Subsea vehicle assisted pipeline commissioning method

Abstract

The present invention is directed to a method for completing the commissioning of a subsea pipeline by purging with a compressed gas to dewater and dry the line wherein the operation is done on the seabed. More specifically, the method is carried out with a subsea vechicle (hereinafter “SV”) that powers pumps located on the seabed or are carried by the SV to inject/remove chemical, dewater, and dry, the pipeline. The present invention may be part of the commissioning of a new or old pipeline or a new portion of a pipeline in which a purging of the line with a compressed gas and drying of the line is required. After commissioning, product flows through the pipeline.

1. A method of cleaning and, dewatering, or hydrostatic testing a pipeline between two subsea manifolds, one of said manifolds having a subsea pig launcher/receiver with a pig and the other having a subsea pig receiver comprising:
 providing a fill and test package comprising one or more pumps mounted on the test and fill package wherein the test and fill package mounted pump or pumps are dimensioned for cleaning, dewatering, and pressurizing to a sufficiently high pressure for hydrostatic pipeline testing; 
 using a submersible vehicle (SV) to deploy the fill and test package to one of the subsea manifolds;  
 using a submersible vehicle (SV) the SV to operate one or more pumps on a the fill and test package to force seawater behind said pig and move the pig from the pig launcher/receiver to the pig receiver; and 
 using said SV to pump more water into said pipeline to a test pressure and maintaining said pressure that there are no leaks in said pipeline supply power to at least one of the one or more pumps for cleaning, dewatering, or hydrostatic testing of the pipeline. 
 
     
     
       2. A method according to  claim 1  wherein the test pressure is read on a gauge mounted on a panel on said pig launcher/receiver. 
     
     
       3. A method according to claim  2  1 wherein said fill and test package is carried by said SV. 
     
     
       4. A method for commissioning cleaning and hydrostatic testing a subsea pipeline while both ends are on the subsea floor between two subsea manifolds, one of said manifolds having a subsea pig launcher/receiver with a pig and the other having a subsea pig receiver comprising:
 providing a fill and test package comprising one or more pumps including at least one high pressure pump dimensioned to pressurize the pipeline to a high-pressure hydrostatic test pressure; 
 using a submersible vehicle (SV) to deploy the fill and test package to one of the manifolds;  
 using a the SV, operating pumps to operate at least one pump on a the fill and test package to force seawater behind said pig and move the pig from the pig launcher/receiver to the pig receiver; and 
 pumpingoperating at least one high pressure pump to pump more waterseawater into said pipeline to apressurize the pipeline to a high-pressure hydrostatic test pressure and maintaining said pressure to assure that there are no leaks in said pipeline; 
 using a SV, connecting a line from a compressed gas pack to said pig launcher/receiver for flow of compressed gas to force said pig to said pig launcher/receiver; and 
 pumping using a dewatering pump to suck water from said pipeline and moving said pig and compressed gas through the pipeline to said pig launcher/receiver. 
 
     
     
       5. A method according to  claim 4  wherein said SV has a robotic arm for connecting and disconnecting pumps said at least one high pressure pump to said pipeline. 
     
     
       6. A method for the hydrostatic testing of a pipeline before its ends are connected wherein both ends are on the seafloor comprising:
 providing a subsea fill and test package comprising one or more pumps including at least one high pressure pump dimensioned to pump sufficient seawater into the pipeline to pressurize the pipeline to a high-pressure hydrostatic test pressure without need for a downline from a surface vessel; 
 using a submersible vehicle (SV) to deploy the fill and test package to one of the ends; and  
 using a submersible vehicle (SV) the SV to operate pumps at least one high pressure pump on a the fill and test package to pump seawater into the pipeline to raise the internal pressure of the pipeline sufficiently for a high-pressure hydrostatic testing of the pipeline commissioning test. 
 
     
     
       7. A method according to claim 4, further comprising:
 using a SV, connecting a line from a compressed gas pack to said pig launcher/receiver for flow of compressed gas to force said pig to said pig launcher/receiver; and   pumping using a dewatering pump to suck water from said pipeline and moving said pig and compressed gas through the pipeline to said pig launcher/receiver.    
     
     
       8. A method for hydrostatic testing of a pipeline on the seafloor comprising:
 using a submersible vehicle (SV) to deploy a fill and test package to a subsea location and to operate one or more pumps mounted on the fill and test package, including at least one high pressure pump dimensioned to pressurize the pipeline to a high-pressure hydrostatic test pressure without need for a downline from a surface vessel to provide pressurization.    
     
     
       9. A method for hydrostatic testing of a water filled pipeline on the seafloor comprising:
 using a submersible vehicle (SV) to deploy a fill and test package to a subsea location and to operate at least one high pressure pump mounted on the fill and test package to pump water into said water filled pipeline to pressurize the pipeline sufficiently for high-pressure hydrostatic testing without need for a downline from a surface vessel to provide pressurization.    
     
     
       10. A method for the hydrostatic testing of a pipeline between two subsea manifolds comprising:
 using a submersible vehicle (SV) to deploy and operate one or more pumps on a fill and test package to pump seawater from near the seafloor to pressurize the pipeline sufficiently for high-pressure hydrostatic testing without need for a downline from a surface vessel to provide pressurization.