A
petroleum well having a well casing, a
production tubing, a source of time-varying current, a downhole chemical
injection device, and a downhole induction
choke. The casing extends within a
wellbore of the well. The tubing extends within the casing. The
current source is located at the surface. The
current source is electrically connected to, and adapted to output a time-varying current into, the tubing and / or the casing, which act as electrical conductors for providing downhole power and / or communications. The
injection device having a communications and control module, a chemical container, and an electrically controllable chemical
injector. The communications and control module is electrically connected to the tubing and / or the casing. The chemical
injector is electrically connected to the communications and control module, and is in fluid communication with the chemical container. The downhole induction
choke is located about a portion of the tubing and / or the casing. The chemical
injector is electrically connected to the communications and control module, and is in fluid communication with the chemical container. The downhole induction
choke is located about a portion of the tubing and / or the casing. The induction choke is adapted to
route part of the
electrical current through the communications and control module by creating a
voltage potential between one side of the induction choke and another side of the induction choke. The communications and control module is electrically connected across the
voltage potential. Also, a method is provided for controllably injecting a chemical into the well downhole, which may be used to: improve lift efficiency with a
foaming agent, prevent deposition of solids with a paraffin
solvent, improve a flow characteristic of the flow
stream with a surfactant, prevent
corrosion with a
corrosion inhibitor, and / or prevent scaling with scale preventers.