Patent Publication Number: US-11035091-B1

Title: Transportation device for offshore platforms and method for installing the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority from Chinese Patent Application No. 202010145105.1, filed on Mar. 4, 2020. The content of the aforementioned applications, including any intervening amendments thereto, is incorporated herein by reference. 
     TECHNICAL FIELD 
     This application relates to installation equipment for offshore platforms, and more particularly to a transportation device for an offshore platform and a method for installing the same. 
     BACKGROUND OF THE DISCLOSURE 
     Offshore platforms include topside modules and offshore installation frames. Generally, the offshore installation frames are constructed in predetermined area, and the topside modules are transferred to the offshore installation frames through vessels, and then the topside module is installed onto the offshore installation frame. Generally, the float-over installation method is adopted to install large-scale offshore platforms. However, the offshore platform has a large span and low structural stiffness, and is easily affected by vibrations. The offshore platform that is installed by traditional float-over installation method is prone to large structural deformation, and devices of the offshore platform may be damaged due to large vibrations. 
     SUMMARY OF THE DISCLOSURE 
     An object of the present disclosure is to provide a transportation device for an offshore platform, which aims to overcome the problem that offshore platforms which have low structural stiffness are easily damaged during the transportation and installation. 
     To solve above technical problems, the present disclosure adopts the following technical solution. 
     In a first aspect, the present disclosure provides a transportation device for an offshore platform, comprising a vessel and a floating structure which are fixedly connected; wherein the floating structure is placed on a sea surface and is configured to assist the vessel to sail; the floating structure is provided with an adjustment mechanism which is configured to adjust the floating structure to rise and fall relative to the sea surface; and the vessel is configured to load a topside module. 
     In some embodiments, the floating structure comprises a floating body which is connected to the vessel; and the adjustment mechanism is arranged at the floating body. 
     In some embodiments, the floating body is provided with reinforcing bars. 
     In some embodiments, the floating body is a closed case. 
     In some embodiments, the adjustment mechanism has an injection end configured to inject water into the floating body and a drain end configured to drain water out of the floating body. 
     In some embodiments, the floating structure further comprises a fixing part which is configured to fix the floating body to the vessel. 
     In some embodiments, the fixing part comprises a plurality of connecting rods which are connected to each other to form a truss structure; and the truss structure is connected between the floating body and the vessel. 
     In some embodiments, the fixing part comprises one connecting rod which is connected between the floating body and the vessel. 
     In some embodiments, the transportation device comprises an auxiliary support; wherein one end of the auxiliary support is connected to the topside module, and the other end of the auxiliary support is connected to the vessel. 
     In some embodiments, the auxiliary support comprises a first support rod which is arranged in an inclined manner; one end of the first support rod is connected to the topside module, and the other end of the first support rod is connected to the vessel. 
     In some embodiments, the auxiliary support further comprises a second support rod which is connected between the first support rod and the topside module. 
     In some embodiments, a rail is provided on the vessel, and the topside module is provided with skid shoes that slide on the rail; and the skid shoes drive the topside module to slide from land to the vessel along the rail. 
     In some embodiments, the transportation device further comprises a support frame configured to support the topside module; wherein the skid shoes are mounted on the support frame. 
     In a second aspect, the present disclosure provides a method for installing an offshore platform, comprising: 
     1) pre-installing a first installation element on a topside module, and pre-installing a second installation element on an offshore installation frame, wherein the offshore installation frame is provided with an area allowing for entry of a vessel; 
     2) reducing buoyancy of a floating structure through an adjustment mechanism to lower the vessel carrying the floating structure until a deck of the vessel is flush with land; and transferring the topside module to the deck of the vessel; 
     3) when the vessel sails offshore, increasing the buoyancy of the floating structure through the adjustment mechanism; and transferring the topside module near the offshore installation frame through the vessel and the floating structure; 
     4) detaching the floating structure from the vessel; 
     5) driving the vessel carrying the topside module to enter the area allowing for entry of the vessel; and aligning the first installation element and the second installation element; and 
     6) sinking the vessel to mate the first installation element with the second installation element. 
