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

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.