Rotator for wireline conveyed wellbore instruments and method for rotating an instrument in a wellbore

An apparatus for rotating an instrument in a wellbore, comprising:

• a non magnetic housing configured to traverse the interior of the wellbore, the housing having an external diameter smaller than an internal diameter of a casing disposed in the wellbore;
• a plurality of electromagnets arranged circumferentially about the interior of the housing and configured to induce magnetic flux through a wall of the housing when actuated and wherein the magnetic flux causes the housing to magnetically clamp to the casing disposed in the wellbore;
• and
• a controller configured to sequentially rotationally actuate the electromagnets, and thereby roll the non magnetic housing around the interior of the casing through at least a plurality of positions while the non magnetic housing remains magnetically clamped to the casing.

A method for rotating a wellbore instrument in a wellbore, comprising:

• causing parts of an instrument housing to be sequentially rotationally magnetically clamped to a casing disposed in the wellbore, wherein the housing has a smaller external diameter than an internal diameter of the casing;
• continuing to cause parts of the instrument housing to be sequentially rotationally magnetically clamped to cause the instrument housing to rotate for a selected time;
• and
• rolling the instrument housing around the interior of the casing through at least a plurality of positions while the instrument housing remains magnetically clamped to the casing.