Perforation Inflow Test Type

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Perforation Inflow tests are a type of closed chamber test that is conducted by allowing reservoir fluid (gas, oil, or water) to flow into the closed wellbore after perforating and monitoring the ensuing pressure buildup with time. This occurs when the well perforated in an under-balanced condition (initial cushion pressure (pwo) < initial reservoir pressure (pi)).

Perforation Injection tests are analogous to this and occur when the well is perforated in an over-balanced condition. These tests have been referenced as: Slug tests, Surge tests, Perforation Inflow Diagnostics (PID), or Closed Chamber tests.

Perforation Inflow tests are attractive in unconventional (low-permeability) reservoirs because estimates of initial reservoir pressure (pi), permeability (k), and skin (s') can be obtained in a shorter duration than buildup tests, and because they don’t require any venting / flaring into the atmosphere. However, the radius of investigation achieved from these tests is less than that of a buildup test.