tools being used in the desert to detect groundwater

A revolution in groundwater, Environmental and Mining science, Javelin delivers high-value NMR logging in a novel, compact, economical design. Technology once reserved for the oil field is now available to everyone for precise and detailed groundwater investigations.


Largest Depth of Investigation

It is crucial during NMR logging that the region of investigation is entirely within the undisturbed native formation. Javelin® and Dart NMR logging tools are uniquely designed and tuned specifically for groundwater and environmental wells where annular drilling disturbances, including mud invasion, are large compared to typical oil or gas wells. Every Javelin tool provides the largest available sensitive zone diameter for its size, ensuring the greatest possible confidence in your NMR data integrity.

Multiple Logging Shells

All Javelin and Dart NMR logging tools have two or four software-selectable concentric NMR sensitive ‘shells.’ This provides multiple, independent measurements at varying distances from the probe.

  • The shallower shells are optimized for high-speed logging when drilling disturbance is known to be minimal.
  • The deeper shells provide a deep view, past potential drilling disturbance.
  • Having both shallow and deep look capabilities in one tool reduces cost and increases the variety of borehole sizes and conditions that can be effectively logged with the same tool.
  • Results from the different measurements shells can be combined, increasing the effective signal to noise ratio.
  • Comparing the results from the different shells can reveal radial variations indicative of borehole washout or mud invasion.
  • The radially profiling capability can even be used to inspect the filter pack or grout in the annular space to ensure quality control or regulatory compliance with well construction standards.
    *Vista Clara US patent 9348054 B2

Widest Variety of Interchangeable Tool Sizes

  • Javelin’s NMR logging tools are offered in a wide range of diameters: 1.75, 2.38, and 3.5 inches.
  • Javelin probes can be used to log PVC-cased wells or open holes.
  • Individual Javelin downhole probes are interchangeable and inexpensive compared to other NMR logging tools, allowing operators to field a range of tools sizes.

diagram info graphic showing detail of the Javelin tool

graphic showing multiple NMR sensitive shells

logging tools in a wide range of diameters

Extended Pre-polarization Magnets for High-Speed Logging

All Javelin NMR logging probes have extended pre-polarization magnets located above and below the main detection coil. This enables pre-polarization of the NMR sensitive zone while the tool is moving, and enables accurate high-speed low-resolution NMR logging of bound and mobile water content, at speeds on the order of 1000 m/hr. This high-speed low-resolution logging capability is useful for acquiring a fast reconnaissance log of a deep well on an initial logging pass, prior to acquiring a high-resolution NMR log in sections of most interest.

Slimline Compatible

Javelin® and Dart are the only NMR logging tools available anywhere than can log 2 inch PVC-cased wells. These 1.75 inch diameter tools provide sensitive zone diameters as large as 10 inches, allowing measurements past the drilling-disturbed annular space which is often 7 to 8 inches or more.

Direct Push Compatibility

Javelin® and Dart are the only NMR logging tools that can be deployed via direct push technology.


or Dart
Javelin Wireline Javelin
Probe ID Dart JP175A JP175B JP175D JP238F JP350F JPX350** JPX525**
Probe Diameter 1.75 in / 44 mm 1.75 in / 44 mm 1.75 in / 44 mm 1.75 in / 44 mm 2.38 in / 61 mm 3.5 in / 89 mm 3.5 in / 89 mm 5.25 in / 134 mm
Probe Length 50.4 in 77.5 in 77.5 in 77.5 in 85 in 73 in 73 in 62 in
Probe Weight 10 lb 18 lb 20 lb 17 lb 29 lb 55 lb 55 lb 93 lb
Vertical Resolution 10 in / 0.25 m 40 in / 1.0 m 40 in / 1.0 m 20 in / 0.5 m 20 in / 0.5 m 20 in / 0.5 m 20 in / 0.5 m 20 in / 0.5 m
Diameters of Investigation 5 in
6 in
7 in
8 in
9 in
10 in
7 in
8 in
8 in
9 in
10.5 in
12 in
10.5 in
12 in
13.5 in
15 in
10.5 in
12 in
13.5 in
15 in
15 in
16.5 in
18.5 in
21 in
Minimum Echo Spacing 500 us 700 us 1000 us 700 us 700 us 700 us 1000 us 1000 us
Max Logging Depth 1600 ft / 500 m 1600 ft / 500 m 1600 ft / 500 m 1600 ft / 500 m 1600 ft / 500 m 1600 ft / 500 m 3300 ft / 1000 m 3300 ft / 1000 m
Logging Speed* 10 m/hr 15 m/hr 15 m/hr 15 m/hr 30 m/hr 60 m/hr 60 m/hr 60 m/hr


* Recommended logging speed for high porosity formations for mobile water content accuracy of +/- 1 porosity unit. Faster logging speeds may be appropriate for different logging objectives and resolution requirements.

** Requires Wireline Javelin Digital Electronics Cartridge @ 97 in / 61 lb.
– Complete assembled Wireline Javelin tool with JP350F: 3.50″ Dia. x Total Length 14ft; Total Weight 116 lbs.
– Complete assembled Wireline Javelin tool with JP525F: 5.25″ Dia. x Total Length 13ft; Total Weight 154 lbs.

Our Logging NMR Products