Equation of state (EOS) modelling in CONVENTIONAL reservoirs is well established and has been successfully employed in PVT studies of basins globally for many years. However, what is the current status of EOS modelling in UNCONVENTIONAL reservoirs, especially those that have undergone significant uplift and late secondary migration of high-maturity gas? (e.g., Montney Formation of western Canada; Woodford/Meramec formations, Arkoma and Anadarko basins)

Such unconventional reservoirs respond dynamically to naturally changing PVT conditions and may end up with intimately co-existing fluids that are not in equilibrium: for example, separated and migrating gas may exist in large “unconfined” pores whereas supercritical fluids exist in small “confined” pores. Such fluids can present problems for PVT recombination and the results may not reflect the in-situ condition of fluid segregation at the micron scale.

I wonder what expert opinions have to say about the above and the the current status of EOS modelling in unconventional reservoirs. I welcome any responses that can shed light on this.

Thanks, Jim.