Welltest 200: PTA Tool Kit

More than Just PTA… Checking differentials provides added value. The operator was ready to walk away from this well due to uneconomically low gas rates. However, note the huge tubing/casing differential, not to mention the casing pressure trend shift from declining to suddenly building up! A check of operation reports revealed that wireline encountered an obstruction and could not install recorders, hence the need to use surface pressure data acquisition equipment (gauges). Casing pressure data indicated a sandface AOF ten-times greater than the tubinghead TOF. In reality this well had a crimp in the coiled tubing string. After repair, the well flowed an economic 20 e³m³/d compared to the test gas rate of only 2.5 e³m³/d.