... now. Extra relaxation due to diffusion in internal field gradient is another example where spatially varying relaxation strength may obscure the direct relationship. Better understanding of their interplay may be exploited to our advantage. In this work, we theoretically investigate the interplay...

..., and estimate in-situ oil viscosity simultaneously. These techniques can also be applied to explore internal magnetic field gradient and characterize the droplet size distribution of emulsion, measure the gas/oil ratio, monitor the alteration of wettability caused by oil-based mud filtrate or chemical...

... is occurring. For example, diffusion coefficient values above the bulk fluid diffusivity indicate the presence of internal field gradients, while values below bulk suggest the presence of restricted diffusion. Diffusion information can also indicate wettability alteration. When an oil phase relaxes...

... Upstream Oil & Gas valuable information application axis well logging information water peak core plug spwla 44 dimension log analysis field gradient diffusion coefficient relaxation time PPM nmr technique provide valuable information Symposium chemical shift SPWLA 44 th...

... time, carries information about, and only about, the liquid-solid surface relaxation and bulk-fluid relaxation. It is neither affected by rock-internal magnetic field gradients nor by differences in fluid diffusivity. Instrument artifacts influence T1 resuits to a much lesser extent than T2 results...

... ABSTRACT The interpretation of restricted diffusion and internal field gradients in rocks from the CPMG spin echo trains is complicated by many issues. These include the applicability of the free diffusion formula, the validity of the Gaussian approximation of the phase distribution...

...SPWLA 41 Annual Logging Symposium, June 4-7,200O INTERNAL FIELD GRADIENTS IN POROUS MEDIA Gigi Qian Zhang, George J. Hirasaki, and Waylon, V. House Rice University, Houston, TX Abstract Strong internal field gradients were observed on North Burbank (N. B.) sandstones and chlorite/fluid slurries...

...; and restricted diffusion. Under laboratory conditions, measured in a homogeneous background magnetic field, internal magnetic field gradients can be calculated from the increase of the transverse relaxation rate of pore fluids with increasing inter-echo time. Whereas a linear relation between the increase...

... paper has described how a pulsed NMR measurement can detect gas in the formation, by taking advantage of the static field gradient to measure the effect of diffusion on the observed T2 relaxation time. The authors proposed the ?Shifted Spectrum? method to observe diffusion from data at two different...

... by surface relaxation mechanisms (as is T,) and diffusion in the presence of magnetic field gradients. The magnetic field gradients can come from two sources: one (external) due to the applied magnetic field in a macroscopic scale much larger than the pore dimensions; and the other (internal) due...