Patent Publication Number: US-2023135913-A1

Title: Non-metallic subsea skid apparatus and methods

Description:
BACKGROUND 
     Field 
     Aspects of the present disclosure relate to non-metallic subsea skid apparatus and associated methods, such as composite subsea valve skid apparatus and methods. 
     Description of the Related Art 
     Subsea skids can be affected by subsea conditions. For example, subsea conditions can corrode the subsea skids, which can involve maintenance and/or reduced lifespans for the subsea skids. The subsea skids can be heavy and can also be difficult to access, such as by diving operations. Furthermore, subsea skids can involve carbon footprints and can become snagged on other subsea components. 
     Therefore, there is a need for subsea skid apparatus and related methods that facilitate increased lifespans, corrosion resistance, reduced weight, anti-snagging capabilities, and reduced carbon footprints. 
     SUMMARY 
     Implementations of the present disclosure relate to non-metallic subsea skid apparatus and associated methods, such as composite subsea valve skid apparatus and methods. 
     In one implementation, a subsea skid includes a plurality of skid tubes, and a plurality of skid joints coupled between the plurality of skid tubes. The plurality of skid tubes and the plurality of skid joints form a frame. The plurality of skid tubes and the plurality of skid joints are each formed of a non-metallic material. 
     In one implementation, a method of forming a subsea skid includes disposing portions of a plurality of skid tubes in legs of a plurality of skid joints to arrange the plurality of skid tubes and the plurality of skid joints as a frame. Each of the plurality of skid joints and the plurality of skid tubes is formed of a non-metallic material. The method includes curing the portions of the plurality of skid tubes to the legs of the plurality of skid joints. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above-recited features of the disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. 
         FIG.  1 A  is a schematic isometric view of a subsea skid, according to one implementation. 
         FIG.  1 B  is an enlarged schematic view of the subsea skid shown in  FIG.  1 A , according to one implementation. 
         FIG.  1 C  is a schematic top cross-sectional view of one of the first set of skid joints shown in  FIG.  1 B , along Section  1 C- 1 C, according to one implementation. 
         FIG.  1 D  is a schematic isometric exploded view of one of the support joints shown in  FIG.  1 A , according to one implementation. 
         FIG.  1 E  is a schematic isometric exploded view of one of the skid joints shown in  FIG.  1 A , according to one implementation. 
         FIG.  2    is a schematic side view of the first side of the subsea skid shown in  FIG.  1 A , according to one implementation. 
         FIG.  3    is a schematic side view of the second side of the subsea skid shown in  FIG.  1 A , according to one implementation. 
         FIG.  4    is a schematic top view of the subsea skid shown in  FIG.  1 A , according to one implementation. 
         FIG.  5    is a schematic isometric view of a tube portion, according to one implementation. 
         FIG.  6    is a schematic isometric view of a valve string fastened to the subsea skid, according to one implementation. 
         FIG.  7    is a schematic block diagram view of a method of forming a subsea skid, according to one implementation. 
       To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one implementation may be beneficially utilized on other implementations without specific recitation. 
     
    
    
     DETAILED DESCRIPTION 
     Aspects of the present disclosure relate to non-metallic subsea skid apparatus and associated methods, such as composite subsea valve skid apparatus and methods. 
       FIG.  1 A  is a schematic isometric view of a subsea skid  100 , according to one implementation. The subsea skid  100  is a valve subsea skid. The subsea skid  100  is non-metallic. The subsea skid  100  includes a plurality of skid tubes  101 - 112  coupled together using a plurality of skid joints  130 - 135 . Each of the skid tubes  101 - 112  and the skid joints  130 - 135  has one or more outer surfaces that have a smooth contour and/or a tapered finish. The subsea skid  100  shown in  FIG.  1 A  includes fifty skid tubes  101 - 112  and twenty-two skid joints  130 - 135 . The subsea skid  100  includes a plurality of padeye plates  141 . Each of the padeye plates  141  is formed in a first set of skid joints  132 . The first set of skid joints  132  include four skid joints  132 . The plurality of padeye plates  141  are lift points for attaching lift devices, such as hoist lines or hooks of cranes, to lift the subsea skid  100 . The skid joints  130 - 135  and the skid tubes  101 - 112  form a frame  150  of the subsea skid  100 . The subsea skid  100  includes a first side  151 , a second side  152 , a third side  153 , and a fourth side  154 . 
