Regulatory Citation(s):

 

78.83b. Casing and cementing – lost circulation.

 

(a) If cement used to permanently cement the surface or coal protective casing is not circulated to the surface despite pumping a volume of cement equal to or greater than 120% of the calculated annular space, the operator shall determine the top of the cement, notify the Department, and meet one of the following requirements as approved by the Department.

 

 

Question:

 

If cement is seen at the surface but it falls back, is it OK to drill out and determine the TOC later?

 

 

Response:

 

Cement returns observed at the surface waive the lost-circulation requirements of Section 73.83b., even in the event of cement fall-back.  If cement returns are observed at the surface, the casing string is considered permanently cemented.  Deviating from engineered pumping rates or any other recommended cementing practices during cementing operations should not be undertaken in an attempt to realize surface returns.  Special care must always be taken to avoid scenarios where the combined effect of hydrostatic pressure and friction pressure in the annulus exceeds the breakdown pressure of the formation (i.e., concept of equivalent circulating density (ECD)).