System and method for converting a floating drilling rig to a bottom supported drilling rig

Abstract

A floating drilling rig configured for performing drilling operations while floating on a body of water is modified to become a converted vessel configured for performing drilling operations while resting on bottom by attaching a support barge component adapted to add rest-on-bottom functionality. The support barge component has a ballast system that alone or by supplementing the ballast system of the floating drilling vessel enables the floating drilling vessel to be ballasted to rest on bottom. The ballast system of the support barge component is adapted to be opened to the water to fill and drain as the water level raises and lowers, and thereby maintain a constant soil pressure. The support barge component may also have a suction breaker system to break suction formed between the support barge and bottom. If the floating drilling rig component was previously classified for service in a defined body of water, the support barge may enable reclassification of the converted vessel for service outside the defined body of water.

We claim:  
     
         1 . A method for operating a converted vessel to perform drilling operations, said method comprising: 
 receiving a floating drilling rig that is configured for drilling operations while floating;    receiving a support barge component;    positioning the floating drilling rig over and affixing the floating drilling rig to the support barge component thereby providing a converted vessel operable to perform drilling operations while supported on a bottom of a water body;    selectively filling a plurality of ballast tanks of the converted vessel to ballast the converted vessel into contact with the bottom; and    performing drilling operations from the converted vessel while the converted vessel is supported on the bottom.    
     
     
         2 . The method of  claim 1  further comprising, floating the converted vessel in water that is shallower than the draft of the floating drilling rig.  
     
     
         3 . The method of  claim 1  wherein a footprint of the support barge component is larger than a footprint of the floating drilling rig and the method further comprises installing additional equipment on the support barge component.  
     
     
         4 . The method of  claim 3  wherein the additional equipment is a cabin.  
     
     
         5 . The method of  claim 1  further comprising, installing at least one vertically movable post on the converted vessel operable to stab into the bottom and laterally retain the converted vessel relative to the bottom.  
     
     
         6 . The method of  claim 5  wherein the at least one vertically movable post is at least two vertically movable posts and the method further comprises: 
 positioning the converted vessel about a drilling location;  
 stabbing one of the at least two vertically movable posts into the bottom;  
 rotating the converted vessel about the vertically movable post stabbed into the bottom; and  
 stabbing the remaining of the at least two vertically movable posts into the bottom.  
 
     
     
         7 . The method of  claim 1  wherein the floating drilling rig is classified for service in a defined body of water and the method further comprises transporting the converted vessel outside the defined body of water.  
     
     
         8 . The method of  claim 1  wherein the floating drilling rig is classified for service in a defined body of water and the method further comprises seeking subsequent classification of the converted vessel for service outside of the defined body of water.  
     
     
         9 . The method of  claim 1  wherein positioning the floating drilling rig over the support barge further comprises filling ballast tanks of the support barge component with water until the support barge component is ballasted to a depth that a top surface of the support barge component is at a lower depth than a lower surface of the floating drilling rig.  
     
     
         10 . The method of  claim 1  further comprising, flowing water out of outlets on a bottom of the support barge component to break suction formed between the support barge component and the bottom of the water body.  
     
     
         11 . The method of  claim 1  further comprising, opening at least one ballast tank of the support barge component to substantially freely communicate with water about the converted vessel.  
     
     
         12 . The method of  claim 11  wherein opening at least one ballast tank of the support barge component comprises opening a valve that allows flow between the at least one ballast tank and the water about the converted vessel.  
     
     
         13 . The method of  claim 11  further comprising, controlling an amount of water in at least one ballast tank near a front of the support barge component to control at least one of a front to rear trim and a port to starboard trim of the converted vessel.  
     
     
         14 . The method of  claim 11  further comprising, opening at least one ballast tank of the floating drilling rig to substantially freely communicate with the water about the converted vessel.  
     
     
         15 . The method of  claim 1  further comprising, opening at least one ballast tank of the floating drilling rig to substantially freely communicate with the water about the converted vessel.  
     
     
         16 . The method of  claim 15  wherein opening at least one ballast tank of the drilling rig comprises opening a valve that allows flow between the at least one ballast tank and the water about the converted vessel.  
     
     
         17 . The method of  claim 1  further comprising, supplying power from the floating drilling rig to the support barge component.  
     
     
         18 . The method of  claim 1  further comprising, supplying at least one of machinery cooling water and fire fighting water to the floating drilling rig.  
     
     
         19 . The method of  claim 1  further comprising, separating the support barge component from the floating drilling rig.  
     
     
         20 . The method of  claim 1  wherein selectively filling a plurality of ballast tanks further comprises filling at least one ballast tank of the floating drilling rig and at least one ballast tank of the support barge component.  
     
