Abstract

The behavior of producing gas-oil ratio GOR in unconventional reservoirs like liquid-rich shales LRS and conventional reservoirs differ This is mainly due to major disparity in the permeability ultra-low in unconventional reservoirs in comparison to that in conventional higherpermeability reservoirs The ultra-low permeability and porosity of shales among other factors contribute to the complex fluid flow mechanisms in these plays Therefore there is a need for a good comprehension of the physics of flow in liquid-rich shale reservoirs This paper particularly investigates how various factors ranging from critical gas saturation to compaction affect producing gas-oil ratio behavior in liquid-rich shale LRS reservoirs Ten different moderately volatile and highly volatile near-critical oil fluid compositions were considered Compositional reservoir simulations for a period of 30 years were run on a base case multi-fractured horizontal well MFHW model for each fluid type Results showed that the different factors had varying impacts on the production performance and GOR behavior of LRS reservoirs some more influential than others Also the fluid type whether moderate or highly volatile oil play a major role in determining how producing gas-oil ratios GOR behave in a LRS reservoir A proper understanding of unconventional reservoir production mechanisms is necessary for reliable reserves estimation production forecasting and improving oil recovery This work contributes to this mission and provides a better understanding of the performance of liquid-rich shale plays