Supercritical Fluid Extraction of Hydrocarbons from the Marcellus Shale by Using CO2

Abstract

Supercritical carbon dioxide was used to extract n-aliphatic hydrocarbons from samples of Marcellus shale, and to evaluate recovery as a function of sample matrix particle size (sieve size). Results show that supercritical CO2 has the potential to liberate diesel-range n-aliphatic hydrocarbons from high-maturity shale at estimated in situ pressure and temperature conditions. Total quantity of resolvable n-aliphatic hydrocarbons ranged from approximately 0.3 - 12 milligrams of hydrocarbon per gram of total organic carbon. No significant differences in extracted hydrocarbons were observed between crushed samples of different sieve sizes (1000 - 500 µm, 250 - 125 µm, and 63 - 25 µm). However, some increase in hydrocarbon extraction efficiency was seen as a function of exposed surface area. Additionally, a slight positive correlation was also observed between hydrocarbon recovery and S1 (free oil content) warranting further investigation.