Which flow regime occurs between wellbore storage and infinite acting radial flow?

Which flow regime occurs between wellbore storage and infinite acting radial flow?

• A. Drawdown
• B. Pseudo Steady State
• C. Bilinear Flow
• D. Partial Penetration (Spherical Flow)

Answer: (D)

The concept being tested is how the flow geometry around a well evolves as the pressure-diffusion field develops after a rate change. When a well is not fully penetrating the formation, the near-well flow is three-dimensional and the diffusion into the formation resembles a spherical pattern around the penetrating interval. This partial-penetration condition produces a spherical flow regime that lies between the early-time near-well behavior (dominated by wellbore storage) and the later-time, fully developed infinite-acting radial flow. As time progresses, the flow field transitions to purely radial flow spreading into the reservoir, which is the infinite-acting radial regime. Drawing in the contrast: drawdown describes pressure drop, not a flow pattern. Pseudo steady state is a late-time behavior for bounded reservoirs, not the intermediate transition here. Bilinear flow is a different transitional pattern that can occur in some partial-penetration scenarios, but the specific case described points to spherical flow due to partial penetration.

The concept being tested is how the flow geometry around a well evolves as the pressure-diffusion field develops after a rate change. When a well is not fully penetrating the formation, the near-well flow is three-dimensional and the diffusion into the formation resembles a spherical pattern around the penetrating interval. This partial-penetration condition produces a spherical flow regime that lies between the early-time near-well behavior (dominated by wellbore storage) and the later-time, fully developed infinite-acting radial flow. As time progresses, the flow field transitions to purely radial flow spreading into the reservoir, which is the infinite-acting radial regime.

Drawing in the contrast: drawdown describes pressure drop, not a flow pattern. Pseudo steady state is a late-time behavior for bounded reservoirs, not the intermediate transition here. Bilinear flow is a different transitional pattern that can occur in some partial-penetration scenarios, but the specific case described points to spherical flow due to partial penetration.