Springer 2010 – Applied Microbiology and Molecular Biology in Oilfield Systems
Chapter 18, pp 237–244
Chapter 28 – Fuel for the Future – Unlocking New Fuel Resourses
With worldwide production of light crude oil reserves expected to last ~50 years, a global energy crisis may ensue. In fact, a recent report by the UK Energy Research Centre stated that ‘conventional oil production may peak before 2030 with a significant risk of a peak before 2020’ (October, 2009). Therefore, there is an increasing need to look towards the use of alternative fuel resources like the heavy/ super heavy crude oils and oil sands. In Canada and Venezuela there are vast oil sands (containing 2,100 billion barrels) that are already being exploited (Clemente and Fedorak, 2005). During oil sand refining, bitumen is extracted, which results in large amounts of contaminated waters (known as tailings pond water, TPW) being generated. TPW contain complex mixtures of toxic alicyclic, aliphatic and aromatic acids known as naphthenic acids (NAs). TPW have to be stored in large ponds for several years until their toxicity is reduced to acceptable levels and consequently they pose a significant environmental risk. TPW contain NA concentrations between 40 to 120 mg/l (Herman et. al, 1994) and with the volume of process water expected to reach 1 billion m3 by 2025 (Hadwin et al., 2006), removal of NAs is of great environmental importance.
NAs are highly recalcitrant compounds that persist in the environment for many years. They have been shown to be toxic to many organisms, including rats (Rogers et al., 2002); fish (Dokholyan and Magomedov, 1984); and microorgan¬isms (Clemente et al., 2004). NAs may also cause severe engineering problems. For example, the presence of NAs in oil increases the total acid number (TAN), devalu¬ing the oil and making it less saleable. NAs can also form calcium naphthenate deposits which can block pipelines and processing equipment causing billions in lost revenue as well as the cost of replacing equipment. NAs are highly corrosive (due to the carboxylic acid group and the polar nature of NAs) which can also cause equipment failure.