Patent Publication Number: US-10309182-B2

Title: Annular blowout preventer apparatus

Description:
BACKGROUND 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the presently described embodiments. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present embodiments. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     Drilling and production operations for the recovery of offshore deposits of crude oil and natural gas are taking place in deeper and deeper waters. Drilling and production operations in deeper waters are typically carried out from floating vessels rather than from stationary platforms resting on the ocean floor and commonly used in shallow water. According to conventional procedures, a vessel is dynamically stationed, or moored, above a well site on the ocean floor. After a wellhead has been established, a blowout preventer (“BOP”) stack including one or more BOPs is mounted on the wellhead to control the pressure in the wellhead. 
     Typical BOPs are used as a large specialized valve or similar mechanical device that seal, control, and monitor oil and gas wells. The two most common categories of BOPs are rain BOPs and annular BOPs. BOP stacks frequently utilize both types of BOPs, typically with at least one annular BOP stacked above several rain BOPs. The annular unit or units allow for sealing off an annulus between a tubular in the BOP bore (e.g., drill pipe) or on an open hole. The rain units in rain BOPs allow for shearing drill pipe in the case of shear rams, sealing off around drill pipe in the case of pipe rains, and sealing the BOP bore in the case of blind rams. Typically, a BOP stack may be secured to a wellhead and may provide a safe means for sealing the well in the event of a system failure. 
       FIG. 1  shows a prior art annular BOP  100 . Annular BOP  100  comprises a vertical bore  102  extending through a housing  104  and disposed about a longitudinal axis  106 . A packing element  108  is disposed within the annular BOP  100  about the longitudinal axis  106 . The packing element  108  includes an annular elastomeric body  110  and a plurality of inserts  112 . The inserts  112  are distributed radially about the longitudinal axis  106 . The packing element  108  includes a bore  114  concentric with the vertical bore  102  of the annular BOP  100 . 
     The annular BOP  100  is actuated by pumping a fluid into a close chamber  116  to apply pressure to a piston  118 , thereby moving the piston  118  upward. As the piston  118  moves upward, the piston translates force to the packing element  108 . The force translated to the packing element  108  from the piston  118  is directed upward toward an inner surface  120  of the annular BOP  100  and inward toward the longitudinal axis  106  of the annular BOP  100 . 
     Because the packing element  108  is retained against the inner surface  120  of the annular BOP  100 , the packing element  108  does not displace upward from the force translated by the piston  118 . Rather, the packing element  108  displaces inward from the translated force, which compresses the packing element  108  toward the longitudinal axis  106  of the annular BOP  100 . In the event a drill pipe is located within the annular BOP  100 , with sufficient radial compression, the packing element  108  will seal about the drill pipe into a closed position. In the event a drill pipe is not present, the packing element  108 , with sufficient radial compression, will completely seal the bore  102 . 
     The annular BOP  100  goes through an analogous reverse movement when fluid is pumped into an open chamber  122 . The fluid translates downward force to the piston  118 , such that the piston allows the packing element to radially expand to an open position. The annular BOP  100  can be cycled between the open and closed positions as necessary. 
     When run into the closed position, the annular BOP  100  seals off only on the pressure below the annular BOP  100  by creating a sealing point around the elastomeric body  110  of the packing element  108 . Because of the geometry of the annular BOP  100  and its packing element  108  as well as the distribution of inserts  112  about the packing element  108 , the annular BOP  100  is not able to seal off pressure from above the annular BOP  100 . That is, pressure from above the annular BOP  100  can access the elastomeric body  110  of the packing element  108 , thereby causing it to extrude. To overcome this problem, operators may include a plurality of annular BOPs in a single BOP stack to ensure sealing above and below the BOP stack. However, inclusion of additional annular BOPs, including additional housings, packing elements, pistons, etc., adds undesirable height to the BOP and is costly. 
