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Nuclear Magnetic Resonance Loggingby Submitted to the Department of Earth, Atmospheric, and Planetary Sciences on May 23, 1997 in partial fulfillment of the requirements for the degree of Master of Science ABSTRACT
The application of nuclear magnetic resonance (NMR) in petroleum well logging
is rapidly expanding. A new generation of pulsed NMR tools, similar in technology
to devices in use in medical imaging, is gaining wide acceptance in petroleum
exploration. However, methods of NMR data collection and interpretation are not
as mature in this application as in medicine; refinement is needed, in particular
to maximize the benefit of costly methodology. Herein is described a novel approach
to formation evaluation in NMR well logging, enhanced by a nonconventional means
of acquiring logging data. Heretofore, both NMR and conventional logs (e.g., acoustic,
density, neutron, gamma-ray, spontaneous potential) were analyzed as input into
a gross water-saturated model based on resistivity. In the new evaluative approach,
in contrast , the NMR measurements - pore size, free fluid, capillary-bound water,
effective porosity, and direct hydrocarbon imaging - are the key parameters; resistivity
and other logs are input into the NMR model. The effectiveness of this evaluation
has been enabled by the development of specific pulse sequences to improve direct
hydrocarbon imaging through imaging of pour fluids. The technique, representing
an extension of the differential spectrum method, exploits T1 and T2 relaxation
methods used effectively to improve tissue contrast in medical magnetic resonance
imaging. In practical application, the NMR evaluative model with use of pore size
has described many prolific geologic formations deemed nonproductive or marginal
by conventional saturation models and analyses. Example novel NMR logs and evaluations
are provided, as is a review of NMR physics and previous NMR and conventional
formation evaluation models. Return to Theses Return to ERL Home Updated: June, 1999
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