NB/T 11638-2024Method for determining the extraction volume of single-layer gas in multi-coal seam by drilling through-seam holes - Measured flow rate method (English PDF)

Preface

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for standardization work Part 1: Structure and drafting rules for standardization documents" Drafting.

1 Scope

This document specifies the principle, general requirements, and Preparation before measurement, measurement process and calculation of measurement results.

This document is applicable to the investigation and determination of the proportion of single-layer extraction volume when through-layer drilling is used to pre-extract gas from multiple coal seams in underground coal mines.

2 Normative references

The contents of the following documents constitute the essential clauses of this document through normative references in this document.

For referenced documents without a date, only the version corresponding to that date applies to this document; for referenced documents without a date, the latest version (including all amendments) applies to this document. document.

GB/T 15663.8 Coal Mine Scientific and Technological Terminology Part 8: Coal Mine Safety

MT/T 642 Technical Specifications for Instruments for Measuring Comprehensive Parameters of Gas Drainage in Pipelines

3 Terms and Definitions

The terms and definitions defined in GB/T 15663.8 and the following apply to this document.

4 Principles of the Method

In the investigation area where coal seams and gas occurrence conditions are relatively stable, drilling holes are constructed in the target coal seams and multiple coal seams respectively.

Under the condition that the sealing process and extraction negative pressure and other parameters are basically the same, the extraction volume of the target coal seam alone and the extraction volume of multiple coal seams are measured respectively.

Calculate the ratio of individual extraction volume to combined extraction volume. Determine the combined pre-extraction volume of multiple coal seams in areas with similar coal seam and gas occurrence conditions.

The basis for calculating the extraction volume of a single target coal seam.

5 General requirements

5.1 The measurement site should be selected in an area where gas extraction has not been carried out, and the coal seams and gas occurrence conditions in the selected area should be representative.

5.2 For adjacent coal seams with an average normal distance of less than 5 m from the target coal seam, the mine may inspect them together with the target coal seam based on actual needs.

5.3 The gas extraction flow rate should be measured manually on site.

6 Preparation before measurement

6.1 Instruments used to measure gas extraction flow should be within the validity period of calibration and meet the following requirements. […]