METHOD OF DETERMINING THE DEPTH OF OCCURRENCE OF A CHEMICALLY REACTIVE BED

The method of determining the depth of occurrence of a chemically reactive bed in the course of drilling a well, as proposed in the present invention resides in the fact that the redox potential of the drilling mud situated in the well, is measured, the walls of the well are stripped of the mud cake, and an additional portion of the drilling mud is prepared, whose redox potential differs, as to value and direction, from that of the drilling mud situated in the well, Then the thus prepared additional drilling mud portion is injected into the well until the drilling mud that has been situated therein previously, is expelled completely, whereupon the circulation of the additional drilling mud portion is suspended for a period of time, wherein relaxation of the ion-exchange processes between the chemically aggressive bed and the additional drilling mud portion occurs. After that the circulation of the additional drilling mud portion resumes, while the time interval between the resumption of the drilling mud circulation till the beginning and end of returning the amount of the additional drilling mud portion that has been in contact with the chemically reactive bed, is registered against the deviation of the value and direction of the redox potential of the drilling mud, whereupon said deviation enables the depth of the occurrence of said bed to be estimated mathematically.