Detecting a tracer in a hydrocarbon reservoir

Abstract

The present disclosure describes methods and systems for detecting a tracer in a hydrocarbon reservoir. One method includes injecting a tracer at a first location in a reservoir, wherein the tracer mixes with subsurface fluid in the reservoir; collecting fluid samples at a second location in the reservoir; mixing a magnetic surface-enhanced Raman scattering (SERS) particle with the fluid samples; applying a magnetic field to the mixed fluid samples; and analyzing the fluid samples to detect a presence of the tracer in the fluid samples.

What is claimed is: 
     
         1 - 20 . (canceled) 
     
     
         21 . A method for synthesizing magnetic surface-enhanced Raman scattering (SERS)-active nanoparticles, comprising:
 synthesizing a plurality of superparamagnetic Fe 3 O 4  nanoparticles;   coating the plurality of superparamagnetic Fe 3 O 4  nanoparticles with SiO 2  to generate Fe 3 O 4 @SiO 2  particles; and   synthesizing the magnetic SERS-active nanoparticles by attaching Ag nanoparticles to the Fe 3 O 4 @SiO 2  particles.   
     
     
         22 . The method of  claim 21 , wherein the coating the plurality of superparamagnetic Fe 3 O 4  nanoparticles comprises finalizing the coating by adding triethoxysilane. 
     
     
         23 . The method of  claim 21 , wherein the coating the plurality of superparamagnetic Fe 3 O 4  nanoparticles comprises finalizing the coating by adding tetraethyl orthosilicate (TEOS). 
     
     
         24 . The method of  claim 21 , wherein the coating the plurality of superparamagnetic Fe 3 O 4  nanoparticles comprises finalizing the coating by adding trimethoxysilane. 
     
     
         25 . The method of  claim 21 , wherein the coating the plurality of superparamagnetic Fe 3 O 4  nanoparticles comprises adding the plurality of superparamagnetic Fe 3 O 4  nanoparticles to a microemulsion of IGEPAL CO-720. 
     
     
         26 . The method of  claim 21 , wherein the attaching the Ag nanoparticles comprising adding AgNO 3  to NaBH 4 . 
     
     
         27 . The method of  claim 21 , wherein the synthesizing the plurality of superparamagnetic Fe 3 O 4  nanoparticles comprises adding FeCl 3 .6H 2 O and FeSO 4 .7H 2 O to water. 
     
     
         28 . The method of  claim 21 , wherein the synthesizing the plurality of superparamagnetic Fe 3 O 4  nanoparticles comprises adding FeCl 2 .4H 2 O and FeSO 4 .7H 2 O to water. 
     
     
         29 . The method of  claim 21 , wherein the synthesizing the plurality of superparamagnetic Fe 3 O 4  nanoparticles comprises adding NH 3 .H 2 O to water. 
     
     
         30 . The method of  claim 21 , wherein the synthesizing the plurality of superparamagnetic Fe 3 O 4  nanoparticles comprises drawing the plurality of superparamagnetic Fe 3 O 4  nanoparticles using magnet. 
     
     
         31 . The method of  claim 21 , wherein the synthesizing the plurality of superparamagnetic Fe 3 O 4  nanoparticles comprises dispersing the plurality of superparamagnetic Fe 3 O 4  nanoparticles in deionized water. 
     
     
         32 . A magnetic surface-enhanced Raman scattering (SERS)-active nanoparticle, comprising:
 a non-magnetic particle shell that is decorated with an Ag particle;   a magnetic core particle that is incorporated into the non-magnetic particle shell, wherein the magnetic core particle comprises Fe 3 O 4 @SiO 2  particles; and   wherein the magnetic SERS-active nanoparticle is synthesized using triethoxysilane.   
     
     
         33 . The magnetic SERS-active nanoparticle of  claim 32 , wherein the magnetic SERS-active nanoparticle is synthesized using tetraethyl orthosilicate (TEOS). 
     
     
         34 . The magnetic SERS-active nanoparticle of  claim 32 , wherein the magnetic SERS-active nanoparticle is synthesized using trimethoxysilane. 
     
     
         35 . The magnetic SERS-active nanoparticle of  claim 32 , wherein the magnetic SERS-active nanoparticle is synthesized using a microemulsion of IGEPAL CO-720. 
     
     
         36 . The magnetic SERS-active nanoparticle of  claim 32 , wherein the magnetic SERS-active nanoparticle is synthesized by adding AgNO 3  to NaBH 4 . 
     
     
         37 . The magnetic SERS-active nanoparticle of  claim 32 , wherein the magnetic SERS-active nanoparticle is synthesized by adding FeCl 3 .6H 2 O to water. 
     
     
         38 . The magnetic SERS-active nanoparticle of  claim 32 , wherein the magnetic SERS-active nanoparticle is synthesized by adding FeCl 2 .4H 2 O to water. 
     
     
         39 . The magnetic SERS-active nanoparticle of  claim 32 , wherein the magnetic SERS-active nanoparticle is synthesized by adding FeSO 4 .7H 2 O to water. 
     
     
         40 . The magnetic SERS-active nanoparticle of  claim 32 , wherein the magnetic SERS-active nanoparticle is synthesized by adding NH 3 .H 2 O to water. 
     
     
         41 . The magnetic SERS-active nanoparticle of  claim 32 , wherein the magnetic SERS-active nanoparticle is synthesized by drawing superparamagnetic Fe 3 O 4  nanoparticles using magnet.