Study on un-sticking mechanism of near horizontal hole in soft coal seam

Abstract

In order to reduce the occurrence of drilling accidents in soft coal seams, this paper analyzes the causes of near-horizontal hole drilling under the coal mine and the formation process of jamming, and establishes a drilling mechanical model for each stage. Through the analysis of the main influencing factors of the sticking drilling, it is concluded that the key to solve the sticking drilling is to reduce the compactness of debris accumulation and improve the slag discharge efficiency. This guides the structure and functional design of the L-shaped spiral groove drill pipe. Through the test comparison of the slag discharge performance of U-shaped groove spiral drill pipe, triangular drill pipe and L-shaped spiral groove drill pipe, it is verified that the slag discharge performance of L-shaped spiral groove drill pipe is optimal. Through the field test, it is verified that the L-shaped spiral groove drill pipe is better than the U-shaped spiral groove drill pipe commonly used in the market.

Keywords

• gas drainage
• soft coal seam
• near-horizontal hole
• mechanical model of sticking drilling
• un-sticking mechanism of drilling