Suction pile cofferdam

Abstract

A cofferdam is disclosed that includes an open frame structure having double walls defining a hollow space within each double wall, with each double wall having an open bottom end and a closed top end. Each of the double walls are configured to act as suction piles allowing liquid to be removed from the space within each double wall to thereby induce negative pressure when the cofferdam is installed in a sub-sea configuration. Each of the double walls may include a plurality of partitions respectively defining a plurality of suction piles, the suction piles fluidically coupled by a manifold that may allow liquid to be removed from the suction pile to thereby drive the cofferdam structure into the subsea surface due to the induced negative pressure. A further embodiment cofferdam structure includes an open frame structure and one or more suction piles attached to the open frame structure.

What is claimed is: 
     
         1 . A cofferdam, comprising:
 an first open frame structure enclosing a first open region and having first structure double walls defining a hollow space within each first structure double wall, each first structure double wall having an open bottom end and a closed top;   a second open frame structure sized for disposition within the first open region of the first open frame structure, the second open frame structure enclosing a second open region and having second structure double walls defining a hollow space within each second structure double wall, each second structure double wall having an open bottom end and a closed top end;   wherein the first structure double walls and second structure double walls are configured to allow liquid to be removed, via one or more fluidic conduits, from the hollow space within each double wall to thereby generate a vacuum within each double wall that induces a negative pressure that generates a force on the closed top ends of the double walls when the first open frame structure is submerged and the second open frame structure is submerged.   
     
     
         2 . The cofferdam of  claim 1 , wherein the first open frame structure is configured to be driven in to a sea floor by the force on the closed top ends of the first structure double walls and the second open frame structure is configured to be driven into the seafloor a distance below a bottom edge of the first open frame structure by the force on the closed top ends of the second structure double walls. 
     
     
         3 . The cofferdam of  claim 1 , wherein the first open frame structure further comprises an extended structure attached proximate to an upper edge of the first structure double walls and that extends in a direction external to the first open region. 
     
     
         4 . The cofferdam of  claim 3 , wherein the extended structure is configured as a mud mat. 
     
     
         5 . The cofferdam of  claim 1 , wherein the first open frame structure further comprises a lip attached proximate to a lower edge of the first structure double walls and that extends in a direction internal to the first open region. 
     
     
         6 . The cofferdam of  claim 1 , wherein the second open frame structure further comprises an extended structure attached proximate to an upper edge of the second structure double walls and that extends in a direction external to the second open region. 
     
     
         7 . The cofferdam of  claim 6 , wherein the extended structure of the second open frame structure is configured to engage the lip of the first open frame structure when the second open frame structure is driven into the seafloor below a bottom edge of the first open frame structure. 
     
     
         8 . The cofferdam of  claim 1 , wherein the first open frame structure and the second open frame structure are configured to be installed independently of each other on a sea floor. 
     
     
         9 . The cofferdam of  claim 1 , wherein at least one of the first open frame structure and the second open frame structure comprises multiple sections. 
     
     
         10 . The cofferdam of  claim 9 , wherein each section of the multiple sections is configured to be installed independently on a sea floor. 
     
     
         11 . The cofferdam of  claim 9 , wherein each section of the multiple sections is configured to be connected to an adjacent section via at least one of a tongue-and-groove attachment, dovetailing, mortise, a hinge or a mortise-and-tenon joint. 
     
     
         12 . The cofferdam of  claim 1 , further comprising:
 a third open frame structure sized for disposition within the second open region of the second open frame structure, the third open frame structure enclosing a third open region and having third structure double walls defining a hollow space within each third structure double wall, each third structure double wall having an open bottom end and a closed top end.   
     
     
         13 . The cofferdam of  claim 1 , wherein each open frame structure further comprises a plurality of fluid conduits associated with a respective hollow space, each conduit configured to allow liquid to be partially or completely removed from the respective hollow space. 
     
     
         14 . The cofferdam of  claim 13 , wherein the one or more of the plurality of fluidic conduits are configured to connect with a fluidic connection provided by an external device to allow the external device to pump liquid out of the hollow space. 
     
     
         15 . A method, comprising:
 lowering a first open frame structure enclosing a first open region to a submerged location, the first open frame structure having first structure double walls defining a hollow space within each first structure double wall, each first structure double wall having an open bottom end and a closed top end; and   removing liquid from the first structure double walls, via one or more fluidic conduits, to thereby generate a vacuum within first structure each double wall that induces a negative pressure that generates a force on the closed top ends of the first structure double walls;   driving the first open frame structure into a sea floor of the submerged location due to the force on the closed top ends of the first structure double walls;   lowering a second open frame structure to the submerged location within an interior of the first open region, the second open frame structure having second structure double walls defining a hollow space within each second structure double wall, each second structure double wall having an open bottom end and a closed top end; and   removing liquid from the second structure double walls, via one or more fluidic conduits, to thereby generate a vacuum within first structure each double wall that induces a negative pressure that generates a force on the closed top ends of the second structure double walls; and   driving the second open frame structure into the sea floor within the first open region and below a bottom edge of the first open frame structure due to the force on the closed top ends of the second structure double walls.   
     
     
         16 . The method of  claim 15 , wherein removing liquid from the double walls further comprises:
 making a fluidic connection between an external device and a fluidic conduit of the first open frame structure or the second open frame structure; and   pumping liquid out of the double walls using a pump provided by the external device.   
     
     
         17 . The method of  claim 15 , wherein lowering the first open frame structure and removing liquid from the first structure double walls is performed prior to lowering the second open frame structure and removing liquid from the second structure double walls. 
     
     
         18 . The method of  claim 15 , further comprising:
 removing sediment from the first open region prior to lowering the second open frame structure.   
     
     
         19 . The method of  claim 15 , wherein the removing liquid is performed by a remote-operated vehicle (ROV). 
     
     
         20 . The method of  claim 15 , wherein driving the second open frame structure into the sea floor comprises driving the second open frame structure into the sea floor until a an external lip proximate to an upper edge of the second open frame structure engages an inward lip proximate to a lower edge of the first open frame structure.