Sandstone pore size distribution determination method and application thereof

Abstract

The invention discloses a sandstone pore size distribution determination method and application thereof, which belong to the technical field of oil and gas reservoir detection. The sandstone pore sizedistribution determination method comprises the following steps of for the same sandstone sample, obtaining a T2 relaxation time distribution curve through nuclear magnetic resonance, and obtaining apore throat radius distribution curve through high-pressure mercury intrusion analysis, normalizing the T2 spectrum signal intensity data in the T2 relaxation time distribution curve, constructing acumulative distribution curve of pore throat radius and T2 relaxation time, establishing a polynomial fitting equation, solving a conversion coefficient C value between the T2 relaxation time and thepore throat radius in a water-saturated state by adopting a linear fitting algorithm, and obtaining the full-aperture pore distribution of the sandstone sample based on the conversion coefficient C and the T2 relaxation time. The method solves the problem of inaccurate determination of the C value of the existing oil and gas reservoir pore size distribution determination method, and has the characteristic of effectively improving the accuracy of quantitative characterization of the pore throat structure of the low-permeability tight oil reservoir.

Description

technical field [0001] The invention belongs to the technical field of oil and gas reservoir detection, and in particular relates to a sandstone pore size distribution measurement method and its application. Background technique [0002] When measuring the pore size distribution of oil and gas reservoirs, nuclear magnetic resonance (NMR) has the advantages of rapidity, non-destructiveness and high accuracy. Compared with high-pressure mercury intrusion (MICP) technology, NMR technology can obtain the pore size distribution of the whole pore size. Therefore, this technique has unique advantages in characterization of pore-throat structures. Since the NMR technique obtains T 2 relaxation time rather than pore throat radius, so the value of conversion factor C is needed to realize T 2 Conversion of relaxation time to pore throat radius. At present, no unified method has been established for the determination of the C value. Previous studies were mostly based on the pore thr...

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Problems solved by technology

[0005] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is to overcome the existing oil and gas reservoir reservoir pore size distribution measurement method when using nuclear magnetic resonance and capillary pressure curve measurement to obtain the C value, there is no consideration of nuclear magnetic resonance T 2 There are differences in the pore space types and pore size distribution intervals reflected by the spectrum and capillary pressure curves, which lead to inaccurate determination of the C value, and then lead to the problem that the finally obtained pore size distribution data cannot truly reflect the actual situation. A method that can effectively improve The accuracy of quantitative characterization of pore-throat structure in low-permeability-tight reservoirs is of great practical significance for in-depth understanding of reservoir heterogeneity and improving the efficiency of exploration and development of low-permeability-tight reservoirs. Sandstone pore size distribution measurement method and its application

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