Patent ID: 11959933
Assignee: CHINA UNIVERSITY OF PETROLEUM (EAST CHINA)
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 2:
3. The experimental method for supercritical CO2/H2O mixed fluid huff and puff for shale oil development according to claim 1, characterized by further comprising a step of calculating the storage factor of supercritical CO2:
after injecting CO2 into the mixing vessel, reading the pressure of the mixing vessel from the first pressure gauge, and calculating the amount of CO2 in the mixing vessel according to the ideal gas law;
the ideal gas law being as follows:

PV=nZRT  (5)

where:
P—pressure of gas, Pa
V—volume of gas, m3 
n—amount of substance of gas, mol
Z—compressibility factor of gas;
R—proportionality coefficient, J/(mol·K)
T—system temperature, K
converting the volume of CO2 at atmospheric pressure measured by the measuring cylinder to a volume of CO2 at the pressure of the mixing vessel:
firstly, deriving a compressibility factor of carbon dioxide at the pressure of the mixing vessel by the formula (5):, Z
      1
     
     =
     
      
       
        P
        1
       
       ⁢
       
        V
        1
       
      
      
       
        n
        1
       
       ⁢
       
        RT
        1
       
      
     
    
   
   
    
     (
     6
     )
    
   
  
 

where:
P1—pressure of carbon dioxide at the pressure of the mixing vessel, Pa
V1—volume of carbon dioxide at the pressure of the mixing vessel, m3 
n1—amount of substance of carbon dioxide at the pressure of the mixing vessel, mol
Z1—compressibility factor of carbon dioxide at the pressure of the mixing vessel;
T1—temperature at the pressure of the mixing vessel, K
obtaining a compressibility factor of carbon dioxide with the equivalent amount of substance at atmospheric pressure:, Z
      2
     
     =
     
      
       
        P
        2
       
       ⁢
       
        V
        2
       
      
      
       
        n
        1
       
       ⁢
       
        RT
        2
       
      
     
    
   
   
    
     (
     7
     )
    
   
  
 

where:
P2—atmospheric pressure, Pa
V2—volume of carbon dioxide at atmospheric pressure, m3 
n1—amount of substance of carbon dioxide at atmospheric pressure, mol
Z2—compressibility factor of carbon dioxide at atmospheric pressure;
T2—room temperature, K
converting the volume of carbon dioxide at atmospheric pressure into a volume at the pressure of the mixing vessel by the following formula:, V
      1
     
     =
     
      
       
        Z
        1
       
       ⁢
       
        P
        2
       
       ⁢
       
        V
        2
       
       ⁢
       
        T
        1
       
      
      
       
        Z
        2
       
       ⁢
       
        P
        1
       
       ⁢
       
        T
        2
       
      
     
    
   
   
    
     (
     8
     )
    
   
  
 

and calculating the storage factor of supercritical CO2 by the following formula:, η
     =
     
      
       V
       flowback
      
      
       V
       injection
      
     
    
   
   
    
     (
     9
     )
    
   
  
 

where:
η—storage factor of supercritical CO2,
VInjection—volume of actually injected mixed fluid, m3 
Vflowback—volume at the pressure of the mixing vessel converted from the volume of CO2 flowed back measured by the measuring cylinder, m3.