Description In homogeneous formations with resistivity higher than 100 ohm m the average radial depth of investigation is about 5 ft (1.5 m) and 2.5 ft (76 cm) for the deep and medium induction curves, respectively, and 1.25 ft (38 cm) for the SFL. This drops...
Description Geological High-Resolution Magnetic Tool (GHMT) provided magnetic susceptibility and total magnetic induction measurements. The main use of the GHMT was to provide a magnetic reversal sequence in sediment. The GHMT consisted of two sondes. The Susceptibility Measurement Sonde (SUMS) made an induction-type measurement to record a signal related to formation susceptibility....
Description The High-Resolution Laterolog Array (HRLA) tool provides six resistivity measurements with different depths of investigation (including the borehole, or mud resistivity, and five measurements of formation resistivity with increasing depth of penetration into the formation). The sonde sends a focused current into the formation and...
Description Long Spacing Sonic Sonde (LSS*) contained two acoustic sources spaced two feet apart located eight feet below a pair of receivers also spaced two feet apart. This provided source-receiver offsets of 8, 10, 10, and 12 feet. The measurement relied on the "depth-derived" borehole...
Description The Hostile Environment Litho-Density Sonde (HLDS) uses a pad that is mechanically identical to that of the Hostile Environment Litho-Density tool (HLDT), but includes magnetic shielding and high-speed electronics. The entire pulse-height spectra from both detectors are recorded and processed into windows identical to those...
Description The Litho-Density Log (LDT*) had a 137Cs source and two detectors, all located on a "skid" (a pad held against the borehole wall by a spring-activated arm). The source emitted gamma rays at an energy of 662 keV. The two detectors (short-spaced and long-spaced) were shielded...
Description The Hostile Environment Natural Gamma Ray Sonde (HNGS) utilizes two bithmus-germanate (BGO) scintillation detectors to measure the natural gamma ray radiation of the formation. The larger detector volume and higher gamma ray stopping power of BGO makes the HNGS a very effective spectral gamma tool....
Description The Schlumberger QSST was a single-axis seismic checkshot tool that ran in-line with the triple combo tool string. The QSST consisted of a single hydrophone and did not utilize a clamping arm like the WST to force it into contact with the borehole wall. Seismic...
Description 137Cs radioactive source and two detectors mounted on a shielded skid which was pressed against the formation by a hydraulically-activated eccentering arm. The 662 keV gamma rays emitted by the source into the formation experienced two types of interaction with the electrons in the formation:...
Description 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...