DGA Focused Gamma Tool

DGA

Directional Gamma Tool (1.36” OD)

DGAThe DGA Directional Gamma Tool is used for Azimuthal Geosteering and is our standard Tungsten-collimated version of the NGT-T gamma tool. These tools are sometimes referred to as “focused” or “shielded” gamma tools. In this design a 67° “window” is machined along the length of the Tungsten shield that surrounds the crystal/phototube detector. Only gamma ray entering from the formation through this window can be detected and counted. When aligned with the tool face or other physical reference, the DGA indicates the direction from which gamma ray energies originate.

The DGA is interchangeable with the standard NGT-T gamma tool. It is same overall length and diameter. Because of the required thickness of the Tungsten shield, the Nal(TI) scintillator crystal is a smaller diameter and a longer length than the NGT-T’s to provide maximum sensitivity.

For higher sensitivity version of DGA, please see DGA-C.

To protect your gamma investment and ensure the best performance use CBG original SNB Snubbers-Shock & Vibration Isolators.

DGA

Directional Gamma Tool

DGA

The DGA, Directional Gamma Tool, is our standard Tungsten-collimated version of the NGT-T gamma tool. These tools are sometimes referred to as “focused” or “shielded” gamma tools. In this design a 67° “window” is machined along the length of the Tungsten shield that surrounds the crystal/phototube detector. Only gamma ray entering from the formation through this window can be detected and counted. When aligned with the tool face or other physical reference, the DGA indicates the direction from which gamma ray energies originate.

The DGA is interchangeable with the standard NGT-T gamma tool. It is same overall length and diameter. Because of the required thickness of the Tungsten shield, the Nal(TI) scintillator crystal is a smaller diameter and a longer length than the NGT-T’s to provide maximum sensitivity.

For higher sensitivity version of DGA, please see DGA-C.

To protect your gamma investment and ensure the best performance use CBG original SNB Snubbers-Shock & Vibration Isolators.

DGA Specifications

P/N 202-000-000

Detector  Nal(TI) Scintillator Crystal 0.625” Diameter  X 6.0” Length
Photomultiplier R3991A (Hamamatsu)
Mechanical Diameter (OD) 1.36”
Length (make-up) 13.7”
Weight 3.0 lb
End Connectors Micro-D Subminiature, 15-Pin
Material Aluminum Alloy (chassis), Tungsten (shield)
Performance Sensitivity 0.35* CPS/API
Front/Back Count Ratio (using source at 6”) 7.4 using Barium-133
1.8 using Cesium-137
Accuracy +/- 5% to 300°F
+/- 10% to 350°F
Thin-Bed Resolution (8” hole Diameter) 8.8”
Operating Temperature 0°F to 350°F
Survival Temperature -40°F to 400°F
Vibration (3 axis) 50-1000Hz, Random 30G (20G RMS)
Environmental Heat/Cool Rate, Max.  5°F per minute
Shock (3 axis) 1000G, 0.5ms, half-sine
Power Requirements DC Input Voltage 17-48 VDC, 50VDC Max.
Tool Current 8-11 mA
Output Signal Negative Pulse +5V to GND, 5 uSec width

* Counts are collected with gamma tool mounted within standard BeCu pressure barrel, (OD 1.875″, ID 1.500″).  API Calibration performed with AEA Technology, QSA Inc., KUTh Field Verifier #188074, S/N 255 Radionuclides: K-40(11.7%), U-238(90 ppm), Th-232(40 ppm).

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