NB/T 11635-2024Measuring method for effective radius of gas emission drilling in coal seam (English PDF)
煤层瓦斯排放钻孔有效排放半径测定方法
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Issued by
NEA
Level / Type
Industry · Recommended
Issue date
September 24, 2024
Implementation date
March 24, 2025
Scope
NB/T 11635-2024 is the English-translated version of 煤层瓦斯排放钻孔有效排放半径测定方法.
NB/T 11635-2024 is a Chinese energy industry method for determining the effective drainage radius of gas drainage boreholes in coal seams. Two methods are given, one based on the natural gas flow from the borehole and one on the gas desorption index of drill cuttings, and where both are used the smaller radius is taken.
The document covers general requirements, preparation before measurement, borehole layout, the measurement process and the rules for deciding the result, with informative record sheets.
It applies to boreholes along and through outburst-prone seams and may serve as a reference for non-outburst seams. Issued on 24 September 2024, it has applied since 24 March 2025.
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Document preview — NB/T 11635-2024
National Standard of the People's Republic of China
- ICS
- 13.100
- Classification
- D 09
Issued by: National Energy Administration of the People's Republic of China
Contents
- Preface
- 1 Scope
- 2 Normative references
- 3 Terms and definitions
- 4 General requirements
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 use of borehole natural gas flow method and drill cuttings gas desorption index method to determine the effective emission half-value of coal seam gas emission boreholes.
Preparation before diameter measurement, drilling arrangement, measurement process and determination principles, etc.
This document is applicable to the determination of the effective discharge radius of the borehole for gas emission along the protruding coal seam and the effective discharge radius of the borehole for gas emission through the layer.
The determination of the effective emission radius of non-protruding coal seam gas emission drilling holes can be used as a reference.
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
KA/T 1065 Determination method of gas desorption index of drill cuttings
MT/T 639 Method for determination of initial velocity of gas emission from boreholes
MT/T 854 Technical Specifications for Electronic Isovolumetric Gas Desorption Apparatus
MT/T 856 Technical Specifications for Pneumatic Drilling Gas Initial Velocity Measurement Device
MT/T 1173 Coal Seam Permeability Coefficient Determination Method-Radial Flow Method
3 Terms and definitions
The terms and definitions defined in GB/T 15663.8 and KA/T 1065 and the following apply to this document.
3.1 Effective emission radius of drilling
After a certain period of natural gas discharge in the coal seam around a borehole of a certain diameter, the gas in the coal seam is reduced to the edge of the range required by the specified index.
The distance from the center of the drill hole along the bedding direction of the coal seam.
3.2 Natural gas flow rate in drilling holes
The amount of gas that flows out of a borehole per unit time under natural conditions.
4 General requirements
4.1 The mine can select the appropriate effective discharge radius of the borehole according to the coal seam gas storage parameters, coal seam permeability, and the sensitivity of the measurement index.
When two methods are used for measurement at the same time, the smaller value of the effective discharge radius of the borehole determined by the two methods shall be taken as the effective discharge radius of the borehole. Effective emission radius.
4.2 The measurement site should be selected in an area where the existing engineering is buried at a great depth, the coal wall is exposed for a short time, and there are no geological structures such as faults and folds.
4.3 If there is a blowout, top drilling or abnormal gas outflow during the drilling process, the measurement should be re-selected.
......
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 15663.8Terms relating to coal mining - Part 8: Mine safety
- MT/T 1173Measurement method of coal permeability coefficient--radial flow method
MT/T 639 · MT/T 854 · MT/T 856
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Related Standards
GB/T 15663.8-2008 — Terms relating to coal mining - Part 8: Mine safety
MT/T 1173-2019 — Measurement method of coal permeability coefficient--radial flow method
NB/T 10086-2025 — Regulations for Compiling Energy Conservation Reports for Wind Farm Projects
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