贵州大湾煤矿复杂地层井下定向钻进施工技术

Downhole Directional Drilling Construction Technology in Complex Formation of Dawan Coal Mine in Guizhou

摘要:

针对大湾煤矿地区复杂煤层地质构造，采用前进式开分支孔布孔方法，用于探测煤层顶底板位置，精确探明煤层走向，为抽掘采提供依据，为后续工作做好前期准备。贵州大湾煤矿在历年瓦斯鉴定中均被定为瓦斯矿井，瓦斯孔施工采取普通钻进工艺时，会遇到钻进工作量大、孔深达不到要求、施钻轨迹无法精准控制、钻孔瓦斯浓度抽采率低等问题。采取顺层定向孔方法在已探明的煤层中施工长距离钻孔，可实现对复杂煤层远距离瓦斯抽采。现场试验表明：采用前进式开分支孔工艺，能够实现复杂煤层地质构造精确探顶，探明钻孔见煤段高达75%；通过优化钻孔设计与高精度控制钻孔轨迹大大增加了顺层定向孔在复杂煤层中的覆盖率，钻孔见煤段达63.7%，提高了瓦斯抽采效率，为巷道的抽掘采工作打好了基础。

Abstract:

In view of the complex geological structure of Dawan coal mining area, advancing open branch hole distribution was adopted to detect the location of coal seam roof and floor for accurate determination of the coal seam and provide the basis for gas drainage, tunneling and mining and preparation for the follow-up work. Dawan coal mine is been defined as gas mine in the past years’ gas identification, while by ordinary drilling process in gas hole construction, large drilling workload with unqualified hole depth, difficult drilling trajectory accurate control and low gas concentration extraction rate will often be encountered. Long distance drilling in the proven coal seam can be constructed with bedding directional hole construction method to realize long-distance gas extraction in the complicated coal seam. The field test shows that by the advancing open branch hole technology, the accurate probe of complex coal seam top in the geological structure can be completed, it is found that the coal section is 75% of drilling length in a borehole. By optimizing drilling design and high precision control of borehole trajectory, the bedding directional hole coverage is greatly increased in the complex coal seam, coal section is up to 63.7% in another borehole, the gas extraction efficiency is also improved, which provides a basis for gas extracting, tunneling and mining.