Measurement of flow fractions, flow velocities, and flow rates of a multiphase fluid using NMR sensing
AssigneeSouthwest Research Institute
InventorsJ. Derwin King, Qingwen Ni, Armando De Los Santos
Life of this patent
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Abstract
Various flowmeters (10, 70, 80) each have at least one NMR sensor (12, 72, 82) for measuring the various flow parameters of a flowing fluid. The NMR sensor may be used to provide a gradient magnetic field, which provides separate velocities when the fluid is multiphase (FIG. 10). The flowmeters may also be used to measure flow rate directly. The flowmeters may also be used to determine the separate flow fractions of a multiphase fluid.
Claims28
A flowmeter for a fluid flowing through a flow channel, comprising:
- a pre-polarizer for polarizing said fluid;
- a NMR sensor for providing NMR output data from the polarized fluid;
- an NMR detector for powering said NMR sensor at the NMR frequency and for amplifying and detecting an NMR signal induced in said sensor from the polarized and energized liquid flow;
- and
- a processor programmed to calculate flow velocity by obtaining a first NMR signal emitted by completely polarized and energized fluid in said NMR sensor, obtaining a second signal emitted by said fluid after a delay time less than the time required for said fluid to flow out of said NMR sensor, and comparing the amplitudes of the said first NMR signal and said second NMR signal;
- wherein said processor is further programmed to calculate a gas fraction of said fluid from the NMR signal amplitude and from temperature and pressure measurements.
A method of determining the velocity of a fluid flowing through a flow channel, comprising:
- pre-polarizing said fluid;
- using an NMR sensor to provide NMR output data from said polarized fluid;
- calculating said flow velocity by obtaining a first NMR signal emitted by completely polarized fluid in said NMR sensor, obtaining a second signal emitted by said fluid after a delay time less than the time required for said fluid to flow out of said NMR sensor, and comparing the amplitudes of the said first NMR signal and said second NMR signal;
- and
- calculating a gas fraction of said fluid from the NMR signal amplitude and from temperature and pressure measurements.
A flowmeter for a flowing fluid having at least two liquid constituents, subject to temporal, spatial, and velocity changes within a flowline, comprising:
- a first pre-polarizer for polarizing said fluid;
- a first NMR sensor for providing NMR output data representing a first NMR output signal from said fluid after polarization by said first pre-polarizer;
- a first NMR detector for powering said first NMR sensor at the NMR frequency and for amplifying and detecting an NMR signal induced in said sensor from the polarized liquid flow;
- a second pre-polarizer for re-polarizing said fluid, said second polarizer providing a polarization time for the flowing fluid;
- a second NMR sensor for providing NMR output data representing a second NMR output signal from said fluid after polarization by said second polarizer;
- a second NMR detector for powering said second NMR sensor at the NMR frequency and for amplifying and detecting an NMR signal induced in said sensor from said polarized liquid flow;
- means for ensuring that the NMR signal from the second NMR sensor is from the same segment of fluid as the NMR signal from the first sensor;
- and
- a processor programmed to calculate the separate fractions of said liquid constituents from said NMR output data, using known values of NMR relaxation times of said liquid constituents.
A method of determining the fractional constituents of a flowing fluid having at least two liquid constituents, subject to temporal, spatial, and velocity chances within a flowline, comprising:
- using a first pre-polarizer to polarize said fluid;
- using a first NMR sensor/detector to provide NMR output data representing a first NMR output signal from said fluid after polarization by said first pre-polarizer;
- using a second pre-polarizer to re-polarize said fluid, said second polarizer providing a different polarization time for said fluid;
- using a second NMR sensor/detector to provide NMR output data representing a second NMR output signal from said fluid after polarization by said second polarizer, said NMR output data from said second NMR sensor being acquired after a delay from the acquisition of data from said first NMR sensor;
- ensuring that the NMR signal from the second NMR sensor is from the same segment of fluid as the NMR signal from the first sensor;
- and
- calculating the separate fractions of said liquid constituents using said NMR output data and known NMR relaxation times of said liquid constituents.
A flowmeter for directly measuring the flow rate of a fluid flowing through a flow channel, comprising:
- a pre-polarizer for polarizing said fluid;
- an NMR sensor for providing an NMR output data from said polarized fluid;
- an NMR detector for powering said first NMR sensor at the NMR frequency and for amplifying and detecting an NMR signal induced in said sensor from the polarized liquid flow;
- means for detecting the flow velocity of said fluid;
- and
- a processor programmed to directly measure flow rate from stored reference NMR response amplitude data, from measured NMR response amplitude data, and from the velocity of said fluid;
- wherein said processor is further programmed to calculate a gas fraction of said fluid from the NMR signal amplitude and from temperature and pressure measurements.
A method of directly measuring the flow rate of a fluid flowing through a flow channel, comprising the steps of:
- pre-polarizing said fluid;
- using an NMR sensor/detector to provide NMR output data from said polarized fluid;
- measuring the velocity of said fluid;
- calculating said flow rate from stored reference NMR response amplitude data, from measured NMR response amplitude data, and from the velocity said fluid;
- and
- calculating a gas fraction of said fluid from the NMR signal amplitude and from temperature and pressure measurements.
Dependencies are inferred from the claim text.