In order for multiple oil-water contacts to exist in a reservoir, fluid-flow barriers must divide the reservoir up into compartments. A fault can be inferred to be acting as a flow barrier if different oil-water contacts (OWC) lie on either side or if the highest known water (HKW) lies at a subsea depth shallower than an OWC or lowest known oil.

Often in a reservoir, faults have throws that are less than the resolution of the 3-D seismic. With fault trends delineated by the seismic it is often prudent to infer or extend faults on the basis of fluid-flow trends.