What type of flow occurs when all boundaries have been encountered in a closed reservoir and the formation is undergoing depletion?

What type of flow occurs when all boundaries have been encountered in a closed reservoir and the formation is undergoing depletion?

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

Answer: (A)

When a reservoir is finite and all boundaries have been reached while the reservoir is being depleted, the pressure field adjusts so that the flow resembles steady-state behavior even though the pressure is still changing with time. This is pseudosteady-state flow: the boundary effects have become dominant, producing a nearly constant pressure gradient from the boundary to the well and a essentially linear pressure distribution with radius. This makes the decline look like a steady process, unlike the early, purely radial flow seen in an effectively infinite reservoir. Radial flow describes flow without boundary influence, bilinear flow applies to certain boundary geometries with two directions of restriction, and spherical flow involves three-dimensional radial symmetry around a point. In a closed, depleted reservoir, the situation best matches pseudosteady-state flow.

When a reservoir is finite and all boundaries have been reached while the reservoir is being depleted, the pressure field adjusts so that the flow resembles steady-state behavior even though the pressure is still changing with time. This is pseudosteady-state flow: the boundary effects have become dominant, producing a nearly constant pressure gradient from the boundary to the well and a essentially linear pressure distribution with radius. This makes the decline look like a steady process, unlike the early, purely radial flow seen in an effectively infinite reservoir. Radial flow describes flow without boundary influence, bilinear flow applies to certain boundary geometries with two directions of restriction, and spherical flow involves three-dimensional radial symmetry around a point. In a closed, depleted reservoir, the situation best matches pseudosteady-state flow.