Weatherford/lamb, Inc.

Cidra Corporation

Rebecca S McGuinn

Daniel L Gysling

Charles Winston

Allen R Davis

John M Faustino

Alan D Kersey

Mark R Myers

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.

Apparatus for sensing fluid in a pipe

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 X apart, and the second measurement region having two other fiber optic strain gauges located a distance X apart, each capable of measuring the unsteady pressure in the pipe . 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 P and other long wavelength pressure disturbances in the pipe and passes short-wavelength low-frequency vortical pressure disturbances P associated with the vortical flow field. The spatial filters provide signals to band pass filters that filter out high frequency signals. The P -dominated filtered signals from the two sensing regions are cross-correlated to determine a time delay &tgr; between the two sensing locations which is divided into the distance &Dgr;X to obtain a convection velocity U (t) that is related to an average flow rate of the fluid (i.e., one or more liquids and/or gases) flowing in the pipe . The invention may also be configured detect the velocity of any desired inhomogeneous pressure field in the flow.

Optical flow rate measurement using unsteady pressures

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

Non-intrusive fiber optic pressure sensor for measuring unsteady pressures within a pipe

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

Measurement of propagating acoustic waves in compliant pipes

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. Each fluid sensor is used to provide information about the speed of sound in its sensing material, and since the speed of sound depends on the DC pressure and temperature of the sensing material, in providing information about the speed of sound, each fluid sensor also provides information about the DC pressure and temperature of the sensing material, which is either the same as that of the production fluid or can be correlated to that of the production fluid.

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Middletown, CT, United States of America

Rebecca S McGuinn