Method for determining nuclear magnetic resonance T2 cutoff value and fluid saturation of tight oil, and apparatus thereof

Abstract

The invention provides a method for determining the nuclear magnetic resonance T2 cutoff value and the fluid saturation of tight oil, and an apparatus thereof. The method comprises the following steps: determining the carbon content of a sample to be measured to generate a carbon content determination result; determining the lower limit value of the pore throat radius of the sample to be measured according to the carbon content determination result; and determining the corresponding T2 cutoff value according to the lower limit value of the pore throat radius and the core relaxation rate of the sample to be measured. The T2 cutoff value is calculated by using the lower limit value of the pore throat radius of the tight oil movable fluid of the practical sample in the above scheme, and the lower limit value of the pore throat radius of the tight oil movable fluid of the practical sample is determined by adopting a course to fine pore throat carbon content gradual approximation technology, so the T2 cutoff value obtained in the invention is true.

Description

technical field [0001] The invention relates to the technical field of petroleum exploration, specifically tight oil nuclear magnetic resonance T 2 Method and device for determining cut-off value and fluid saturation. Background technique [0002] Nuclear Magnetic Resonance (NMR) is an important technique for monitoring the saturation of movable fluid in rocks. The T2 relaxation time spectrum in the NMR experiment contains information about the distribution of the rock pore structure and the fluid contained in it, which is the basis for the NMR experiment to determine the saturation of the movable fluid in the rock. The T2 distribution is related to the pore size. The movable fluid in larger pores has a weak interaction force with the rock pore solid surface, and the T2 relaxation time is relatively long. In contrast, the bound fluid has a strong interaction force with the rock pore solid surface, and the T2 relaxation time is small. [0003] The study of T2 cut-off value...

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Problems solved by technology

[0006] It can be seen that there are many inaccuracies in the actual centrifuge experiment when dealing with tight oil, especially samples with strong pore heterogeneity.

The centrifugal force in the centrifugal experiment needs to be large enough to centrifuge the movable water in the small hole, but the centrifugal force in the current centrifugal experiment technology often cannot meet the corresponding requirements. Most importantly, it is difficult to quantify the pore distribution and centrifugal force. correspond

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