NMR Parameter Characterization Method of Pore Structure in Low Permeability and Low Viscous Reservoir

Abstract

The invention provides a nuclear magnetic resonance parameter characterization method for the pore structure of a low-permeability and low-viscosity oil reservoir. The nuclear magnetic resonance parameter characterization method comprises: carrying out nuclear magnetic resonance experiment analysis after real rock cores are saturated with different low-viscosity oil to obtain the nuclear magneticresonance relaxation time T2 distribution of the rock core saturated with different viscosity oil; carrying out pore structure analysis on the real rock core to obtain the pore throat radius r distribution of the rock core; establishing a reference model for the conversion between the relaxation time T2 value and the pore throat radius r; establishing the relationship among the conversion coefficient M, the fluid viscosity and the geometric mean of the rock core T2 under the fluid, and determining the conversion factor M; and combining the reference model and the conversion coefficient to obtain a universal conversion model so as to obtain the pseudo-capillary pressure curve, the pore structure distribution and the characteristic parameter of the reservoir. With the nuclear magnetic resonance parameter characterization method of the present invention, the continuous and quantitative reservoir pore structure parameters can be obtained from the nuclear magnetic well logging data to evaluate and study the reservoir, such that the complete and accurate reservoir data can be provided for the rational and effective development of the low-permeability oil reservoir.

Description

technical field [0001] The invention relates to the technical field of oil field development, in particular to a method for characterizing the pore structure of a low-permeability and low-viscosity oil layer by nuclear magnetic resonance parameters. Background technique [0002] As an advanced technology for core analysis, nuclear magnetic resonance technology uses the response of atomic nuclei in a magnetic field to describe and evaluate the internal structure and microscopic morphology of the medium through the nuclear magnetic resonance characteristics of the fluid saturated or adsorbed in the pores of the medium. It is non-destructive, non-toxic, Harmless, fast, multiple detectable objects and other multiple advantages. [0003] A major problem in the development of low-permeability reservoirs is how to use NMR logging data to study the pore structure of the oil layer in the reservoir, because the NMR responses of oil and water in the rock pores are different, and the ex...

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Problems solved by technology

[0003] A major problem in the development of low-permeability reservoirs is how to use NMR logging data to study the pore structure of the oil layer in the reservoir, because the NMR responses of oil and water in the rock pores are different, and the existing NMR logging data The method of studying the pore structure of the reservoir with data is only suitable for the water layer, and cannot be applied to the nuclear magnetic logging data of the oil layer section

The pore throats of low-permeability reservoirs are fine, and most of the crude oil contained in the pores has low viscosity. Therefore, we invented a NMR parameter characterization method for the pore structure of low-permeability and low-viscosity oil reservoirs, which solved the above technical problems

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