A review of the applications of magnetic susceptibility measurements for improved reservoir characterization

In the past, the application of magnetic susceptibility of diamagnetic and paramagnetic minerals to the study of rock magnetism was believed to be limited, due to both of their susceptibility signals being small compared to those of minerals in other magnetic. However, recent works have proved the usefulness of diamagnetic and paramagnetic susceptibility for reservoir studies. This paper summarizes results from previous studies showing the application of magnetic susceptibility measurements for characterizing different reservoir properties. Studies on the magnetic susceptibility of crude oils from different oil field regions around the world have shown good correlations of the susceptibility values with crude oil densities as well as other physical and chemical properties. In other studies, the measurements of magnetic susceptibility at the low and high fields have also been applied on rock core samples collected from different types of oil and gas reservoirs such as clastic shoreface, carbonate, shale and oil sand reservoirs. The magnetic susceptibility measurements for core samples without damaging the core by using the probe magnetic technique is probably used as a rapid, reasonable screening method for the initial estimation of core samples. The susceptibility of rock samples does not only show good correspondence with other reservoir characterizing methods, such as downhole gamma ray, spontaneous potential logs and core permeability, but it also shows some advantages over the traditional ones. The results suggested that the measurements of magnetic susceptibility could be used as an independent and improved method for distinguishing crude oil from different types of reservoirs, identifying main lithologies and predicting the permeable zone of a reservoir as well as estimating clay mineral contents.