Proving Movable Reserves. In this example a high permeability sandstone overlaid a shale zone. Decline curve analysis indicated natural gas (#LNG) reserves greater than volumetrics could justify. It was hypothesized that the shale gas reserves migrated vertically, due to pressure differential, to be produced with the sandstone reserves. The shale was perforated first and exhibited a pressure increase, thus proving additional movable gas reserves. The second perforation response was from the high permeability (high #AOF) sandstone. The PID #welltest has also proven incremental by-passed reserves in Alberta’s east-central tight gas sands (Milk River/Medicine Hat/Second White Specks).