远端钻铤式方位伽马在煤层储气开采中的应用

Application of distal drill collar-type azimuthal gamma in coalbed methane extraction from thick coal seams

摘要:

为降低厚煤层中煤层气开采成本，提高水平井钻井经济效益，本文对不同类型随钻方位伽马进行了综合对比，重点阐述了远端钻铤式方位伽马的工作原理及技术优势。通过分析远端钻铤式方位伽马在煤层气水平井应用，判断地层及二次入层关键工况的上下伽马曲线变化，并与相应工况下的录井钻时、气测、岩屑等参数进行对比，结果表明远端钻铤式方位伽马可精确判断井眼轨迹与地层相对位置关系，并为现场地质导向提供判断依据，满足实际钻井需求。同时远端钻铤式方位伽马比探管式方位伽马具有更高的响应度，相同地层及工况条件下其使用成本比近钻头式方位伽马降低了50%以上。研究成果对远端钻铤式方位伽马在其他非常规能源开发中的推广应用具有借鉴意义。

Abstract:

To reduce the extraction cost of coalbed methane （CBM） in thick coal seams and improve the economic efficiency of horizontal well drilling， this paper conducts a comprehensive comparison of different types of azimuthal gamma-while-drilling （AGWD） tools， with a focus on elaborating the working principle and technical advantages of the distal drill collar-type azimuthal gamma tool. By analyzing the changes in upper and lower gamma curves of the distal drill collar-type azimuthal gamma tool in terms of formation identification and key working conditions of re-entry into the target formation during its application in CBM horizontal wells， and comparing these curves with logging parameters such as drilling time， gas logging， and cuttings under the corresponding working conditions， the results show that the distal drill collar-type azimuthal gamma tool can accurately determine the relative positional relationship between the wellbore trajectory and the formation. It also provides a basis for on-site geological steering， meeting the actual drilling requirements. Meanwhile， the distal drill collar-type azimuthal gamma tool has higher responsiveness than the probe-type azimuthal gamma tool， and its operating cost is reduced by more than 50% compared with the near-bit azimuthal gamma tool under the same formation and working conditions. This has reference significance for its popularization and application in the development of other unconventional energy sources.