     The subsea skid  100  tubes include vertical skid tubes  109 , horizontal skid tubes  101 ,  104 - 107 ,  110 - 112 , and angled skid tubes  102 ,  103 ,  108 . At least some of the angled skid tubes  102  are disposed in a horizontal plane (parallel to the X-Y plane), and at least some of the angled skid tubes  103 ,  108  are disposed in vertical planes (parallel to the Y-Z plane for the angled skid tubes  103  and parallel to the X-Z plane for the angled tubes  108 ). Each of the skid joints  130 - 135  includes a plurality of legs protruding outward from a center of the respective skid joint  130 - 135 . Each leg receives a portion (such as an end portion) of one of the skid tubes  101 - 112 . The plurality of legs includes a number of legs, and the number of legs is within a range of two to five. In one example, the skid joints  130 - 135  include T-joints having three legs. In the implementation shown in  FIG.  1 A , each of the skid joints  130 - 134  includes four legs or five legs. The skid joints  130 - 135  and the skid tubes  101 - 112  are cured together to form the subsea skid  100 . The curing occurs after the portions (such as the end portions) of the skid tubes  101 - 112  are disposed within the respective legs of the skid joints  130 - 135 . 
     The skid joints  130 - 135  include a plurality of support joints  135 . The support joints  135  are valve support joints. The subsea skid  100  shown includes three support joints  135 . The support joints  135  are similar to the skid joints  130 - 134 . The support joints  135  include two legs  136   a ,  136   b . Each of the support joints  135  includes a support flange  137  formed therein for supporting equipment, such as valve equipment. Each support flange  137  includes one or more fastener openings  138  formed therein. Each support joint  135  includes flanges  139   a ,  139   b  extending between the respective legs  136   a ,  136   b  and the support flange  137 . Each support flange  137  is configured to couple to equipment using one or more fasteners extending through the one or more fastener openings  138 . 
     Each of the skid tubes  101 - 112  and the skid joints  130 - 135  is formed of a non-metallic material. The support flanges  137  and the padeye plates  141  are formed of the non-metallic material. In one embodiment, which can be combined with other embodiments, the non-metallic material is polymeric and includes one or more polymers. In one embodiment, which can be combined with other embodiments, the non-metallic material is a composite material. The composite material is a carbon composite, such as a carbon fiber material. In one embodiment, which can be combined with other embodiments, the non-metallic material includes one or more of glass fiber reinforced polymer (GFRP) and/or carbon fiber reinforced polymer (CFRP). Each of the skid tubes  101 - 112  and the skid joints  130 - 135  (such as the legs of the skid joints  130 - 135 ) includes a tube wall thickness T 1  (shown in  FIG.  5   ). The tube wall thickness T 1  is within a range of 8 mm to 12 mm. 
     The skid tubes  101 - 112  and the skid joints  130 - 135  each include one or more tube portions that are formed of the non-metallic material. The skid tubes  101 - 112  each include a single tube portion. The skid joints  130 - 135  each include a number of tube portions that is equal to the number of legs. In one embodiment, which can be combined with other embodiments, the tube portions are formed of filament wound carbon fiber tubes. 
       FIG.  1 B  is an enlarged schematic view of the subsea skid  100  shown in  FIG.  1 A , according to one implementation. Each of the padeye plates  141  is formed on an outer surface of one of the first set of skid joints  132 . Each of the padeye plates  141  includes one or more lift openings  142  formed therein. A shackle, including a shackle body  193  and a shackle pin  194 , is coupled to each of the padeye plates  141 . Each shackle body  193  is configured to attach to one or more lift devices used to lift the subsea skid  100 . 
     Each of the first set of skid joints  132  includes five legs  171 - 175 . An end portion  181 - 185  of each one of the respective skid tubes  103 ,  108 - 111  is disposed in a respective leg  171 - 175  of the respective skid joint  132 . The respective end portion  181 - 185  is disposed in a central opening (e.g., a circular opening) of the respective leg  171 - 175 . 
