wireline formation test

1. n. [Well Testing]
Test taken with a wireline formation tester. The wireline formation pressure measurement is acquired by inserting a probe into the borehole wall and performing a minidrawdown and buildup by withdrawing a small amount of formation fluid and then waiting for the pressure to build up to the formation pore pressure. This measurement can provide formation pressures along the borehole, thereby giving a measure of pressure with depth or along a horizontal borehole. The trend in formation pressure with depth provides a measure of the formation-fluid density, and a change in this trend may indicate a fluid contact. Abrupt changes in formation pressure measurements with depth indicate differential pressure depletion and demonstrate barriers to vertical flow. Lateral variation in formation pressure measurements along a horizontal well or in multiple vertical wells indicate reservoir heterogeneity.