Three-dimensional modelling of reservoir fluid typing by applying nuclear magnetic resonance (NMR) and thermophysical parameters

Reservoir fluid typing is one of the key parameters in reservoir evaluation and field development planning. Nuclear magnetic resonance (NMR) is one of the most effective and useful methods for fluid identification, based on the petrophysical parameters. NMR determines the kind of hydrocarbon fluids using the parameters obtained from the hydrogen nucleus polarization. A novel algorithm is proposed employing the NMR dependent parameters and thermophysical fluid properties. The NMR intensification index (INMR) is defined as a function of NMR parameters (i.e. longitudinal relaxation time, transverse relaxation time, and diffusion coefficient). This index can provide effective separation boundaries within the reservoir fluids as the three major classes, including gas, oil and brine phases. The boundaries between the fluid zones are determined by computing the 3D gradient model of INMR variable against the temperature and viscosity. Using this gradient model, three major fluids with two sharp drops and three transition zones are recognizable. The gaseous phase has the highest value of INMR while its lowest level is related to the brine-bearing zone. The proposed model can effectively determine the boundaries between different major and transition phases, such as gas, gas-oil, oil, oil-water, water, water-brine and brine zones.