The primary use of our ruggedized detectors is for oil and gas exploration. Our reputation for designing and manufacturing detectors capable of surviving use in the harsh environmental conditions of oil exploration has gained us wide recognition and acceptance in this industry.
Reasons for high performance of our product:
- Patented Polyscin® NaI(Tl) provides enhanced resistance to thermal/mechanical shock
- All-welded package ensures hermiticity in harsh environments
- Unique glass-to-metal sealing technology for high-temperature reliability
- Photomultiplier tube integration options for turnkey detection solutions
Our detectors, as integral components of gamma-ray logging tools, provide superior performance and survivability under the most extreme environmental conditions. The newer generation of exploration and production logging tools place incredible performance demands on scintillation-based sub-assemblies. Several patented features in our crystal packages and our series of integrated detector designs provide gamma logging professionals significant advantages.
Design Considerations
Complex sets of dynamic engineering principles are used in the design of our geophysical detectors to assure that they meet both mechanical survivability and performance specifications demanded by the Logging Service Industry. Each gamma-ray tool requires a custom detector design. The fundamental elements of a downhole device must take into account the following considerations:
- Space Constraints
- Environmental Considerations (Temperature, Shock, Vibration)
- Nuclear Performance Demands
- Energy of Interest (Gross Counting vs. Spectral)
- Photomultiplier Tube Performance
Design Options
- Detectors can be customized for very specific applications
- All-welded hermetic package and glass-to-metal seal options to withstand the rugged Wireline & MWD operating environments
- Choice of scintillators:
- LaBr3(Ce): Highest light output at temperature, fast counting for pulse neutron activated measurement, more accurate energy level determination
- NaI(Tl): Versatile, industry standard for wireline and MWD applications
- CsI(Tl): One of the brightest scintillators with very good stopping power
- BGO: High gamma stopping power for wireline logging, without intrinsic radioactivity
- Integration with photomultiplier tubes available, thus allowing for unmatched survivability and performance of a fully functioning gamma-ray detector system
Survivability and Performance –
Detectors are designed with the strongest, most reliable hermetic seals possible. The glass-to-metal or soldered eyelet seal, combined with the all-welded package construction, constitutes the basis for our detector survivability.
Our seals withstand temperature extremes and cycling stresses that eventually cause both epoxy and other seals to fail. Sodium iodide (the principal scintillator in Wireline and MWD applications) is a brittle, reactive material sensitive to thermal shock. By placing the crystal in the Geophysical package under substantial compression, we assure the survival of the sodium iodide crystal at the limits of Wireline and MWD shock and vibration.
Our MWD detector technology incorporates all the dynamic design considerations of our ruggedized detectors with the advantages of an integrated photomultiplier tube and engineered design, thus allowing for unmatched survivability and performance of a fully functioning gamma-ray detector system.
- Unique glass to metal sealing technology and all-welded construction eliminates epoxy seals for high-temperature reliability
- Operating Temperature +25°C to +175°C (Gradient 3°C per minute maximum)
- Mechanical Survival Shock 100g @ 11ms – 3 shocks per axis; 2 axis total. (X & Z)
- Vibration Random 5GRMS 50-500Hz 15 minute duration per axis; 2 axis total
- Unique glass to metal sealing technology and all-welded construction eliminates epoxy seals for high-temperature reliability
- Operating Temperature +25°C to +175°C (Gradient 3°C per minute maximum)
- Mechanical Survival Shock 1000g @ 1ms – 3 shocks per axis; 2 axis total. (X & Z)
- Vibration Random 20GRMS 30-1000Hz 30 minute duration per axis; 2 axis total
- Maximized crystal volume - Larger crystals provide increased count rates
- Thinner wall allows for larger crystal, more counts, and greater low energy sensitivity
- Stronger sapphire window is much thinner for increased light transmittance
- High strength sapphire-to-metal seals
Custom Temperature, Shock, and Vibration Specifications available upon request.
