Wellbore strengthening in low permeability formations

Wellbore strengthening methods, via the creation of 'stress cages' have recently been proposed to increase the fracture gradient of underground formations. The most successful technique consists in inducing short propped fractures at the borehole wall. However, this approach has been rather ineffective when applied to low permeability rocks. This paper proposes a solution to this limitation by 'setting' the stress cage after first lowering the temperature of the drilling mud, reducing the tangential stresses at the borehole wall. Fracture growth will then be controlled by this induced temperature gradient.