     In some embodiments, the first installation element comprises a leg mating unit (LMU) and a transition structure; the transition structure is connected between the LMU and the topside module; and the LMU is configured to connect with the second installation element; or 
     the first installation element comprises a transition structure, and the second installation element comprises an LMU; one end of the transition structure is connected to a lower end of the topside module, and the LMU is mounted at an upper end of the offshore installation frame and is configured to connect with the other end of transition structure. 
     The transportation device of the present invention has the following beneficial effects. The floating structure is connected to the vessel. When transporting the topside module  40  to the vessel, the buoyancy of the floating structure is reduced by the adjustment mechanism, and the vessel carrying the floating structure falls until the rail on the vessel is flush with the land, so as to transfer the topside module to the vessel. After the topside module is loaded, the vessel sails offshore, and the buoyancy of the floating structure is increased through the adjustment mechanism, and then the floating structure increases the buoyancy of the vessel, so that the floating structure provides sufficient anti-rolling moments beside the vessel, thereby ensuring the vessel to stably sail and reducing the vibration of the topside module caused by the winds and waves during the sailing. As a result, during the transportation, the structure of the topside module is effectively protected, and the potential damage to the topside module is reduced. 
     The method of the present invention has the following beneficial effects. During the installation, the topside module is stably transferred to the offshore installation frame through the vessel and the floating structure, which effectively prevents the topside module from damage during the transportation. The removal of the floating structure from the vessel reduces the space occupied by the vessel, which enables the vessel to move in the limited area after the vessel drives the topside module to enter the area allowing for the entry of the vessel of the offshore installation frame. Then, the vessel carries the first installation element of the topside module to align with the second installation element of the offshore installation frame. This makes the mating accurate, achieving a good installation effect. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will be described with reference to the embodiments and the accompanying drawings, from which the technical solutions of the disclosure will be clearer. Obviously, the accompanying drawings are only a part of embodiments. Other drawings can be obtained without creative effort by those skilled in the art based on the embodiments described herein. 
         FIG. 1  is a schematic diagram of a transportation device for an offshore platform according to an embodiment of the present disclosure, on which a topside module is not loaded. 
         FIG. 2  is a schematic diagram of the transportation device for an offshore platform according to an embodiment of the present disclosure, on which the topside module is loaded. 
         FIG. 3  is a schematic diagram of the transportation device for an offshore platform according to an embodiment of the present disclosure, in which the topside module is being transported to an area for entry of the vessel. 
         FIG. 4  schematically shows the installation of the topside module on the offshore installation station according to an embodiment of the present disclosure. 
         FIG. 5  a schematic diagram of the topside module which is installed to the offshore installation frame according to an embodiment of the present disclosure, in which the topside module is installed. 
         FIG. 6  is an enlarged view of portion A in  FIG. 4 . 
         FIG. 7  is a flowchart of a method for installing the offshore platform according to an embodiment of the present disclosure. 
     
    
    
     In the drawings:  10 , vessel;  11 , rail;  20 , floating structure;  21 , adjustment mechanism;  211 , injection end;  212 , drain end;  22 , floating body;  23 , fixing part;  231 , connecting rod;  30 , auxiliary support;  31 , first support rod;  32 , second support rod;  40 , topside module;  41 , first installation element;  411 , LMU;  412 , transition structure;  42 , support column;  50 , support frame;  60 , skid shoes;  70 , offshore installation frame;  71 , second installation element;  72 , area for entry of the vessel. 
     DETAILED DESCRIPTION OF EMBODIMENTS 
     The present disclosure will be further described as follows with reference to the accompanying drawings and embodiments, from which the objects, technical solutions and advantages of the present disclosure become clear. It should be understood the embodiments described herein are only intended to illustrate the present disclosure, but not to limit the scope of the present disclosure. 
