Focused Magnetic Resonance Tool

Provides accurate porosity, fluid saturation, and pore-size distribution at multiple depths of investigation


  • Lithology-independent porosity
  • Fluid identification and saturation
  • Hydrocarbon characterization and viscosity
  • Moveable-hydrocarbon identification in laminated, low-contrast, complex-lithology, and unconventional reservoirs
  • Permeability index
  • Capillary pressure

Features and Benefits

  • Minimizes borehole effects while maximizing formation response with an eccentered sidewall-focused design and high-efficiency antenna
  • Delivers precise data in high-salinity mud (0.02 ohm-m) and large boreholes without a mud excluder
  • Enables radial saturation profiling with multifrequency operation
  • Maximizes multidimensional-inversion response and accuracy by incorporating unique acquisition sequences that provide enhanced fluid identification and characterization
  • Offers a unique pre-job planning process that selects the acquisition sequence to client requirements and the wellbore environment
  • Provides stationary measurements via comprehensive activation sequences
  • Yields spectra for T1 and T2 at the wellsite, and provides single-pass data for advanced post-processing, including 2D inversion for T1, T2, and diffusion constant
  • Offers variable logging speeds depending on the selected activation sequence

Tool Description

The focused magnetic resonance (FMR) tool provides accurate porosity, fluid saturations in the flushed zone, and pore-size distribution* at multiple depths of investigation. Based on the same principles used in medical magnetic resonance imaging technology (MRI), the FMR offers unique acqui­sition sequences that both quantify and characterize rock and fluid types. 

Post processing of FMR tool data provides critical rock and fluid information, including porosity, pore-size distribution, permeability, viscosity, capillary pressure, hydrocarbon type, and saturation

* For water wetting phase





Porosity; porosity partitioning; T1 and T2 spectra

Depth of investigation 

1.68 in. (4.3 cm) to 4.27 in. (10.8 cm) 

Antenna aperture 

18 in. (45.7 cm)

Minimum echo spacing

0.4 ms 

Number of frequency bands


Measurement range

Porosity: 0 to 100 pu
T1 and T2 spectral range: 0.1 to 20,000 ms


Total NMR porosity: ±1 pu at BHT




Sonde: 5 in. (12.7 cm)
Electronics: 4.25 in. (10.8 cm)
Energy cartridge: 3.38 in. (8.6 mm)


23.5 ft (7.16 m) 


780 lb (326.6 kg) 

Maximum temperature

350°F (177°C) 

Maximum pressure

20,000 psi (138 MPa)

Minimum hole size

5.875 in. (14.92 cm)

Maximum hole size

No limit

Minimum mud resistivity

0.02 ohm-m


Answer Products

Field deliverables

Total porosity

Permeability index

Porosity partitions (free, capillary, and clay-bound fluids)

T1 and T2 spectra

Standard interpretation

Magnetic resonance porosity: permeability analysis

Porosity partition: permeability index adjusted by T2 cutoff (free, capillary, and clay-bound fluids)

Rock quality index

Calibrated permeability

Advanced interpretation

Fluid identification and saturations

Petrophysical analysis

Oil viscosity analysis

Under-called porosity (gas, TOC, heavy oil)

Focused Magnetic Resonance Tool

The Weatherford focused magnetic resonance (FMR) tool provides a complete nuclear magnetic resonance (NMR) formation-evaluation solution.

Reach out to optimize reservoir performance

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