Abstract: A method for transmitting data from the bottom of a well to the surface is disclosed. The method includes measuring data indicative of at least one drilling condition at the bottom of a well, transmitting into a stream of drilling mud injected into a well pipe string a series of encoded pressure pulses representative of the data measurement, and detecting the encoded pulses at the surface using a pressure sensor which is in communication with the stream of drilling mud as it is being injected into an inlet of the pipe string. The method also includes, as a way of improving data detection, using a surface sensor to measure vibrations in the pipe string which are generated as a result of the propogation of the encoded pulses through the drilling mud.

Abstract: Method for conducting an oil drilling operation, during which a drill-stem produces the rotation of a tool in an oil well. The method consists of the following steps: continually measuring the rotational speed of the upper end of the drill-stem; continuously measuring the torque applied to that end of the drill-stem; determining the torque applied to that end of the drill-stem; determining the torque variation; establishing the period of torque variation if the amplitude of the variation exceeds a predefined threshold; verifying the stability of this period; comparing the latter, if stable, with at least one predefined theoretical period; and reporting the results obtained to the user in order to control the drilling operation.