Methods and systems for processing crude oil

Abstract

Methods and systems for processing crude oil may include adding water to crude oil, for example, in a desalter, to produce hydrocarbon and brine and a rag layer emulsion, which may include hydrocarbon and brine and solids. The emulsion may be modified, including adding one or more of additional hydrocarbon and, a demulsifier, a reverse demulsifier, a coagulant, and a flocculant, for example, in a mixer. The modified emulsion may be directed through a dead-end filter assembly to remove solids.

1 . A method for processing crude oil comprising:
 adding water to crude oil to produce hydrocarbon and brine and a rag layer including an emulsion comprising hydrocarbon and brine and solids;   modifying the emulsion, including adding one or more of additional hydrocarbon, a demulsifier, a reverse demulsifier, a coagulant, and a flocculant to the emulsion; and   directing the modified emulsion through a dead-end filter assembly to remove solids.   
     
     
         2 . The method of  claim 1 , further comprising separating a portion of the brine from the emulsion before modifying the emulsion. 
     
     
         3 . The method of  claim 1 , wherein adding water to the crude oil includes passing crude oil and water into a desalter, the method further comprising recirculating filtrate from the filter assembly to the desalter. 
     
     
         4 . The method of  claim 1 , further comprising directing filtrate from the filter assembly to a coalescer assembly and separately extracting filtered hydrocarbon and brine from the coalescer assembly. 
     
     
         5 . The method of  claim 4 , when the filtrate includes filtered hydrocarbon and brine, the method further comprising separating a portion of the brine from the filtered hydrocarbon and directing the filtered hydrocarbon to the coalescer assembly. 
     
     
         6 . The method of  claim 1  wherein adding one or more of additional hydrocarbon, a demulsifier, a reverse demulsifier, a coagulant, and a flocculant includes mixing the additional hydrocarbon, demulsifier, reverse demulsifier, coagulant, and/or flocculant with the emulsion. 
     
     
         7 . The method of  claim 1  further comprising directing the emulsion or the modified emulsion through a magnetic filter before directing the modified emulsion through the filter assembly. 
     
     
         8 . A system for processing crude oil, the system comprising:
 a desalter including one or more inlets for introducing crude oil and water into the desalter, the desalter producing hydrocarbon and brine and a rag layer including an emulsion comprising hydrocarbon and brine and solids, the desalter further including a first outlet for discharging at least a portion of the hydrocarbon and one or more additional outlets for discharging brine and the emulsion;   a mixer coupled to the desalter to modify the emulsion including adding one or more of additional hydrocarbon, a demulsifier, a reverse demulsifier, a coagulant, and a flocculant to the emulsion; and   a dead-end filter assembly coupled to the mixer to filter solids from the modified emulsion.   
     
     
         9 . The system of  claim 8 , further comprising a separator coupled to the desalter to separate at least a portion of the brine from the discharged emulsion, wherein the mixer is coupled to the separator. 
     
     
         10 . The system of  claim 8 , wherein the filter assembly includes a filtrate outlet coupled to an inlet of the desalter. 
     
     
         11 . The system of  claim 8 , further comprising a coalescer assembly coupled to the dead-end filter assembly to separate filtrate from the filter assembly into filtered hydrocarbon and brine. 
     
     
         12 . The system of  claim 8  wherein the dead-end filter assembly includes a settling region for separating at least a portion of the filtered brine from the filtrate, the filter assembly including an outlet for the brine-depleted filtrate coupled to the coalescer assembly. 
     
     
         13 . The system of  claim 8  further comprising a magnetic filter positioned upstream of the dead-end filter assembly to remove magnetic solids.