conveyor system or a pipe lifting mechanism, that assists up-hole cable  14  or down-hole cable  16  to pull drill string  18  through guide  20 . In some embodiments, base  22  and/or side walls  24 ,  26  may be provided with idler rollers or the like (not shown) so that rather than sliding drill string  18  along base  22  as it is pulled through guide  20 , drill string  18  may roll along guide  20 . 
     In some embodiments, guide  20  is convertible between a lowered configuration, shown in  FIG. 4A , and a raised configuration, shown in  FIG. 4B , by suitable movement of tail section  21 A including tail end  21  of guide  20  relative to the remainder  23 A of guide  20 . In the lowered configuration, tail section  21 A is moved relative to remainder section  23 A to provide a smooth shaped channel, so that up-hole cable  14  can pull drill string  18  upwardly out of wellbore  19  and through guide  20  through the smoothly shaped channel and down-hole cable  16  can pull drill string  18  downwardly through guide  20  through the smoothly shaped channel for insertion into wellbore  19 . In the raised configuration, tail section  21 A is moved relative to remainder section  23 A to introduce a discontinuity into the shape of the channel (as shown in  FIG. 4B ). This channel-shape discontinuity may prevent drill string  18  from entering into or exiting from guide  20 . When guide  20  is not in use, guide  20  can be in the raised configuration, so that guide  20  does not interfere with drilling operations. In other embodiments, tail section  21 A is removably coupled to remainder section  23 A. In such embodiments, when guide  20  is not in use, tail section  21 A may be removed from remainder section  23 A. 
     In some embodiments, guide  20  has an open-shaped channel (e.g. an upwardly opening channel  28 ) in head section  23 A and an enclosed-shaped channel in tail section  21 A and/or tail end  21 .  FIG. 5A  shows a cross sectional view of head section  23 A of guide  20 . Head section  23 A has a base  22  and two side walls  24 ,  26 , together defining an open-shaped (e.g. upwardly opening) channel  28  for receiving drill string  18 . The open-shaped channel  28  of  FIG. 5A  surrounds only a portion of a transverse cross-section of drill string  18  located in the elongated channel  28  at the head section  23 A.  FIG. 5B  shows a cross sectional view of tail section  21 A of guide  20 . Tail section  21 A has a base  22 , a cover  25  and two side walls  24 ,  26 , together defining an enclosed-shaped channel  28 A—i.e. a channel with one or more walls that surround a transverse cross-sectional perimeter of drill string  18  in tail section  21 A (or at least a portion thereof). Closed channel  28 A prevents drill string  18  from kicking out from guide  20 —e.g. once down-hole end  18 C of drill string  18  approaches the surface of wellbore  19  or otherwise. 
     In some embodiments, cover  25  is hingedly joined to one of two side walls  24 ,  26  or otherwise removably joined to side walls  24 ,  26 , so that cover  25  can pivot relative to side walls  24 ,  26  (or otherwise be removed from guide  20 ). Such configuration may help to feed drill string  18  into guide  20  by providing unobstructed access to open channel  28  (e.g. similar to  FIG. 5A ). For example, when drill string  18  is introduced into guide  20  or when up-hole cable  14  is connected to up-hole end  18 A, cover  25  may be pivoted open or removed to provide an upwardly opening channel  28  and thereby help feed drill string  18  into guide  20 . After drill string  18  is fed into guide  20 , cover  25  may be pivoted closed or connected to side walls  24 ,  25  to provide closed channel  28 A and prevent drill string  18  from kicking out from guide  20 . 
     In some embodiments, guide  20  is equipped with wheels  30  (as shown schematically in  FIGS. 6A and 6B ) to improve its mobility. 
     In some embodiments, apparatus  10  is used with an offshore well (not shown) for pulling a drill string out from a wellbore and lowering the drill string back into the wellbore, with minimal or no disassembly of the drill string. 
       FIGS. 7A-7B  show drill string  18  as it is withdrawn (e.g. pulled upwardly out) from wellbore  19 . To pull drill string  18  up and out from wellbore  19 , up-hole cable  14  is connected to up-hole end  18 A of drill string  18 . Winch  13  pulls up-hole cable  14  and thereby pulls drill string  18  up and out from wellbore  19 , and through channel  28  of guide  20 . 
     When mid-section  18 B of drill string  18  is about to enter or has just entered into open channel  28  of guide  20 , down-hole cable  16  may be connected to a connection location  27  in mid-section  18 B of drill string  18 . In other embodiments, down-hole cable  16  is additionally or alternatively connected to up-hole end  18 A of drill string  18  when up-hole cable  14  is connected to up-hole end  18 A of drill string  18  or when mid-section  18 B of drill string  18  is about to enter or has just entered into open channel  28  of guide  20 . 
