Method for the use of nitrates and nitrate reducing bacteria in hydraulic fracturing

Controlling sulfides in subterranean formations, comprising; Injecting an inorganic nitrate in to the formation and Allowing the inorganic nitrate to increase the growth rate of nitrogen-reducing bacter (NRB) in the formation to inhibit the growth rate of sulphate-reducing bacteria (SRB) in the formation. The inorganic nitrate may be potassium, sodium or ammonium salts of nitrate or mixtures thereof. The method may further comprise injecting NRB in to the formation where the NRB may be from the group Campylobacter sp. Nitrobacter sp. Nistromonas sp. Thiomicrospira sp. Sulfurospirillum sp. Thauera sp. Paracoccus sp. Pseudomonas sp. Rhodobacter sp. Desulfovibrio sp. and mixtures thereof. The method may further comprise injecting a molybdate salt which may be sodium or lithium molybdate and/or injecting 9,10-anthraquinon in to the formation. Fracturing fluid may be injected in to a subterranean formation where the fracturing fluid contains brine and the other ingredients of the above method. The fracturing fluid may further comprise a scale inhibitor (eg polyacrylates) and/or a friction reducer (eg polyacrylamide) and may comprise a gel.