Patent ID: 11952869
Assignee: CHINA UNIVERSITY OF PETROLEUM (EAST CHINA)
Field: Civil engineering (Other fields)
Classification: CPC E | IPC E

Claim 3:
4. The high-efficiency yield-increasing exploitation method for the natural gas hydrates according to claim 3, wherein in step (ii), a preparation process of the foam cement slurry is as follows:
mixing a certain mass of cement with water to form cement slurry, and adding a certain mass of foaming agent and foam stabilizer to the cement slurry with stirring to form foam cement slurry;
in the preparation of the foam cement slurry, according to the properties of the required foam cement slurry and a mix proportioning principle thereof, the using amount of the cement is as follows:, M
      
       s
       ⁢
       n
      
     
     =
     
      
       
        V
        gfc
       
       ·
       
        ρ
        gfc
       
      
      
       s
       a
      
     
    
   
   
    
     (
     5
     )
    
   
  
 

wherein Msn is the using amount of the cement, kg; ρgfc is the design dry density of the foam cement, kg/m3; Vgfc is the volume of the dry foam cement, m3; Sa is a mass coefficient, which is dimensionless, wherein the mass coefficient is 1.2 for ordinary Portland cement, and 1.4 for sulfate cement;
water supply volume:

Mw=α·Msn  (6), wherein Mw is the water supply volume; a is a basic ratio of water to materials, which is dimensionless;
the using amount of the foaming agent:, M
      p
     
     =
     
      
       
        V
        py
       
       ·
       
        ρ
        py
       
      
      
       b
       +
       1
      
     
    
   
   
    
     (
     7
     )
    
   
  
 

wherein Mp is the mass of the foaming agent in the foam cement slurry, kg; Vpy is the volume of a foam concentrate formed from the foaming agent, m3; ρpy is the density of the foam concentrate formed from the foaming agent, kg/m3; b is the times of foaming of the foaming agent, which is dimensionless; and
the using amount of the foam stabilizer is half of that of the foaming agent.