     It should be noted that the terms “fix” or “arrange” should be understood broadly. For example, an element may be directly or indirectly fixed or arranged on another element. In addition, the term “connect” should be understood broadly. For example, two elements may be directly or indirectly connected. The terms “upper”, “lower”, “left”, “right”, etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for ease of description, but not intended to indicate or imply that devices or elements must have a specific orientation or be constructed and operated in a specific orientation. Therefore, this is not intended to limit the scope of the present disclosure, and for those skilled in the art, the specific meanings of above-mentioned terms should be understood based on the specific conditions. The terms “first” and “second” are for ease of description, and cannot be understood as indicating or implying relative importance or the number of technical features. Unless specified, the term “a plurality of” means at least two. 
     The technical solutions of the present disclosure will be described in detail with reference to the accompanying drawings and embodiments. 
     Referring to  FIGS. 1-3 , this embodiment provides a transportation device for an offshore platform, including a vessel  10  and a floating structure  20  which are fixedly connected. The floating structure  20  is placed on a sea surface and is configured to assist the vessel  10  to sail. The floating structure  20  is provided with an adjustment mechanism  21  which is configured to adjust the floating structure  20  to rise and fall relative to the sea surface. The vessel  10  is configured to load a topside module  40 . 
     In this embodiment, the vessel  10  is connected to the floating structure  20 . Before the topside module  40  is loaded onto the vessel  10 , the buoyancy of the floating structure  20  is reduced through the adjustment mechanism  21 , so that the floating structure  20  drives the vessel  10  to sink to a certain depth, so as to allow the vessel  10  to be flush with the land, facilitating the transmission of the topside module  40  onto the deck of the vessel  10 . After the topside module  40  is loaded, the vessel  10  sails offshore, and the buoyancy of the floating structure  20  is increased through the adjustment mechanism  21 , and then the floating structure  20  increases the buoyancy of the vessel  10 , so that the floating structure  20  provides sufficient anti-rolling moments beside the vessel  10 , thereby ensuring the vessel  10  to stably sail and reducing the vibration of the topside module  40  caused by the winds and waves during the sailing. As a result, during the transportation, the structure of the topside module  40  is effectively protected, and the probability of damage to the topside module  40  is reduced. When the installation site is arrived, the floating structure  20  can be detached from the vessel  10 . 
     A plurality of floating bodies  20  can be arranged at the periphery of the vessel  10 , which can effectively ensure that the floating bodies  20  provide sufficient anti-rolling moment during the sailing of the vessel  10 , thereby facilitating the stable sailing of the vessel  10 . The floating bodies  20  may be symmetrically arranged at the periphery of the vessel  10 , or may be arranged based on winds and waves or sea conditions, so as to ensure the stable sailing of the vessel  10 . 
     Universal wheels or other wheels may be arranged on the topside module  40 , so that the topside module  40  is easy to be smoothly moved to the vessel  10 . 
     In some embodiment, as shown in  FIG. 2 , the floating structure  20  includes a floating body  22  connected to the vessel  10 . The adjustment mechanism  21  is arranged at the floating body  22 . Specifically, the floating body  22  is able to synchronously sail with the vessel  10 , and the adjustment mechanism  21  is configured to change the weight of the floating body  22  so as to change the buoyancy of the floating body  22 , so that the floating body  22  assists the vessel  10  to sail. The floating body  22  may be loaded with various objects, such as rocks, iron topside modules or sea water, so that the weight of the object on the floating body  22  is reduced or increased to change the buoyancy of the floating body  22  on the sea. When the installation site is arrived and the floating structure  20  needs to separate from the vessel  10 , the floating structure  20  and the vessel  10  can be disconnected. 
     In some embodiments, the floating body  22  is provided with reinforcing bars. Specifically, the reinforcing bars can effectively improve the structural strength of the floating body  22 , i.e., the probability of damage to the floating body  22  caused by striking of waves is effectively reduced, so that the floating body  22  can effectively assist the vessel  10  to sail. 
