Description
The QL40-DEN Compensated Density & Caliper probe is a versatile wireline tool that can be used in a wide variety of logging applications. Measurements include SSD (short-spaced density), LSD (long-spaced density), Compensated density (dual density), and Caliper. The tool section is designed for operation in 2 to 12 inch (5 – 30 cm) boreholes.
This dual detector, high resolution density tool is fully characterized, producing accurate near and far density measurements transformed into compensated density by use of stand-off / compensation algorithms. These algorithms produce effective data even when borehole rugosity and fractures adversely affect accuracy of uncompensated logs.
The QL40-DEN tool is stackable within the Quick Link (QL) product line or it can be run as a standalone tool.
Applications
- Quantitative In-situ Density
- Petrophysical Properties
- Coal Quality and Delineation
- Density Porosity
- Caliper Borehole Volume
Operating Conditions
Borehole Fluid
[X] Water
[X] Mud
[X] Dry
Casing
[X] Uncased
[_] PVC Borehole
[_] Steel
Centralization
[_] Required
[X] Tool is De-Centralized
Features & Benefits
- Real-time Quantitative Density
- Improved thin bed resolution
- Advanced compensation algorithms produce accurate density data even when borehole rugosity and fractures are obstacles
- Easy to calibrate with Nylon and Aluminum calibration blocks.
- Cesium-137 or Cobalt-60 source
- Strong and reliable caliper, driven by gas-charged piston-type actuator
- Operates on any standard wireline (Mono, 4, 7 conductor, or Coax)
- Can be combined with other logging tools of the QL product line or operated as a standalone tool.

Example QL40-DEN Density through Coal Seam
Specifications – Metric/English
Specification | Metric | Imperial |
Diameter | 50.8 mm | 2″ |
Length | 1.85 m | 73″ |
Weight | 19.2 Kg | 42 lbs. |
Max. Temp. | 85ºC | 185ºF |
Max. Pressure | 206 bar | 3000 psi |
Short Spaced Source Detector (SSD): 20 cm (7.87”)
Long Spaced Source Detector (LSD): 35 cm (13.77”)
Density Range: 1 – 4 g/cc (depends on source)
Source: 100 – 250 mCurie Cs-137 or Co-60
Density Accuracy: 0.1 g/cc (100 mC Cs-137)
Density Resolution: 0.05 g/cc (100 mC Cs-137)
Caliper Maximum: 30 cm (12”)
Caliper Accuracy: 2.54 mm (0.1”)
Caliper Resolution: 0.64 mm (0.025”)
QL Stack Possibilities
- QL40DEN + QL40GR (Gamma): Exploration, Petrophysics Properties
- QL40DEN + QL40GR (Gamma) + QL40DEV (Deviation) : Exploration, Borehole Deviation
- QL40DEN + QL4SGR (Spectral Gamma) + QL40ELOG (Resistivity): The ‘Coal Suite’ tool set, Quantitative Analysis, Lithology, Porosity Estimates