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)).