Schlumberger Technology Corporation

Joseph M Steiner, Jr

Edward Alan Pierce

Andrew L Kurkjian

Kevin A Eyl

David J Lineman

Ramon Hernandez-Marti

Christopher Edward Morriss

Bart J Bombay

John A Booker

John E Smaardyk

Don Thornton Macune

Terry L Mayhugh

Lloyd D Clark, Jr

Richard W Oldigs

Jason P MacInnis

Gilbert R Martinez

Suzanne D Richardson

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

NMR logging apparatus is provided which produces a strong, static and homogeneous magnetic field B.sub.0 in a Volume of an adjacent formation on one side of the tool to measure nuclear magnetic resonance characteristics thereof at two different depths of investigations. In the preferred embodiment, the tool has an RF antenna mounted on the outside of the metal body of the tool, directing focused oscillating magnetic fields B.sub.1 at said Volume to polarize or tip the magnetic moments of hydrogen nuclei of fluids within rock pores. The same antenna can be used to receive signals of proton precession in the Volume of interest immediately after transmission of the RF polarizing field B.sub.1. One of the NMR readings is employed to compensate for inaccuracies in the other NMR reading to provide an overall improved NMR log.

Borehole measurement of NMR characteristics of earth formation

A well logging system includes a digital threshold crossing data generation system (TCDG System) disposed in a well tool, adapted to be disposed in a borehole, and a digital first motion detection (DFMD) software disposed in a memory of a well truck computer. The TCDG system generates a series of threshold crossings for each analog signal received from a receiver of the well tool, the threshold crossings including a plurality of threshold crossing events for each analog signal and representing compressed versions of digitized analog waveforms. The well logging truck computer receives the threshold crossing data from the TCDG system and executes the DFMD software. When the software is executed, a first set of compressional wave first arrival times are determined from a startup routine in the software using the threshold crossing data. A second set of compressional wave first arrival times are determined from a tracking routine in the software using four different prediction methods and a voting procedure to select the second set of arrival times from among the four predictions. A cycle skip detection routine in the software determines if any cycle skips are associated with either the first or second set of compressional first arrival times. Finally, a cycle skip recovery routine determines which set of compressional first arrival times to select depending upon the outcome of the cycle skip detection routine.

Method and apparatus for determining compressional first arrival times

Growing community of inventors

Austin, TX, United States of America

Joseph M Steiner, Jr