Underreamer for increasing a wellbore diameter

摘要

An underreamer for increasing a diameter of a wellbore. The underreamer includes a body having an axial bore extending at least partially therethrough. A mandrel is disposed within the bore of the body and has a port formed radially therethrough. A sleeve is disposed radially-outward from the mandrel. The sleeve blocks fluid flow through the port in the mandrel when the sleeve is in a first position, and the sleeve is axially-offset from the port in the mandrel when the sleeve is in a second position. A flow tube is coupled to the mandrel. The sleeve moves from the first position to the second position when fluid flows through the flow tube and through a channel disposed in the mandrel. A cutter block is movably coupled to the body and is responsive to fluid flow from the axial bore through the port in the mandrel.

主权项

1. An underreamer for increasing a diameter of a wellbore, comprising:
a body having an axial bore extending at least partially therethrough; a mandrel disposed within the bore of the body and having a port formed radially therethrough; a sleeve disposed radially-outward from the mandrel and configured to move axially with respect to the mandrel from a first position to a second position, the sleeve blocking fluid flow through the port in the mandrel when in the first position and the sleeve allowing fluid flow through the port in the mandrel when in the second position; a flow tube coupled to the mandrel, the sleeve arranged and designed to move axially from the first position to the second position when fluid flows through the flow tube; a piston disposed radially-outward from the mandrel and proximate to the sleeve, wherein a chamber is defined between the piston and the mandrel, and a channel is defined through the mandrel and provides a path of fluid communication between the flow tube and the chamber, wherein the piston includes a port formed radially therethrough, and wherein the port in the piston is aligned with the port in the mandrel when the sleeve is in the second position; and a cutter block movably coupled to the body, an outer surface of cutter block being aligned with, or positioned radially-inward from, an outer surface of the body when the sleeve is in the first position, and the outer surface of the cutter block being positioned radially-outward from the outer surface of the body when the sleeve is in the second position.