Depth correlation device for fiber optic line

A wellbore depth correlation apparatus, comprising:

• a tubular string interval extending in a wellbore;
• a line adjacent said string that in said interval is a different length than said string;
• at least one device mounted to said string at a predetermined location and capable of correlating actual running length of said line to a position in said interval where said device is mounted;
• said device transmits a signal sensed by said line;
• said line collects data from the wellbore;
• said line comprises a fiber optic;
• said line collects wellbore temperature data;
• said device transmits heat or vibration to said fiber optic;
• said transmitted heat is discretely detected among the well temperature data collected by said fiber optic;
• said line has slack in said interval.

A wellbore depth correlation apparatus, comprising:

• a tubular string interval extending in a wellbore;
• a line adjacent said string that in said interval is a different length than said string;
• at least one device mounted to said string at a predetermined location and capable of correlating actual running length of said line to a position in said interval where said device is mounted;
• said at least one device comprises a plurality of devices at predetermined locations in said interval;
• said line is at least in part coiled around said string.