Abstract: An apparatus (100) for determining an azimuth of a drilling tool (304) during drilling of a borehole. The apparatus (100) comprises a rate sensor (102) configured to collect rate sensor data indicative of a component of a rate of rotation of the earth for determining the azimuth by gyrocompassing. The rate sensor (102) is further configured for communication with a surface unit (306). The apparatus (100) also comprises a drill pipe extension detector (104) configured to detect a process associated with extension of a drill pipe (312) connecting the drilling tool (304) to the surface unit (306). The rate sensor (102) is configured to transmit collected rate sensor data to the surface unit (306) based on the detected process associated with extension of the drill pipe (312).

Abstract: An apparatus (100) for determining an azimuth of a drilling tool (304) during drilling of a borehole. The apparatus (100) comprises a rate sensor (102) configured to collect rate sensor data indicative of a component of a rate of rotation of the earth for determining the azimuth by gyrocompassing. The rate sensor (102) is further configured for communication with a surface unit (306). The apparatus (100) also comprises a drill pipe extension detector (104) configured to detect a process associated with extension of a drill pipe (312) connecting the drilling tool (304) to the surface unit (306). The rate sensor (102) is configured to transmit collected rate sensor data to the surface unit (306) based on the detected process associated with extension of the drill pipe (312).

Abstract: A method and apparatus for collecting borehole survey data indicative of geometry of a borehole, using a borehole survey instrument comprising at least one rate sensor and an inclination sensor. The borehole survey instrument is dropped into the borehole, such that the borehole survey instrument freefalls to a bottom of the borehole, and out run data, indicative of azimuth and inclination of the borehole, is continuously measured using the at least one rate sensor, and the inclination sensor, as the borehole survey instrument is removed from the borehole.