Patent ID: 9097069
Filing Date: 2015-08-04
Classification: E21B

Abstract:
1. A tool for centralizing a casing or liner in a borehole, comprising: a tubular section to be inserted between two sections of the casing or liner, a plurality of pressure cylinders mounted in bores along the circumference of the tubular section, wherein the pressure cylinders are adapted to expand radially by means of a pressure exerted on the inside of the tubular section, a ring piston running in a ring cylinder in the wall of the tubular section, a number of intake channels leading from the inside of the tubular section to a first side of the ring piston, a number of pressure channels leading from a second side of the ring piston to each pressure cylinder, and mechanism for preventing the ring piston from going from an activated position in which the pressure cylinders are expanded back to an in-activated position selected from the group consisting of: locking grooves in the ring piston co-operating with locking hooks arranged in the wall of the ring cylinder, and check valves arranged in the pressure channels.