Patent attributes
A wellbore chemical injection assembly includes an extension flange including two ends and defining a flange bore. The first end can be fluidically coupled to a tubing spool inlet of a wellhead installed at a wellbore surface. The second end can be fluidically coupled to a chemical reservoir from which chemical is injected through the flange bore into the tubing spool. The assembly includes a mandrel positioned within the extension flange. A portion of the mandrel resides within the flange bore, while a remainder extends out. The mandrel defines an interior opening spanning an axial length of the mandrel. Outer coupling threads formed on the mandrel can removably mate with counterpart threads in the tubing spool inlet. Inner coupling threads formed on an inner surface of a portion of the interior opening can removably mate with coupling threads on a valve assembly removably seated in the interior opening.