A Pore-Geometry-Based Thermodynamic Model for the Nanoconfined Phase Behavior in Shale Condensate Reservoirs

Abstract

Abstract Shale condensate reservoirs, as one of the most important unconventional resources, have been attracting more and more attention recently. Researchers have developed several models for analyzing the phase behavior in nanopores. However, investigation of pore-geometry-based nanopore confinement is still lacking in the oil industry. Therefore, we develop a comprehensive thermodynamic model to satisfy this gas and simulate to the Eagle Ford shale condensate reservoirs. The model is first built with modification of the PR-EOS coupling the pore-geometry-based capillarity and adsorption. The Multicomponent Langmuir (ML) adsorption model is utilized. A good agreement is shown between this proposed model and the experimental data, which is associated with bulk fluid and confined fluid. After that, phase behavior of C1-C10 and C1-C4 mixtures is analyzed. Results indicate that capillarity and adsorption can result in noticeable deviation in the phase envelope. Additionally, pores with square and triangular cross-sections are analyzed, illustrating that pore geometries also have a significant influence on the phase behavior. Finally, a case study of the Eagle Ford shale condensate reservoir is performed. Phase behaviors in different pore geometries are analyzed by the ML adsorption model in detail, which will be more realistic than only circle pores. Moreover, we examine the physical properties of fluid in the Eagle Ford shale condensate reservoir. This work provides useful insights into the phase behavior of nanopores in shale formation, especially in the case of CO2-EOR in the shale condensate reservoirs.