Flow module placement between a subsea tree and a tubing hanger spool

BACKGROUND OF THE INVENTION

p-00021. Field of the Invention

p-0003This invention relates in general to subsea production apparatuses and, in particular, to an improved flow module placement between a subsea tree and a tubing hanger spool.

p-00042. Brief Description of Related Art

p-0005A conventional subsea wellhead assembly includes a wellhead housing that supports one or more casing hangers located at upper ends of strings of casing extending into the well. A tubing hanger spool or “THS” is landed on the wellhead assembly. A production tree or “tree” is landed on the THS for controlling the production of well fluids. The tree usually carries a choke and valves to control the flow of well fluids and sensors to monitor the flow of well fluids.

p-0006The subsea tree will control the flow of hydrocarbons out of the wellhead, and direct the hydrocarbons to associated equipment, such as manifolds, flowlines, and the like for further operation. Subsea trees may have a flow module, such as a choke bridge module, manufactured as an integral component of the subsea tree and used to control fluid flow out from the tree to external components. Generally, these flow modules are installed along with the subsea tree, but positioned within the tree so that the flow module may be retrieved without having to retrieve the full tree. Portions of the tree, such as flow meters, or chokes that control the flow of hydrocarbons through the outboard flowlines, may wear and fatigue at rates faster than the remaining portions of the subsea tree. Using a flow module containing these components puts more of the retrievable portions of the tree on a recoverable module that allows you to retrieve those portions for repair without disturbing the well completion and associated barrier valves.

p-0007In some vertical tree installations, the subsea trees sit on top of a tubing hanger spool. An outboard flowline then runs from the flow module on the subsea tree to a tubing hanger spool flowline. The tubing hanger spool flowline then runs to external equipment such as a manifold or a facility. This outboard flowline from the flow module is generally quite long and must wind through the subsea tree in order to connect with the tubing hanger spool flowline. As a result, there is a significant pressure drop through the outboard flowline from the flow module. In addition, the longer outboard flowline from the flow module leads to a greater heat loss from the well fluid into the surrounding environment. This can lead to an increase in the viscosity of the well fluid. An increased well fluid viscosity necessitates additional work input to move the fluid through the outboard flowline from the flow module. Furthermore, the length of the outboard flowline from the flow module increases the total area from which leaks can form; thus the longer outboard flowline from the flow module increases the likelihood of leak development. The length of the outboard flowline from the flow module may also cause an increase in the cost of production. This results from both the increase in the amount of material needed to construct the line and the increased labor cost to construct the lengthy outboard flowline from the flow module. Thus, there is a need for an improved flow module placement between a subsea tree and a tubing hanger spool that overcomes these problems.

SUMMARY OF THE INVENTION

p-0008These and other problems are generally solved or circumvented, and technical advantages are generally achieved, by preferred embodiments of the present invention that provide an improved flow module placement between a subsea tree and a tubing hanger spool, and a method for the same.

p-0009In accordance with an embodiment of the present invention, a subsea production assembly is disclosed. The subsea production assembly includes a wellhead having an axis, and a tubing hanger spool disposed on the wellhead axially above the wellhead so that production fluid may flow from the wellhead through the tubing hanger spool. A tubing hanger spool frame mounts to and extends laterally from the tubing hanger spool. A downstream flowline having an upward facing hub is supported by the tubing hanger spool frame. The assembly includes a subsea tree disposed on the tubing hanger spool axially above the tubing hanger spool so that production fluid may flow from the tubing hanger spool through the tree. The tree has a tree frame mounted to and extending laterally from the subsea tree. An upstream flowline is supported by the tree frame and connected to the tree, the upstream flowline having an upward facing hub. The assembly includes a flow module having downward facing flowlines that couple to the hubs, such that flow from the tree passes in a flow path from the upstream flowline through the flow module and the downstream flowline. The weight of the flow module is distributed between the frame of the tubing hanger spool and the frame of the subsea tree.

