Controlled downhole chemical injection

Abstract

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.