Subsea autonomous dispersant injection system and methods

Abstract

A system for autonomously supplying a chemical dispersant to a subsea hydrocarbon discharge site which comprises a subsea storage vessel configured to store the chemical dispersant subsea is described herein. The storage vessel includes a dispersant outlet in fluid communication with the subsea hydrocarbon discharge site.

1 . A system for autonomously supplying a chemical dispersant to a subsea hydrocarbon discharge site, comprising:
 a subsea storage vessel configured to store the chemical dispersant subsea, wherein the storage vessel includes a dispersant outlet in fluid communication with the subsea hydrocarbon discharge site.   
     
     
         2 . The system of  claim 1 , further comprising a first subsea manifold including a dispersant inlet in fluid communication with the dispersant outlet of the storage vessel and a dispersant outlet in fluid communication with the subsea hydrocarbon discharge site. 
     
     
         3 . The system of  claim 2 , further comprising:
 a plurality of subsea storage vessels, wherein each storage vessel is configured to store the chemical dispersant subsea and includes a dispersant outlet;   wherein the first subsea manifold includes a plurality of dispersant inlets, each dispersant inlet in fluid communication with the dispersant outlet of one of the storage vessels.   
     
     
         4 . The system of  claim 3 , wherein each storage vessel comprises:
 the dispersant outlet;   a dispersant inlet;   an outlet valve configured to control the flow of dispersant through the dispersant outlet;   an inlet valve configured to control the flow of dispersant through the dispersant inlet; and   a check valve configured to allow one-way fluid communication of the dispersant through the inlet valve to the storage vessel.   
     
     
         5 . The system of  claim 4 , wherein each storage vessel further comprises:
 a support structure;   a flexible bladder disposed within the support structure, wherein the bladder is configured to store the dispersant and is in fluid communication with the dispersant outlet of the storage vessel.   
     
     
         6 . The system of  claim 5 , wherein the support structure of each storage vessel includes a lower base, a plurality of guide rails extending perpendicularly from the base, and an upper plate slidably mounted to the guide rails;
 wherein the flexible bladder of each storage vessel is disposed between the lower base and the upper plate.   
     
     
         7 . The system of  claim 5 , wherein the support structure of each storage vessel includes a lower base, a plurality of support posts extending perpendicularly from the base, and an upper plate fixed to the support posts;
 wherein the flexible bladder of each storage vessel is suspended from the upper plate.   
     
     
         8 . The system of  claim 2 , further comprising:
 a first plurality of subsea storage vessels;   a second plurality of subsea storage vessels;   wherein each storage vessel is configured to store the chemical dispersant subsea and includes a dispersant outlet;   wherein the first subsea manifold includes a plurality of dispersant inlets, each dispersant inlet of the first subsea manifold in fluid communication with the dispersant outlet of one of the storage vessels of the first plurality of subsea storage vessels;   a second subsea manifold including a plurality of dispersant inlets and a dispersant outlet, each dispersant inlet of the second subsea manifold in fluid communication with the dispersant outlet of one of the storage vessels of the first plurality of subsea storage vessels;   a delivery manifold including a plurality of dispersant inlets and at least one dispersant outlet, wherein each dispersant inlet of the delivery manifold is in fluid communication one of the dispersant outlets of the first subsea manifold or the second subsea manifold;   wherein the at least one dispersant outlet of the delivery manifold is in fluid communication with the subsea hydrocarbon discharge site.   
     
     
         9 . The system of  claim 8 , further comprising a venturi eductor mounted to the discharge site, wherein the venturi eductor includes a converging-diverging nozzle adapted to flow a stream of hydrocarbons and a dispersant inlet in fluid communication with the diverging nozzle;
 wherein the dispersant inlet of the venturi eductor is in fluid communication with the at least one outlet of the delivery manifold.   
     
     
         10 . The system of  claim 8 , further comprising a subsea pump system configured to pump the chemical dispersant from the storage vessels to the subsea hydrocarbon discharge site;
 wherein the subsea pump system comprises:
 a dispersant inlet in fluid communication with a pump outlet of the delivery manifold; 
 a dispersant outlet in fluid communication with a pump inlet of the delivery manifold; 
 a primary pump in fluid communication with the dispersant inlet of the pump system and the dispersant outlet of the pump system; 
 a first backup pump in fluid communication with the dispersant inlet of the pump system; 
 a first plurality of batteries configured to power the primary pump; and 
 a second plurality of batteries configured to power the first backup pump. 
   