p-0010In accordance with another embodiment of the present invention, another subsea production assembly is disclosed. The subsea production assembly includes a wellhead having an axis, and a tubing hanger spool disposed on the wellhead axially above the wellhead so that production fluid may flow from the wellhead through the tubing hanger spool. A tubing hanger spool frame mounts to and extends laterally from the tubing hanger spool. A downstream flowline having an upward facing hub is supported by the tubing hanger spool frame, the upward facing hub secured to the tubing hanger spool frame. A subsea tree is disposed on the tubing hanger spool axially above the tubing hanger spool so that production fluid may flow from the tubing hanger spool through the tree. A tree frame mounts to and extends laterally from the subsea tree. An upstream flowline is supported by the tree frame and connects to the tree, the upstream flowline having an upward facing hub secured to the tree frame. The assembly includes a choke bridge module having downward facing flowlines that couple to the hubs, such that flow from the tree passes in a flow path from the upstream flowline through the choke bridge module and the downstream flowline. The weight of the choke bridge module is distributed between the frame of the tubing hanger spool and the frame of the subsea tree. The hub of the downstream flowline is at a lower elevation than the hub of the upstream flowline. The tree frame includes a hub supporting portion that supports the hub of the upstream flowline that is at a higher elevation than, but not directly above, the tubing hanger spool frame. The tubing hanger spool frame includes a hub supporting portion that supports the hub of the downstream flowline and is at a lower elevation than, but not directly below, the tree frame. Any weight transferred to the upward facing hubs by the choke bridge module is further transferred to the tubing hanger spool frame and the subsea tree frame.

p-0011In accordance with yet another embodiment of the present invention, another subsea production assembly is disclosed. The subsea production assembly includes a wellhead having an axis, and a tubing hanger spool disposed on the wellhead axially above the wellhead so that production fluid may flow from the wellhead through the tubing hanger spool. A tubing hanger spool frame mounts to and extends laterally from the tubing hanger spool. A downstream flowline having an horizontally facing hub is supported by the tubing hanger spool frame, the horizontally facing hub secured to the tubing hanger spool frame. The assembly includes a subsea tree disposed on the tubing hanger spool axially above the tubing hanger spool so that production fluid may flow from the tubing hanger spool through the tree. A tree frame mounts to and extends laterally from the subsea tree. An upstream flowline is supported by the tree frame and connects to the tree, the upstream flowline having an horizontally facing hub secured to the tree frame. The downstream flowline horizontally facing hub and the upstream flowline horizontally facing hub are on a same side of and face horizontally away from the tree. The assembly includes a choke bridge module having downward facing flowlines with horizontal terminations that couple to the hubs, such that flow from the tree passes in a flow path from the upstream flowline through the choke bridge and the downstream flowline. The weight of the choke bridge module is distributed between the frame of the tubing hanger spool and the frame of the subsea tree. The hub of the downstream flowline is at a lower elevation than the hub of the upstream flowline. The tree frame includes a hub supporting portion that supports the hub of the upstream flowline that is at a higher elevation than, but not directly above, the tubing hanger spool frame. The tubing hanger spool frame includes a hub supporting portion that supports the hub of the downstream flowline and is at a lower elevation than, but not directly below, the tree frame. Any weight transferred to the horizontally facing hubs by the choke bridge module is further transferred to the tubing hanger spool frame and the subsea tree frame.

p-0012In accordance with still another embodiment of the present invention, a method for assembling a subsea production assembly is disclosed. The method begins by landing and setting a tubing hanger spool on a subsea wellhead, the tubing hanger spool including a tubing hanger spool flowline having a tubing hanger spool hub at a first location. The method then runs, lands, and sets a subsea tree on the tubing hanger spool, the subsea tree including a subsea tree flowline having a subsea tree hub located proximate to the first location. The method then runs, lands, and sets a flow module on the subsea tree and the tubing hanger spool, such that the weight of the flow module is partially supported by the subsea tree and partially supported by the tubing hanger spool.

p-0013An advantage of a preferred embodiment is a shorter flow path from the flow module to external production devices. This leads to a reduction in the pressure drop across the system, and a reduction in the amount of heat lost through the outboard flowlines. In addition, the shorter flowline provides fewer opportunities for leaks to occur. Still further, the disclosed embodiments allow for production of the subsea production assembly at a reduced cost. This arises as a result of the significant decrease in the amount of material needed to connect the flow module to the external production devices, and a decrease in the man-hours needed to construct the tree and flow module.