     Accordingly, an annular BOP capable of sealing off pressure from above and below the annular BOP is desirable. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       For a more detailed description of the embodiments, reference will now be made to the following accompanying drawings: 
         FIG. 1  shows a partial cross-sectional elevational view of a prior art annular blowout preventer; 
         FIG. 2  shows a side elevation view of a subsea blowout preventer stack; 
         FIG. 3  shows another side elevation view of the subsea blowout preventer stack of  FIG. 2 ; 
         FIG. 4  shows a partial cross-sectional elevation view of an annular blowout preventer in an open position, in accordance with one or more embodiments; 
         FIG. 5  shows a partial cross-sectional elevation view of the annular blowout preventer of  FIG. 4  in a closed position, in accordance with one or more embodiments; 
         FIG. 6  shows a partial cross-sectional elevation view of an annular blowout preventer in an open position, in accordance with one or more embodiments; 
         FIG. 7  shows a partial cross-sectional elevation view of the annular blowout preventer of  FIG. 6  in a closed position, in accordance with one or more embodiments; 
         FIG. 8  shows a partial cross-sectional elevation view of an annular blowout preventer in an open position, in accordance with one or more embodiments; and 
         FIG. 9  shows a partial cross-sectional elevation view of the annular blowout preventer of  FIG. 8  in a closed position, in accordance with one or more embodiments. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIGS. 2 and 3  provide two views of a subsea BOP stack shown generally at  200 . Various hydraulic lines, framework and control apparatuses for operating the BOP stack  200  are not shown for purposes of clarity. The stack  200  includes four rain-type BOPs  202 ,  204 ,  206  and  208  including various types of ram assemblies configured to close in on and central bore of the BOP stack  200 . An annular BOP  210 , a connector  212 , a second annular BOP  214  and a flex joint  216  are arrayed above the ram-type BOPs  202 - 208 . One or both of annular BOPs  210  and  214  can be located on the BOP stack, as shown. Alternatively, one or both of the annular BOPs  210  and  214  may be located on a lower marine riser package (“LMRP”) positioned above and in fluid communication with the BOP stack  100 . When using an annular BOP according to the present disclosure, the second annular BOP  214  can be eliminated from the BOP stack. A riser adapter  218  is positioned at the top of the stack  200  for connection to a LMRP (not shown). A wellhead connector  220  is located at the bottom of the stack  200  for connection to a high pressure wellhead housing below (not shown). In general, the number and kind of BOPs in a stack, as well as the order in which they are arrayed in the stack, may vary depending on the needs of the end user. 
       FIG. 4  shows a partial cross-sectional elevation view of an annular BOP  400  in an open position, in accordance with one or more embodiments. The annular BOP  400  could be included in a subsea BOP stack, such as BOP stack  200  illustrated in  FIGS. 2 and 3 . The annular BOP  400  comprises a housing  402  including an upper or first housing  404  and a lower or second housing  406 . The housing  402  includes a vertical bore  408  extending therethrough and disposed about a longitudinal axis  410 . An upper or first packing element  412  is disposed within the housing  402  about the longitudinal axis  410 . The upper packing element  412  includes an annular elastomeric body  414  and a plurality of inserts  416 . The inserts  416  are distributed radially about the longitudinal axis  410 . The upper packing element  412  includes a bore  418  concentric with the vertical bore  408  of the annular BOP  400 . 
     The housing  402  further includes a lower or second packing element  420  disposed about the longitudinal axis  410 . An annular wear plate  430  is located between the upper and lower packing elements  412  and  420 . The lower packing element  420  includes an annular elastomeric body  422  and a plurality of inserts  424 . The inserts  424  are distributed radially about the longitudinal axis  410 . The lower packing element  420  includes a bore  426  concentric with the vertical bore  408  of the annular BOP  400  and of a similar diameter to upper packer element bore  418 . 