     Once drill string  18  is removed from wellbore  19 , it may be repaired and/or the like. In some embodiments, some sections of side walls  24 ,  26  may be removed from guide  20  to improve access to drill string in guide  20  to facilitate repair of drill string  18  in situ in guide  20 . 
       FIGS. 7C-7E  show drill string  18  as it is reinserted (e.g. pulled downwardly back from guide  20 ) into wellbore  19 . To return drill string  18  back into wellbore  19 , down-hole cable  16  is connected to a connection location  27  in mid-section  18 B of drill string  18  (as previously discussed and as shown in  FIG. 7C ). Down-hole cable  16  may be connected to connection location  27  in mid-section  18 B of drill string  18  as drill string  18  is withdrawn from wellbore  19 . In some embodiments, down-hole cable  16  may additionally or alternatively be connected to up-hole end  18 A of drill string  18 . Then, as shown in  FIG. 7C , winch  12  pulls down-hole cable  16  and drill string  18  downwardly through guide  20 . The rigidity of drill string  18  may cause the down-hole end of drill string  18  to descend into wellbore  19 . 
     As the connection location  27  where down-hole cable  16  is attached to mid-section  18 B of drill string  18  approaches winch  12  and/or the upper end  19 A of well bore  19  (as shown in  FIG. 7D ), then gravity may start to pull drill string  18  down into wellbore  19 , since the connection location  27  where down-hole cable  16  is attached to mid-section  18 B may be at or near the center of gravity of drill string  18 . This  FIG. 7D  configuration may be referred to herein as a release configuration. In the release configuration, at least an up-hole portion of drill string  18  is located in guide  20  and at least a down-hole portion of drill string  18  is located in wellbore  19 . In the release configuration, down-hole cable  16  may optionally be disconnected from drill string  18  (as shown in  FIG. 7E ). At some point, it may not be necessary to further pull drill string  18  downwardly out of guide  20 , as gravity will draw drill string  18  downwardly out of guide  20  as drill string  18  extends into wellbore  19 . 
     The release configuration may occur when a length of down-hole cable  16  between second tension mechanism  12  and connection location  27  is a minimum. The release configuration may occur when a force of gravity that tends to pull drill string  18  back into the wellbore  19  becomes greater than frictional forces that tend to hold drill string  18  in guide  20 . The release configuration may occur immediately prior to connection location  27  entering wellbore  19 . 
     In the illustrated embodiment, as shown for example in  FIG. 7E , up-hole cable  14  remains connected to the up-hole end  18 A of drill string  18  and first tension mechanism  13  (via up-hole cable  14 ) may maintain tension on drill string  18  to prevent drill string  18  from free falling into wellbore  19  by gravity. First tension mechanism  13  via up-hole cable  14  may then lower drill string  18  into wellbore  19 . A suitable controller  31  programmed with corresponding control algorithms may be used to control first tension mechanism  13  and to thereby control the rate at which drill string  18  moves downwardly out of guide  20  and into wellbore  19 . An operator may also use first tension mechanism  13  to control the rate at which drill string  18  moves downwardly out of guide  20  and into wellbore  19 . 
     In some embodiments, down-hole cable  16  is disconnected from the mid-section  18 B of drill string  18  as the mid-section  18 B of drill string  18  passes by winch  12 . In other embodiments, down-hole cable  16  remains connected to mid-section  18 B of drill string  18  as drill string  18  descends into wellbore  19 . 
     In some embodiments, down-hole cable  16  is disconnected from up-hole end  18 A of drill string  18  as the mid-section of drill string  18  passes by winch  12 . In other embodiments, down-hole cable  16  remains connected to up-hole end  18 A of drill string  18  as drill string  18  descends into wellbore  19 . 
       FIG. 8  shows a path  30  along which the  FIG. 1  apparatus  10  can guide drill string  18 . With the advent of much deeper wells, correspondingly longer drill strings  18  are often used. Pulling a drill string  18  out from a wellbore  19 , without disassembling the drill string  18 , may require multiple guides  20  to direct the drill string  18  along a particular path. The particular path can be non-linear. For example, the particular path may be spiral in shape to accommodate limited space situations, e.g. offshore wells. Such a path may require bending of the drill string  18 . As such, guides support the drill string  18  and prevent it from being damaged when the drill string  18  is pulled along a curved path. 
     While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are consistent with the broadest interpretation of the specification as a whole.