Monitoring carbon sequestration in source rock reservoirs using stable isotopic fractionation to quantify its retention efficiency

Abstract

A process for monitoring and quantifying anthropogenic carbon retained within a reservoir includes, measuring δ13C and δ18O of in situ reservoir CO2 and calculating endpoint values of the in situ CO2 using δ13C and δ18O, measuring δ13C, and δ18O of anthropogenic CO2 and calculating endpoint value of the anthropogenic CO2 using δ13C and δ18O, injecting anthropogenic CO2 into the reservoir, obtaining volume or mass of anthropogenic CO2, collecting a produced sample from the reservoir after a period of time, measuring δ13C, and δ18O of a mixed in situ and anthropogenic CO2, and calculating the anthropogenic CO2 sequestered in the reservoir by using the endpoint values. A anthropogenic CO2 monitoring and quantifying system includes, injection wells, production wells, measurement devices for measuring an amount of CO2 injected and produced, and a measurement collection and analysis system for receiving gas samples and for measuring an amount of CO2 sequestered within the reservoir.

What is claimed: 
     
         1 . A process for monitoring and quantifying anthropogenic carbon retained within a reservoir, the process comprising:
 measuring δ13C and δ18O of in situ CO2 from a reservoir;   calculating endpoint values of the in situ CO2 using the δ13C and the δ18O;   measuring δ13C, and δ18O of anthropogenic CO2;   calculating endpoint values of the anthropogenic CO2 using the δ13C, and the δ18O;   injecting the anthropogenic CO2 into the reservoir via an injection well;   obtaining a volume or mass the anthropogenic CO2 injected into the reservoir;   collecting a produced sample from the reservoir via a production well after a period of time;   measuring δ13C, and δ18O of a mixed in situ and anthropogenic CO2; and   calculating fraction of the anthropogenic CO2 sequestered in the reservoir by using the endpoint values.   
     
     
         2 . The process of  claim 1 , further comprising measuring δ13C and δ2H of in situ CH4 from the reservoir. 
     
     
         3 . The process of  claim 2 , further comprising calculating endpoint values of the in situ CH4 using the δ13C and δ2H. 
     
     
         4 . The process of  claim 1 , wherein measuring of in situ CO2 comprises measuring an amount of CO2 recovered from a mud gas-separator. 
     
     
         5 . The process of  claim 1 , wherein collecting comprises collecting multiple produced samples over a time interval. 
     
     
         6 . The process of  claim 5 , wherein the time interval is two or more weeks. 
     
     
         7 . The process of  claim 1 , wherein collecting comprises collecting produced sample in an isotube. 
     
     
         8 . The process of  claim 1 , wherein measuring δ13C, and δ18O of a mixed CO2 comprises measuring CO 2  recovered from a mud gas separator. 
     
     
         9 . The process of  claim 1 , wherein the reservoir is shut in for a period of time after injecting the anthropogenic CO2 into the reservoir via an injection well. 
     
     
         10 . The process of  claim 9 , wherein the reservoir is shut in for at least a one month period before production commences. 
     
     
         11 . The process of  claim 1 , wherein calculating the fraction is accomplished by using an isotope mixing equation. 
     
     
         12 . The process of  claim 11 , wherein the isotope mixing equation is modified by a compensation factor. 
     
     
         13 . The process of  claim 1 , wherein collecting produced sample from the reservoir via a production well is during enhanced oil recovery or during drilling operations. 
     
     
         14 . An anthropogenic CO2 monitoring and quantifying system comprising:
 one or more injection wells;   one or more production wells;   one or more measurement devices associated with the one or more injection wells for measuring an amount of CO2 injected into a reservoir via the one or more injection wells; and   a measurement collection and analysis system configured for receiving gas samples and for measuring an amount of CO2 sequestered within the reservoir.   
     
     
         15 . The system of  claim 14 , wherein CO2 monitoring and quantifying system further comprises a mud gas separator. 
     
     
         16 . The system of  claim 14 , wherein CO2 monitoring and quantifying system further comprises a CO2 storage plant. 
     
     
         17 . The system of  claim 14 , wherein CO2 monitoring and quantifying system further comprises a processing plant. 
     
     
         18 . The system of  claim 14 , wherein the reservoir is a depleted reservoir. 
     
     
         19 . The system of  claim 14 , wherein the reservoir is undergoing enhanced oil recovery or drilling operations.