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A foam depression test is designed to calculate accurate producing pressures in pumping wells by conducting a series of fluid level shots. The initial shot is conducted at the time that the casing valve is closed (note: the well is still pumping during the test, only the casing valve is closed). Subsequent fluid levels are taken following the closing of the casing valve, and the fluid level is tracked as it moves down the wellbore. Based on the change in interface pressure and the change in fluid level, the annular gradient can be determined. This gradient, or combination of gradients is used to determine the producing pressure at MPP. An annular fluid depression test is generally conducted if a significant amount of fluid is indicated in the annulas after the first shot (Using an "assumed" annullar liquid gradient could introduce great inaccuracies in producing pressure calculations). |
