Casing Inspection - Cased-Hole Log Analysis and Reservoir Performance Monitoring - page 233

Fig. 13.13 Internal anomaly and OD pit. Courtesy Schlumberger

Comments
No inner-surface anomaly is indicated, therefore defect is neither measureable nor
present on ID. Defect at 2127 ft is larger than defect at 2156 ft. Defect at 2127 ft
may be severe OD defect since it has high PAT response and appears on ETT. Defect
is probably OD pit or internal void due to ETT response at 2127 ft. OD pits are far
more common than any other point defects not on ID. Magnetic anomalies have
been observed in new N-80 casing. Stress points may occasionally be observed a
few feet below collars as a result of clamping joint with tongs.

Fig. 13.14 Through hole and ID pit. Courtesy Schlumberger

Comments
If in new casing log indicates defects. If through holes they would correspond as
follows:
2112 ft ¾ ″ , through hole (drilled); 2119 ft ½ ″ , through hole (drilled): 2132 ft 3/8 ″ ,

through hole (drilled):2170 ft 1 through hole (drilled). Inner-surface eddy-current

measurement is not capable of less than ½

″

″ diameter resolution. Flux-leakage response