Question

36) To prevent the souring of crude oil, ________ is added to oil well injection water to encourage ________ instead of ________.

A) oxygen / aerobic respiration / sulfate reduction
B) sulfate / sulfate reduction / fermentation
C) sulfate / sulfate reduction / nitrate reduction
D) nitrate / nitrate reduction / sulfate reduction

Answer 1

Sulfate is added to oil well injection water to encourage sulfate reduction and prevent the souring of crude oil by avoiding the production of hydrogen sulfide, caused by sulfate-reducing bacteria.

Step-by-step explanation:

To prevent the souring of crude oil, sulfate is added to oil well injection water to encourage sulfate reduction instead of nitrate reduction. This is because sulfate-reducing bacteria can cause the production of hydrogen sulfide, which is detrimental to the quality of the crude oil, leading to souring. The addition of sulfate encourages these bacteria to use sulfate as an electron acceptor for anaerobic respiration, which prevents the production of hydrogen sulfide.