In which flow can permeability, average pressure, and wellbore skin be calculated?

• A. Radial Flow
• B. Bilinear Flow
• C. Image Wells
• D. Pseudosteady-State Flow

Answer: (A)

Radial flow is the regime around a single well where the flow pattern is circularly symmetric and depends primarily on the distance from the well. Because the pressure distribution follows a cylindrical form of the diffusion equation in this setup, standard well-test solutions relate the pressure response directly to permeability, formation thickness, fluid viscosity, and compressibility. This clean framework lets you extract permeability from the pressure change data, estimate the average reservoir pressure from late-time or buildup behavior, and account for near-wellbore losses as skin, which appears as an additional pressure drop at the well. Other flow descriptions describe more complex or different geometries—bilinear flow applies to fractures or layered media where flow isn't purely radial, image wells are a mathematical construction to handle boundaries rather than a flow regime, and pseudosteady-state flow is a late-time approximation with different pressure behavior—so they don’t provide the same straightforward means to determine all three quantities from the data.