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Detecting the Presence of Two Hydrogen Bearing Fluids Through the T2 Distribution Under Circumstances Similar to Those Found in Near Surface NMR

Katie E. Martin and Yaoguo Li
Colorado School of Mines

The nuclear magnetic resonance (NMR) method has been used successfully to detect the presence and types of multiple hydrogen-bearing fluids in petroleum applications. Such approaches employ strong magnetic fields generated by active sources. There is a growing interest in using lower-field, and lower-gradient NMR for the same purposes in near surface applications such as environmental clean up. Laboratory study and algorithmic development have indicated that such an approach is feasible. Our exploratory investigation begins with some of the practical aspects of using NMR for this purpose in a low- magnetic field and gradient setting. This includes altering the data acquisition parameters as well as implementing an improved inversion method for recovering distribution of the relaxation time, T2. Here, we discuss the use of the enhanced diffusion method (EDM) as well as a new inversion algorithm implementing the logarithmic barrier method combined with using generalized cross validation (GCV) to recover the T2 distribution from laboratory data. The inversion method allows for more resolution in the T2 distribution than has previously been recovered with other methods. The results show that we are able to recover the expected bimodal T2 distribution, enabling us to detect the presence of two types of hydrogen-bearing fluids.

AAPG Search and Discovery Article #90182©2013 AAPG/SEG Student Expo, Houston, Texas, September 16-17, 2013