The invention provides a
tight oil reservoir fluid occurrence type identification method and
system based on
nuclear magnetic resonance, and belongs to the technical field of
petroleum geology exploration and development. The method comprises the following steps: on the basis of comparison between a
nuclear magnetic resonance T2 relaxation time cumulative distribution curve of a
tight oil reservoir sample and a high-pressure mercury injection pore
throat diameter cumulative distribution curve, dividing pore
throat types, and converting T2 relaxation time into pore
throat diameters; judging occurrence fluids in different types of pore throats through a
nuclear magnetic resonance spectrum to obtain fluid occurrence types corresponding to different
signal domain ranges, and calculating the relative fluid content of each fluid occurrence type; and based on the
signal domain range of each fluid occurrence type of the plurality of samples, establishing a nuclear magnetic
resonance fluid occurrence type identification chart, and defining an identification standard of each fluid occurrence type. According to the method, the pore size distribution of the T2 relaxation time is combined with the nuclear magnetic
resonance spectrum, the pore size range corresponding to the fluid occurrence type is determined, and the relative content of the fluid is calculated through the
signal intensity of each signal domain, so that the accuracy is higher.