At least one parameter of at least one fluid in a pipe (12) is measured using a spatial array of acoustic pressure sensors (14, 16, 18) placed at predetermined axial locations x1,x2,x3 along the pipe (12). The pressure sensors (14, 16, 18) provide acoustic pressure signals P1(t), P2(t), P3(t) on lines (20, 22, 24) which are provided to signal processing logic (60) which determines the speed of sound amix of the fluid (or mixture) in the pipe (12) using acoustic spatial array signal processing techniques with the direction of propagation of the acoustic signals along the longitudinal axis of the pipe (12). Numerous spatial array processing techniques may be employed to determined the speed of sound amix. The speed of sound amix is provided to logic (48) which calculates the percent composition of the mixture, e.g., water fraction, or any other parameter of the mixture or fluid which is related to the sound speed amix. The logic (60) may also determine the mach number (MX) of the fluid. The acoustic pressure signals P1(t), P2(t), P3(t) measured are lower frequency (and longer wavelength) signals than those used for ultrasonic flow meters, and thus is more tolerant to inhomogeneities in the flow. No external source is required and thus may operate using passive listening. The invention will work with arbitrary sensor spacing and with as few as two sensors if certain information is known about the acoustic properties of the system.

Fluid parameter measurement in pipes using acoustic pressures

A multiphase flow meter distributed system is disclosed that is capable of measuring phase flow rates of a multiphase fluid. The distributed system includes at least one flow meter disposed along the pipe, an additional sensor disposed along the pipe spatially removed from the flow meter, and a multiphase flow model that receives flow related parameters from the flow meter and the additional sensor to calculate the phase flow rates. The flow meter provides parameters such as pressure, temperature, fluid sound speed and/or velocity of the fluid, and the additional sensor provides a parameter indicative of pressure and or temperature of the fluid. Depending on production needs and the reservoir dimensions, the distributed system may utilize a plurality of flow meters disposed at several locations along the pipe and may further include a plurality of additional sensors as well. The distributed system preferably uses fiber optic sensors with bragg gratings. This enables the system to have a high tolerance for long term exposure to harsh temperature environments and also provides the advantage of multiplexing the flow meters and/or sensors together.

Distributed sound speed measurements for multiphase flow measurement

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 the 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 wavelength μ 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.

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

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

According to one embodiment of the present invention, the apparatus comprises a first filter for measuring a pressure field at a first axial location along the pipe and providing a first pressure signal indicative of the vortical pressure field. The apparatus further comprises a second filter for measuring the vortical pressure field at a second axial location along the pipe and providing a second pressure signal indicative of the vortical pressure field. The apparatus further comprises a signal processor, responsive to the first and the second pressure signals, which provides a velocity signal indicative of a velocity of the vortical pressure field moving in the pipe.

Flow rate measurement using unsteady pressures

A method for determining the flow situation in a transport system where the flow medium occurs in multi-phase and is conducted through a structural detail such as a choke valve, which acts on the flow of the medium and produces turbulence causing acoustic energy signals which are generated in and immediately close to the structural detail. The acoustic energy signals are sensed by one or a plurality of acoustic sensors with an acoustic broad-band connection with the structural detail. The sensor converts the energy signal to transmittable signals to a signal processing unit utilizing known signal analysis principles to provide interpretable information on the actual flow situation and the flowing medium which is influenced by the structural detail. The structural detail to which the acoustic sensor is connected may be incorporated in a subsea production system.

Hope Bjorn R

Papers

A method for recording multi-phase flows through a transport system.