US Patent 11708736 Cutting wellhead gate valve by water jetting

A well tool assembly to cut a wellhead gate valve by water jetting includes a water jetting head lowered into a wellhead tree coupled to a wellbore. The head includes a housing, an orifice plate and a jetting port. The housing defines a tubular region to receive water. The orifice plate is positioned within the tubular region downstream of a first end and upstream of a second end of the housing, and defines an orifice to accelerate a flow rate of the water received at a first flow rate upstream of the orifice plate to a second flow rate, greater than the first, downstream of the plate. At the second flow rate, the water can mill a gate valve within the wellhead. The jetting port is downstream of the orifice plate, and can receive the water at the second flow rate and guide the received water to the gate valve.