Method of detecting methane in the bore of a blowout preventer stack

Abstract

The method of sensing methane type gases in the bore of a subsea blowout preventer stack comprising collecting a sample of the fluids in the blowout preventer stack into a vacuum chamber, expanding the volume of the chamber to allow the methane type gases in the sample to evaporate either expand or evaporate, and then measuring the change in pressure before and after the expansion to determine the characteristics of the sample.

That which is claimed is: 
     
         1 . The method of sensing gas in the bore of a subsea blowout preventer stack, comprising
 collecting a sample of the fluids in said blowout preventer stack into a chamber,   expanding the volume of said chamber to allow said gas in said sample to evaporate either expand or evaporate, and   measuring the change in pressure before and after said expanding to determine the characteristics of said sample.   
     
     
         2 . The method of  claim 1  further comprising comparing said characteristics with the characteristics of known fluids and gases to determine what gases gasses are present in said sample. 
     
     
         3 . The method of  claim 1  further comprising alternately drawing said sample of fluids into a test chamber and expelling said sample of fluids from said test chamber. 
     
     
         4 . The method of  claim 3  further comprising providing a piston to alternately draw said sample of fluids into a test chamber and expelling said sample of fluids from said test chamber. 
     
     
         5 . The method of  claim 3  further comprising drawing said sample of fluids through a filter and expelling said sample of fluids through the same filter to clean said filter. 
     
     
         6 . The method of  claim 1  further comprising drawing said sample of fluids through a first check valve and
 expelling said sample of fluids through a second check valve causing said sample of fluids to be at least partially refreshed on each cycle. 
 
     
     
         7 . The method of  claim 6  further comprising opening a third check valve with the movement of a piston in a first direction. 
     
     
         8 . The method of  claim 6  further comprising closing said third check valve with the movement of said piston in a second direction allowing a vacuum to be drawn by further movement is said second direction. 
     
     
         9 . The method of  claim 1  further comprising said gas is a methane type gas. 
     
     
         10 . The method of  claim 1  further comprising said gas is methane. 
     
     
         11 . The method of sensing methane type gases in the bore of a subsea blowout preventer stack, comprising
 collecting a sample of the fluids in said blowout preventer stack into a chamber;   expanding the volume of said chamber to allow said methane type gases in said sample to evaporate either expand or evaporate, and   measuring the change in pressure before and after said expanding to determine the characteristics of said sample.   
     
     
         12 . The method of  claim 11  further comprising comparing said characteristics with the characteristics of known fluids and gases to determine what gases gasses are present in said sample. 
     
     
         13 . The method of  claim 11  further composing alternately drawing said sample of fluids into a test chamber and expelling said sample of fluids from said test chamber. 
     
     
         14 . The method of  claim 13  further comprising providing a piston to alternately draw said sample of fluids into a test chamber and expelling said sample of fluids from said test chamber. 
     
     
         15 . The method of  claim 13  further comprising drawing said sample of fluids through a filter and expelling said sample of fluids through the same filter to clean said filter. 
     
     
         16 . The method of  claim 11  further comprising drawing said sample of fluids through a first check valve and
 expelling said sample of fluids through a second check valve causing said sample of fluids to be at least partially refreshed on each cycle. 
 
     
     
         17 . The method of  claim 16  further comprising opening a third check valve with the movement of a piston in a first direction. 
     
     
         18 . The method of  claim 16  further comprising closing said third check valve with the movement of said piston in a second direction allowing a vacuum to be drawn by further movement is said second direction. 
     
     
         19 . The method of  claim 11  further comprising said gas is a methane type gas. 
     
     
         20 . The method of  claim 1  further comprising said gas is methane.