Microwave doppler flowmeter for hydrocarbon wells

A downhole tool used to measure and analyze a multiphase fluid present in a hydrocarbon well, the tool being adapted for displacement along and within the hydrocarbon well comprising at least one flowmeter intended for use within a hydrocarbon well for measuring a fluid velocity and/or a fluid direction of a moving multiphase fluid present in the hydrocarbon well, said flowmeter including:

• a microwave front end module comprising at least one transmit antenna and at least one receive antenna and a microwave circuit, the microwave circuit comprising an oscillator coupled to the transmit antenna for causing said antenna to transmit microwave signals towards the multiphase fluid at a high frequency ranging from 10 to 100 GHz, a mixer coupled to the receive antenna and to a filter for generating an analog in-phase doppler signal depending on microwave signals returned from moving multiphase fluid;
• an analog electronics module comprising an amplifier and an analog-to-digital converter converting the analog doppler signal successively into an amplified analog doppler signal and a digital doppler signal;
• a digital processing module comprising a Fast Fourier Transform algorithm for processing the digital doppler signal into a Doppler frequency spectrum and a filter providing a compressed Doppler frequency spectrum, said Doppler spectrum containing information indicative of the fluid velocity and/or the fluid direction of the moving multiphase fluid;
• and
• a protective shell protecting the microwave front end module, the analog electronics module and the digital processing module from multiphase fluid, the protective shell comprising a first part positioned over said antennas and being transparent to microwave signals, and a second part being opaque to microwave signals.

A method for measuring radial and/or axial flow of a fluid mixture present within a hydrocarbon well according to multiple cross-sections of the hydrocarbon well, the method comprising:

• running a flowmeter along a defined distance within the hydrocarbon well, said flowmeter including:
• a microwave front end module comprising at least one transmit antenna and at least one receive antenna and a microwave circuit, the microwave circuit comprising an oscillator coupled to the transmit antenna for causing said antenna to transmit microwave signals towards the multiphase fluid at a high frequency ranging from 10 to 100 GHz, a mixer coupled to the receive antenna and to a filter for generating an analog in-phase doppler signal depending on microwave signals returned from moving multiphase fluid;
• an analog electronics module comprising an amplifier and an analog-to-digital converter converting the analog doppler signal successively into an amplified analog doppler signal and a digital doppler signal;
• a digital processing module comprising a Fast Fourier Transform algorithm for processing the digital doppler signal into a Doppler frequency spectrum and a filter providing a compressed Doppler frequency spectrum, said Doppler spectrum containing information indicative of the fluid velocity and/or the fluid direction of the moving multiphase fluid;
• a protective shell protecting the microwave front end module, the analog electronics module and the digital processing module from multiphase fluid, the protective shell comprising a first part positioned over said antennas and being transparent to microwave signals, and a second part being opaque to microwave signals;
• transmitting microwave signals towards the multiphase fluid at a high frequency ranging from 10 to 100 GHz,
• receiving microwave signals returned from moving multiphase fluid, and
• processing said returned microwave signals such as to provide a flow profile image of the hydrocarbon well.