     The upper and lower inserts  416  and  424  can comprise any material or materials suitable for use in an annular blowout preventer, such as metal and/or metal alloys. The elastomeric bodies  414  and  422  can comprise any elastomeric material or materials. The annular wear plate  430  can comprise any material or materials suitable for the upper and lower inserts  416  and  424 , such as metal and/or metal alloys. In the illustrated embodiment, packing elements  412  and  420  comprise hemispherical geometries. However, other geometries are envisioned, as will be discussed further below. 
     The annular BOP  400  upper and lower packing elements  412  and  420  are actuated by pumping a fluid into a close chamber (not shown) to apply pressure to a piston  428 , thereby moving the piston  428  upward. The piston  428  has a complimentary hemispherical geometry to that of the lower packing element  420 . As the piston  428  moves upward, the piston  428  translates force directly to the lower packing element  420  and indirectly to annular wear plate  430  and upper packing element  412 . The force translated to the lower packing element  420 , annular wear plate  430 , and upper packing element  412  from the piston  428  is directed upward toward an inner surface  432  of the annular BOP  400  housing  402 , and inward toward the longitudinal axis  410  of the annular BOP  400 . 
     Because the upper packing element  412  is retained against the inner surface  432  of the annular BOP  400  housing  402 , the upper packing element  412 , annular wear plate  430 , and lower packing element  420  do not displace upward from the force translated by the piston  428 . Rather, the upper and lower packing elements  412  and  420  push off annular wear plate  430  and displace inward from the translated force, which compresses the upper and lower packing elements  412  and  420  toward the longitudinal axis  410  of the annular BOP  400 . Accordingly, in one or more embodiments, the annular BOP  400  may be configured to seal off a well, including sealing off pressure from above and below the annular BOP  400 . Specifically, the annular BOP  400 , as shown in  FIG. 4 , can be configured into a closed position to seal off the well without the presence of a pipe or other downhole equipment disposed within the annular BOP  400 , i.e., sealing an open hole. In the event a drill pipe (as shown in  FIG. 5 ) is located within the annular BOP  400 , with sufficient radial compression, the upper and lower packing elements  412  and  420  will seal about the drill pipe into a closed position. 
       FIG. 5  shows a partial cross-sectional elevation view of the annular BOP  400  of  FIG. 4  in the closed position, in accordance with one or more embodiments. In particular, the piston  428  in  FIG. 5  has moved upward as discussed above. In doing so, the piston  428  has displaced upper and lower packing elements  412  and  420  toward the longitudinal axis  410  of the annular BOP  400 , thereby allowing for bi-directional sealing functionality. That is, inclusion of upper and lower packing elements  412  and  420  provides for sealing pressure from above and below the annular BOP  400 . In particular, upper packing element  412  creates a sealing point and seals pressure from below the annular BOP  400 . The lower packing element  420  creates another seal point and seals pressure from above the annular BOP  400 . Accordingly, the upper and lower packing elements  412  and  420  will seal about a drill pipe  434  into a closed position. As a result, fewer annular BOPs may be required in a BOP stack, thereby reducing the overall height of the stack and saving costs. 
     In order to transition the annular BOP  400  from the closed position shown in  FIG. 5  back to the open position shown in  FIG. 4 , fluid is pumped through an open chamber (not shown) to reverse the process. The fluid translates downward force to the piston  428 , such that the piston allows the upper and lower packing elements  412  and  420  to radially expand to the open position. The annular BOP  400  can be cycled between the open and closed positions as necessary. 
       FIG. 6  shows a partial cross-sectional elevation view of an annular blowout preventer  600  in an open position, in accordance with one or more embodiments. The annular BOP  600  could be included in a subsea BOP stack, such as BOP stack  200  illustrated in  FIGS. 2 and 3 . The annular BOP  600  comprises a housing  602  including an upper housing  604  and a lower housing  606 . The housing  602  includes a vertical bore  608  extending therethrough and disposed about a longitudinal axis  610 . An upper packing element  612  is disposed within the housing  602  about the longitudinal axis  610 . The upper packing element  612  includes an annular elastomeric body  614  and a plurality of inserts  616 . The inserts  616  are distributed radially about the longitudinal axis  610 . The upper packing element  612  includes a bore  618  concentric with the vertical bore  608  of the annular BOP  600 . 
