US Patent 9995115 Boost assisted force balancing setting tool

A setting tool is provided for positioning in a subterranean wellbore. The tool carries a pre-charged, pressurized chamber, preferably filled with inert gas. A force-balanced piston assembly, with the piston chamber initially at atmospheric pressure, is in selective fluid communication with the pressurized chamber. A release mechanism, rupture disc, or valve is selectively operable to open the pressurized chamber and allow fluid flow to the piston chamber. The pressurized gas drives the piston which, in turn, drives a power rod for setting a downhole tool. Preferably a flow restrictor is incorporated in the gas flow path to meter the fluid and control the setting speed. In a preferred embodiment, the pressurized chamber is opened by rupturing a disc. A pyrotechnic device, which qualifies as a non-explosive device and is triggered by a low-powered battery, drives a piercing member into and through the rupture disc.