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GB/T 42035-2022Determination of pore size distribution of coal and rock—Nuclear magnetic resonance (English PDF)

煤和岩石孔径分布的测定核磁共振法

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Issued by

SAMR; SAC

Level / Type

National · Recommended

Issue date

October 12, 2022

Implementation date

October 12, 2022

Scope

GB/T 42035-2022 is the English-translated version of 煤和岩石孔径分布的测定核磁共振法.

GB/T 42035-2022 is the Chinese national nuclear magnetic resonance method for measuring the pore size distribution of coal and rock.

It sets out the measuring principle, the reagents and materials, the apparatus, the sample requirements, the determination of the NMR T2 spectrum, the data processing and the quality requirements, and defines the T2 relaxation time and the T2 cutoff value that separates movable from bound pore fluid.

Informative annexes cover the T2 characteristic parameters and the NMR porosity calculation, the signal, mercury intrusion and T2-r record tables, the data fitting plot and the pore size distribution result.

It is intended for medium and high rank coal and sandstone, and is a reference for low rank coal and shale. Issued on 12 October 2022, it has applied since the same date.

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Document preview — GB/T 42035-2022

National Standard of the People's Republic of China

ICS: 73.040
Classification: D 21

Issued by: State Administration for Market Regulation; Standardization Administration of the PRC

Preface
1 Scope
2 Normative references
3 Terms and Definitions
4 Principle of NMR measurement
5 Reagents and Materials
6 Device
7 Sample Requirements
8 Determination of NMR T2 spectrum
9 Data processing
10 Quality requirements
Appendix A (Informative) T2 Characteristic Parameters and NMR Porosity Calculation
Appendix B (informative) NMR signal data record table
Appendix C (informative) NMR data fitting figure
Appendix D (Informative) Mercury Intrusion Data Record Table
Appendix E (Informative) T2-r Data Record Table
Appendix F (informative) Coal and rock pore size distribution results Figure

Foreword

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for Standardization Work Part 1: Structure and Drafting Rules of Standardization Documents" drafted.

1 Scope

This document specifies the principles, test procedures, calculation formulas, data processing, etc.

This document is suitable for the determination of pore size distribution of medium and high rank coal and sandstone, and is used for reference of low rank coal and shale.

2 Normative references

The contents of the following documents constitute essential provisions of this document through normative references in the text. Among them, dated citations documents, only the version corresponding to that date applies to this document; for undated references, the latest edition (including all amendments) applies to this document.

GB/T 474 Preparation method of coal samples

GB/T 21650.1 Determination of pore size distribution and porosity of solid materials by mercury porosimetry and gas adsorption - Part 1: Mercury porosimetry

GB/T 23561.3-2009 Determination methods for physical and mechanical properties of coal and rock - Part 3: Determination method for the density of coal and rock blocks

GB/T 29171-2012 Determination of rock capillary pressure curve

GB/T 29172-2012 Core Analysis Method

SY/T 6490-2014 Specification for laboratory measurement of rock sample nuclear magnetic resonance parameters

3 Terms and Definitions

The following terms and definitions apply to this document.

3.1 Free induction decay

NMR signals that oscillate sinusoidally and decay exponentially.

3.2 T2 relaxation time T2time

Time constant describing the recovery process of the transverse component of nuclear magnetization.

Note 1. Also known as transverse relaxation time or spin relaxation time.

Note 2. It reflects the process that the horizontal component of the non-equilibrium magnetization vector decays to zero. This decay is caused by the inhomogeneity of the local field of the adjacent nucleus and the static magnetic field. disperse phase.

3.3 T2 cutoff value T2cutoffvalue

On the NMR T2 spectrum, the boundary of the relaxation time of the movable fluid and the bound fluid.

Note: When the relaxation time is greater than this, the pore fluid is called movable fluid; when it is less than the relaxation time, the pore fluid is called bound fluid.

3.4 Inversion

The process of obtaining the fluid relaxation signal in each pore from the overall relaxation signal.

3.5 Nuclear magnetic resonance

Under the action of an external magnetic field, the spin energy level of an atomic nucleus with a non-zero magnetic moment undergoes Zeeman splitting, and the resonance absorbs a certain frequency of radio frequency radiation. physical process.

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 15 pages — is available in the English PDF.

Referenced standards

Normative references

GB/T 474

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