Abstract: The invention relates to the monitoring of the drilling operations of a well using a drill bit mounted at the end of a drill string, which can be taken up by the travelling block of a lifting gear installed in a derrick, in order to permit the addition or removal of members from the drill string. By measurement with the aid of sensors associated with the lifting gear and connected to a processing unit, the altitude and the hook load of the travelling block, it is possible to plot the curve, form which it is possible to deduce information concernig the structure and the behavior of the well being drilled.

Abstract: This invention is intended for use in the process of drilling an oil well and has to do with a process for the detection of fluid influx which could lead to a blow-out. This process consists of measuring the inlet flow rate A of the drilling mud coming into the well and the outlet flow rate B of the drilling mud rising from the well in order to arrive at the quantity:C=a.B-Awhere a is a scale factor the value of which can be altered so as to bring about a recalibration of the outlet rate measurement. Such recalibration is made each time the average value of C, in relation to a given period of time, reveals a significant difference between the rates, and an alarm is set off in accordance with the frequency of the recalibrations corresponding to an excess in the outlet rate in relation to the inlet rate.