Mercury removal from crude oil

Abstract

A process for decreasing the level of elemental mercury contained in a crude oil at the well site by separating the crude oil stream into a gaseous hydrocarbon stream containing hydrocarbons, mercury and water, and a liquid hydrocarbon stream containing hydrocarbons and elemental mercury; removing mercury from the gaseous hydrocarbon stream in a mercury removal unit, thereby forming a treated gas stream; contacting a recycle gas stream comprising a portion of the treated gas stream with at least a portion of the liquid hydrocarbon stream for transfer of at least a portion of the elemental mercury contained in the liquid hydrocarbon stream to the recycle gas stream; thereby forming a mercury rich gas stream, and a treated liquid hydrocarbon stream; and passing the mercury rich gas stream, along with the gaseous hydrocarbon stream, to the mercury removal unit, is disclosed.

1 . A process comprising:
 a) extracting a crude oil stream comprising elemental mercury, hydrocarbons and water from a crude oil well;   b) separating said crude oil stream into a gaseous hydrocarbon stream comprising hydrocarbons, mercury and water, and a liquid hydrocarbon stream comprising hydrocarbons and elemental mercury;   c) charging a mercury-containing gas feed, including in part at least a portion of said gaseous hydrocarbon stream, to a mercury removal unit for removal of mercury from said mercury-containing gas feed, thereby forming a treated gas stream;   d) contacting a recycle gas stream comprising a portion of said treated gas stream with at least a portion of said liquid hydrocarbon stream for transfer of at least a portion of the elemental mercury contained in said liquid hydrocarbon stream to said recycle gas stream; thereby forming a mercury rich gas stream, and a treated liquid hydrocarbon stream; and   e) passing said mercury rich gas stream to said mercury removal unit as a portion of said mercury-containing gas feed.   
   
   
       2 . A process in accordance with  claim 1  wherein water is removed from said mercury-containing gas feed prior to charging to said mercury removal unit in step c). 
   
   
       3 . A process in accordance with  claim 1  wherein said contacting of step d) occurs in a vessel, and wherein said recycle gas stream is charged to said vessel below the location said liquid hydrocarbon stream is charged to said vessel, and wherein said mercury rich gas stream is removed from said vessel at a location above the location said liquid hydrocarbon stream is charged to said vessel, and wherein said treated liquid hydrocarbon stream is removed from said vessel at a location below the location said liquid hydrocarbon stream is charged to said vessel. 
   
   
       4 . A process in accordance with  claim 1  wherein said gaseous hydrocarbon stream comprises hydrocarbons containing from about 1 to about 6 carbon atoms per molecule. 
   
   
       5 . A process in accordance with  claim 1  wherein the temperature of said crude oil in step (a) is at least about 50° C., and wherein the pressure of said separation step (b) is at least about 0.5 Bars. 
   
   
       6 . A process in accordance with  claim 1  wherein the temperature of said crude oil in step (a) is at least about 60° C., and wherein the pressure of said separation step (b) is at least about 1 Bars. 
   
   
       7 . A process in accordance with  claim 1  wherein said mercury removal unit has a fixed bed comprising a mercury sorbent material. 
   
   
       8 . A process in accordance with  claim 1  wherein said treated gas stream comprises less than about 20 wt. % of the mercury contained in said mercury-containing gas feed. 
   
   
       9 . A process in accordance with  claim 1  wherein said treated gas stream comprises less than about 10 wt. % of the mercury contained in said mercury-containing gas feed. 
   
   
       10 . A process in accordance with  claim 1  wherein said treated liquid hydrocarbon stream comprises less than about 50 wt. % of the elemental mercury contained in said liquid hydrocarbon stream. 
   
   
       11 . A process in accordance with  claim 1  wherein said treated liquid hydrocarbon stream comprises less than about 20 wt. % of the elemental mercury contained in said liquid hydrocarbon stream. 
   
   
       12 . A process in accordance with  claim 1  wherein said liquid hydrocarbon stream comprises at least about 10 ppb elemental mercury. 
   
   
       13 . A process in accordance with  claim 1  wherein said liquid hydrocarbon stream comprises at least about 200 ppb elemental mercury. 
   
   
       14 . A process in accordance with  claim 1  wherein said contacting of step d) occurs at a temperature in the range of from about 70° C. to about 300° C., and a pressure in the range of from about 0.5 Bars to about 15 Bars, and a gas to liquid ratio in the range of from about 50 to about 300 SCF/bbl. 
   
   
       15 . A process in accordance with  claim 1  wherein said contacting of step d) occurs at a temperature in the range of from about 150° C. to about 200° C., and a pressure in the range of from about 1 Bar to about 10 Bars, and a gas to liquid ratio in the range of from about 100 to about 200 SCF/bbl. 
   
   
       16 . A process in accordance with  claim 1  wherein said contacting of step d) occurs at a temperature in the range of from about 150° C. to about 200° C., and a pressure in the range of from about 2 Bars to about 7 Bars, and a gas to liquid ratio in the range of from about 100 to about 200 SCF/bbl. 
   
   
       17 . A process in accordance with  claim 3  wherein said liquid hydrocarbon stream comprises hydrocarbons, elemental mercury and water; and wherein water is separated from said liquid hydrocarbon stream and removed from said vessel at a location below the location said treated liquid hydrocarbon stream is removed from said vessel.