Schlumberger Technology Corporation

Lloyd D Clark, Jr

Terry L Mayhugh

Bart J Bombay

Guy P Vachon

Jimmy Everett Neeley

Ramon Hernandez-Marti

John A Booker

Marvin W Rasmussen

Joseph M Steiner, Jr

Gilbert R Martinez

Suzanne D Richardson

Terry L Mayhugh, Jr

A wireline telemetry system and method of transmitting data on multiple carrier frequencies. The system and method adjust power level and number of bits-per-carrier to optimally or near-optimally utilize the capacity of the wireline cable. Due to the nature of wireline telemetry the overall power level is restricted only by the output capability of the downhole telemetry cartridge and the input power restrictions of the uphole telemetry unit receiver. The optimal power level is determined during a training sequence and is a function of such factors as cable length, cable material, cable temperature and cable geometry. The uplink and downlink transmission are executed using different modulation techniques.

Method and apparatus for transmission of well-bore data on multiple carrier frequencies

A digital telemetry system having improved data rate and robustness. The telemetry system has a data transmission cable having a first end and a second end, and is capable of transmitting data between the first and second end on at least two propagation modes. A data source connected at the first end has data transmission circuitry to generate data signals on these propagation modes. A receiver connected to the second end of the wireline cable has a first receive circuitry to receive signals on a first of the at least two propagation modes and a second receive circuitry to receive signals on a second of the at least two propagation modes. An adaptive far-end cross-talk cancellation circuitry connected to the first receive circuitry and to the second receive circuitry cancels out far-end cross-talk between the at least two propagation modes.

Method and apparatus for transmission of data on multiple propagation modes with far-end cross-talk cancellation

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 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.

Growing community of inventors

Cedar Park, TX, United States of America

Lloyd D Clark, Jr