BRIEF DESCRIPTION OF THE DRAWINGS

p-0014So that the manner in which the features, advantages and objects of the invention, as well as others which will become apparent, are attained, and can be understood in more detail, more particular description of the invention briefly summarized above may be had by reference to the embodiments thereof which are illustrated in the appended drawings that form a part of this specification. It is to be noted, however, that the drawings illustrate only a preferred embodiment of the invention and are therefore not to be considered limiting of its scope as the invention may admit to other equally effective embodiments.

p-0015<figref idrefs="DRAWINGS">FIG. 1</figref> is a schematic representation of an embodiment of the present invention.

p-0016<figref idrefs="DRAWINGS">FIG. 2</figref> is a schematic top view representation of the embodiment of <figref idrefs="DRAWINGS">FIG. 1</figref>.

p-0017<figref idrefs="DRAWINGS">FIG. 3</figref> is a schematic representation of an alternative embodiment of the present invention.

p-0018<figref idrefs="DRAWINGS">FIG. 4</figref> is a schematic top view representation of the embodiment of <figref idrefs="DRAWINGS">FIG. 3</figref>.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

p-0019The present invention will now be described more fully hereinafter with reference to the accompanying drawings which illustrate embodiments of the invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout, and the prime notation, if used, indicates similar elements in alternative embodiments.

p-0020In the following discussion, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be obvious to those skilled in the art that the present invention may be practiced without such specific details. Additionally, for the most part, details concerning rig operation, well drilling, downhole well completion, and the like have been omitted inasmuch as such details are not considered necessary to obtain a complete understanding of the present invention, and are considered to be within the skills of persons skilled in the relevant art.

p-0021Referring to <figref idrefs="DRAWINGS">FIG. 1</figref>, a subsea production system <b>11</b> includes a subsea wellhead <b>13</b>, a tubing hanger spool <b>15</b>, a subsea tree <b>17</b>, and a flow module <b>19</b>. Subsea wellhead <b>13</b> is disposed within a wellbore located at a sea floor. Tubing hanger spool <b>15</b> is positioned on subsea wellhead <b>13</b> and is coupled to subsea wellhead <b>13</b> such that a tubing hanger (not shown) and an associated tubing string (not shown) may be suspended from tubing hanger spool <b>15</b>. The tubing string may run down into the wellbore to a production zone to serve as a production flowline for hydrocarbons produced from the subsea strata.

p-0022Tubing hanger spool <b>15</b> may include a tubing hanger spool frame <b>35</b> supporting tubing hanger spool <b>15</b> and a tubing hanger spool flowline <b>31</b>, so named due to its proximity to tubing hanger spool <b>15</b>. Tubing hanger spool flowline <b>31</b> may couple to additional flowlines <b>49</b> that in turn couple to subsea manifolds, facilities (not shown), or the like. An opposite end of tubing hanger spool flowline <b>31</b> may terminate at an upward facing hub <b>33</b> proximate to an exterior of tubing hanger spool frame <b>35</b>. Frame <b>35</b> is supported by tubing hanger spool <b>15</b> and extends laterally from tubing hanger spool <b>15</b>. A person skilled in the art will understand that upward facing hub <b>33</b> may comprise a male or female piping connection of any suitable variety to receive an outboard flowline <b>39</b> of flow module <b>19</b>.