     In some embodiments, as shown in  FIG. 2 , the floating body  22  is a closed case. Specifically, when the floating body  22  is a closed case, it is easy to enable the floating body  22  to sail with the vessel  10 . During the sailing, the adjustment mechanism changes the amount of seawater loaded in the floating body  22 , which is easy to use, and has a simple structure and low cost. 
     In some embodiments, as shown in  FIG. 2 , the adjustment mechanism  21  has an injection end  211  which is configured to inject water into the floating body  22  and a drain end  212  which is configured to drain the water out of the floating body  22 . Specifically, when the floating body  22  is a closed case, the amount of water in the floating body  22  can be adjusted in time by using the injection end  211  and the drain end  212 , which is safe and convenient. The injection end  211  can pump seawater into the floating body  22  through an injection pump, and the drain end  212  can pump the seawater out of the floating body  22  through a drain pump. The injection end  211  and the drain end  212  are automatically or manually controlled. 
     In some embodiments, as shown in  FIG. 2 , the floating structure  20  further includes a fixing part  23  which respectively connects with the floating body  22  and the vessel  10 . Specifically, the floating body  22  is fixed to the vessel  10  through the fixing part  23 , which facilitates the mounting of the floating body  22 . In addition, through the fixing part  23 , it is convenient to adjust the angle between the floating body  22  and the vessel  10 . Specifically, the floating body  22  may be perpendicular to the side of the vessel  10 , or an acute angle may be formed between the floating body  22  and the side of the vessel  10 . Due to different angles between the floating body  22  and the vessel  10 , the floating body  22  applies forces of different directions to the vessel  10  through the fixing part  23 . Thus, the direction of the force that the floating body  22  exerts on the vessel  10  can be adjusted by adjusting the mounting angle between the floating body  22  and the vessel  10 , so that the floating body  22  can better assist the vessel  10  to sail. When the floating body  22  needs to separate from the vessel  10  after the installation site is arrived, the fixing part  23  can be removed from the vessel  10 . 
     In some embodiments, as shown in  FIG. 2 , the fixing part  23  includes a plurality of connecting rods  231  which are connected to each other to form a truss structure. The truss structure is connected between the floating body  22  and the vessel  10 . Specifically, the connecting rods are connected to each other to form a truss structure with multiple triangles. Such truss structure has high structural strength and large impact resistance. When the truss structure is connected between the floating body  22  and the vessel  10 , the floating body  22  is capable of withstanding complex sea conditions and impact of waves on the sea, which prevents the floating body  22  from separating from the vessel  10  during the transportation, thereby ensuring the safety of the sailing. 
     In some embodiments, as shown in  FIG. 2 , the fixing part  23  includes a connecting rod  231  which is connected between the floating body  22  and the vessel  10 . Specifically, the fixing part  23  is one connecting rod  231 , which has a simple structure and low cost. Besides, when using one connecting rod, it is convenient to connect the floating body  22  and the vessel  10 , and the angle between the floating body  22  and the vessel  10  is easy to be adjusted, so that the direction of the force that the floating body  22  exerts on the vessel  10  is easy to be adjusted. 
     In some embodiments, as shown in  FIG. 3 , the transportation device further includes auxiliary supports  30 . One end of the auxiliary support  30  is connected to the topside module  40 , and the other end of the auxiliary support  30  is connected to the vessel  10 . Specifically, through the auxiliary supports  30 , the topside module  40  is stably transported on the sea. After the topside module  40  is transported to a predetermined area, the auxiliary supports  30  are detached from the topside module  40 , facilitating subsequent installation and positioning of the topside module  40 . The auxiliary supports  30  may be symmetrically arranged at the periphery of the topside module  40 , or may be arranged based on winds and waves or sea conditions, so as to ensure that the topside module is stably arranged on the vessel  10 . 
