摘要:
A bottom hole assembly (10) for horizontal directional drilling that improves the accuracy of surveying while boring by enabling the progress of the bore to be monitored and tracked with the aid of a sonde (108). In one embodiment the sonde (108) is received in the wall of a housing area (41) of a mud motor (12) surrounding the bearing mandrel (18), in another embodiment the sonde (108) is carried in the wall of a collar (126) surrounding the bearing mandrel housing (18), and in an additional embodiment the sonde (108) is carried in an adapter (131) between the bearing mandrel (18) and the bit (11).