NMR (nuclear magnetic resonance) characterization method for pore wettability of equal-particle-size pulverized coal

Abstract

The invention provides an NMR (nuclear magnetic resonance) characterization method for pore wettability of equal-particle-size pulverized coal, which comprises the following steps: S1, respectively dripping quantitative water into pulverized coal samples with various particle sizes, and measuring NMR transverse relaxation time T2 of the pulverized coal sample with each particle size; s2, measuring the NMR transverse relaxation time T2'of the pulverized coal sample with each particle size in a saturated state; s3, making a linear regression graph according to the NMR transverse relaxation time T2'in the saturated state; s4, determining the equivalent wetting aperture Rg of the wetting area; and S5, drawing a linear fitting curve of the equivalent wetting aperture and the particle size of the pulverized coal sample so as to determine a pore wettability expression. According to the method, the wetting characteristics of the coal reservoir can be obtained, mutual comparison under different (or the same) particle size or different (or the same) pore size can be facilitated, and the method has important significance in potential productivity evaluation of the reservoir, process optimization of all links of development and production, coal seam water injection outburst elimination, coal seam hydraulic fracturing and the like.

Description

technical field [0001] The invention belongs to the technical field of coal wettability characterization research, and in particular relates to a pore wettability NMR characterization method of equal particle size coal powder. Background technique [0002] Pore ​​wettability affects coal reservoir fluid migration and distribution, CO 2 Geological storage, water flooding efficiency and the development and utilization of coalbed methane play a crucial role. Coal is a porous medium. Compared with surface wettability, pore wettability takes into account the influence of complex pore structure and physical and chemical properties on the wetting environment, which has more practical guiding significance. However, there are two shortcomings in the current research on pore wettability. First, the traditional surface wettability characterization method (contact angle method) is often used to indirectly characterize the pore wettability. However, this simple characterization relation...

AI Technical Summary

Problems solved by technology

However, there are two deficiencies in the current research on pore wettability. One is that the traditional surface wettability characterization method (contact angle method) is often used to indirectly characterize the pore wettability. However, this simple characterization relationship is limited. Second, the research object of pore wettability is simplified to the contact angle characterization of capillary glass tubes, which is also debatable for the guiding value of the pore wettability of real materials (such as coal)

The limitations of the two aspects greatly limit the guiding role of pore wettability for practical engineering

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