     The housing  602  further includes a lower packing element  620  disposed about the longitudinal axis  610 . An annular wear plate  630  is located between the upper and lower packing elements  612  and  620 . The lower packing element  620  includes an annular elastomeric body  622  and a plurality of inserts  624 . The inserts  624  are distributed radially about the longitudinal axis  610 . The lower packing element  620  includes a bore  626  concentric with the vertical bore  608  of the annular BOP  600  and of a similar diameter to upper packer element bore  618 . 
     The upper and lower plurality of inserts  616  and  624  can comprise any material or materials, such as metal and/or metal alloys. The elastomeric bodies  614  and  622  can comprise any elastomeric material or materials. The annular wear plate  630  can comprise any material or materials, such as metal and/or metal alloys. In the illustrated embodiment, packing elements  612  and  620  comprise conical geometries. However, other geometries are envisioned, as discussed above. 
     The annular BOP  600  upper and lower packing elements  612  and  620  are actuated by pumping a fluid into a close chamber (not shown) to apply pressure to a piston  628 , thereby moving the piston  628  upward. The piston  628  has a complimentary conical geometry to that of the lower packing element  620 . As the piston  628  moves upward, the piston  628  translates force directly to the lower packing element  620  and indirectly to annular wear plate  630  and upper packing element  612 . The force translated to the lower packing element  620 , annular wear plate  630 , and upper packing element  612  from the piston  628  is directed upward toward an inner surface  632  of the annular BOP  600  housing  602 , and inward toward the longitudinal axis  610  of the annular BOP  600 . 
     Because the upper packing element  612  is retained against the inner surface  632  of the annular BOP  600  housing  602 , the upper packing element  612 , annular wear plate  630 , and lower packing element  620  do not displace upward from the force translated by the piston  628 . Rather, the upper and lower packing elements  612  and  620  push off annular wear plate  630  and displace inward from the translated force, which compresses the upper and lower packing elements  612  and  620  toward the longitudinal axis  610  of the annular BOP  600 . As a result, the annular BOP  600  can be configured to a closed position to seal off a well without the presence of a pipe or other downhole equipment disposed within the annular BOP  600 , i.e., sealing an open hole. In the event a drill pipe (as shown in  FIG. 7 ) is located within the annular BOP  600 , with sufficient radial compression, the upper and lower packing elements  612  and  620  will seal about the drill pipe into a closed position. 
       FIG. 7  shows a partial cross-sectional elevation view of the annular blowout preventer of  FIG. 6  in a closed position, in accordance with one or more embodiments. In particular, the piston  628  in  FIG. 7  has moved upward as discussed above. In doing so, the piston  628  has displaced upper and lower packing elements  612  and  620  toward the longitudinal axis  610  of the annular BOP  600 , thereby allowing for bi-directional sealing functionality. That is, inclusion of upper and lower packing elements  612  and  620  provides for sealing pressure from above and below the annular BOP  600 . In particular, upper packing element  612  creates a seal point and seals pressure from below the annular BOP  600 . The lower packing element  620  creates another seal point and seals pressure from above the annular BOP  600 . As shown in  FIG. 7 , a drill pipe  634  can be located within the annular BOP  600 . Accordingly, with sufficient radial compression, the upper and lower packing elements  612  and  620  will seal about the drill pipe  634  into a closed position. As a result, fewer annular BOPs may be required in a BOP stack, thereby reducing the overall height of the stack and saving costs. 
     In order to transition the annular BOP  600  from the closed position shown in  FIG. 7  back to the open position shown in  FIG. 6 , fluid is pumped through an open chamber (not shown) to reverse the process. The fluid translates downward force to the piston  628 , such that the piston allows the upper and lower packing elements  612  and  620  to radially expand to the open position. The annular BOP  600  can be cycled between the open and closed positions as necessary. 