     
     
         11 . The system of  claim 8 , wherein each dispersant inlet of the delivery manifold includes a check valve configured to allow one-way fluid flow through the inlet into the delivery manifold. 
     
     
         12 . The system of  claim 8 , wherein the delivery manifold includes a plurality of dispersant outlets, each dispersant outlet of the delivery manifold configured to flow the dispersant to the subsea discharge site;
 Wherein each dispersant outlet of the delivery manifold includes an outlet valve configured to control the flow of dispersant through its corresponding dispersant outlet.   
     
     
         13 . A method for autonomously supplying a chemical dispersant to a subsea hydrocarbon discharge site, comprising:
 (a) installing a system on the sea floor, the system comprising a plurality of subsea storage vessels, each storage vessel including a dispersant outlet;   (b) storing a chemical dispersant in the subsea storage vessels;   (c) flowing the chemical dispersant from one or more of the subsea storage vessels to the subsea hydrocarbon discharge site.   
     
     
         14 . The method of  claim 13 , further comprising:
 placing the system in stand-by after (a) and before (c);   activating the system to flow the chemical dispersant from one or more of the subsea storage vessels in (c).   
     
     
         15 . The method of  claim 14 , further comprising evacuating a surface facility or surface operation after activating the system. 
     
     
         16 . The method of  claim 15 , wherein (c) is performed without human intervention. 
     
     
         17 . The method of  claim 13 , wherein the system further comprises a first manifold including a plurality of dispersant inlets and a dispersant outlet; and
 wherein (c) comprises:   (c1) flowing the chemical dispersant from one or more of the subsea storage vessels to the first manifold; and   (c2) flowing the chemical dispersant from the first manifold to the subsea hydrocarbon discharge site.   
     
     
         18 . The method of  claim 17 , wherein (c) comprises pumping the chemical dispersant from one or more of the subsea storage vessels to the first manifold; and
 wherein (d) comprises pumping the chemical dispersant from the first manifold to the subsea hydrocarbon discharge site.   
     
     
         19 . The method of  claim 17 , wherein (a) comprises mounting a venturi eductor to the subsea discharge site, the venturi eductor including a converging-diverging nozzle and a dispersant inlet. 
     
     
         20 . The method of  claim 19 , further comprising:
 flowing a stream of hydrocarbons through the converging-diverging nozzle of the venturi eductor;   generating a low pressure region in the venturi eductor while flowing the stream of hydrocarbons through the converging-diverging nozzle of the venturi eductor;   relying on the low pressure region in the venturi eductor to flow the chemical dispersant from one or more of the subsea storage vessels to the first manifold and to flow the chemical dispersant from the first manifold to the subsea hydrocarbon discharge site.   
     
     
         21 . The method of  claim 13 , further comprising filling each storage vessel with the chemical dispersant subsea. 
     
     
         22 . The method of  claim 21 , wherein each storage vessel comprises:
 a dispersant inlet including an inlet valve and a check valve;   a support structure;   a flexible bladder disposed within the support structure, wherein the bladder is configured to store the dispersant;   wherein the dispersant outlet of each storage vessel includes an outlet valve.   
     
     
         23 . The method of  claim 22 , wherein filling each storage vessel comprises:
 opening the inlet valve of the storage vessel;   flowing the dispersant through the inlet and check valve of the storage vessel into the bladder; and   expanding the bladder.   
     
     
         24 . The method of  claim 17 , further comprising restricting the flow of dispersant from the first manifold to one or more of the storage vessels. 
     
     
         25 . The method of  claim 17 , wherein the system further comprises:
 a first plurality of subsea storage vessels;   a second plurality of subsea storage vessels;   a second manifold including a plurality of dispersant inlets and a dispersant outlet;   wherein each storage vessel includes a dispersant outlet;   a delivery manifold including a plurality of dispersant inlets and a dispersant outlet;   wherein (c) further comprises flowing the chemical dispersant from each storage vessel of the first plurality of storage vessels to the first manifold and flowing the chemical dispersant from each storage vessel of the second plurality of storage vessels to the second manifold;   wherein (d) further comprises flowing the chemical dispersant from the first manifold and the second manifold to the delivery manifold and flowing the chemical dispersant from the delivery manifold to the subsea hydrocarbon discharge site.