Schlumberger Technology Corporation

Guy P Vachon

Terry L Mayhugh

Marvin W Rasmussen

Jimmy Everett Neeley

Lloyd D Clark, Jr

Bart J Bombay

Heather A Campbell

Terry L Mayhugh, Jr

In order to ensure that at least some of the tools ( - ) to - ) in a string of tools that is permanently installed in an oil well ( ) are kept in operation even in the event of a localized fault, the link ( ) interconnecting the tools and a surface installation ( ) is subdivided into segments by switch members ( ). More precisely, a switch member is associated with each tool. In addition, the link ( ) forms a loop with both ends thereof being connected to the surface installation ( ).

Method of saving string of tools installed in an oil well and a corresponding transmission assembly

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. Additional improvements are described, namely a method for predicting downhole current, adjustments for power supply distortions, and diagnostic metrics.

Method and apparatus for predicting peak voltage of a cable conveyed tool

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.

Magnetic mark detection

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.

A method of reproduction in a discrete reproduction system where the available colors are arranged in equally perceptible steps. Because in a discrete reproduction system only a limited set of points can be produced from the gamut of colors, the present method selects the color variables describing the set of points such that the difference between colors is equiperceptible. Preferably, a numerical approximation to the Munsell book of color is used to determine the hue, saturation, and luminance of the colors used in the reproduction system. The preferred embodiment is a gray scale printer where the preceived contrast between levels of gray is uniform--i.e. equiperceptible. To achieve equiperceptible gray scale requires that the increments in print density be nonuniform. To determine the desired print density to achieve an equiperceptible gray scale, the print density is determined using a numerical approximation of the Munsell value coordinates.

System and method of selecting the reproducible colors in a discrete

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.

Peripheral I/O bus and programmable bus interface for computer data

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.

Growing community of inventors

Austin, TX, United States of America

Guy P Vachon