Definition - What does Frac Gradient mean?
Frac Gradient, also known as Fracture gradient, is the slope of pressure and depth that is required to induce a fracture in the bedrock. The determination of the fracture gradient is an extremely crucial process, as it helps in conducting safe drilling practices while accessing an oil well. It is important to consider the slope and depth while drilling a well so as to ensure circulation is not hindered. In order to find out this gradient, tests such as leak-off tests are carried out. There are other factors along with fracture gradient that need to be paid attention to while drilling an oil well.
Petropedia explains Frac Gradient
The pressure at which a formation will get fractured is indicated by frac gradient. The value is converted into a gradient psi/ft as it is convenient to use. Frac gradient is essential in order to initiate a fracture or a crack into a rock formation. It is necessary to break into the arrangement of the rocks underground, so that conducive channels can be prepared for oil and gas to flow easily. Before fracturing is carried out, several factors should be considered, such as the slope, depth and pressure required to break the formation. It is through fracture gradient determination that these factors are taken care of by carrying out a leak-off test prior to the fracturing.
Frac Gradient = Delta P / Delta D
Where, Delta P is the difference in the pressure in Psi and Delta D is the difference in the depth in feet.
Unit of Frac Gradient is psi/ft.