the present invention relates to the bioupgrading of crude oil is directed to a process for decreasing the acidity of an acidic crude oil , comprising contacting an acidic crude oil with a mixture nitrogen containing compounds selected from the group comprising ammonia , ammonia hydroxide , amines and the salts thereof , and in the presence of lipase enzyme , under conditions of suitable temperature and pressure sufficient to form the corresponding amide . the resulting naphthenic acid derived amides can then be processed normally in a refinery using such processes as cracking or hydrotreating and converted to hydrocarbon , ammonia and carbon dioxide without causing damage to the refinery infrastructure . this enzyme process is done at reduced temperatures and pressures requiring less energy .