p-0023Subsea tree <b>17</b> lands on and secures to tubing hanger spool <b>15</b> such that hydrocarbons produced from the wellbore may flow from tubing hanger spool <b>15</b> into the flowlines of subsea tree <b>17</b>. Subsea tree <b>17</b> may include a series of valves <b>21</b> that may operate to direct or shut off the flow of fluid through subsea production system <b>11</b>. Subsea tree <b>17</b> includes a tree frame <b>23</b>, shown schematically in <figref idrefs="DRAWINGS">FIG. 1</figref>. Tree frame <b>23</b> is supported by and extends laterally from subsea tree <b>17</b>. Subsea tree <b>17</b> also includes an inboard flowline <b>25</b>. Inboard flowline <b>25</b> may extend from valves <b>21</b> to a point on tree frame <b>23</b> proximate to an exterior of subsea tree <b>17</b>. Outboard flowline <b>25</b> may terminate in an upward facing hub <b>27</b>. Upward facing hub <b>27</b> may comprise a male or female piping connection adapted to receive an inboard flowline <b>29</b> of flow module <b>19</b>. Preferably, upward facing hub <b>33</b> and upward facing hub <b>27</b> may be located on the same exterior side of subsea production system <b>11</b>. Upward facing hub <b>27</b> is located a higher elevation than upward facing hub <b>33</b> is this embodiment. In other embodiments, upward facing hub <b>27</b> may be at a lower elevation than upward facing hub <b>33</b> or at the same elevation as upward facing hub <b>33</b>.

p-0024Flow module <b>19</b> may land on upward facing hub <b>27</b> and upward facing hub <b>33</b> such that inboard flowline <b>29</b> of flow module <b>19</b> may couple to upward facing hub <b>27</b> and an outboard flowline <b>39</b> of flow module <b>19</b> may couple to upward facing hub <b>33</b>. Flow module <b>19</b> may couple to both tree frame <b>23</b> and tubing hanger spool frame <b>35</b> such that a portion of the weight of flow module <b>19</b> may be supported by tree frame <b>23</b>, and a portion of the weight of flow module <b>19</b> may be supported by tubing hanger spool frame <b>35</b>.

p-0025During subsea assembly, tubing hanger spool <b>15</b> along with tubing hanger spool frame <b>35</b> and tubing hanger spool flowline <b>31</b>, may be run down in a conventional manner, landed, and set on wellhead <b>13</b>. Similarly, subsea tree <b>17</b> and valves <b>21</b> along with tree frame <b>23</b> and inboard flowline <b>25</b> may be run in a conventional manner, landed, and set on tubing hanger spool <b>15</b>. Preferably, upward facing hub <b>33</b> and upward facing hub <b>27</b> may be in proximity to one another. Flow module <b>19</b> may then be run to subsea production system <b>11</b> in a separate trip. Inboard flowline <b>29</b> of flow module <b>19</b> may be connected to upward facing hub <b>27</b>, and outboard flowline <b>39</b> of flow module <b>19</b> may be connected to upward facing hub <b>33</b>. Thus, increased proximity of upward facing hub <b>27</b> and upward facing hub <b>33</b> may reduce the length of the inboard and outboard flowlines <b>29</b>, <b>39</b> of flow module <b>19</b>.

p-0026Referring to <figref idrefs="DRAWINGS">FIG. 2</figref>, wellhead <b>13</b>, tubing hanger spool <b>15</b>, and subsea tree <b>17</b> are all coaxial with an axis <b>12</b> of wellhead <b>13</b>. Tree frame <b>23</b> is positioned axially over tubing hanger spool frame <b>35</b>. Flow module <b>19</b> may be run to the subsea location and positioned to land partially on tree frame <b>23</b> and partially on tubing hanger spool frame <b>35</b> as shown. Preferably, tree frame <b>23</b> may include a frame portion <b>41</b> extending beyond an edge <b>43</b> of tubing hanger spool frame <b>35</b>. Frame portion <b>41</b> may be in the same plane as tree frame <b>23</b>. Similarly, tubing hanger spool frame <b>35</b> may include a frame portion <b>45</b> extending beyond an edge <b>47</b> of tree frame <b>23</b>. Frame portion <b>45</b> may be in the same plane as tubing hanger spool frame <b>35</b>. Preferably, frame portion <b>41</b> of tree frame <b>23</b> may extend from tree frame <b>23</b> in a plane parallel to frame portion <b>45</b> of tubing hanger spool frame <b>35</b>. Frame portion <b>41</b> may be axially above, but may not be directly over frame portion <b>45</b>. In this manner, a portion of flow module <b>19</b> may extend below tree frame <b>23</b> to land on tubing hanger spool frame <b>35</b>. Flow module <b>19</b> may secure to both tree frame <b>23</b> and tubing hanger spool frame <b>35</b> at frame portion <b>41</b> and frame portion <b>45</b>, respectively. Thus, flow module <b>19</b> is supported by both tree frame <b>23</b> and tubing hanger spool frame <b>35</b>. A person skilled in the art will understand that tree frame <b>23</b> and tubing hanger spool frame <b>35</b> may be formed of any suitable material. For example, both tree frame <b>23</b> and tubing hanger spool frame <b>35</b> may be constructed of steel beams, plates, or the like.

