Abstract:
The method of installing a plurality of casing sections in a well, that includes providing a hanger supporting the casing sections to extend longitudinally in the well, landing the hanger on structure in the well, whereby weight of the casing sections longitudinally compresses the hanger, cementing the casing sections in position in the well, below the hanger, adjusting the hanger to provide for controllable longitudinal shortening of hanger length, thereby removing exertion of casing weight on the hanger, and removing at least part of the hanger away from the well head.

Description:
This invention claims priority from provisional application Ser. No. 61/262,912, filed Nov. 19, 2009. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to methods and apparatus utilized in the completion of hydrocarbon wells, and is particularly directed to methods for reducing the amount of drillrig time and associated expense associated with hanging casing or tubing within a previously installed concentric outer casing. 
     A hydrocarbon well typically employs a plurality of tubular or concentric casing strings extended from the ground surface toward the subsurface hydrocarbon reservoir, with the outermost string having the largest diameter and being the shortest in length, with each inner string having a smaller diameter and a longer length. The outermost pipe, the conductor pipe, is installed as part of site preparation and will be present when the drilling rig moves onto the location. The conductor pipe typically extends from a depth of 20 to 100 feet, and will have a diameter of 4 inches or larger. A starting head/drilling rig is attached to the top of the conductor pipe for connecting to blowout prevention equipment, i.e. BOP and typically a diverter. The casing head typically on the surface casing will usually have an internal shoulder. 
     Once moved on location, the drilling rig drills to the surface/next casing point, which is a predetermined depth set below freshwater bearing zones, or difficult strata such as sloughing clay or gravel zones. Typically, this first casing point extends from a few hundred to a thousand feet below ground surface. Once the first casing point is reached, the surface casing is run into the well, and cemented in place, usually by pumping cement down through the inside of the casing, and continuing to pump until the cement exits the bottom of the casing and circulates up into the annulus between the open hole and the outside of the surface casing. 
     Once cementing operations have been completed on the surface casing and the cement adequately hardened, a blowout preventer (BOP) stack is nippled down and removed from under the rig. The drilling rig is cut off and removed. The surface casing is cut and dressed to land/install a surface casing well head. A BOP is re-installed and attached or nippled up to the casing head. Drilling thereafter continues, until the next casing point is reached, at which time a smaller string of casing is run into the well. Depending upon the integrity of the drilled strata and the anticipated depth of the well, the casing point may extend all of the way to the production zone, and production casing installed. Alternatively, one or more intermediate strings of casing may be concentrically installed within the surface casing. The production casing typically extends from the ground surface to the production zone which may be thousands of feet down. In some cases, the production casing is hung or attached to the bottom of the surface casing, or intermediate casing. 
     The production casing is cemented in place, and after all of the cement has been pumped into place, the casing string is held stationary while the cement sets up. Thereafter, a slip-type casing hanger is placed around the top joint of the production casing, which is typically landed against an internal shoulder of a casing spool or newly attached wellhead. 
     In well completions the casing is preferably hung in tension to reduce the possibility of casing collapse. Such collapse is possible when the top of the casing is locked into position within the wellhead. For example, if the well is subject to thermal stimulation, the casing will expand and place the casing string into buckling, because the top of the casing is locked in place at the wellhead. 
     In most applications, before landing the surface casing, production casing string, or intermediate casing string, it is necessary to remove the blowout preventer stack to land the casing string within a well head spool at wellhead. Removal of the blowout preventer stack is time consuming, and requires a drilling rig to sit idle for hours while the stack is removed, the casing spool or wellhead attached, and the blowout preventers nippled back up. Because of the relatively high expense for rig time, this delay is expensive. In addition, if the well proves to be productive, the wellhead and casing hanging equipment utilized in this procedure are permanently installed in the well. These devices are usually expensive and add substantially to the expense of the well. 
     SUMMARY OF THE INVENTION 
     It is a major object of the invention to provide method and apparatus to meet needs associated with the above described operations. Basically, the method of installing a plurality of casing sections in a well, includes the steps
         a) providing a hanger supporting the casing sections to extend longitudinally in the well,   b) landing the hanger on structure in the well, whereby weight of the casing sections longitudinally compresses the hanger,   c) cementing casing sections in position in the well, below the hanger,   d) adjusting the hanger to provide for controllable longitudinal shortening of hanger length, thereby removing exertion of casing weight on the hanger,   e) and removing at least part of the hanger away from the well head.       