       FIG. 8  shows a partial cross-sectional elevation view of an annular blowout preventer  800  in an open position, in accordance with one or more embodiments. The annular BOP  800  could be included in a subsea BOP stack, such as BOP stack  200  illustrated in  FIGS. 2 and 3 . The annular BOP  800  comprises a housing  802  including an upper housing  804  and a lower housing  806 . The housing  802  includes a vertical bore  808  extending therethrough and disposed about a longitudinal axis  810 . A packing element  812  is disposed within the housing  802  about the longitudinal axis  810 . The packing element  812  includes an annular elastomeric body  814 , an upper plurality of inserts  816   a , and a lower plurality of inserts  816   b . The inserts  816   a  and  816   b  are distributed radially about the longitudinal axis  810 . The packing element  812  includes a bore  818  concentric with the vertical bore  808  of the annular BOP  800 . 
     The upper and lower plurality of inserts  816   a  and  816   b  can comprise any material or materials, such as metal and/or metal alloys. The elastomeric body  814  can comprise any elastomeric material or materials. In the illustrated embodiment, packing element  812  comprises a dual conical geometry. However, other geometries are envisioned, as discussed above. 
     The annular BOP  800  packing element  812  is actuated by pumping a fluid into a close chamber (not shown) to apply pressure to a piston  828 , thereby moving the piston  828  upward. The piston  828  has a complimentary conical geometry to that of the lower plurality of inserts  816   b . As the piston  828  moves upward, the piston  828  translates force directly to the packing element  812 . The force translated to the packing element  812  from the piston  828  is directed upward toward an inner surface  832  of the annular BOP  800  housing  802 , and inward toward the longitudinal axis  810  of the annular BOP  800 . 
     Because the packing element  812  is retained against the inner surface  832  of the annular BOP  800  housing  802 , the packing element  812  does not displace upward from the force translated by the piston  828 . Rather, the packing element  812  is compressed as a result of the contact between the upper plurality of inserts  816   a  and the inner surface  832  and between the lower plurality of inserts  816   b  and the piston  828 . As a result, the packing element  812  is compressed toward the longitudinal axis  810  of the annular BOP  800 . For example, the packing element  812  may be configured to a closed position to seal off a well without the presence of a pipe or other downhole equipment disposed within the annular BOP  800 , i.e., sealing an open hole. In the event a drill pipe (as shown in  FIG. 9 ) is located within the annular BOP  800 , with sufficient radial compression, the packing element  812  will seal about the drill pipe into a closed position. 
       FIG. 9  shows a partial cross-sectional elevation view of the annular blowout preventer of  FIG. 8  in a closed position, in accordance with one or more embodiments. In particular, the piston  828  in  FIG. 9  has moved upward as discussed above. In doing so, the piston  828  has displaced the packing element  812  toward the longitudinal axis  810  of the annular BOP  800 , thereby allowing for bi-directional sealing functionality. That is, inclusion of the upper and lower plurality of inserts  816   a  and  816   b  provides for multiple sealing points and seals pressure from above and below the annular BOP  800 . When a drill pipe  834  is located within the annular BOP  800 , the packing element  812  will seal about the drill pipe  834  into a closed position with sufficient radial compression. 
     In order to transition the annular BOP  800  from the closed position shown in  FIG. 9  back to the open position shown in  FIG. 8 , fluid is pumped through an open chamber (not shown) to reverse the process. The fluid translates downward force to the piston  828 , such that the piston allows the packing element  812  to radially expand to the open position. The annular BOP  800  can be cycled between the open and closed positions as necessary. 
     In embodiments, an annular BOP comprising upper and lower packing elements (such as annular BOPs depicted in  FIGS. 4-7 ) or a single packing element (such as annular BOP depicted in  FIGS. 8 and 9 ) can be moved between an open position and a closed position, with or without a downhole component disposed in the annular BOP, using a piston located above the packing element(s). To move to an open position, the piston is actuated to move downward, compressing the packing element(s) against an inner surface of the BOP housing on the lower portion of the BOP housing. To move to a closed position, the piston is displaced upward to move the packing element(s) toward a longitudinal axis of the BOP. With respect to  FIGS. 4-9 , one or more pistons may be used to move the packing element(s) and thus, configure the BOP into an open position or a closed position. 
