System and methods for formation evaluation while drilling
AssigneeHalliburton Energy Services, Inc.
InventorManfred Prammer
Life of this patent
Estimating the term…
Abstract
A logging while drilling (LWD) and measuring while drilling (MWD) method and device are disclosed for reducing the sensitivity of NMR measurements to tool motions. The invention is based on NMR relaxation measurements determining longitudinal relaxation times T1 instead of the standard T2 measurements, and involves saturating a relatively wide sensitive region of the formation and processing NMR echo signals which originate approximately from the center of the sensitive region. In another aspect, the invention uses novel pulse sequences and processing algorithms to reduce the time for the relaxation measurement and to provide real-time transfer of data uphole.
Claims25
A method for making nuclear magnetic resonance (NMR) measurements of a geologic formation using an NMR logging tool, comprising the steps of:
- (a) applying downhole one or more forced magnetization recovery pulse sequences;
- (b) applying at least one T1 saturation-recovery sequence following the one or more forced magnetization recovery pulse sequences;
- (c) receiving NMR echo signals in response to pulse sequences applied in steps (a) and (b);
- and
- (d) processing the received NMR echo signals to determine properties of the geologic formation.
A system for making nuclear magnetic resonance (NMR) measurements of a geologic formation using an NMR logging tool, comprising the steps of:
- (a) means for applying downhole one or more forced magnetization recovery pulse sequences;
- (b) means for applying at least one T1 saturation-recovery sequence following the one or more a forced magnetization recovery pulse sequences;
- (c) means for receiving NMR echo signals in response to NMR pulse sequences;
- and
- (d) means for processing the received NMR echo signals to determine properties of the geologic formation.
Dependencies are inferred from the claim text.