     In one mode, the d) and e) steps may include:
         d) adjusting the hanger to allow controllable expansion of at least a portion of the hanger and longitudinal shortening of hanger length in response to relief of hanger generally sideward compression,   e) and removing at least said expanded portion of the hanger from the well.       

     As will be seen, the hanger may typically have interengaged wedge surfaces that interengage to induce lateral expansion of the hanger portion. Also, such wedge surfaces preferably extend angularly laterally and longitudinally, and define upper and lower interengaged surfaces, as for example with V-shape, and/or converted V-shaped. 
     A further object includes provision for use of a hanger that has an expansible wall portion on which at least one of such wedge surfaces is located. Retention means is typically provided and used for blocking the wall portions against expansion, and is adjustable to allow unblocking of lateral expansion of the hanger. 
     Yet another object includes the step of severing the upper portion of the hanger from a lower mandrel portion of the hanger, to allow removing of the upper portion of the hanger from the well. In this method, lateral expansion of the hanger serves to facilitate removal of the upper portion of the hanger from the well. The mandrel is typically landed prior to such severing, in supporting relation to the wedge surfaces, to allow their relative sliding. 
     Accordingly, the present method and apparatus are directed toward eliminating the need to lock the top of a casing into a wellhead, as well as the need to remove and reinstall a blowout preventer stack as part of the process in landing a string of casing joints within a hydrocarbon well, where the casing is to be cemented in place. Attached to the last joint of the string run into the well is a hanger, embodiments of which are disclosed herein. The hanger is landed onto a load shoulder, or other structure installed within or upon the uppermost joint of the previously installed string of casing outside of the string being installed. 
     The method and apparatus allow the utilization of an alternative assembly, as disclosed, for attachment of the blowout preventer, although the conventional assembly may also be utilized. Installation of the equipment may take place after the hanging of the casing using an embodiment of the disclosed hanger. A diverter spool may be made up directly to the top of the conductor pipe, with the blowout preventer made up to the diverter spool. The hanger and casing may be hung and cemented in place below the mandrel load shoulder of the lower bowl, with cement return taken through the diverter spool. After the cement has hardened, the blowout preventer may be removed and the wellhead installed, with the casing already landed and cemented in place. 
     In contrast to known casing hangers, the hanger utilized in the present method typically and preferably comprises length adjustment means, where the hanger is adjustable between a first length and a second length, and where the first length is longer than the second length. The casing string is suspended from the hanger, and the hanger, in turn, is suspended within the well. Cement is thereafter circulated within the well, whereby the cement forms a sheath around a portion of the casing string, and the casing is typically in tension. After the cement is allowed to reach a predetermined strength, the hanger is adjusted to second length, after which tension on the casing string is released, the top of the casing not being rigidly locked into place. Because the disclosed hanger is landed within the uppermost joint of the previously installed casing strings, there is no need to nipple down the blowout preventer. 
     A further object is to provide axially exerted force acting on the hanger, by one of the following:
         i) axially extending bolts exerting force on axially spaced hanger sections,   ii) axially extending hydraulic ram structure exerting force on axially spaced hanger sections,   iii) axially extending jacking structure exerting force on axially spaced hanger sections.       

     While the above is a description of various embodiments of the present invention, further modifications may be employed without departing from the spirit and scope of the present invention. Thus the scope of the invention should not be limited according to these factors, but according to the claims to be filed in the forthcoming utility application. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an isometric view of a casing hanger; 
         FIG. 2  shows a side view of the casing hanger shown in  FIG. 1 ; 
         FIG. 3  shows a front view of the casing hanger shown in  FIG. 1 ; 
         FIG. 4  shows a top view of the casing hanger shown in  FIG. 1 ; 
         FIG. 5  is a section taken on lines  5 - 5  of  FIG. 2 ; 
         FIG. 6  shows a side view of the hanger supporting well casing; 
         FIG. 7  shows a front view of the  FIG. 6  hanger and casing shown in  FIG. 5 ; 
         FIG. 8  is a section taken on lines  8 - 8  of  FIG. 6 ; 
         FIG. 9  shows an isometric view of an upper wedge member of the hanger; 
         FIG. 10  shows a side view of the wedge member as shown in  FIG. 9 ; and  FIG. 10   a  is a section taken on lines  10   a - 10   a  of  FIG. 10 ; 
         FIG. 11  shows a front view of the wedge member as shown in  FIG. 9 ; 
         FIG. 12  shows a top view of the wedge member as shown in  FIG. 9 ; 
         FIG. 13  shows an isometric view of an intermediate wedge member of the casing hanger; 
         FIG. 14  shows a side view of the intermediate wedge member shown in  FIG. 13 ; 
         FIG. 15  shows a top plan view of the top wedge member of  FIG. 13 ; 
         FIG. 16  shows a top plan view of one section of the two sections wedge member of  FIG. 15 ; 
         FIG. 17  shows an isometric view of the bottom wedge member of the casing hanger; 
         FIG. 18  shows a side view of the bottom wedge member, seen in  FIG. 17 ; 
         FIG. 19  shows a front view of the bottom wedge member shown in  FIG. 17 ; 
         FIG. 20  shows a top view of the bottom wedge member shown in  FIG. 17 ; 
         FIG. 21  is a section taken on lines  21 - 21  of  FIG. 18 ; 
         FIG. 22  shows an isometric view of a mandrel section of the casing hanger; 
         FIG. 23  shows a side view of the mandrel section seen in  FIG. 22 ; 
         FIG. 24  shows a front view of the mandrel section shown in  FIG. 22 ; 
         FIG. 25  shows a top view of the mandrel section shown in  FIG. 22 ; 
         FIG. 26  shows the hanger of  FIG. 6  with the upper section dropped down; 
       FIG.  26 ′ is a schematic view of structure seen in  FIG. 26 ; 
         FIG. 27  shows a front view of the hanger of  FIG. 26 ; 
         FIG. 28  is a section taken on lines  28 - 28  of  FIG. 27 ; 
         FIG. 29  shows a top view of top wedge member seen in  FIG. 27 , and which may be utilized in the  FIG. 26  hanger; 
         FIG. 30  is an isometric view of the  FIGS. 26-18  shortened hanger; 
         FIG. 31  shows a modified form of hanger shortening apparatus; and FIG.  31 ′ shows the  FIG. 31  apparatus in adjusted state; 
         FIG. 32  is a side view of the  FIG. 31  apparatus; 
         FIG. 33  is a section taken on lines  33 - 33  of  FIG. 32 ; 
         FIG. 34  is a top plan view of the  FIG. 32  apparatus; 
         FIGS. 35 ,  36  and  37  correspond to  FIGS. 32. 33  and  34 , but after hanger shortening as in FIG.  31 ′; 
         FIGS. 38-40  correspond to  FIGS. 32-34 , but show another modified hanger apparatus, prior to shortening; 
         FIG. 41  is an isometric view of the  FIGS. 32-34  apparatus; 
       FIG.  41 ′ shows the  FIG. 41  apparatus after shortening; 
         FIGS. 42-44  correspond to  FIGS. 38-40 , showing the hanger after shortening; 
         FIGS. 45-47  correspond to  FIGS. 30-40  and show another modified hanger, prior to shortening; 
         FIG. 48  is an isometric view of the  FIGS. 45-47  hanger apparatus; 
       FIG.  48 ′ shows the  FIG. 48  apparatus after shortening; 
         FIGS. 49-51  correspond to  FIGS. 45-47 , but show the apparatus after shortening; 
         FIGS. 52-56  are an isometric view, side views, a section view, and a top view of a bowl unit that receives the lower sealing element seen in  FIGS. 2 and 3 ; 
         FIGS. 57-61  correspond to  FIGS. 52-56 , but show a modification, and show a sealing element seated at lower bowl; 
         FIG. 62  shows a double hung casing installation; and 
         FIG. 63  shows slidable mandrel sealing. 
     
    
    
     DETAILED DESCRIPTION 
     Referring first to  FIGS. 6 and 26 , they show hanger  99  upper, lower and intermediate members  110 ,  111  and  112  prior to ( FIG. 6 ) and after ( FIG. 26 ) lateral translation or expansion of intermediate member  112  relative to upper and lower members  110  and  111 . Simplified schematic view  26 ′ corresponds to  FIG. 26 . Such lateral translation is facilitated by sliding slippage of upward facing upper V-shaped wedge surfaces  111   a  and  111   b  on member  111 , relative and with respect to downward facing upper V-shaped wedge surfaces  110   a  and  110   b  on  110 ; and simultaneous sliding slippage of downward facing lower inverted V-shaped wedge surfaces  111   c  and  111   d  relative and with respect to upward facing lower inverted V-shaped wedge surfaces  112   c  and  112   d  on  112 . This enables downward bodily displacement of  110  relative to and beneath wall casing  103  flange or shoulder  103   a  previously landed on the top  99   a  of hanger  99 , the casing then connected in position in the well, whereby casing loading on the shortened hanger is relieved. This in turn enables sideward and outward removal of meshing  110  and  111  from beneath member  99 . 
     Note, that member  111  is in two sections,  111   e  and  111   f  held in  FIG. 6  position (prior to lateral displacement) by a fastener device or devices, such as bolts  102  that extend horizontally between the sections  111   e  and  111   f . Upon loosening of those bolts, the downwardly composed weight effects member sliding, as referred to. A further advantage of this V-shaped configuration of sliding surfaces is the maintenance of vertical alignment of the members  110 - 112 , precluding interference with well structure, at the side or sides of the hanger structure. Angularity of the V-shaped member surfaces is typically about 30° relative to horizontal. 
     Centering guides  96  and  97  on  99  and  111  serve to center the hanger in position at the well head. 
     Accordingly, the members  99 ,  110  and  111  are then easily removed, and the mandrel  20  below and supporting member  111  is upwardly removed, whereby the hanger is removed, from support at  106 , leaving the casing  103  projecting upwardly in the top well zone  107 . Support shoulder  106  is typically provided by outer casing in the well. Accordingly, means is provided whereby the hanger is expanded laterally and lengthwise shortened, in response to disconnection of hanger elements, such as bolt  102  and in response to imposed casing weight, facilitating ease of removal of the hanger from the top zone of the well. 
     Referring now to  FIGS. 1-8 , the hanger  99  is generally tubular, and is shown in its first length configuration. It may be adjusted to its second and shortened length by loosening the bolts  102  that clasp together flanges  12   a  on the two sections of  111 , at opposite sides of axes  90 . The intermediate wedge member sections slide laterally oppositely along diagonal upper and lower surfaces as referred to and sections  111   c  and  111   d  move radially outwardly. The casing hanger moves to shortened position. The casing hanger  99  may further comprise the lower supporting mandrel  20  having rubber O-rings  20   a  to seal against casing bore, or outer conductor casing. See bore  150  in  FIGS. 2 and 5 . Mandrel  20  may be left in the well to provide a seal in the annulus between the casing being hung with the casing hanger  99  and the previously installed casing string, in which the casing hanger is suspended. The mandrel is typically bolted to hanger section  112 .  FIGS. 2 and 27  show hanger length dimensions A and B, before and after hanger adjustment, below casing flange  103   a.    
     As shown in the Figures and described, the intermediate section  111 , is of split construction  111   e  and  111   f  which allows the hanger to be taken apart in place in sections, facilitating removal of the hanger from the cemented casing or tubing, and below casing flange  103   a.    
     Referring now to  FIGS. 31-37 , they show an alternative form of the hanger  126  that employs vertical bolts or fasteners  125  rotatable to shorten the hanger length as from a long measurement A (see  FIG. 32 ) to a short measurement B (see  FIG. 35 ). This lowers the casing flange support shoulder  126 ′ on the top of the hanger by amount A-B below the casing flange  103   a , relieving energy or tension in the initially hanger supported casing  103 . Bolts  125  can easily be removed to allow removal of the hanger upper and lower elements  110 ′ and  111 ′ described above. Upper element  110 ′ is spaced above element  111 ′. Bolt adjustment moves bolt flange  110   a ′ toward bolt flange  111   a ′ on  111   a . 
     FIGS.  31  and  31 ′ show the hanger prior to after its axial shortening. 
