Flow control device

A fluid flow control device comprising:

• a) a housing arranged as an inflow port for fluids from a fluid reservoir to a production pipe in a subterranean oil well, the reservoir containing oil as well as fluids with a lower viscosity and/or density than oil, the reservoir fluids being at a pressure P1, said housing comprising:
• a primary flow path located inside the housing comprising a primary fluid inlet for receiving reservoir fluids and a primary fluid outlet for discharging reservoir fluids into the interior of the production pipe,
• a secondary flow path located in the housing comprising a secondary fluid inlet for receiving reservoir fluids and a secondary fluid outlet for discharging reservoir fluids into the interior of the production pipe,
• a valve device arranged between the primary fluid inlet and the primary fluid outlet, said valve device moveable from an open position in which the primary fluid path is open, to a closed position in which the primary fluid path is closed,
• a chamber, in which is arranged an actuator for the valve device, said chamber being in fluid communication with the secondary flow path, said chamber being exposed to a pressure P2 determined at least in part by the viscosity, density and/or velocity of the fluid flowing through the secondary flow path,
• b) at least one flow restrictor arranged in the secondary flow path, said flow restrictor or restrictors tuned to the viscosity and/or density of the fluid and arranged such that, when the fluid flowing through the secondary flow path is oil, P2 is sufficient to permit pressure P1 to force the valve into the open position, and when the fluid flowing through the secondary flow path has a viscosity and/or density lower than oil P2 is sufficient to actuate the valve to the closed position,
• whereby the fluid control device automatically and reversibly opens and closes dependent at least in part upon the viscosity and/or density of the fluid flowing therethrough.