Patent ID: 7453265

Claim:
A device for monitoring the position of an oil/water contact between an oil-continuous fluid overlying a water-continuous fluid within a casing pipe in a production well, the device comprising: a transmitter for generating an electromagnetic signal (S T ); a voltage signal generator for providing electrical energy (G T ) to said transmitter; an insulated conductive wire extending down through said oil-water contact and near an inward facing wall of said casing pipe, said insulated conductive wire constituting a waveguide for a transverse-electric field (E TE ) along a two-way path for the electromagnetic signals propagating downwards and reflected signals (SR) from said oil-water contact, said transmitter being arranged within said oil-continuous fluid and above said oil-water contact to impose said transverse-electric field on said insulated conductive wire, said conductive wire constituting a waveguide for said transverse-electric field along a two-way path for the electromagnetic signals propagating downwards and reflected signals (S R ) from said oil-water contact; a sensor arranged within said oil-continuous fluid and above said oil-water contact and within said casing pipe, said sensor being operable to detect said reflected signals; a receiver operable to receive sensor signals (R R ) from said sensor; and an analyzing device operable analyze said sensor signals, forwarded from said receiver, with respect to two-way propagation time or amplitude in order to calculate an elevation level for said oil-water contact within said casing pipe.