     In addition to the embodiments described above, many examples of specific combinations are within the scope of the disclosure, some of which are detailed below: 
     Example 1 
     An annular blowout preventer (“BOP”) apparatus, comprising:
         a housing comprising a bore extending therethrough;   a first packing element located in the housing;   a second packing element located in the housing and spaced axially from the first packing element; and   a piston configured to move the first and second packing elements radially with respect to the bore.       

     Example 2 
     The apparatus of Example 1, the first packing element comprising an annular elastomeric body and inserts embedded within the elastomeric body. 
     Example 3 
     The apparatus of Example 2, wherein the first packing element inserts and first packing element elastomeric body comprise different materials. 
     Example 4 
     The apparatus of Example 1, the second packing element comprising an annular elastomeric body and inserts embedded within the elastomeric body. 
     Example 5 
     The apparatus of Example 4, wherein the second packing element inserts and second packing element elastomeric body comprise different materials. 
     Example 6 
     The apparatus of Example 1, wherein the first and second packing elements are movable from an open position in which the first and second packing elements are radially withdrawn from the bore to a closed position in which the first and lower packing elements are radially moved into the bore. 
     Example 7 
     The apparatus of Example 6, wherein the first and second packing elements are configured to seal the bore above and below the housing in the closed position. 
     Example 8 
     The apparatus of Example 6, wherein the first and second packing elements are configured to seal about a device located within the bore in the closed position. 
     Example 9 
     The apparatus of Example 1, further comprising an annular plate located axially between the first and second packing elements. 
     Example 10 
     The apparatus of Example 1, wherein the piston is locatable in a piston recess located in the housing. 
     Example 11 
     The apparatus of Example 1, wherein the piston and the lower packing element have complimentary geometries. 
     Example 12 
     The apparatus of Example 1, wherein an inner surface of the housing and the upper packing element have complimentary geometries. 
     Example 13 
     The apparatus of Example 1, wherein the piston is configured to move the first and second packing elements simultaneously. 
     Example 14 
     An annular blowout preventer (“BOP”) apparatus, comprising:
         a housing comprising a bore extending therethrough;   a packing element located in the housing and movable from an open position radially withdrawn from the bore to a closed position radially within the bore;   a piston configured to move the packing element between the open and closed positions, and   wherein the packing element is configured to form a first seal and a second seal in the bore in the closed position.       

     Example 15 
     The apparatus of Example 14, wherein the packing element comprises an annular elastomeric body and inserts embedded within the elastomeric body. 
     Example 16 
     The apparatus of Example 14, wherein the packing element is configured to seal about a device located within the vertical bore in the closed position. 
     Example 17 
     The apparatus of Example 14, wherein the piston is locatable in a piston recess located in the housing. 
     Example 18 
     The apparatus of Example 14, wherein an inner surface of the housing and an upper surface of the packing element have complimentary geometries. 
     Example 19 
     The apparatus of Example 14, wherein the piston and a lower surface of the packing element have complimentary geometries. 
     Example 20 
     The apparatus of Example 14, wherein the packing element inserts and packing element elastomeric body comprise different materials. 
     This discussion is directed to various embodiments of the present disclosure. The drawing figure is not necessarily to scale. Certain features of the embodiments may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. It is to be fully recognized that the different teachings of the embodiments discussed may be employed separately or in any suitable combination to produce desired results. In addition, one skilled in the art will understand that the description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to intimate that the scope of the disclosure, including the claims, is limited to that embodiment. 
     Certain terms are used throughout this description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but are the same structure or function. The drawing figure is not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness. 
     In this discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” 
     Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present disclosure. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. 
     Although the present invention has been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims.