Abstract: Disclosed is a downhole video system that is suitable for use with a standard wireline transmission line, without the need for coaxial or fiber optic cable. A downhole video camera transmits a digitized video signal that may be multiplexed with orientation, sound, and other telemetry data. At the surface, an enhanced video is displayed simultaneously with processed sound to give an operator a better understanding of the conditions downhole. In addition, multiple modes are provided, including a “burst” mode to provide high resolution, full motion video, thereby circumventing the severe bandwidth limitations of standard electrical transmission lines.

Abstract: The method of remotely actuating a downhole device provides the initiation of an acoustic signal. The acoustic signal is amplified within a resonance chamber and is transmitted down a fluid column in the tubing string or in the annulus around the tubing string. The signal can be coded to allow activation of multiple downhole devices. The use of a resonance chamber allows for the amplification of the actuation signal to ensure that a downhole receiver can detect it. The receiver can be either a transducer or a hydrophone. The apparatus and method allow for remote actuation without the need for intervention into the well.

Abstract: The invention is an acoustic transmitter that imparts vibratory stresses onto a signal propagation medium such as oil well tubing when actuated by an electric driver. In one embodiment, the acoustic transmitter utilizes a mechanical driver that includes piezoelectric elements to generate the vibratory stresses. The acoustic transmitter is mechanically attached at only one point to the signal propagation medium. This single point attachment eliminates loading on the acoustic transmitter from compressive and tensile forces carried by the signal propagation medium. A mass backing the mechanical driver may be used to extend the frequency range over which the acoustic transmitter is operable. In addition, the resonance response of the acoustic transmitter may be minimized by the use of a viscous dampener. The viscous dampener is configured to "couple" with the mechanical driver when the acoustic transmitter is operating and to "uncouple" with the mechanical driver at other times.

Abstract: A poppet and orifice mud pulser assembly is disclosed for use in an MWD system. The mud pulser is capable of generating pressure pulses in the column of drilling mud of various amplitudes to increase the data rate of the mud pulse telemetry system. The mud pulser includes a piston assembly that positions the poppet with respect to the orifice. The piston assembly comprises part of a by-pass conduit which defines a mud flow path around the orifice. Mud flow in the piston assembly generates a force tending to shut the poppet, because the surface area of the piston A.sub.2 is greater than the surface area of the poppet A.sub.1. Mud flow through the conduit (and thus through the piston) tends to force the poppet into a closed position because the force on the piston is greater than the force on the poppet, because of the greater surface area of the piston. A pilot valve is provided to enable and disable flow through the conduit, thus allowing the poppet to open and close.

Abstract: An acoustic detector in a mud pulse telemetry system includes a bypass loop in parallel with a section of the main mud line that supplies drilling mud to a drill string. The detector includes a pair of pressure sensing ports in the bypass line, and one or more pressure transducers for detecting the pressure at different locations in the bypass loop so that the differential pressure can be measured. The bypass loop has a small internal passageway relative to the main mud supply line and may include a constriction so as to create two regions in the passageway that differ in cross sectional areas. Forming the pressure sensing ports in the regions of differing cross sectional areas allows the pressure transducers to more precisely detect the mud pulse signals. Because of its relatively small cross sectional area, only a small fraction of the drilling mud flows through the bypass loop. The bypass loop may thus be constructed of hydraulic hose and a relatively small rigid body having a central through bore.

Abstract: A nonlinear equalizer aids in transmitting data with more speed and accuracy by reducing nonlinear signal distortion such as found in a mud transmission channel in an MWD telemetry system. The nonlinear equalizer receives an input signal that is modified by at least one nonlinear function element. The nonlinear equalizer also includes multiple linear equalizers: one such linear equalizer receives the unmodified input signal, and the other linear equalizers receive output signals from the nonlinear function elements. Output signals of the linear equalizers are summed to provide the nonlinear equalizer's output signal.

Abstract: In a well logging tool forming a data stream for telemetry to the surface, an encoding system is located downhole cooperative with surface located decoding equipment. The encoder converts serial data into NRZ symbols, then duobinary code of seven levels and then into quadrature modulating signals on a complex carrier. The decoder at the well surface receives the quadrature modulated complex carrier, forms inphase and quadrature components and decodes the two components. The decoder includes circuit means removing the intersignal distortion and also intersymbol smearing. This enables very significant telemetry ratio.

Abstract: The operation of hostile environment logging tools at temperatures up to 250.degree. C. stresses not only the tools, it also places severe demands upon the wireline telemetry due to the wide variations in the logging cable transmission characteristics. A robust adaptive wireline telemetry system for use in hostile environments has been developed that combines sophisticated digital communication methods with modern Digital-Signal-Processing (DSP) techniques. The downhole telemetry transmitter outputs a multilevel signal. The uphole receiver includes an adaptive transversal-filter equalizer (TFE) that is continually optimized to correct for changing signal distortion. The system operates robustly at high data rates over the temperature range of 0.degree. to 250.degree. C.

Abstract: An adaptive transversal filter is incorporated with an SP conductor extending through a logging cable to the surface from an SP electrode supported on a sonde. This logging cable is operated in a noisy environment and there is the risk of noise on the logging cable obscuring the SP signal. The SP signal is obtained at the surface and is passed through a filter system. One input to the filter system utilizes an AC ammeter connected to the AC power source for the logging cable and that signal is input to a multi-stage adaptive transversal filter. The filter output is a recreation of the noise imposed on the SP conductor and when summed with the SP output signal, provides a signal which is substantially noise free.

Abstract: The present disclosure is directed to an improved telemetry system and data recovery telemetry receiver apparatus for installation with a logging cable supported sonde. In the sonde, a data stream is modulated onto a carrier after conversion by an encoder. Encoding involves conversion from a stream of binary data into four state symbols which are then encoded into seven duobinary levels. The availability of redundant levels permits correlation between encoded symbols and adjacent symbols. This is transmitted up the monocable to the surface and is recovered. The recovery involves amplification by an automatic gain control amplifier, conversion from an analog to digital form in an ADC, demodulation and reconstruction of the transmitted signal by means of a adaptive transversal filter equalizer featuring fractionally spaced sampling. Reconstructed output levels are then provided, and a slicer adjusts those values to the permitted seven levels. The data is then decoded.