2.
n. [Production Testing]
A type of
deliverability test conducted in gas wells to generate a
stabilized gas deliverability
curve (
IPR). This test overcomes the limitation of the
isochronal test, which requires long shut-in times to reach the
average reservoir pressure.
In the modified isochronal test, the shut-in periods are of equal duration, as are the flowing periods. The final shut-in
pressure before the beginning of the new flow is used as an approximation of the average
reservoir pressure. The same procedure is typically repeated four times. A stabilized point (
pseudosteady state) is usually obtained at the end of the test.
Modified isochronal tests are commonly used in gas wells, because they require less time and money to produce results comparable to the isochronal test.