Abstract
The Petroleum industry for decades has relied on the acquisition and correct interpretation of reservoir logs to provide important reservoir information used to determine the "payzone" of the reservoir. One such logging tool is based on the principles of Nuclear Magnetic Resonance (NMR), the alignment of hydrogen proton spins with an applied magnetic field and the subsequent proton relaxation observed when the external magnetic force is removed. This technique has become a useful non destructive and seemingly matrix independent method for determining pore size distribution in fluid filled pores. However, the presence of paramagnetic material such as iron or manganese within reservoir rock, particularly sandstones, increases the proton relaxation rate and as a result the pore size distribution appears smaller and subsequent permeability calculations will be erroneous.
The significance of this paramagnetic material and its effect on surface relaxation is the essence of this study. There were two series of synthetic core samples created, one with a varying paramagnetic concentration and constant grain size and the other with a varying grain size and constant paramagnetic concentration. NMR experiments were conducted using these core samples to study the surface relaxivity effect
The NMR analysis of the synthetic core samples has shown a strong correlation to NMR theory.
