Measuring method of sandstone pore size distribution and its application

Abstract

The invention discloses a method for measuring sandstone pore size distribution and its application, belonging to the technical field of detection of oil and gas reservoirs, including: for the same sandstone sample, obtaining T through nuclear magnetic resonance 2 Relaxation time distribution curve, pore throat radius distribution curve obtained by high-pressure mercury intrusion analysis; for T 2 T in the relaxation time distribution curve 2 The spectral signal intensity data were normalized; the pore-throat radius, T 2 Relaxation time cumulative distribution curve; establish polynomial fitting equation; use linear fitting algorithm to obtain T under water-saturated state 2 Conversion factor C value between relaxation time and pore throat radius; based on conversion factors C and T 2 relaxation time to obtain the full-diameter pore distribution of the sandstone sample. The invention solves the problem of inaccurate determination of the C value in the existing method for measuring the pore size distribution of oil and gas reservoirs, and has the characteristics of effectively improving the accuracy of quantitative characterization of the pore-throat structure of low-permeability-tight oil reservoirs.

Description

technical field [0001] The invention belongs to the technical field of oil and gas reservoir detection, and in particular relates to a method for measuring the pore size distribution of sandstone and its application. Background technique [0002] When determining 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, nuclear magnetic resonance technology can obtain the pore size distribution of full pore size. Therefore, this technique has unique advantages in the characterization of pore-throat structures. Since the NMR technique obtained T 2 The relaxation time is not the pore throat radius, so the conversion factor C value is needed to achieve T 2 Conversion of relaxation time to pore throat radius. At present, there is no unified method for the determination of the C value. The previous studies are mos...

AI Technical Summary

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

Images