Active and passive imaging of hydraulic fractures

Hydraulic fracturing is a method commonly used to stimulate production in low‐permeability reservoirs. With this method, a viscous polymer‐based fluid is injected into the formation, opening a fracture perpendicular to the direction of least principal stress. This is followed by injection of a suspension of sand in liquid (proppant) which prevents the fracture from closing after the fluid pressure is allowed to bleed off. After a fracture treatment, the reservoir can be produced from the vicinity of a fracture surface which is substantially larger than the surface of the borehole.