Estimation of Molecular Size Distributions in Forming Fluid Samples When Using a Wellhead nmr Fluid Analyzer

摘要

Patent specification: "Estimation of molecular size distributions in forming fluid samples when using a borehole nmr fluid analyzer". The present invention relates to a method for estimating a subsurface material property which includes extracting a sample of the material using a downhole tester and performing a plurality of nuclear magnetic resonance (nmr) measurements. ) at a sensitive volume in the sample where each plurality measurement is performed on a static homogeneous magnetic field with a pulsed magnetic field gradient that is different in magnitude from other nmr measurements to obtain a waveform signal.¶ the method also includes transforming each received signal from the time domain waveform into a frequency domain and comparing the frequency domain signal to a reference to obtain proton chemical change information related to a chemical property of one or more molecules in the sample and transforming frequency domain signals into a full number domain exo which quantifies changes in waveform signal amplitude to obtain one or more diffusion rates where each diffusion rate is associated with a corresponding frequency.