Sweetening of sour gas wells

A method, comprising:

• supporting a production tubing in a wellbore from a terranean surface into a subterranean zone to a first depth in the wellbore, the subterranean zone comprising a formation fluid that comprises a hydrocarbon fluid having a first concentration of an acid gas, the first concentration being greater than a threshold concentration of acid gas;
• supporting a second tubing in the wellbore and within the production tubing to a second depth in the wellbore less than the first depth, the second depth between 500 feet and 2,000 feet in the wellbore;
• guiding, with the second tubing, a second fluid to an outlet of the second tubing at a longitudinal end of the second tubing at the second depth;
• and
• circulating, with the outlet of the second tubing, the second fluid into the formation fluid disposed in the production tubing, the second fluid configured to dilute the formation fluid in the production tubing to a second concentration of the acid gas that is less than the threshold concentration.