p-0027As shown in <figref idrefs="DRAWINGS">FIG. 2</figref>, upward facing hub <b>27</b> of inboard flowline <b>25</b> may terminate on frame portion <b>41</b> of tree frame <b>23</b>. Upward facing hub <b>27</b> may be positioned so that inboard flowline <b>29</b> of flow module <b>19</b> may stab into upward facing hub <b>27</b> during landing of flow module <b>19</b>. Similarly, upward facing hub <b>33</b> of tubing hanger spool flowline <b>31</b> may terminate on frame portion <b>45</b> of tubing hanger spool frame <b>35</b>. Upward facing hub <b>33</b> may be positioned so that outboard flowline <b>39</b> of flow module <b>19</b> may stab into upward facing hub <b>33</b> during landing of flow module <b>19</b>. By configuring the position of flow module <b>19</b> as illustrated herein, a significant reduction in the length of the combined outboard flowline <b>39</b> from flow module <b>19</b> and tubing hanger spool flowline <b>31</b> to a terminal of additional flowlines <b>49</b> for connection to external production devices, such as a manifold or other subsea device, is accomplished. This provides a significant advantage over prior art designs that necessitated that the outboard flowline <b>39</b> must wind through subsea tree <b>17</b> before connecting to tubing hanger spool flowline <b>31</b>.

p-0028Subsea production system <b>11</b> of <figref idrefs="DRAWINGS">FIG. 1</figref> may include horizontally facing hubs <b>34</b>, <b>28</b> in place of upwardly facing hubs <b>33</b> and <b>27</b>, respectively, as shown in <figref idrefs="DRAWINGS">FIG. 3</figref>. As illustrated in <figref idrefs="DRAWINGS">FIG. 3</figref>, horizontally facing hub <b>34</b> may be located at an end of tubing hanger spool flowline <b>31</b> and be adapted to receive outboard flowline <b>39</b>. A person skilled in the art will understand that horizontally facing hub <b>34</b> may comprise a male or female piping connection of any suitable variety to receive outboard flowline <b>39</b> of flow module <b>19</b>. Preferably, tubing hanger spool flowline <b>31</b> will terminate horizontally on tubing hanger spool frame <b>35</b> so that the terminus of tubing hanger spool flowline <b>31</b> faces outward away from tubing hanger spool <b>15</b>. Horizontally facing hub <b>28</b> may comprise a male or female piping connection adapted to receive inboard flowline <b>29</b> of flow module <b>19</b>. Preferably, inboard flowline <b>25</b> will terminate horizontally on tree frame <b>23</b> so that the terminus of inboard flowline <b>25</b> faces outward away from subsea tree <b>17</b>. In addition, horizontally facing hub <b>34</b> and horizontally facing hub <b>28</b> may be located on the same exterior side of subsea production system <b>11</b>. As shown, horizontally facing hub <b>28</b> is located a higher elevation than horizontally facing hub <b>34</b> is this embodiment. A person skilled in the art will understand that horizontally facing hub <b>28</b> may be located at the same elevation as horizontally facing hub <b>34</b> or at a lower elevation than horizontally facing hub <b>34</b>. In the illustrated embodiment, outboard flowline <b>39</b> and inboard flowline <b>29</b> will have horizontal terminations so that ends proximate to horizontally facing hubs <b>34</b>, <b>28</b> may be coupled to horizontally facing hubs <b>34</b>, <b>28</b> to allow for fluid flow between inboard flowline <b>25</b> and inboard flowline <b>29</b>, and outboard flowline <b>39</b> and tubing hanger spool flowline <b>31</b>. Preferably, horizontally facing hubs <b>34</b>, <b>28</b> face the same horizontal direction and the terminations of outboard and inboard flowlines <b>39</b>, <b>29</b> of flow module <b>19</b> face in the same horizontal direction, but opposite that of horizontally facing hubs <b>34</b>, <b>28</b> to allow flowlines <b>39</b>, <b>29</b> to stab into hubs <b>34</b>, <b>28</b>.

