1963 Paper (M)

LOGGING ANOMALIES ASSOCIATED WITH METALLIC "FISH" IN DRILL-HOLES

by

Hamilton M. Johnson Geology Department, Tulane University New Orleans, Louisiana

ABSTRACT

The metallic "fish" most often encountered in drill-holes are pipe, either twisted-off drill pipe or casing. They may be single joints, ranging in length from several feet to as much as forty feet if including the cement shoe, or they may be multiple joints and of great length. They may be centered in the hole, so that the logging device passes through the pipe, or may be displaced so that the logging device never touches the pipe in passing beside it. They may even be present in a side-track of the hole now being logged.

All such "fish", due to distortion of the applied electrical field, will cause disturbances (anomalies) in the curves of any log measuring electrical properties of the rocks. These anomalies vary with pipe length, pipe location, the type log being recorded, and the resistivities of the surrounding beds. Fifteen actual field examples are presented, mostly electrical logs, recorded in both oil-emulsion muds and the usual fresh-water clay muds, but also including both the induction log and a microlog. These illustrations include various conditions of pipe length and position.