Rapid deployment subsea chemical injection system

Abstract

A rapid deployment, subsea chemical injection skid assembly includes a non-buoyant skid lowered on a weight bearing line from a surface vessel. The skid carries a chemical injection pump, as well as at least one chemical tank in fluid communication with the chemical injection pump. The skid assembly may include a recirculation/mixing system to limit separation or solids drop out of chemicals arising from medium or long-term storage of chemicals in the chemical tank. The skid assembly may include a seawater filtration system to supply seawater for mixing with chemicals prior to injection. The skid assembly is operable by a separately tethered remotely operated vehicle.

What is claimed is: 
     
         1 . A system for treating subsea hydrocarbon production facilities comprising:
 a non-buoyant skid suspended from a first cable configured to support the weight of the skid, the skid including a chemical injection pump and a chemical tank mounted thereon; and   a remotely operated vehicle independent of the skid and attached to an umbilical cable, wherein the remotely operated vehicle is configured to couple the pump to the subsea hydrocarbon production facilities.   
     
     
         2 . The system of  claim 1 , further comprising at least two chemical tanks mounted on the skid. 
     
     
         3 . The system of  claim 1 , wherein the skid comprises an on-board power supply carried by the skid and disposed to power an electric motor carried by the skid. 
     
     
         4 . The system of  claim 1 , wherein the chemical tank is a bladder tank. 
     
     
         5 . The system of  claim 1  further comprising a recirculating system mounted on the skid, wherein the recirculating system is in fluid communication with the chemical tank. 
     
     
         6 . The system of  claim 5 , wherein the recirculating system is in fluid communication with two or more tanks. 
     
     
         7 . The system of  claim 5 , wherein the recirculating system comprises an Archimedes screw within a tube. 
     
     
         8 . The system of  claim 1 , further comprising a control panel operable mounted on the skid and operable by an ROV. 
     
     
         9 . The system of  claim 1 , further comprising a seawater filtration system mounted on the skid. 
     
     
         10 . The system of  claim 1 , further comprising one or more mud mats extending outward from a lower portion of skid. 
     
     
         11 . A chemical injection skid for deployment to a subsea hydrocarbon production facility, the chemical injection skid comprising:
 a skid frame:   a chemical tank mounted on the skid frame;   a chemical injection pump mounted on the skid frame and in fluid communication with the chemical tank, wherein said chemical injection pump is adapted to inject a lower volume of viscous chemical into a subsea hydrocarbon production facility.   
     
     
         12 . The skid of  claim 11 , further comprising at least two chemical tanks mounted on the skid frame. 
     
     
         13 . The skid of  claim 12 , further comprising a chemical mixing system mounted on the skid frame, wherein the chemical mixing system is in fluid communication with the chemical tank. 
     
     
         14 . The skid of  claim 13 , further comprising a seawater filtration system mounted on the skid frame. 
     
     
         15 . A method for injecting chemicals into a subsea hydrocarbon production facility, the method comprising:
 lowering a skid carrying a chemical injection pump and chemical tank to a subsea position adjacent a hydrocarbon production facility;   utilizing an ROV to attach a chemical injection line in fluid communication with the chemical injection pump to an injection point of the hydrocarbon production facility; and   once the chemical injection line has been attached, utilizing the ROV to operate the skid in order to inject a first chemical from the tank into the hydrocarbon production facility.   
     
     
         16 . The method of  claim 15 , further comprising evaluating an effect of the first chemical on the hydrocarbon production facility; and
 utilizing the ROV to operate the chemical injection skid in order to inject a second chemical into the hydrocarbon production facility and thereafter evaluating an effect of the second chemical on the hydrocarbon production facility.   
     
     
         17 . The method of  claim 15 , further comprising utilizing a first power source to initiate start-up of the chemical injection pump and a second power source, different from the first power source, to continue operation of the chemical injection pump during pumping. 
     
     
         18 . The method of  claim 17  where the first power source is selected from the group consisting of an on-board power source carried by the skid, an electrical cable extending from a surface vessel and power supplied by the ROV; and the second power source is selected from the group consisting of an on-board power source carried by the skid, an electrical cable extending from a surface vessel, power supplied by the ROV, power supplied by a subsea production system. 
     
     
         19 . The method of  claim 15 , further comprising operating the chemical injection pump to pump a first chemical carried in a first tank on the skid into the hydrocarbon production facility and evaluating the effect of the first chemical on the hydrocarbon production facility and thereafter; operating the chemical injection pump to pump a second chemical carried in a second tank on the skid into the hydrocarbon production facility and evaluating the effect of the second chemical on the hydrocarbon production facility; and based on the evaluated effect of the first and second chemicals on the hydrocarbon production facility, selecting one of the first and second chemicals for long term treatment of the hydrocarbon production facility. 
     
     
         20 . The method of  claim 15 , further comprising operating a chemical preparation mechanism carried by the skid to recirculate chemicals contained within the chemical tank in order to maintain the chemicals in a well-mixed, cohesive state and reduce separation of components due to differing specific gravities.