Radiant energy – Geological testing or irradiation – Well testing apparatus and methods
Reexamination Certificate
2007-08-16
2010-02-23
Porta, David P (Department: 2884)
Radiant energy
Geological testing or irradiation
Well testing apparatus and methods
C250S266000
Reexamination Certificate
active
07667192
ABSTRACT:
A method for determining at least one formation property calculated from neutron measurements acquired with a downhole tool includes emitting neutrons from a source in the tool into the formation, detecting neutrons with at least one detector in the downhole tool, calculating a first slowing-down length (L1) based on the detected neutrons, and deriving a second slowing-down length (L2) based on the first slowing-down length (L1). Further steps include deriving a correlation function for relating slowing-down lengths from a first tool to slowing-down lengths associated with a different source, wherein the correlation function depends on formation properties such as bulk density; and applying the correlation function to the slowing-down length of the first tool to derive the slowing-down length of the second tool. A method for determining a thermal neutron formation porosity based on a slowing-down length from epithermal neutron measurements from an electronic neutron source includes converting the slowing-down length into a computed neutron slowing-down length from thermal neutron measurements from a chemical neutron source, wherein the converting uses a correlation function that depends on formation bulk density; deriving a thermal neutron countrate ratio based on the computed neutron slowing-down length, wherein the deriving uses a function that depends on the formation bulk density and formation sigma; and computing the thermal neutron formation porosity from the thermal neutron countrate ratio.
REFERENCES:
patent: 3483376 (1969-12-01), Locke et al.
patent: 3942004 (1976-03-01), Kehler
patent: 4423323 (1983-12-01), Ellis et al.
patent: 5684299 (1997-11-01), DasGupta
patent: 5767510 (1998-06-01), Evans
patent: 5789752 (1998-08-01), Mickael
patent: 5804820 (1998-09-01), Evans et al.
Alger et al., “The dual-spacing neutron log—CNL,”J. Petrol., 24:1073-1083, 1972.
McKeon and Scott, “SNUPAR—a nuclear parameter code for nuclear geophysics applications,”IEEE Transactions on Nuclear Science, 36(1):1215-1219, 1989.
McKeon and Scott, “SNUPAR—a nuclear parameter code for nuclear geophysics applications,”Nuclear Geophysics, 2(4):215-230, 1988.
Neville et al, “Integrated interpretation of a rich data set from a new-generation LWD tool,” Paper 97224,SPE Annual Technical Conference&Exhibition, Dallas, TX, Oct. 9-12, 2005.
Scott et al., “Response of a multidetector pulsed neutron porosity tool,”SPWLA 35thAnnual Logging Symposium, Jun. 19-22, 1994.
Weller et al., “A new integrated LWD platform brings next-generation formation evaluation services,”SPWLA 46thAnnual Logging Symposium, Jun. 26-29, 2005.
Adolph Robert A.
Evans Mike
Fricke Scott H.
Boosalis Faye
Castano Jaime
Fonseca Darla P.
Porta David P
Schlumberger Technology Corporation
LandOfFree
Thermal neutron porosity from neutron slowing-down length,... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thermal neutron porosity from neutron slowing-down length,..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermal neutron porosity from neutron slowing-down length,... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-4218962