Abstract: An electromagnetic borehole telemetry system for transmitting information between a borehole transceiver and a surface transceiver located at or near the surface of the earth. Tubulars, such as steel casing and liners, are typically set within the well borehole to stabilize the wall of the borehole and to assist in hydraulically isolating penetrated formations. The invention utilizes these tubulars cooperating with one or more signal wires to reduce attenuation and noise in signals transmitted between the borehole and surface transceivers. The one or more signal wires are typically disposed within an annulus formed by the borehole wall and the outside surface of the casing. The one or more signal wires are connected at one end to one or more connection terminals positioned preferably near the bottom a tubular string. Opposing ends of the one or more signal wires are connected to one or more terminals of the surface transceiver.

Abstract: An electromagnetic borehole telemetry system for transmitting information between a borehole transceiver and a surface transceiver located at or near the surface of the earth. Tubulars, such as steel casing and liners, are typically set within the well borehole to stabilize the wall of the borehole and to assist in hydraulically isolating penetrated formations. The invention utilizes these tubulars cooperating with one or more signal wires to reduce attenuation and noise in signals transmitted between the borehole and surface transceivers. The one or more signal wires are typically disposed within an annulus formed by the borehole wall and the outside surface of the casing. The one or more signal wires are connected at one end to one or more connection terminals positioned preferably near the bottom a tubular string. Opposing ends of the one or more signal wires are connected to one or more terminals of the surface transceiver.

Abstract: The present invention is directed toward the determination of moisture content per unit volume of material penetrated by a gas filled borehole. An alternate application of the invention is the detection of fractures and vugular cavities in the immediate vicinity of a liquid filled borehole. The apparatus comprises a probe which is conveyed along the borehole. The probe contains a source of neutrons and an epithermal neutron detector at essentially zero longitudinal spacing from the neutron source along the axis of the borehole. In the preferred embodiment, the neutron source is Californium-252 and the epithermal neutron detector comprises a glass scintillator. The response of the system is independent of the thermal neutron absorption properties of the material and the fluid within the borehole.

Abstract: The present invention relates to the determination of a spatial formation parameter such as slowing down length and porosity in a measurement while drilling ("MWD") tool. The invention, more particularly, relates to the use of a neutron source and multiple neutron detectors in an MWD tool to determine the slowing down length of neutrons in the formation and to derive the formation porosity from the determined slowing down length.

Abstract: The present invention relates generally to increasing the accuracy of MWD nuclear based measurement systems. Specifically, the present invention provides a secondary measurement system for determining the tool displacement from the bore-hole wall for calculated compensation of nuclear measurement data.

Abstract: Variable frequency induction well logging methods and apparatus are disclosed having an approximately constant vertical response function. The frequency of operation is automatically selected to minimize propagation effects. These techniques permit an N point deconvolution of apparent formation conductivity to yield an approximation of the true conductivity of incremental layers of cylindrically symmetrical earth formations, including formations having adjacent layers of arbitrary thicknesses and conductivities.

Abstract: A well-logging method and apparatus in which a fast real time portion of a logging signal is sequentially sampled at discrete times. These sampled segments are stored and then are clocked out of storage over an expanded time period.The rms amplitude portion of the logging signal occurring prior to the compression wave part of the logging signal (the nominal noise level) may be used for AGC regulation of an amplifier which amplifies the time-expanded output.A similar development of an rms value can be used for establishing a threshold level for a peak detector, which level is set slightly higher than such rms value. The first three successive samples greater than the threshold level detected by the detector are presumed to be the first three samples of the compression wave. This presumed compression wave is recorded and convolved against the expanded-time digital form of the logging signal to locate the compression wave in a second received signal and, later, the similarly appearing "shear" wave.