     In some embodiments, as shown in  FIG. 3 , the auxiliary supports include a plurality of first support rods  31  which are arranged in an inclined manner. One end of the first support rod  31  is connected to the topside module  40 , and the other end of the first support rod  31  is connected to the vessel  10 . Specifically, the first support rods  31  are arranged in an inclined manner. One end of the first support rod  31  abuts against the side of the topside module  40 , and the other end of the first support rod  31  abuts against the deck of the vessel  10 , so that a triangular support structure is formed by the topside module  40 , the deck of the vessel  10  and the first support rod  31 , which can stably support the topside module  40 . This effectively prevents the topside module  40  from moving relative to the vessel  10  during the transportation, thereby protecting the topside module  40 . The first support rod  31  may be connected to a middle of the topside module  40 , so that the topside module  40  is subject to a more even force during the supporting, leading to a good support effect. 
     In some embodiments, as shown in  FIG. 3 , the auxiliary support  30  further includes a second support rod  32  which is connected between the first support rod  31  and the topside module  40 . Specifically, the second support rod  32  is connected between the first support rod  31  and the side of the topside module  40 , so that a triangular support structure is formed by the first support rod  31 , the side of the topside module  40  and the second support rod  32 . In this way, the topside module  40  is supported more stably, preventing the topside module  40  from moving relative to the vessel  10  during the transportation. The second support rod  32  may be horizontally connected between the first support rod  31  and the topside module  40 , which allows the triangle support structure formed by the first support rod  31 , the side of the topside module  40  and the second support rod  32  to be more stable, realizing a better support effect. 
     In some embodiments, as shown in  FIGS. 1 and 3 , the vessel  10  is provided with a rail  11 , and the topside module  40  is provided with skid shoes  60 . The skid shoes  60  are configured to slide on the rail  11 , so that the topside module  40  is carried to slide from the land to the vessel  10  along the rail  11 . Specifically, when transporting the topside module  40  to the vessel  10 , the buoyancy of the floating structure  20  is reduced by the adjustment mechanism  21 , and the floating structure  20  drives the vessel  10  to fall until the rail  11  on the vessel  10  is flush with the land. This allows the skid shoes  60  on the topside module  40  to be easily placed on the rail  11  and smoothly move on the rail  11 , so that the topside module  40  is transferred to the vessel  10 . In this way, the topside module  40  is smoothly transferred to the vessel  10 , preventing the topside module  40  from suffering structural damages when it is transferred to the vessel  10 . After the topside module  40  is transferred to the vessel  10 , the skid shoes  60  are locked on the rail  11 , so as to prevent the skid shoes from sliding on the rail  11  during the transportation of the topside module  40 , i.e., to avoid the sliding of the topside module  40  during the transportation. 
     In some embodiments, as shown in  FIGS. 2-4 , the transportation device further includes a support frame  50  which is configured to support the topside module  40 . The skid shoes are mounted on the support frame  50 . Specifically, the support frame  50  is located at the middle of the lower part of the topside module  40 , so as to ensure that the center of gravity of the topside module  40  is stable during the transportation, which allows the topside module  40  to suffer a uniform force during the transportation. In this way, the topside module  40  with a larger span is prevented from structural deformations during the transportation, thus effectively protecting the topside module  40 . 
     As shown in  FIGS. 2, 4, 5 and 7 , this embodiment provides a method for installing the offshore platform, comprising the following steps. 
     S 1 ) A first installation element  41  is pre-installed at the topside module  40 , and a second installation element  71  is pre-installed at an offshore installation frame  70 , where the offshore installation frame  70  is provided with an area  72  for the entry of the vessel  10 . 
     S 2 ) The adjustment mechanism  21  reduces the buoyancy of the floating structure  20 , so that the floating structure  20  drives the vessel  10  to fall until the deck of the vessel is flush with the land, and then the topside module  40  is transferred onto the deck of the vessel  10 . 
     S 3 ) when the vessel  10  sails offshore, the buoyancy of the floating structure  20  is increased through the adjustment mechanism  21 , and the topside module  40  is transferred to the offshore installation frame  70  by the vessel  10  and the floating structure  20 . 
     S 4 ) The floating structure  20  is removed from the vessel  10 . 
     S 5 ) The vessel  10  drives the topside module  40  to enter the area  72  allowing for entry of a vessel, and the first installation element  41  aligns with the second installation element  71 . 
