Abstract: A computer controlled heave compensation wireline logging winch system and method of use that compensates for the effects of wave motion on floating installations performing wireline logging measurements. A wireline winch and wireline cable with a logging measurement tool attached is installed on a floating installation. Vessel vertical movement is measured and is physically compensated for by a change in speed of the wireline cable so that the logging data is obtained at a controlled speed. Any error in this physical compensation is detected by a depth measurement system and is used to adjust the true depth at which the logging tool measurements are being recorded.

Abstract: A method and apparatus for predicting the peak voltage at the load end of a power transmission cable having a power supply end and a load end, where direct measurement at the load end is not practical. The method samples the current and voltage waveforms at the power supply end of the cable. The current waveform is used to estimate a current function which includes a full width at half maximum and adjustments for cable reactive current, distortions, and load. The product of the current function and a peak voltage sample from the power supply end is an estimate of the peak voltage at the load end. The method and apparatus have been applied to oil well logging where one or more logging tools are lowered at the end of a transmission cable into an oil well and it is desirable to predict peak voltage at the tools to ensure proper tool performance. An important improvement is a more accurate current function which compensates for capacitive current flow in the cable and includes a quadratic term.

Abstract: A method and apparatus for detecting magnetic marks on a wireline logging cable and for more accurately making depth measurements during logging is described. The method uses depth-based, rather than time-based, samples and calculations. A Hall Effect sensor samples the cable at regular depth intervals approximated by an encoder mechanism. The signal values from the Hall Effect sensor are signal processed to better discriminate the precise location of the magnetic marks on the cable. The location of the magnetic marks is used to refine the depth measurements from the encoder mechanism. Depth-based sampling eliminates detection dependence on cable speed, enhances detection ability, reduces computational load, and leads to more accurate determination of the location of magnetic marks.

Abstract: An undervoltage protection circuit, system and method is prodded for sending a reset signal to an electronic device during undervoltage time periods in which the device power supply voltage is less than a desired amount. The protection circuit includes a sensing circuit and a latching network adapted to quickly discharge a storage capacitor when the sensing circuit senses the undervoltages. A buffer network is included to send a reset signal to the electronic device whenever the storage capacitor discharges to a low latched level. The reset signal exists substantially throughout the undervoltage time period and also for a set delay period after the undervoltage time period ceases. During receipt of the reset signal, the electronic device will be inhibited from incurring damage or loss of data.

Abstract: A well-logging well-site data acquisition and data processing system is disclosed. A central processing unit including a main memory and a single data bus is provided for data transfers with a first plurality of peripheral units. A plurality of serial link units are also provided. Each serial link unit includes a plurality of serial data input/output channels where each serial channel sends on transmit lines and receives on receive lines serial data between a second plurality of peripheral units connected to a serial link unit. A processor interface unit is provided for controlling the transfer of data between the host central processor unit and the plurality of serial link units. A microprocessor unit is provided as a communications controller for initiating the transfer of data between the plurality of serial link units and the processor interface unit.