       FIG.  1 C  is a schematic top cross-sectional view of one of the first set of skid joints  132  shown in  FIG.  1 B , along Section  1 C- 1 C, according to one implementation. A circumferential outer surface of each respective end portion  181 - 185  is cured to a circumferential inner surface of the respective leg  171 - 175 . A circumferential outer surface  186  is cured to a circumferential inner surface  187  of leg  174 . A circumferential outer surface  188  is cured to a circumferential inner surface  189  of leg  175 . 
     Each of the skid tubes  101 - 112  and the skid joints  130 - 135  includes a plurality of sections cured together. Each of the plurality of sections is formed of the non-metallic material. Each section of the plurality of sections includes one or more curved portions and two or more planar flange portions extending relative to the one or more curved portions. 
       FIG.  1 D  is a schematic isometric exploded view of one of the support joints  135  shown in  FIG.  1 A , according to one implementation. The support joint  135  includes a plurality of sections  191 ,  192  (two are shown) cured together to form the support joint  135 . Each section  191 ,  192  includes one or more curved portions  193 - 195  (three are shown) and two or more planar flange portions  196 - 198  (three are shown) extending relative to the one or more curved portions  193 - 195 . Two or more planar surfaces  199   a - 199   d  (four are shown) of the two or more planar flange portions  196 - 198  of the section  192  are interfaced with and cured to two or more planar surfaces  199   a - 199   d  of the two or more planar flange portions  196 - 198  of the section  191 . 
     The skid tubes  101 - 112  can extend partially into respective legs of the skid joints  130 - 135  (as is shown in  FIG.  1 C ) or the skid tubes  101 - 112  can extend through and past respective legs of the skid joints  130 - 135  (as is shown in  FIG.  1 D  for the skid tube  105  extending through and past the curved portions  193 ,  194  of each of the sections  191 ,  192 ). The curved portions  193 ,  194  of the sections  191 ,  192 , when cured together, form the two respective legs  136   a ,  136   b  (shown in  FIG.  1 A ) of the support joint  135 . In the implementation shown in  FIG.  1 D , an intermediate portion of the skid tube  105  is disposed in the two respective legs  136   a ,  136   b  of the support joint  135 , and the intermediate portion is cured to the two respective legs  136   a ,  136   b  of the support joint  135 . The planar flange portions  196 ,  197  of the sections  191 ,  192 , when cured together, form the flanges  139   a ,  139   b  (shown in  FIG.  1 A ) of the support joint  135 . The planar flange portions  198  of the sections  191 ,  192 , when cured together, form the support flange  137  (shown in  FIG.  1 A ) of the support joint  135 . 
       FIG.  1 E  is a schematic isometric exploded view of one of the skid joints  132  shown in  FIG.  1 A , according to one implementation. The skid joint  132  includes a plurality of sections  1001 - 1007  (seven are shown) cured together to form the skid joint  132 . Each section  1001 - 1007  includes one or more curved portions and two or more planar flange portions extending relative to the one or more curved portions. Two or more planar surfaces of the two or more planar flange portions of each section  1001 - 1007  are interfaced with and cured to two or more planar surfaces of the two or more planar flange portions one or more adjacent sections  1001 - 1007 . The curved portions and the planar flange portions of the sections  1001   1007  are cured together to form the legs  171 - 175  shown in  FIG.  1 B . A planar surface  1010  of a planar flange portion  1011  of section  1001  is interfaced with and cured to a planar surface  1012  of a planar flange portion  1013  of section  1002  to form the padeye plate  141  shown in  FIG.  1 B . The sections of the skid joints  130 - 135  (such as the sections  1001 - 1007 ) are formed prior to being cured together to form the respective skid joints  130 - 135 . In one embodiment, which can be combined with other embodiments, the sections of the skid joints  130 - 135  are formed using molding, such as composite molding. Other methods of forming the sections of the skid joints  130 - 135  are contemplated. 
