What is a fracture bed?

A fracture bed is a zone in the subsurface where brittle failure of the rock occurs as a result of overpressuring. Fracture beds can be either open or filled, depending on the pressure regime and the presence of mobile fluid. Open fracture beds are characterized by high porosity and permeability, and are often associated with hydrocarbon reservoirs. Filled fracture beds, on the other hand, have low porosity and permeability, and act as barriers to fluid flow.