Abstract: A method for use with equipment located downhole in a subterranean well includes providing a model describing behavior of the equipment and measuring a state of the equipment downhole. An indication is received of the state at a surface of the well, and the model is modified based on the indication. The system includes a communication link, a circuit and a machine. The communication link is adapted to furnish an indication of a state of the equipment to the surface of the well. The circuit is located downhole and is adapted to detect the state and produce the indication. The machine is adapted to provide a model describing behavior of the equipment and modify the model based on the indication.

Abstract: A system for use with a well includes a surface device, a communications link coupled to the surface device and extending into the well, and a plurality of downhole devices coupled to different points on the communications link in the well. The surface device and the plurality of devices are adapted to determine distortions of different portions of the communications link coupling the surface device and downhole devices and to compensate for the distortions when communicating. Transfer characteristics of the communications link portions may be determined, from which equalization parameters may be determined to compensate for distortions caused by communications link portions.

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: 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 approximation adjusted as required for load, cable type, and cable length. 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.

Abstract: A bus interfacing device suitable for use in computerized data acquisition systems for interfacing a main processor bus to an auxiliary peripheral bus. The operation of peripherals connected to the auxiliary peripheral bus can be controlled by either the main processor or the bus interfacing device. The device also allows data gathered from peripherals on the auxiliary bus to be stored in a dual-ported RAM for transfer in DMA-type fashion over the main processor bus.

Abstract: A method for measuring wireline depths in a borehole using paired encoder wheels frictionally engaging the wireline is disclosed. The method allows for the correction of the measurement from a slipping encoder wheel without corrupting the measurement from the non-slipping encoder wheel.The method comprises incrementing corresponding depth counters whenever a pulse is produced by one of the encoder wheels. The depth counts are compared and if a significant difference exists, the value of the counter corresponding to the slipping encoder wheel is set equal to the value or the other wheel.