       FIG.  2    is a schematic side view of the first side  151  of the subsea skid  100  shown in  FIG.  1 A , according to one implementation. Each of the skid tubes  103  is disposed in a plane parallel to the Y-Z plane at an oblique angle A 1  relative to an axis parallel to the Z-axis. The oblique angle A 1  is within a range of 30 degrees to 50 degrees, such as 33 degrees. The subsea skid  100  has a length L 1  that is within a range of 450 inches to 500 inches. The frame  150  includes (from the side view of the first side  151 ) a trapezoidal pattern  162 . The frame  150  includes the trapezoidal pattern  162  from a side view of the third side  153 . 
       FIG.  3    is a schematic side view of the second side  152  of the subsea skid  100  shown in  FIG.  1 A , according to one implementation. The subsea skid  100  has a height H 1  that is within a range of 115 inches to 150 inches. The frame  150  includes (from a side view of the third side  153 ) a trapezoidal pattern  163 . The frame  150  includes the trapezoidal pattern  163  from a side view of the fourth side  154 . The support joints  135  extend above central axes of the horizontal skid tubes  101 ,  102 ,  104 - 107 ,  112  by a height H 2  that is within a range of 20 inches to 30 inches. Each of the skid tubes  103  is disposed in a plane parallel to the X-Z plane at an oblique angle A 2  relative to an axis parallel to the Z-axis. The oblique angle A 2  is within a range of 30 degrees to 50 degrees, such as 33 degrees. 
       FIG.  4    is a schematic top view of the subsea skid  100  shown in  FIG.  1 A , according to one implementation. The subsea skid  100  has a width W 1  that is within a range of 250 inches to 275 inches. The frame  150  of the subsea skid  100  includes (from the top view) a rectangular pattern  157  having four sides and four corners, and two trapezoidal patterns  158   a ,  158   b  disposed outwardly of two opposing sides of the rectangular pattern  157 . The padeye plates  141  are formed on four skid joints  132  that are disposed respectively at the four corners of the rectangular pattern  157  Each of the four padeye plates  141  extends inwardly toward a center C 1  of the rectangular pattern  157  from the respective corner of the four corners. Each of the skid tubes  102  is disposed in a plane parallel to the X-Y plane at an oblique angle A 3  relative to an axis parallel to the Y-axis. The oblique angle A 3  is within a range of 30 degrees to 50 degrees, such as 33 degrees. 
       FIG.  5    is a schematic isometric view of a tube portion  500 , according to one implementation. The tube portion  500  can be used as the skid tubes  101 - 112 . The present disclosure contemplates that the tube portion  500  can be used as to form tube portions of the skid joints  130 - 135 , such as to form legs of the skid joints  130 - 135 . The tube portion  500  is a filament wound carbon fiber tube formed of filament wound carbon fiber. The filament wound carbon fiber is wound using a layup of plies, In one embodiment, which can be combined with other embodiments, the layup of plies is wound at an angle within a range of −45 degrees to 45 degrees. In one embodiment, which can be combined with other embodiments, the layup of plies is wound at an angle within a range of −10 degrees to 10 degrees. In one example, which can be combined with other examples, the filament wound carbon fiber includes a flexural modulus that is within a range of 70 GPa to 100 GPa, such as about 80 GPa. 
       FIG.  6    is a schematic isometric view of a valve string  601  fastened to the subsea skid  100 , according to one implementation. The valve string  601  includes a plurality of valves  615 ,  616  coupled to pipes  617 ,  618 ,  619 , such as steel pipes. The valve string  601  includes a plurality of flanges  610  fastened to the support flanges  137  using a plurality of fasteners  620 . 
       FIG.  7    is a schematic block diagram view of a method  700  of forming a subsea skid, according to one implementation. Operation  702  includes disposing portions of a plurality of skid tubes in legs of a plurality of skid joints to arrange the plurality of skid tubes and the plurality of skid joints as a frame. The portions are end portions and/or intermediate portions of the skid tubes. The disposing the portions of the plurality of skid tubes in legs of the plurality of skid joints can include abutting planar surfaces of sections of each skid joint against each other to form the legs of the respective skid joint. Each of the plurality of skid joints and the plurality of skid tubes is formed of a non-metallic material. 