       FIGS. 38-44  correspond to  FIGS. 31-37 , respectively, and show another alternative form of the hanger  127  and that employs two or more hydraulic rams, instead of adjustable bolts, for shortening hanger  127  length as from long measurement A (see  FIG. 38 ) to a short measurement B (see  FIG. 42 ). As before, this lowers the casing flange support shoulder  127 ′ on the top of the hanger, by amount A-B below the casing flange  103   a , thereby relieving energy or tension in the initially hanger suspended casing  103 . The hydraulic rams include pistons  135  connected to upper hanger element  310 , and projecting downwardly in cylinders  136  connected to lower hanger element  312 . Pressurized fluid in the cylinders at  313  is controllably relieved by valve means  314  to allow element  310  to be lowered, shorten the hanger. Valve means  314 ′ controls fluid pressure input to  336 . FIGS.  41  and  41 ′ show the hanger prior to and after its axial shortening. 
       FIGS. 45-51 , correspond to  FIGS. 38-44  respectively, and show a further alternative form of the hanger  140 , and that employs an hydraulic jack type means, instead of adjustable bolts or multiple hydraulic rams, for shortening the hanger  140  length, as from a long measurement A (see  FIG. 45 ) to a short measurement B (see  FIG. 49 . This lowers the casing flange support shoulder  140 ′ on the top of the hanger, by amount A-B below the casing flange  103   a , relieving energy or tension in the initially hanger suspended casing  103 . The jack means includes a cylindrical piston  145  connected to upper hanger element  140 ′, and projecting downwardly in the cylinder  146  connected to hanger lower element  147 , corresponding to  112 . Pressurized fluid in the cylinder space  148  is controllably relieved by valve means  149  to allow element  140  to be lowered to shorten the hanger allowing upward removal of  140 ′,  146  and  147 . FIGS.  48  and  48 ′ show the hanger prior to and after axial shortening. 
       FIGS. 52-56  show a retrievable lower bowl assembly  270  which is of generally cylindrical configuration to receive the hanger lower sealing element, as shown at  20  in  FIG. 6 , for sealing. An internal seating shoulder appears at  271 . Downwardly tapered bowl surface is shown at  272 . 
       FIGS. 57-61  are like  52 - 56  and show a retrievable lower bowl assembly, at  280 , and which also is generally cylindrical. A modified mandrel  20 ′ is received in the bowl assembly and seats at annular shoulder  282 . Mandrel  20 ′ connects to and is part of the hanger assembly, as described. The bowl assembly is typically welded to well conductor pipe. Other attachment means can be used. 
     Accordingly, the invention provides a retrievable landing system capable of landing casing string weight before or during cement jobs. It enables removal of casing string weight off the landing system which then can be easily removed and re-used 
       FIG. 62  shows a double hung casing installation, including first means at dual vertical levels or locations  150  and  151  at a well head  152 , for supporting larger diameter hung casing  153  at lower location  150 , and for supporting smaller diameter hung casing  154  at upper location  151 . Structure  157  supported on collar  153   a  supports  151 . 
     Each or both of the first means at the locations  150  and  151  may take the form of the devices shown in  FIGS. 1-8 , or  FIGS. 31-37  or  FIGS. 38-43 , or  FIGS. 45-51 . Removable surrounding spools are indicated at  160 - 162 . 
     Second means for controlling releasing energy stored in the double hung casing, or in each of such casings, in response to controlled reduction in casing support, is provided, for example in the adjustments described above in connection with operation of elements in said Figures. 
       FIGS. 62 and 63  also show an annular supporting mandrel  170  extending about the casings, and bodily relatively movable or slidable on and lengthwise of the casing, below the double or single hung casing location. As seen in  FIGS. 62 and 63 , the slidable mandrel carries and is sealed by O-rings  172 , as at  172   a  with the bore  173  of structure  174 , and by O-ring  175  as at  175   a  with the outer surface  176  of casing  153 . That ring is pressurized or deformed for sealing. A landing shoulder for the mandrel bevel is provided at  177 . 
     Accordingly, an additional object includes provision of:
         a) a first means providing a double hung casing installation, at a well head, and characterized by energy storage in supported casing,   b) And second means for controllably releasing energy storage in the double hung casing in response to controlled reduction in casing support, whereby associated equipment maybe retrieved at the well head, saving time and expense.       

     Another object includes provision of adjustable support structure extending under casing head structure or structures, and controllably bodily movable out from under the casing head structure or structures after cementing of casing lower extent or extents in the well, and after energy release, as referred to.