William Dean Loomis, 83Watertown, WI

5171986, Dec 15, 1992

Sep 27, 1991

7/767177

William A. Loomis - Ridgefield CT
James A. Grau - Ridgefield CT
Jerome A. Truax - Brookfield CT

Schlumberger Technology Corporation - New York NY

G01C 2500
G01V 500

2502521

The energy-to-channel response of a bismuth germanate scintillator (BGO) gamma ray spectra measurement system is calibrated by use of the 10. 2 MeV gamma ray peak originating from epithermal neutron capture within the BGO crystal as a calibration reference line. The 10. 2 MeV peak is located by successively fitting the detected spectrum to the combination of a gaussian-shaped gamma ray peak and an exponentially-shaped background, beginning at the upper end of the spectrum and successively sliding the fitting window downwards until the peak is reached. Once the 10. 2 MeV peak has been located, the spectral gain is adjusted to shift the peak to an assigned calibration channel location adjacent the upper end of the overall spectral window.

5420422, May 30, 1995

Jan 11, 1994

8/179787

William A. Loomis - Ridgefield CT

Schlumberger Technology Corporation - Ridgefield CT

G01N 510

2502694

The first and second moments of an epithermal neutron slowing down time curve are determined and are combined in accordance with a predetermined empirical relationship to derive a raw measurement of the porosity of an earth formation surrounding a borehole. The raw porosity value is then combined with the second moment in accordance with further predetermined empirical relationships to derive a standoff measurement and a standoff-correction factor to be applied to the raw porosity measurement to produce a standoff-corrected porosity measurement. Where the raw porosity value changes appreciably from depth level to depth level, a differential spatial filter is applied to the raw porosity measurement and to the standoff-correction factor to provide a more precise standoff-corrected porosity measurement.

RE36012, Dec 29, 1998

Sep 25, 1996

8/710997

William A. Loomis - Ridgefield CT
Kenneth E. Stephenson - Cambridge, GB2
Jerome A. Truax - Brookfield CT
Wolfgang P. Ziegler - Ridgefield CT
S. Zema Chowdhuri - Bloomington IN
Benoit Couet - Bethel CT
Michael L. Evans - Missouri City TX
Paul Albats - Ridgefield CT
Bradley A. Roscoe - Ridgefield CT
Jacques M. Holenka - Missouri City TX
Keith A. Moriarty - Houston TX
William R. Sloan - Missouri City TX

Schlumberger Technology Corporation - Ridgefield CT

G01V 510

2502694

Measurement-while-drilling apparatus includes a 14 MeV neutron accelerator, a near-spaced neutron detector which primarily senses source neutrons and whose output is proportional to source strength, one or more intermediately-spaced epithermal neutron detectors eccentered against the drill collar wall and primarily responsive to formation hydrogen concentration, and a third far-spaced radiation detector, either gamma ray or neutron, primarily responsive to formation density. The intermediately-spaced and far-spaced detector outputs, normalized by the near-spaced detector output, are combined to provide measurements of porosity, density and lithology and to detect gas. A thermal neutron detector and/or a gamma ray detector may also be provided at intermediate spacings to provide additional information of interest, such as standoff measurements and spectral analysis of formation composition. Tool outputs are related to the angular or azimuthal orientation of the measurement apparatus in the borehole.

5539225, Jul 23, 1996

Sep 16, 1994

8/307894

William A. Loomis - Ridgefield CT
Kenneth E. Stephenson - Newtown CT
Jerome A. Truax - Brookfield CT
Wolfgang P. Ziegler - Ridgefield CT
S. Zema Chowdhuri - Bloomington IN
Benoit Couet - Bethel CT
Michael L. Evans - Missouri City TX
Paul Albats - Ridgefield CT
Bradley A. Roscoe - Ridgefield CT
Jacques M. Holenka - Missouri City TX
Keith A. Moriarty - Houston TX
William R. Sloan - Missouri City TX

Schlumberger Technology Corporation - Ridgefield CT

G01V 510

2502694

Measurement-while-drilling apparatus includes a 14 MeV neutron accelerator, a near-spaced neutron detector which primarily senses source neutrons and whose output is proportional to source strength, one or more intermediately-spaced epithermal neutron detectors eccentered against the drill collar wall and primarily responsive to formation hydrogen concentration, and a third far-spaced radiation detector, either gamma ray or neutron, primarily responsive to formation density. The intermediately-spaced and far-spaced detector outputs, normalized by the near-spaced detector output, are combined to provide measurements of porosity, density and lithology and to detect gas. A thermal neutron detector and/or a gamma ray detector may also be provided at intermediate spacings to provide additional information of interest, such as standoff measurements and spectral analysis of formation composition. Tool outputs are related to the angular or azimuthal orientation of the measurement apparatus in the borehole.

4972082, Nov 20, 1990

Mar 16, 1989

7/324776

William A. Loomis - Ridgefield CT
David J. Le Poire - Woodridge IL
William B. Nelligan - North Bay Village FL

Schlumberger Technology Corporation - New York NY

G01V 510

250269

The porosity of an earth formation is derived in a plused neutron logging tool by use of a directionalized and borehole-shielded eptithermal neutron detector array and by processing detector count rate measurements of the epithermal neutron die-away curve in accordance with a multi-parameter fit to obtain as one parameter the epithermal neutron decay time of the formation and as a second parameter an indication of detector standoff (environmental) effects. The multi-parameter fitting procedure separates the formation and standoff effects on the measured count vs time curve, and yields a decay time measurement that is primarily representative of formation porosity and substantially free of environmental effects. To enhance count rate statistics, the neutron source and one or more of the epithermal neutron detector may be located at the same depth in the borehole. The neutron burst centroid is monitored an used to define a fiducial window for processing the die-way curve data.