p-0029As shown in <figref idrefs="DRAWINGS">FIG. 4</figref>, horizontally facing hub <b>28</b> of inboard flowline <b>25</b> may terminate on frame portion <b>41</b> of tree frame <b>23</b>. Horizontally facing hub <b>28</b> may be positioned so that inboard flowline <b>29</b> of flow module <b>19</b> may stab into horizontally facing hub <b>28</b> during landing of flow module <b>19</b>. Similarly, horizontally facing hub <b>34</b> of tubing hanger spool flowline <b>31</b> may terminate on frame portion <b>45</b> of tubing hanger spool frame <b>35</b>. Horizontally facing hub <b>34</b> may be positioned so that outboard flowline <b>39</b> of flow module <b>19</b> may stab into horizontally facing hub <b>34</b> during landing of flow module <b>19</b>. This may be accomplished in part by running flow module <b>19</b> to a subsea location proximate to subsea production system <b>11</b>. Preferably, ends of outboard flowline <b>39</b> and inboard flowline <b>29</b> are proximate to horizontally facing hub <b>34</b> and horizontally facing hub <b>28</b>, respectively. Flow module <b>19</b> may then be shifted horizontally to stab ends of outboard flowline <b>39</b> and inboard flowline <b>29</b> into horizontally facing hubs <b>34</b>, <b>28</b>, respectively. In so doing, a portion of the weight of flow module <b>19</b> will be transferred to both frame portion <b>45</b> and frame portion <b>41</b>. As shown in <figref idrefs="DRAWINGS">FIG. 4</figref>, horizontal shift assistance mechanisms (HSAMs) <b>51</b>, <b>53</b> may be secured to frame portion <b>41</b> and frame portion <b>45</b>, respectively. HSAMs <b>51</b>, <b>53</b> may comprise hydraulic cylinders, mechanical slide screws, or the like. HSAMs <b>51</b>, <b>53</b> will couple to flow module <b>19</b> in a manner that allows HSAMs <b>51</b>, <b>53</b> to exert a horizontal force that may shift flow module <b>19</b> horizontally to make up the flow connection between outboard flowline <b>39</b>, and horizontally facing hub <b>34</b>, and inboard flowline and horizontally facing hub <b>28</b>. By configuring the position of flow module <b>19</b> as illustrated herein, a significant reduction in the length of the combined outboard flowline <b>39</b> from flow module <b>19</b> and tubing hanger spool flowline <b>31</b> to a terminal of additional flowlines <b>49</b> for connection to external production devices, such as a manifold or other subsea device, is accomplished. This provides a significant advantage over prior art designs that necessitated that the outboard flowline <b>39</b> must wind through subsea tree <b>17</b> before connecting to tubing hanger spool flowline <b>31</b>.

p-0030Accordingly, the disclosed embodiments provide numerous advantages. For example, the disclosed embodiments, provide a shorter flow path from the flow module to external production devices. This leads to a reduction in the pressure drop across the system, and a reduction in the amount of heat lost through the outboard flowlines. In addition, the shorter flowlines provide fewer opportunities for leaks to occur. Still further, the disclosed embodiments allow for production of the subsea production assembly at a reduced cost. This arises as a result of the significant decrease in the amount of material needed to connect the flow module to the external production devices.

p-0031It is understood that the present invention may take many forms and embodiments. Accordingly, several variations may be made in the foregoing without departing from the spirit or scope of the invention. Having thus described the present invention by reference to certain of its preferred embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered obvious and desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.