Unusually physical and chemical characteristics of oil sands from Qaidam basin, NW China

Gas chromatography (GC), gas chromatography-mass spectrometry (GC/MS), supercritical fluid chromatography (SFC), elemental analysis, infrared absorption spectroscopy (IR), thermal analysis (TG/DTA), Rock-Eval pyrolysis, as well as viscosity and density analysis revealed that oil sands from Qaidam basin, Qinghai Province of China, are highly concentrated in light components (£C23), with saturated hydrocarbons (including most n-alkanes) comprising between 49.6 to 71.4% of total organics (wt.%). Their physicochemical characteristics are very similar to those of heavy oils, rather than other oil sand bitumens. The above analyses suggest that Qinghai oil sands originate from a terrigenous source, similar to oils from the surrounding area. Additionally, the existence of n-alkanes shows that the oil sands are weakly biodegraded, and that the formation of these unusual oil sands is related to the particular geographic/climatic conditions of Qaidam basin. No other known oil sands with chemical composition and distribution similar to that in Qinghai have been documented. Exploitation should be initiated with drilling wells followed by open pit mining.