Well interference is a common phenomenon in unconventional‐reservoir development. The completion and production of infill wells can lead to either positive or negative well‐interference impacts on the existing producers. Many researchers have investigated the well‐interference phenomenon; however, few of them attempted to apply rigorous simulation methods to analyze both positive and negative well‐interference effects, especially in two different formations. In this work, we develop a comprehensive compositional reservoir model to study the well‐interference phenomena in the Eagle Ford Shale/Austin Chalk production system. The reservoir model considers capillary pressure in the vapor/liquid‐equilibrium (VLE) equation (nanopore‐confinement effect), and applies the embedded discrete‐fracture model (EDFM) for dynamic fracture modeling. We also include a multisegment‐well model to characterize the wellbore‐crossflow effect introduced by fracture hits. The simulation results indicate that negative well‐interference impact is much more common in the production system. With a smaller permeability difference, the hydraulic‐fracturing effect can lead to a positive well‐interference period of several hundred days. The nanopore‐confinement effect in the Eagle Ford Shale can contribute to the negative well‐interference effect. We also analyze the impact of other factors such as initial reservoir pressure, matrix porosity, initial water saturation, and the natural‐fracture system on the well performance. Our work provides valuable insights into dynamic well performance under the impact of well interference.