Actuator switch for a downhole tool, tool and method

摘要

An actuator switch for actuation of a downhole tool, the actuator switch comprising:
a rheomagnetic fluid (30) having a state convertible between a liquid and a solid by the application of a magnetic field thereto, a change in the state of the rheomagnetic fluid acting to actuate the downhole tool; and a magnet (34) installed in the tool and moveable relative to the rheomagnetic fluid to apply or remove the magnetic field to the rheomagnetic fluid, the magnet being moved by through tubing operations in an inner diameter of the downhole tool.