Method of forming a window in a casing

A method of cutting through a tubular of a wellbore at a selected location in the wellbore using a remotely controlled electrically powered cutting tool that comprises (a) a tool body, (b) a cutting head provided with a cutting means, the cutting head being pivotally mounted on the tool body at or near the lower end thereof, (c) an electrically actuatable means for pivoting the cutting head, and (d) a biasing means, the method comprising the steps of:

• passing the cutting tool to the selected location in the wellbore with the longitudinal axis of the cutting head aligned with the longitudinal axis of the tool body;
• electrically actuating the pivoting means to pivot the cutting head with respect to the tool body to a position where the cutting means of the cutting head is adjacent the wall of the tubular;
• actuating the biasing means to urge the cutting means of the cutting head against the wall of the tubular;
• and
• actuating the cutting means to cut through the tubular of the wellbore,
• wherein the biasing means is an elongate arm that is an extension of the cutting head, said arm being moveable between a retracted position where said elongate arm lies within a longitudinal recess in the tool body and an extended position.