The lockable flapper valve (LFV) is a component of the APC/XCB Bottom Hole Assembly (BHA). It is hinged and sprung on one side and is designed to prevent fluids from backflowing up the drill pipe. The LFV presents an obstacle for the logging operation, as a closed LFV...
Description Although the standard Schlumberger sonic logs could provide accurate compressional velocities, the additional information from the multi-channel sonic log tool (MCS) enabled determination of the elastic properties of the formation and a qualitative estimate of fracture transmissivity. The MCS was a multi-receiver, single-source sonic logging tool...
Description The Natural Gamma Ray Tool (NGT) utilized a sodium-iodide scintillation detector to measure the natural gamma ray radiation of the the three most common components of the naturally occurring radiation: potassium, thorium, and uranium. The high-energy part of the spectrum was divided into three energy windows, each covering...
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 The Array Induction Imager tool accurately measures the borehole formation conductivity in open holes as a function of both depth and distance from the borehole; the SlimXtreme version (QAIT) was designed to work in slim holes under severe environmental conditions. Wireline array induction tools employ...
Description During DSDP and the early part of ODP, the Scintillation Gamma Ray Tool (SGT) was more widely known as the Natural Gamma Ray Tool (GR). All gamma ray tools record naturally occurring gamma rays in the formation adjacent to the borehole. Therefore, they provide a...
Description The Versatile Seismic Imager (VSI) represents the latest available technology in the acquisition of seismic waves generated by a seismic source. The VSI employs three-axis single sensor seismic hardware and software and advanced telemetry for efficient transmission of the data from the borehole to the...
Description The Core Barrel- Extended Memory Drill String Accelerometer (CB-DSA-XM) was developed during ODP at USIO Science Services/LDEO as a modification of the CB-DSA, which was used on several ODP legs. The CB-DSA-XM operates as a memory tool that measures and records drill string acceleration and...
Description The WST was a Schlumberger single axis check shot tool used for zero offset vertical seismic profiles (VSP). The WST consisted of a single geophone, pressed against the borehole wall, that was used to record the acoustic waves generated by an air gun located near...
Description In fast formations, where shear velocity is faster than the velocity of the drilling fluid, the SDT obtained direct measurements for shear, compressional, and Stoneley wave values. In a slow formation, the SDT obtained real-time measurements of compressional, Stonily, and mud wave velocities. Shear wave values could then be...