Casing collar locator and method for locating casing collars

A casing collar locator adapted to detect casing collars disposed in a wellbore, comprising:

• a fiber optic line carrying an optical signal;
• a magnetic device adapted to become magnetically connected to a casing collar as the magnetic device passes the casing collar;
• a modulator that is functionally connected to the magnetic device;
• wherein the optical signal is modulated by the modulator when the magnetic device passes the casing collar;
• wherein the optical signal is modulated by imparting a strain on the fiber optic line;
• wherein the magnetic device comprises a permanent magnet and a coil.

A casing collar locator adapted to detect casing collars disposed in a wellbore, comprising:

• a fiber optic line carrying an optical signal;
• a magnetic device adapted to become magnetically connected to a casing collar as the magnetic device passes the casing collar;
• a modulator that is functionally connected to the magnetic device;
• wherein the optical signal is modulated by the modulator when the magnetic device passes the casing collar;
• wherein the optical signal is modulated by imparting a strain on the fiber optic line;
• wherein the magnetic connection generates a voltage that causes a piezoelectric material mechanically coupled to the fiber optic line to constrict and strain the fiber optic line.

A casing collar locator adapted to detect casing collars disposed in a wellbore, comprising:

• a fiber optic line carrying an optical signal;
• a magnetic device adapted to become magnetically connected to a casing collar as the magnetic device passes the casing collar;
• a modulator that is functionally connected to the magnetic device;
• wherein the optical signal is modulated by the modulator when the magnetic device passes the casing collar;
• wherein the modulator moves in relation to the fiber optic line to cause the modulation of the optical signal;
• wherein the magnetic device comprises a permanent magnet and a moving magnet and the moving magnet moves in relation to the permanent magnet when the magnetic device passes the casing collar;
• wherein movement of the moving magnet causes the movement of the modulator in relation to the fiber optic line;
• wherein the moving magnet is biased to a stationary position by a spring.

A casing collar locator adapted to detect casing collars disposed in a wellbore, comprising:

• a fiber optic line carrying an optical signal;
• a magnetic device adapted to become magnetically connected to a casing collar as the magnetic device passes the casing collar;
• a modulator that is functionally connected to the magnetic device;
• wherein the optical signal is modulated by the modulator when the magnetic device passes the casing collar;
• wherein the modulator moves in relation to the fiber optic line to cause the modulation of the optical signal;
• wherein the magnetic device comprises a permanent magnet and a moving magnet and the moving magnet moves in relation to the permanent magnet when the magnetic device passes the casing collar;
• wherein movement of the moving magnet causes the movement of the modulator in relation to the fiber optic line;
• wherein the modulator comprises a component having alternately placed black and white lines.

A method for identifying the location of casing collars disposed in a wellbore, comprising:

• providing a magnetic device adapted to become magnetically connected to a casing collar as the magnetic device passes the casing collar;
• and
• modulating an optical signal transmitted through a fiber optic line when the magnetic device passes the casing collar;
• wherein the modulating step comprises imparting a strain on the fiber optic line;
• wherein the imparting step comprises creating a magnetic connection between the magnetic device and the casing collar when the magnetic device passes the casing collar;
• and generating a voltage that causes a piezoelectric material mechanically coupled to the fiber optic line to constrict and strain the fiber optic line.

A method for identifying the location of casing collars disposed in a wellbore, comprising:

• providing a magnetic device adapted to become magnetically connected to a casing collar as the magnetic device passes the casing collar;
• and
• modulating an optical signal transmitted through a fiber optic line when the magnetic device passes the casing collar;
• wherein the modulating step comprises moving a modulator in relation to the fiber optic line;
• wherein the moving step comprises moving a moving magnet in relation to a permanent magnet when the magnetic device passes the casing collar;
• the method further comprising biasing the moving magnet to stationary position by use of spring.