Welltest 106: Impulse & Closed Chamber Tests

Perforation Inflow Distribution Diagnostic (PIDD) Tests. The PID #welltest is analogous to production logging when two or more intervals are perforated. Based on changes to the Dp/Dt slope, gas (#LNG) inflow and AOF ratios can be estimated. Starting with the interval of least anticipated influx potential, multiple perforation runs are conducted. Subsequent to each perforation run, pressures are allowed to build up for a set period of time, being a function of permeability and rate of pressure increase. It may be necessary to blow down the well if pressures exceed the critical flow cut-off point of one-half (½) the static reservoir pressure. This first example illustrates four intervals perforated with no cushion. Perforated intervals two and three obviously exhibited an increment in slope, contributing subsequently higher inflow ratios. Perforation interval number four did not exhibit an increment in slope and thus contributed negligible gas.