1. n. [Well Testing]
The characteristic plot of pressure versus time obtained from the mechanical recording of pressure gauges in a DST tool. Pressure rises as the tool is lowered into the hole and the hydrostatic head above the tool increases. The pressure stabilizes when the tool reaches bottom and then moves when the packer is set. Pressure drops immediately upon opening of the downhole valve to match the pressure in the drillstring, and then rises as fluid flows into the string. When the downhole valve is closed, the pressure buildup period begins immediately and continues until the valve is closed again.
Alternate Form: drillstem test
