Modeling Fluid Flow in Tight Unconventional Reservoirs: Nano Scale Mobility/Trapability Mechanistic Approach!

Abstract Fluid flow through UCRs (Unoconventional Reservoirs) is governed by several mechanisms such as viscous, convection (comprises of diffusion and advection), sorption (comprises of absorption and adsorption), capillary and inertial forces taking places in two different domains - inorganic (rock) domain and organic (kerogen) domain. These mechanisms act in two main pore scale levels, Micro- and Nano-pores, in addition to the Macro scale level considered to host the flow within fractures and fissures whenever encountered (naturally existing or induced). This research aims at building a comprehensive model, based on thorough understanding of these fluid flow complexities of UCRs. The developed modeling technique assumed to predict fluid flow by coupling the effect of both displacement and trapability forces and relating these forces within the three pore scale levels (Macro, Micro and Nano). A fundamental model for the above mentioned mechanisms has been established. Sensitivity study to determine the contributions of these specific mechanisms along with a criterion to develop tight UCRs is presented. A new and unique flow behavioral model to enable predicting flow characteristics through tight UCRs within nanopores has been established. This model will be used in estimating realistic hydrocarbon-in-place, reserves, and profiling production performance using different potential methods. This research has the following specific outcomes: (1) Comprehensive workflow and methods of UCR characterization. (2) A model to predict the fluid flow behavior through UCRs. (3) A criterion to predict the effects of different flow parameters (displacement & trapability) on fluid flow behavior in UCRs. (4) A new field-development scheme suitable for tight UCRs.