- 100g Crystal Package
- 1000g Crystal Package
- Integrated for Wireline
- Integrated for MWD
- Titanium Packaging
- LaBr in Titanium
G – Style Crystal Package - Standard with glass to metal seals
| Operating Temperature | +25°C to +175°C |
| Survival Temperature | -20°C to +200°C |
| Gradient | 3°C per minute maximum |
| Mechanical Survival Shock | 100g @ 11ms – 3 shocks per axis; 2 axis total. (X & Z) |
| Vibration | Random 5gRMS 50-500Hz 15-minute duration per axis; 2 axis total |
SG & SG-XR Styles Crystal Package - Standard with glass to metal seals
| Operating Temperature | +25°C to +175°C |
| Survival Temperature | -20°C to +200°C |
| Gradient | 3°C per minute maximum |
| Mechanical Survival Shock | 1000g @ 1ms – 3 shocks per axis; 2 axis total. (X & Z) |
| Vibration | Random 20gRMS 30-1000Hz 30-minute duration per axis; 2 axis total |
| Mechanical Performance | * (-XR Type Only) |
| Vibration | Random 20gRMS 30-1000Hz 2.5 minute duration per axis; 2 axis total per the following power spectral density profile: 30-80Hz. @ 6db/octav 80-1000Hz .43g2/Hz |
| Acceptance Criteria | Vibration induced counts per second not to exceed base + 2 X SQRT(BASE) |
MG Style - Integrated Detector Assemblies for Wireline Applications
| Operating Temperature | +25°C to +150°C |
| Survival Temperature | -20°C to +175°C |
| Gradient | 3°C per minute maximum |
| Mechanical Survival Shock | 100g @ 11ms – 3 shocks per axis; 2 axis total. (X & Z) |
| Vibration | Random 5gRMS 50-500Hz; 2 axis total |
MWD and MWD-XR Styles - Integrated Detector Assemblies for MWD Applications
| Operating Temperature | +25°C to +150°C |
| Survival Temperature | -20°C to +200°C |
| Gradient | 3°C per minute maximum |
| Mechanical Survival Shock | 1000g @ 1ms – 3 shocks per axis; 2 axis total. (X & Z) |
| Vibration | Random 20gRMS 30-1000Hz 30-minute duration per axis; 2 axis total |
| Mechanical Performance | * (-XR Type Only) |
| Vibration |
Random 20gRMS 30-1000Hz 2.5-minute duration per axis; 2 axis total per the following power spectral density profile: 30-80Hz. @ 6db/octav 80-1000Hz .43g2/Hz |
| Acceptance Criteria | Vibration induced counts per second not to exceed base + 2 X SQRT(BASE) |
The combination of titanium and sapphire packaging technology provides increased scintillation performance with the same rugged specifications Saint-Gobain has provided for years in its geophysical designs.
These new features are available for wireline, MWD and multi-phase flow applications and can be provided with integrated phototubes and electronics, if desired. Custom designs and specifications are available upon request.
- Stronger titanium housing material yields thinner walls for higher crystal volume
- Larger crystals provide increased count rates
- Increased Efficiency
- Greater Sensitivity
- Larger crystals provide increased count rates
- High strength sapphire-to-metal seals for ruggedness
- Stronger sapphire window is much thinner for increased light transmittance
- 15-30% increase in light output when compared to standard designs
- Stronger sapphire window is much thinner for increased light transmittance
- Integration with photomultiplier tubes available.
- Fully qualified for wireline and MWD operation
- Guaranteed for performance and hermetic seal integrity.
Specifications
| Pulse Height Resolution (FWHM) at 662keV |
Typical NaI(Tl) crystal as measured on a standard laboratory 2” phototube 8.5% at 25°C and 12.5% at 150°C |
| Temperature (Survival) |
-20°C to +175°C 3°C per minute gradient |
| Maximum Vibration (MWD applications) |
Random 20grms, 30-1000Hz per the following power spectral density profile: Acceptance Criteria: Counts per second not to exceed BASE+ 2σ during specified vibration. (σ =SQRT(Bkg.)) |
| Maximum Shock (MWD applications) |
1000g @ 1ms – half sine |
| Available crystal sizes | Diameter: ½” through 3” Length: sizes up to 18” |
All standard geophysical LaBr crystals are packaged in titanium housings with our proprietary sapphire window assemblies to get the absolute best performance.
| Features | Benefits |
|---|---|
| Sharper PHR | Less Pulse Pile-up |
| Faster Counting | More Accurate Isotope Identification |
| Higher Light Output | More Accurate Energy Level Determination |
| Greater Linearity | Better Fidelity at High Temperatures |
These allow the greatest possible light transmission from the LaBr crystals. The design allows more crystal volume than in standard designs and offers an increase of up to 30% in light output versus the standard designs with stainless steel housings and conventional welded or soldered glass-to-metal seals or windows. The LaBr line of scintillation detectors has been fully qualified in MWD environments, including testing at temperatures from -55ºC to +175ºC survival. For operations, we recommend and rate detectors from -20ºC to +150ºC.
Compared to NaI(Tl), LaBr has a higher density, has nearly half the FWHM (full width at half maximum) photopeak resolution and twice the light output at high temperature. Also, the degradation of the light yield as a function of temperature for LaBr is less than 5% in the range of -65ºC to +140ºC.
| Material | Density | Light Yield photons/kev | Decay Time tau (ns) | Timing FOM* ________________ tau/(photons/keV) |
Peak Emission Wavelength (nm) |
| LaBr3(Ce) | 5.1 | 63 | 16 | 0.5 | 380 |
| NaI(Tl) | 3.7 | 38 | 250 | 2.6 | 415 |
| BGO | 7.1 | 9 | 300 | 5.8 | 480 |
| CsI(Na) | 4.5 | 41 | 630 | 3.9 | 420 |
