摘要 |
An apparatus is described for controlling flow of fluid in a subterranean formation based on a selected characteristic of fluid flow, such as viscosity, velocity or density, as that characteristic varies over time. A pathway-dependent resistance assembly, such as a vortex chamber having two inlets and an outlet, provides varying resistance to fluid flow based on the ratio of flow from the inlets, the direction of flow as directed by the inlets, and the characteristic of the fluid. The incoming flow ratio is preferably determined by flowing fluid through a plurality of passageways having differing flow rate responses to fluid having differing characteristics. Fluid of a selected characteristic will encounter lesser resistance to flow across the system, while fluid of an un-favored characteristic will encounter greater resistance to flow. Thus, flow of well fluids can be autonomously restricted as the fluid characteristics change over time. |