Standing Injection Valve with Hydraulically Dampened Valve Closure

An injection valve assembly for use in a well, where pressurized gas or fluid from uphole in the well displaces a perforated valve head from a valve seat, allows for fluid flow of the pressurized gas or fluid into the valve head and further downhole in the well toward an electric submersible pump. A compression spring is coiled around a valve stem connected to the valve head, pushing the valve stem and valve head in an uphole direction opposite to the force from pressurized gas or fluid. The compression spring is in a chamber filled with hydraulic fluid, where the hydraulic fluid can pass through a dampening system assembly and a flow restrictor assembly, thereby regulating the speed at which the valve stem and valve head can move relative to the valve seat.