NB/T 11470-2023
Technical specifications for high-position directional long drilling on the roof of coal mining face for gas drainage (English Version)

Standard No.

NB/T 11470-2023

Language

Chinese, Available in English version

Release Date

2023

Published By

Professional Standard - Energy  CN  /  NB

Latest

NB/T 11470-2023

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Introduction

Analysis of the core content of the standard

NB/T 11470-2023 standard systematically specifies the technical requirements for gas extraction from high-position directional long boreholes in coal seam roof for the first time. Its technical framework includes:

Technical elements	Conventional drilling	Directional long drilling
Drilling length	≤100m	≥200m
Trajectory control accuracy	±1.5m	±0.5m
Extraction efficiency	40-60%	75-90%

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Key technological breakthroughs

1. Drilling structure design

A three-level segmented structure is adopted: casing hole section (Φ200mm×9m), penetrating hole section (Φ153mm), and target layer hole section (Φ153mm). The differentiated design balances construction safety and extraction efficiency.

2. Composite directional drilling technology

Innovatively adopt the "sliding directional drilling + composite drilling" dual mode, equipped with a mine measurement while drilling system (MWD), to achieve:

• Deflection intensity ≤3°/m
• Azimuth control accuracy ±2°
• Trace adjustment response time <15min

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Typical application case

Implementation data of a certain working face of Huaibei Mining:

• Total length of borehole: 426m
• Target layer: roof fracture zone 12-15m
• Gas extraction concentration: 82%
• Extraction pure amount: 6.8m³/min

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Implementation Suggestions

1. Preferably use dual-power composite reaming drill (torque ≥4500N·m)
2. 1.75° large-angle screw motor should be used in complex formations
3. The water-cement ratio of sealing cement slurry should be strictly controlled at 0.6-0.8
4. A hole-mouth gas-water separation device
must be equipped

NB/T 11470-2023 Referenced Document

• GB 50471 Standard for design of the gas drainage engineering of coal mine

NB/T 11470-2023 history

• 2023 NB/T 11470-2023 Technical specifications for high-position directional long drilling on the roof of coal mining face for gas drainage

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