     
         21 . The method of  claim 1  wherein selectively filling a plurality of ballast tanks of the converted vessel comprises, selectively filling a plurality of ballast tanks of the converted vessel so that the converted vessel contacts the bottom with a first load then adjusting the level in the ballast tanks so that the converted vessel contacts the bottom with a second, lesser load than the first load.  
     
     
         22 . The method of  claim 21  wherein a magnitude of the first load is a function of at least one of a weight of the converted vessel, an environmentally induced load, and a load due to drilling operations.  
     
     
         23 . A method for converting a floating drilling rig component configured for conducting drilling operations while floating to use in conducting drilling operations while supported on a bottom of a water body, said method comprising: 
 receiving a floating drilling rig component;    receiving a support barge component, said support barge component adapted for attachment to the floating drilling rig component and having a ballast system;    positioning the floating drilling rig component over and affixing the floating drilling rig component to the support barge component, thereby constructing a converted vessel operable to perform drilling operations while supported on the bottom.    
     
     
         24 . The method of  claim 23  wherein the support barge component is sized such that the converted vessel has a shallower draft than a draft of the floating drilling rig component alone.  
     
     
         25 . The method of  claim 23  wherein the support barge component is configured to contribute to a center of gravity of the converted vessel that substantially minimizes the amount of ballast water needed for trimming the converted vessel.  
     
     
         26 . The method of  claim 25  wherein the support barge is configured to at least partially compensate for an eccentric center of gravity of the drilling rig component.  
     
     
         27 . The method of  claim 23  wherein a footprint of the support barge component is larger than a footprint of the floating drilling rig component and the method further comprises installing additional equipment on the support barge component.  
     
     
         28 . The method of  claim 23  further comprising, installing at least one vertically movable post on the converted vessel, the at least one vertically movable post operable to stab into the bottom and laterally retain the converted vessel relative to the bottom.  
     
     
         29 . The method of  claim 23  wherein the floating drilling rig component is classified for service in a defined body of water and the method further comprises seeking classification of the converted vessel for service outside of the defined body of water.  
     
     
         30 . The method of  claim 23  wherein the support barge component is adapted to flow water out of outlets on the bottom of the support barge component to break suction formed between the support barge component and the bottom of the water body.  
     
     
         31 . The method of  claim 23  wherein the ballast system comprises a plurality of ballast tanks, and wherein at least one of the ballast tanks is adapted to substantially freely communicate with water about the converted vessel.  
     
     
         32 . The method of  claim 23  wherein the support barge component is adapted to contribute to a center of gravity of the converted vessel that is near it's center of buoyancy.  
     
     
         33 . The method of  claim 23  wherein the support barge component is adapted to provide at least one of electricity, machine cooling water, and fire water to the floating drilling rig component.  
     
     
         34 . A composite converted vessel for performing drilling operations while supported on a bottom of a water body, comprising: 
 a floating drilling rig component having equipment for performing drilling operations, said floating drilling rig configured for performing drilling operations while floating; and    a support barge component attached to the floating drilling rig component, the support barge component adapted to enable the composite converted vessel to perform drilling operations while supported on the bottom of the water body.    
     
     
         35 . The converted vessel of  claim 34  wherein the support barge component is sized such that the converted vessel has a shallower draft than a draft of the floating drilling rig component alone.  
     
     
         36 . The converted vessel of  claim 34  wherein the support barge component has a larger footprint than a footprint of the floating drilling rig component and at least one piece of equipment resides on the support barge component.  
     
     
         37 . The converted vessel of  claim 34  further comprising at least one vertically movable post disposed on the converted vessel said post operable to stab into the bottom of the water body and retain the converted vessel laterally relative to the bottom.  
     
     
         38 . The converted vessel of  claim 34  wherein the floating drilling rig is classified for service in a defined body of water and the converted vessel is classified for service outside of the defined body of water.  
     
     
         39 . The converted vessel of  claim 34  wherein the support barge component has a plurality of ballast tanks and at least one of the ballast tanks is adapted to be opened to water about the support barge component and allow water to flow freely in and out of the ballast tanks.  
     
     
         40 . The converted vessel of  claim 34  wherein the floating drilling rig component has a substantially planar bottom portion that abuts a substantially planar deck portion of the support barge component.  
     
     
         41 . The converted vessel of  claim 34  wherein the support barge component has a suction breaking system operable to flow water out of outlets on a bottom of the support barge component to break suction formed between the support barge component and the bottom of the water body.  
     
     
         42 . The converted vessel of  claim 34  wherein the support barge component is adapted to contribute to a center of gravity of the converted vessel being near a center of buoyancy of the converted vessel.