The phase behavior of petroleum fluids is essential in shale oil and gas production. The fluid properties in low permeability, low porosity shales are different from those in conventional reservoirs, which have high porosity and high permeability. Shales have nano-scale pores. Due to the strong surface-fluid interactions and complex pore geometries in shale nanopores, PVT properties of fluids in shale are different than in conventional reservoirs and thus cannot be described by bulk-phase thermodynamics.<br/>In this work, we investigate phase changes in three different hydrocarbons (toluene, heptane, decane) and water with and without the effect of confinement (nano-sized porous materials) using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). SBA-15 and SBA-16 were synthesized to use as confined systems in this work. Both SBA-15 and SBA-16 have pores of about 4 nm in size. To compare the effect of confinement on phase changes, SiO<sub>2, </sub>which has similar grain size to SBA-15 and SBA-16 but no nano-sized pores, is used under the same experimental conditions. Also, mesoporous SBA-15 has hexagonal pores, while SBA-16 has cubic pores. The effect of pore morphology on phase changes in hydrocarbons is also studied. Boiling and melting points were affected by the nano-sized porous samples, and the degree of change depends on the pore morphology, including pore volume and grain shape. Also, we studied the effect of confinement on phase transitions at high pressures. These findings can contribute to expanding our understanding of phase change/phase behavior in natural porous media, including shales. <br/>

Effect of confinement on phase transitions of hydrocarbons in nanoporous materials

2019 Fall National Meeting

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