T his paper presents a comprehensive characterization of a stratified reservoir employing hydrocarbon well test interpretation through the Tiab’s Direct Synthesis (TDS) Technique. The reservoir system in question exhibits cross f low phenomena and is separated by a low-permeability layer. Our mathematical model takes into account the interplay between formations, with an observation well situated in one stratum and an active well in another. To analyze the system, we generated multiple pressure and pressure derivative curves in dimensionless form. These curves were systematically integrated to unveil distinctive features, subsequently leading to the derivation of analytical equations. These equations are designed for easy, precise, and practical use. They facilitate the calculation of various essential parameters, including: total transmissibility, transmissibility in the support layer, transmissibility in the producing layer, dimensionless storage coefficient, interlayer flow parameter, capacity ratio, total and vertical flow ratio, dimensionless cross, the support layer and the semipermeable layer, among others. The developed expressions have undergone rigorous testing with both field and synthetic data, consistently yielding outstanding results. This study contributes valuable insights into the characterization of complex stratified reservoirs, offering practical solutions for reservoir engineers and geoscientists.