Method and apparatus for determining speed and properties of flowing fluids using NMR measurements

A method for determining a property of a flowing fluid by nuclear magnetic resonance, comprising:

• applying a static magnetic field to the flowing fluid;
• acquiring a suite of nuclear magnetic resonance measurements on the flowing fluid using a pulse sequence comprising a longitudinal relaxation investigation pulse sequence and an acquisition pulse sequence, wherein the suite of nuclear magnetic measurements have different values for a delay time within the longitudinal relaxation investigation pulse;
• and
• fitting the suite of nuclear magnetic resonance measurements to a forward model for responses of the flowing fluid to derive a parameter selected from a flow speed, longitudinal relaxation times of the flowing fluid, and a combination thereof.

A method for monitoring contamination in a flowing fluid being withdrawn into a formation fluid testing tool using nuclear magnetic resonance, comprising:

• applying a static magnetic field to the flowing fluid;
• acquiring a suite of nuclear magnetic resonance measurements of the flowing fluid using a pulse sequence comprising a spoiling pulse, a wait time, and an acquisition pulse sequence, wherein the suite of nuclear magnetic measurements have different values for the wait time;
• fitting the suite of nuclear magnetic resonance measurements to a forward model for responses of the flowing fluid to derive a property of the flowing fluid;
• and
• monitoring a level of contamination in the flowing fluid based on the derived property of the flowing fluid.

A nuclear magnetic resonance apparatus, comprising:

• a flow pipe including a prepolarization section and an investigation section, wherein the prepolarization section is upstream of the investigation section;
• a magnet disposed around the flow pipe for creating a static magnetic field covering the prepolarization section and the investigation section;
• an antenna disposed around the flow pipe at the investigation section for generating an oscillating magnetic field having a magnetic dipole substantially perpendicular to a magnetic dipole of the static magnetic field, and for receiving a nuclear magnetic resonance signal;
• and
• a circuitry for controlling generation of the oscillating magnetic field and reception of the nuclear magnetic resonance signal by the antenna, wherein the circuitry includes a program having instructions for acquiring a suite of nuclear magnetic resonance measurements of a flowing fluid using a pulse sequence comprising a spoiling pulse, a wait time, and an acquisition pulse sequence.

A nuclear magnetic resonance apparatus, comprising:

• a flow pipe including a prepolarization section and an investigation section, wherein the prepolarization section is upstream of the investigation section;
• a magnet disposed around the flow pipe for creating a static magnetic field covering the prepolarization section and the investigation section;
• an antenna disposed around the flow pipe at the investigation section for generating an oscillating magnetic field having a magnetic dipole substantially perpendicular to a magnetic dipole of the static magnetic field, and for receiving a nuclear magnetic resonance signal;
• and
• a circuitry for controlling generation of the oscillating magnetic field and reception of the nuclear magnetic resonance signal by the antenna, wherein the circuitry includes a program having instructions for acquiring a suite of nuclear magnetic resonance measurements of a flowing fluid using a pulse sequence comprising a longitudinal relaxation investigation pulse sequence and an acquisition pulse sequence, wherein the suite of nuclear magnetic measurements have different values for a delay time within the longitudinal relaxation investigation pulse.