Methods of Cementing in Subterranean Formations Involving Reduced Pumping Pressure

Abstract

A method of initiating fluid circulation in a well bore with a casing inner diameter and an annulus is provided. The method includes increasing the casing inner diameter fluid pressure at the top of the well bore; flowing a cement composition into the casing inner diameter at the top of the well bore; maintaining a difference in pressure between the fluid pressure of the casing inner diameter and the fluid pressure of the annulus until enough of the cement composition has entered the casing inner diameter to drive fluid circulation by the added cement composition weight; reducing the casing inner diameter fluid pressure at the top of the well bore while flowing a further portion of cement composition into the casing inner diameter; and pumping at a relatively higher fluid pressure the cement composition from the casing inner diameter into the annulus through a lower end of the casing.

1 . A method of initiating fluid circulation in a well bore through a casing inner diameter and an annulus outside the casing, the method comprising: 
 increasing the casing inner diameter fluid pressure at the top of the well bore;    flowing a cement composition into the casing inner diameter at the top of the well bore;    maintaining a difference in pressure between the fluid pressure of the casing inner diameter and the fluid pressure of the annulus until enough of the cement composition has entered the casing inner diameter to drive fluid circulation by the added cement composition weight;    reducing the casing inner diameter fluid pressure at the top of the well bore while flowing a further portion of cement composition into the casing inner diameter; and    pumping at a relatively higher fluid pressure the cement composition from the casing inner diameter into the annulus through a lower end of the casing.    
   
   
       2 . A method of initiating fluid circulation in a well bore as claimed in  claim 1 , wherein said increasing the casing inner diameter fluid pressure comprises pumping a cement composition into the casing inner diameter with an electric pump.  
   
   
       3 . A method of initiating fluid circulation in a well bore as claimed in  claim 1 , wherein said increasing the casing inner diameter fluid pressure comprises pumping a cement composition into the casing inner diameter with a standpipe.  
   
   
       4 . A method of initiating fluid circulation in a well bore as claimed in  claim 1 , wherein said increasing the casing inner diameter fluid pressure comprises pumping a cement composition into the casing inner diameter with a rig pump.  
   
   
       5 . A method of initiating fluid circulation in a well bore as claimed in  claim 1 , wherein said increasing the casing inner diameter fluid pressure comprises pumping a cement composition into the casing inner diameter with a siphon pump.  
   
   
       6 . A method of initiating fluid circulation in a well bore through a casing inner diameter and an annulus outside the casing, the method comprising: 
 decreasing the annulus fluid pressure by removing fluid from the annulus;    flowing a cement composition into the casing inner diameter at the top of the well bore;    maintaining a difference in pressure between the fluid pressure of the casing inner diameter and the fluid pressure of the annulus until enough of the cement composition has entered the casing inner diameter to drive fluid circulation by the added cement composition weight; and    pumping at a relatively higher fluid pressure the cement composition from the casing inner diameter into the annulus through a lower end of the casing.    
   
   
       7 . A method of initiating fluid circulation in a well bore as claimed in  claim 6 , wherein said decreasing the annulus fluid pressure comprises pumping circulation fluid out of the annulus with an electric pump.  
   
   
       8 . A method of initiating fluid circulation in a well bore as claimed in  claim 6 , wherein said decreasing the annulus fluid pressure comprises pumping circulation fluid out of the annulus with a Venturi pump.  
   
   
       9 . A method of initiating fluid circulation in a well bore as claimed in  claim 6 , wherein said decreasing the annulus fluid pressure comprises pumping circulation fluid out of the annulus with a rig pump.  
   
   
       10 . A method of initiating fluid circulation in a well bore through a casing inner diameter and an annulus outside the casing, the method comprising: 
 depositing a gas within the fluid in the annulus, whereby a portion of the fluid in the annulus is displaced by the gas;    flowing a cement composition into the casing inner diameter at the top of the well bore;    maintaining a difference in pressure between the fluid pressure of the casing inner diameter and the fluid pressure of the annulus until enough of the cement composition has entered the annulus to drive fluid circulation by the added cement composition weight; and    pumping at a relatively higher fluid pressure the cement composition from the casing inner diameter into the annulus through a lower end of the casing.    
   
   
       11 . A method of initiating fluid circulation in a well bore as claimed in  claim 10 , wherein said depositing a gas in the fluid in the annulus comprises injecting gas into the annulus.  
   
   
       12 . A method of initiating fluid circulation in a well bore as claimed in  claim 10 , wherein said depositing a gas in the fluid in the annulus comprises injecting pressurized gas into the annulus to displace circulation fluid from the casing inner diameter and releasing the pressurized gas from the annulus.  
   
   
       13 . A method of initiating fluid circulation in a well bore as claimed in  claim 10 , wherein said depositing a gas in the fluid in the annulus comprises injecting a fluid into the annulus, and allowing fluid in the annulus to vaporize.  
   
   
       14 . A method of initiating fluid circulation in a well bore as claimed in  claim 10 , wherein said depositing a gas in the fluid in the annulus comprises dropping gas-filled containers into the annulus and releasing the gas from the containers.