EXPERIMENTAL STUDY ON NMR MEASUREMENT PARAMEERS AND RESERVOIR PROPERTIES

Nuclear magnetic resonance(NMR) logging can be directly used to determine the properties of the reservoir fluid.But it is affected by instrument parameters of pre-logging and the characters of the fluid itself.In this paper,the influences of echo spacing(T_E),wait time(T_W),oil saturation and salinity of formation water on the T₂ spectrum shapes and the transformation rules were discussed based on the experiments of cores with different porosities acquired from different oilfields.The experimental results indicate that if the parameter T_E is selected illogically,the NMR spectrum will lose some reservoir information and decrease the resolution capability to the short relaxation components.Different T_W results in different fluid polarization,and the variation in the oil saturation and formation water salinity have different responses on T₂ spectrum shape.Therefore,the influence on T₂ spectrum of these factors should be considered in NMR logging data processing and interpretation.