Evaluating Pore Space Connectivity by NMR Diffusive Coupling
by Giovanna Carneiro (Schlumberger-Doll Research), SPWLA Distinguished Lecturer
was presented on the 6 th of May, 2015.
Nuclear magnetic resonance (NMR) measurements have been used as a way to evaluate reservoir rocks based, on the longitudinal and transverse relaxation times, T1 and T2, and the time dependent diffusion coefficient, D(t). Relaxation time distributions can be related to pore sizes and to the free and bound fluid fractions. In addition, there are well established equations correlating relaxation times to permeability. Regarding diffusion, at short times D(t) is linked to the pore volume to surface area ratio while at long times it is related to pore tortuosity. Diffusive coupling between pores complicates the interpretation of NMR measurements because the relaxation time distribution will no longer be an accurate representation of the pore size distribution . On the other hand, analyzing the effects of diffusive coupling can provide information about connectivity within the pore space. In particular, knowing whether the macro-pores are connected to each other or are connected only through the micro-pores would provide valuable insight regarding the permeability.
Giovanna Carneiro, CV
Giovanna is a Research Associate at Schlumberger Brazil Research and Geoengineering Center. She has a M.S. in Chemistry from Federal University of Espirito Santo, Brazil, and is currently a Ph.D. student at Chemistry Department at Federal Fluminense University. Giovanna joined Schlumberger in 2011 as an intern at Schlumberger-Doll Research in Cambridge, Massachusetts.