What Does Shut-In Pressure (Ps) Mean?
Shut-in pressure is the stage at which the fluid pressure begins to decline after injection is stopped during a hydraulic fracturing test. A hydraulic fracturing test is a proven method and is used for enhancing oil well efficiency, and in designing of tunnels, oil & gas lines and other underground installations.
Well shut-ins after hydraulic fracturing greatly increases hydrocarbon outputs, while fluid loss and invasion of aqueous phase into the formation can reduce hydrocarbon production and damage matrix permeability.
Trenchlesspedia Explains Shut-In Pressure (Ps)
In an hydraulic fracturing test, fluid is injected into the wellbore till cracks begin to appear around the wellbore. At this stage the fluid injection is stopped causing a decline in fluid pressure. In a curve on the plotted graph, the significant point associated with minimum horizontal in-situ stress indicates the shut-in pressure. The breakdown pressure and the shut-in pressure are measured during the shut-in stage. Even though injection is stopped at the shut-in stage, enough energy is present to propagate cracks until the fluid pressure drops and becomes constant in the crack by leaking off from the fracture and borehole.