Coating of the piston for a rotating percussion system in downhole drilling

摘要

A system and method of fabricating a percussion tool that includes one or more coatings applied onto a piston, casing, and/or flow tube. The percussion tool includes a piston positioned in sliding contact within a casing. The piston includes an inner wall and an outer wall, where the inner wall defines a passageway extending longitudinally therethrough. The outer wall is positioned in close fitting relationship with an internal surface of the casing. One or more coatings are disposed on at least one of the casing's internal surface and/or the piston's outer wall. A flow tube may be placed through the passageway such that an outer wall of the flow tube is in a close fitting relationship with the piston's inner wall. One or more coatings can be disposed on at least one of the piston's inner wall and/or the flow tube's outer wall.

主权项

1. A downhole percussion tool, comprising:
a casing comprising a top end, a bottom end, and an internal surface extending from the top end to the bottom end, the internal surface defining a casing passageway extending longitudinally therein; a mandrel being supported within a lower portion of the casing; a piston slidably mounted within the casing passageway above the mandrel and moveable to deliver an impact force onto the mandrel, the piston comprising:
an interior wall extending from an upper surface of the piston to a lower surface of the piston and defining a piston passageway extending therethrough; andan exterior wall surrounding the interior wall and extending from the upper surface of the piston to the lower surface of the piston, the exterior wall and the casing being positioned in close fitting relationship, wherein, at least one of:
the internal surface of the casing is nitrided, andthe exterior wall of the piston is nitrided; and a first coating bonded to the nitrided one of the internal surface and the exterior wall.