Definition - What does Non-Homogenous Stress mean?
Non-homogenous stress in the context of in-situ stress refers to the stress in underground formations that are not uniform. Confined underground formations experience vertical stress, minimum horizontal stress and maximum horizontal also called principal stresses. The magnitude and direction of these stresses depend on tectonic conditions and influence rock failure.
Stresses in underground formations are not uniform and change in magnitude based on direction. The stresses are generally non-homogenous, compressive, and anisotropic.
Trenchlesspedia explains Non-Homogenous Stress
Underground formations that confined and under stress fall into three principal stresses namely vertical stress (σ1), minimum horizontal stress (σ2) and maximum horizontal stress (σ3). These stresses are not uniform and vary in magnitude based on direction.
The magnitude and direction of these stresses are therefore important as they control factors such as the pressure required to create a fracture and propagate it and the shape, extent, and direction of the fracture.
A hydraulic fracture propagates perpendicular to the minimum principal stress, which in some shallow foundations is the overburden stress causing a horizontal fracture. Non-homogenous stresses influence the behavior of rock and therefore the mud weight required for the operation.
Considering a non-homogenous field is important in obtaining a realistic analysis as rock material properties are usually not homogenous in all drilled layers.