     S 6 ) The vessel  10  is sunk to mate the first installation element  41  with the second installation element  71 . 
     During the installation, the topside module  40  is stably transferred to the offshore installation frame  70  through the vessel  10  and the floating structure  20 , which effectively prevents the topside module  40  from damage during the transportation. The removal of the floating structure  20  from the vessel  10  reduces the space occupied by the vessel  10 , which enables the vessel  10  to move in the limited area  72  after the vessel  10  drives the topside module  40  to enter area  72  of the offshore installation frame  70 . Then, the vessel carries the first installation element  41  of the topside module  40  to align with the second installation element  71  of the offshore installation frame  70 . This makes the mating accurate, achieving a good installation effect. 
     Multiple groups of the first installation element  41  and the second installation element  71  may be provided to improve the connection between the topside module  40  and the offshore installation frame  70 . 
     In some embodiments, as shown in  FIGS. 4-6 , the first installation element  41  includes a leg mating unit (LMU)  411  and a transition structure  412 . The transition structure  412  is connected between the LMU  411  and the topside module  40 , and the LMU  411  is configured to connect the second installation element  71  which is a support such as a steel tube. Specifically, after the offshore installation frame  70  is installed in the target sea area in advance, actual distances of the second installation elements  71  on the offshore installation frame  70  are measured, and the first installation elements  41  are installed on the topside module  40  on the land according to the measured data. This eliminates the adverse impact of the construction errors of the second installation elements  71  on the mating of the first installation elements  41  and the second installation elements  71 . Thus, when constructing the second installation elements  71  on the offshore installation frame  70 , the construction error of the second installation elements  71  can be appropriately increased, so that the construction process of the offshore installation frame  70  can be greatly simplified and the construction difficulty of the offshore installation frame  70  is reduced. The first installation element  41  mates with the second installation element  71  by the LMU  411  at the end of the first installation element  41 . A transition structure  412  is provided between the topside module  40  and LMU  411 , and center lines of two ends of the transition structure  412  are offset, so that the construction error of the LMU  411  can be offset by the transition structure  412 , which effectively improves the range for mating the LMU  411  and the second installation element  412 . In this way, the requirement for position accuracy of the LMU  411  can be lowered, so as to reduce the difficulty of the construction. 
     The transition structure  412  may be a tapered object which is hollow, and center lines of openings at two ends of the tapered object are offset. The transition structure  412  may be a tubular object, and center lines of openings at two ends of the tubular object are offset. 
     A support column  42  is arranged between the topside module  40  and the transition structure  412  to support the topside module  40 . The LMU is located at the lowermost end of the support column  42 , and is configured to mate with the second installation element  71  on the offshore installation frame  70 . 
     In some embodiments, the first installation element  41  includes the transition structure, and the second installation element  71  includes the LMU. One end of the transition structure is connected to a lower end of the topside module  40 , and the LMU is arranged on the upper end of the offshore installation frame  70  and is connected to the other end of the transition structure. Specifically, when the LMU is arranged on the offshore installation frame  70 , the topside module  40  mates with the LMU through the transition structure of the first installation element  41  which is a support such as a steel pipe. The mounting process is as follows. The LMUs are mounted on the upper end of the offshore installation frame  70 , and position data of the LMUs on the offshore installation frame  70  is measured. Based on the measured position data, the transition structures are added onto the topside module  40  on the land, and positions of the transition structures are adjusted on the topside module  40 . As a result, requirements for the precision of positions of the LMU and the transition structure are reduced, thereby reducing the difficulty of construction. 
     When installing the topside module  40  on the offshore installation frame  70 , a buffer sandbox may be arranged on the offshore installation frame  70 , so as to reduce strong collisions between the vessel  10  and the offshore installation frame  70 . 
     The above are only a part of embodiments of the present disclosure, and are not intended to limit the scope of the present disclosure. Various modifications and changes of these embodiments can be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall fall within the scope of the appended claims.