     Operation  704  includes curing the portions of the plurality of skid tubes to the legs of the plurality of skid joints. In one embodiment, which can be combined with other embodiments, the curing includes heating and pressurizing the plurality of skid tubes and the plurality of skid joints in an autoclave. In one embodiment, which can be combined with other embodiments, the plurality of skid tubes and the plurality of skid joints are heated to a cure temperature within a range of 60 degrees Celsius to 120 degrees Celsius. In one embodiment, which can be combined with other embodiments, the curing occurs at an ambient temperature, such as at an offshore site. The ambient temperature is up to 45 degrees Celsius. The present disclosure contemplates that other temperatures, such as temperatures higher than the ambient temperature and the cure temperature, can be used for the curing. The curing can include using a bonding material, which can include resin, to bond the plurality of skid tubes and the plurality of skid joints together. The curing can include curing sections of each respective skid joint together. Other curing operations are contemplated. 
     Operation  706  includes fastening a plurality of flanges of a valve string to a plurality of support flanges of the plurality of skid joints. The present disclosure contemplates that equipment other than valve strings can be fastened to the plurality of support flanges of the plurality of skid joints. 
     Benefits of aspects of the present disclosure (such as the non-metallic material) include lifecycle cost savings of 25%-30% and more, longer operational lifespans for subsea skids, modularity and flexibility in design and application, reduced lead times, anti-snagging and avoiding anchor wire catching, reduced or eliminated corrosion of skids, eliminated need for cathodic protection, reduced maintenance, increased and easier (less obstructions for) access for diver operations and ROV operations, weight reductions of 70% or more for skids, and reduced carbon footprint in manufacturing and operating skids. 
     As an example, using the non-metallic material facilitates reduced weight and eliminated need for cathodic protection that would involve heavy sacrificial anodes. The eliminated need for cathodic protection reduces or eliminates the need for maintenance conducted on the subsea skid  100 . Using the non-metallic material also facilitates the ability to use larger gaps between the skid tubes  101 - 112  (such as larger gaps in the rectangular pattern  157  and the trapezoidal patterns  158   a ,  158   b ) to reduce obstructions for access to components of the subsea skid  100 . As another example, the non-metallic material facilitates stress performance under loading applied as a result of operational conditions, such as water pressure at deep subsea levels and loading resulting from lifting and supporting the subsea skid  100  at the padeye plates  141  to lower the subsea skid  100  to the seafloor. The non-metallic material also facilitates stress performance when an object, such as other subsea equipment, contacts the subsea skid  100 . The non-metallic material, the skid joints, and the skid tubes facilitate modularity and flexibility in design and application of subsea skids. 
     Lifting expenditures are reduced as the lifting forces needed to lift and manipulate the subsea skid  100  are reduced. The lower lifting expenditures facilitate use of smaller offshore vessels. Using the non-metallic material, smooth contours and tapered finishes can be used on outer surfaces of the subsea skid  100  to facilitate reduced wire catching and snagging, such as reduced anchor wire snagging. For example, the contours of the curved portions and the planar flange portions of the skid joints  130 - 135  facilitate reduced protrusions, which facilitates reduced wire catching and snagging. 
     It is contemplated that one or more of the aspects disclosed herein may be combined. Moreover, it is contemplated that one or more of these aspects may include some or all of the aforementioned benefits. As an example, it is contemplated that one or more of the aspects, features, components, and/or properties of the subsea skid  100 , the tube portion  500 , the valve string  601 , and/or the method  700  can be combined. 
     It will be appreciated by those skilled in the art that the preceding embodiments are exemplary and not limiting. It is intended that all modifications, permutations, enhancements, equivalents, and improvements thereto that are apparent to those skilled in the art upon a reading of the specification and a study of the drawings are included within the scope of the disclosure. It is therefore intended that the following appended claims may include all such modifications, permutations, enhancements, equivalents, and improvements. The present disclosure also contemplates that one or more aspects of the embodiments described herein may be substituted in for one or more of the other aspects described. The scope of the disclosure is determined by the claims that follow.