Numar Corporation

Schlumberger Technology Corporation

John E Smaardyk

Paul F Rodney

Manfred G Prammer

George David Goodman

Marian Morys

James H Dudley

Chen-Kang David Chen

Michael Louis Larronde

Roger P Bartel

Dale Allen Jones

Peter Masak

Jason P MacInnis

Robert Freedman

Christopher Edward Morriss

Don Thornton Macune

Joseph M Steiner, Jr

Richard W Oldigs

A method for manufacturing NMR measurement-while-drilling tool having the mechanical strength and measurement sensitivity to perform NMR measurements of an earth formation while drilling a borehole, and a method and apparatus for monitoring the motion of the measuring tool in order to take this motion into account when processing NMR signals from the borehole. The tool has a permanent magnet with a magnetic field direction substantially perpendicular to the axis of the borehole, a steel collar of a non-magnetic material surrounding the magnet, antenna positioned outside the collar, and a soft magnetic material positioned in a predetermined relationship with the collar and the magnet that helps to shape the magnetic field of the tool. Due to the non-magnetic collar, the tool can withstand the extreme conditions in the borehole environment while the borehole is being drilled. Motion management apparatus and method are employed to identify time periods when the NMR measurements can be taken without the accuracy of the measurement being affected by the motion of the tool or its spatial orientation.

Method and apparatus for nuclear magnetic resonance measuring while drilling

An NMR measurement-while-drilling tool having the mechanical strength and measurement sensitivity to perform NMR measurements of an earth formation while drilling a borehole, and a method and apparatus for monitoring the motion of the measuring tool in order to take this motion into account when processing NMR signals from the borehole. The tool has a permanent magnet with a magnetic field direction substantially perpendicular to the axis of the borehole, a steel collar of a non-magnetic material surrounding the magnet, antenna positioned outside the collar, and a soft magnetic material positioned in a predetermined relationship with the collar and the magnet that helps to shape the magnetic field of the tool. Due to the non-magnetic collar, the tool can withstand the extreme conditions in the borehole environment while the borehole is being drilled. Motion management apparatus and method are employed to identify time periods when the NMR measurements can be taken without the accuracy of the measurement being affected by the motion of the tool or its spatial orientation.

A system includes a wellbore tool disposed in a wellbore and a surface apparatus disposed at a surface of the wellbore. Prior to operating the tool to take an initial measurement, the wellbore tool is first calibrated to take into account magnetic junk which is magnetically attracted to and accumulated on a magnet housing of the tool. To calibrate the tool, a new tuning frequency, called the Larmor frequency, is determined, and the tool is tuned to the new Larmor frequency before taking an initial measurement. The wellbore tool and the surface apparatus each include a processing system. Each processing system includes a memory. A first part of a tuning frequency determination software is stored in the memory of the tool, and a second part of the frequency determination software is stored in the memory of the surface apparatus. To determine the tuning frequency, the processing system in the wellbore tool initiates execution of the first part of the tuning frequency determination software. Results from this first execution are transmitted uphole to the surface apparatus. The processing system in the surface apparatus then initiates execution of the second part of the tuning frequency determination software. When this second execution is complete, the new tuning frequency, known as the Larmor frequency, is determined. The wellbore tool is then tuned to the new Larmor frequency.

Method and apparatus for determining the in situ larmor frequency of a

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

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Houston, TX, United States of America

John E Smaardyk