The HTGC had a gamma-ray detector that was made of a NaI crystal, a photo multiplier tube, a high-voltage generation circuit, and a preamplifier of the gamma-ray pulse, all built in one package. The number of output pulses from the detector was counted at a rate of 8 Hz, and the count sent uphole. Housed in a heatsink and dewar flask that allowed operations in high-temperature environments (260°C), this tool also had a 31-pin upper and lower head asset and was combinable with any standard 3.375-in tool without additional adaptors. The data acquisition software could not distinguish between the tools, but the HTGC had the correct length and measure point and gamma-ray response for the flasked tool.
The HTGC was deployed at the top of the triple combo tool string on two sites during ODP Leg 193.
|Temperature rating||500° F (260° C)|
|Pressure rating:||25 kpsi (172 MPa)|
|Length:||10.7 ft (3.26 m)|
|Weight:||265 lbs (120 kg)|
|Diameter:||4.75 in (12.1 cm)|
|Vertical resolution:||12 in (30.48 cm)|
|Depth of investigation:||2 4in (60.96 cm)|
|Logging speed:||1,800 ft/hr (549 m/hr)|