One-trip wellhead installation systems and methods

Abstract

Methods and devices are described for efficiently installing sea-borne wellhead components and tying back sub-sea wellhead components with them. In specific aspects, a single running and setting tool is used to land a tubing head housing upon the stem of a floating platform and tension and pressure testing casing string risers extending between a subsea wellhead and a floating vessel.

What is claimed is:  
     
         1 . A wellhead assembly system for assembling a tubing head onto a floating vessel and for testing the integrity of a riser string disposed between a floating vessel and a subsea wellhead, the assembly system comprising: 
 a) a tubing head to be landed upon a stem of a floating vessel, the tubing head comprising a housing having a generally vertically-disposed bore therethrough and a landing profile for selectively engaging a stem of a floating vessel;    b) a running and setting tool comprising: 
 a central piston assembly radially disposed within the bore of the tubing head and being axially moveable therewithin,  
 a landing sub affixed to a lower end of the central piston assembly and being selectively securable to a casing section member;  
 a fluid bore disposed through the central piston assembly and landing sub; and  
 a matching profile upon the central piston assembly for reversably interconnecting the central piston assembly with the tubing head housing.  
   
     
     
         2 . The wellhead assembly system of  claim 1  further comprising a tubular casing sleeve secured to a lower end of the tubing head and sized to retain a casing string member radially within, and a securing assembly for securing an end of a casing string member radially within the casing sleeve.  
     
     
         3 . The wellhead assembly system of  claim 2  wherein the securing assembly further comprises a ratchet suspension assembly having a plurality of radially interior teeth to interengage a radial exterior of a casing string member.  
     
     
         4 . The wellhead assembly system of  claim 1  further comprising a fluid chamber formed between the tubing head and the central piston assembly that can be selectively filled to move the piston assembly axially with respect to the tubing head.  
     
     
         5 . The wellhead assembly system of  claim 1  wherein the tubing head further includes a load cell for measuring tension upon a riser string extending between the tubing head and a subsea wellhead.  
     
     
         6 . The wellhead assembly system of  claim 1  further comprising means for selectively securing the central piston assembly within the tubing head to preclude axial movement between the central piston assembly and the tubing head.  
     
     
         7 . The wellhead assembly system of  claim 6  wherein the means for selectively securing comprises a set screw.  
     
     
         8 . A running and setting tool for landing portions of a wellhead upon the stem of a floating platform, the tool comprising: 
 a central piston assembly radially disposed within a bore of a tubing head to be axially moveable therewithin,    a landing sub affixed to a lower end of the central piston assembly and being selectively securable to a casing section member;    a fluid bore disposed through the central piston assembly and landing sub; and    a profile upon the central piston assembly for reversably interconnecting the central piston assembly with a tubing head.    
     
     
         9 . The running and setting tool of  claim 8  wherein the landing sub further comprises a seal assembly for selectively creating a fluid seal within a surrounding sleeve.  
     
     
         10 . The running and setting tool of  claim 8  further comprising means for selectively securing the central piston assembly within a tubing head to preclude axial movement between the central piston assembly and the tubing head.  
     
     
         11 . The running and setting tool of  claim 10  wherein the means for selectively securing comprises a set screw.  
     
     
         12 . A method of assembling a tubing head onto a floating vessel and testing the integrity of a riser string disposed between a floating vessel and a subsea wellhead, comprising the steps of: 
 reversibly securing an upper portion of a central piston assembly to a tubing head;    reversibly affixing a landing sub on a lower portion of a central piston assembly to a casing member in a casing string;    pressure testing the casing-string;    landing the tubing head onto the stem of a floating platform; and    energizing a riser seal between the landing sub and a surrounding sleeve.    
     
     
         13 . The method of  claim 12  further comprising the step of pressure testing the riser seal.  
     
     
         14 . The method of  claim 12  wherein the step of energizing the riser seal comprises axially moving the central piston assembly with respect to the tubing head assembly.  
     
     
         15 . The method of  claim 14  wherein the step of axially moving the central piston assembly with respect to the tubing head assembly further comprises the step of pressurizing a fluid chamber.  
     
     
         16 . The method of  claim 12  further comprising the step of tensioning the casing string.  
     
     
         17 . The method of  claim 16  further comprising the step of measuring the tension load upon the casing string via a load cell within the tubing head.  
     
     
         18 . The method of  claim 12  further comprising the step of landing a blowout preventer atop the tubing head.