Polymeric red mud-based killing fluid and uses thereof

A high-density red mud-based kill fluid composition includes a neutralized red mud slurry, a polymeric material, and an H2S capturing agent. A method of neutralizing red mud includes providing a red mud slurry, adding gypsum to the red mud slurry, and providing a neutralized red mud slurry, wherein the neutralized red mud slurry has a pH ranging from 7.5 to 9.0. A method of treating a sour well includes injecting a red mud-based kill fluid including a neutralized red mud slurry, a polymeric material, and an H2S capturing agent into the sour well, wherein the sour well comprises H2S gas and CO2 gas, solidifying the red mud-based kill fluid, and treating the H2S gas and the CO2 gas in the sour well.