Abstract: An apparatus for non-intrusively sensing fluid flow within a pipe is provided. The apparatus includes a first sensing array for sensing acoustic signals traveling at the speed of sound through fluid flow within the pipe, a second sensing array for sensing local pressure variations traveling with the fluid flow, and a housing attached to the pipe for enclosing the sensing arrays. The first sensing array includes a plurality of first optical pressure sensors and the second sensing array includes a plurality of second optical pressure sensors.

Abstract: A fiber optic strain gauge based flow rate measurement system includes two measurement regions located an average axial distance &Dgr;X apart along the pipe, the first measurement region having two fiber optic strain gauges located a distance X1 apart, and the second measurement region having two other fiber optic strain gauges located a distance X2 apart, each capable of measuring the unsteady pressure in the pipe 12. Signals from each pair of fiber optic strain gauges are differenced by summers to form spatial wavelength filters. Each spatial filter filters out acoustic pressure disturbances Pacoustic and other long wavelength pressure disturbances in the pipe and passes short-wavelength low-frequency vortical pressure disturbances Pvortical associated with the vortical flow field. The spatial filters provide signals to band pass filters that filter out high frequency signals.

Abstract: Non-intrusive pressure sensors 14-18 for measuring unsteady pressures within a pipe 12 include an optical fiber 10 wrapped in coils 20-24 around the circumference of the pipe 12. The length or change in length of the coils 20-24 is indicative of the unsteady pressure in the pipe. Bragg gratings 310-324 impressed in the fiber 10 may be used having reflection wavelengths &lgr; that relate to the unsteady pressure in the pipe. One or more of sensors 14-18 may be axially distributed along the fiber 10 using wavelength division multiplexing and/or time division multiplexing.

Abstract: A pipe 16 having a produced fluid 18 (liquid an/or gas) and at least two acoustic pressure sensors 20-24, is provided with a cylindrical sleeve 30 attached to the pipe 16 at two locations around a sensing region where the sensors 20-24 are located, the sleeve forming a closed cavity 32 filled with a fluid (or material) having an acoustic impedance (&rgr;c2) that is much less than the acoustic impedance (&rgr;c1) of the produced fluid 18 in the pipe 16 (i.e., &rgr;c2<<&rgr;c1), which causes the sleeve 20 to isolate the acoustic sensors 20,22,24 from being affected by acoustic properties of the cavity 32 and the acoustic properties outside the pipe 16. For most effective acoustic, the cavity 32 may be evacuated.

Abstract: An apparatus for non-intrusively sensing fluid flow within a pipe is provided. The apparatus includes a first sensing array for sensing acoustic signals traveling at the speed of sound through fluid flow within the pipe, a second sensing array for sensing local pressure variations traveling with the fluid flow, and a housing attached to the pipe for enclosing the sensing arrays. The first sensing array includes a plurality of first optical pressure sensors and the second sensing array includes a plurality of second optical pressure sensors.

Abstract: A DC pressure and temperature sensor system for sensing and measuring the DC pressure and temperature of a production fluid (such as oil, gas and water mixtures) in tubing, such as tubing used to extract production fluid from a drilled site. The sensor system includes at least one fluid sensor, but sometimes two. Only one is needed if either the DC pressure or temperature of the production fluid (but not both) is provided by an independent measurement. In general, though, the sensor system includes: a first and second fluid sensor, the first using a first sensing material, and the second using a second sensing material in which sound travels at a rate that depends on the DC pressure and temperature of the second sensing material in a measurably different way than for the first sensing material. Each sensing material is coupled to the production fluid, preferably via a thin-walled membrane, so as to be at a DC pressure and temperature that is, preferably, the same as for the production fluid.