Negative Pressure Test
A negative pressure test, also called the inflow test is aimed at testing the barriers placed in the well for ensuring well integrity. The barriers in a well are installed to avoid fluid flowing past the barrier from the formation into the well or vice versa. To ensure well integrity, it is important to test whether the barrier fulfills this requirement.
A negative pressure test is essentially the inverse of a positive pressure test performed in the well. In the inflow test or negative pressure test procedure, a differential pressure is created in the direction from the formation to the well. It is achieved by reducing the hydrostatic pressure above a barrier to a level below the formation pressure. The test is designed to check if any formation fluid will leak past the barrier into the well.