Detecting tool motion effects on spin echoes obtained with nuclear magnetic resonance measurements
AssigneeSchlumberger Technology Corporation
InventorPeter Speier
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Abstract
An NMR measurement obtained with a logging tool is potentially subject to relative motion between the apparatus and a sample. An echo train is produced having a plurality of spin echo signals. At least two of the spin echo signals are analyzed to determine a effect of tool motion on the NMR measurement.
Claims14
A method for detecting motion effects on a nuclear magnetic resonance measurement obtained from a tool positioned within a borehole traversing an earth formation, comprising the steps of:
- producing an echo train having a plurality of spin echo signals;
- selecting at least two spin echo signals wherein each spin echo signal is influenced differently by tool motion;
- and
- analyzing the selected signals to determine motion effects on the spin echo by using the NMR spin echo measurement itself.
A method for detecting motion effects on a nuclear magnetic resonance measurement obtained from a tool positioned within a borehole traversing an earth formation, comprising the steps of:
- producing an echo train having a plurality of spin echo signals;
- separating the spin echo signals of the echo train into a plurality of subsets, comprising the steps of:
- selecting a first subset of the spin echo signals wherein each spin echo in the subset is influenced in substantially the same manner by tool motion;
- and, selecting a second subset of the spin echo signals wherein each spin echo in the second subset is influenced in substantially the same manner by tool motion, the separating step is performed so that tool motion influences signals in the first subset differently from signals in the second subset;
- selecting at least one spin echo signal from each subset;
- and
- analyzing the selected signals to determine motion effects on the spin echo by using the NMR spin echo measurement itself.
Dependencies are inferred from the claim text.