| 摘要 |
<p>A method for determining the depth of occurrence of a chemically aggressive stratum in the course of drilling the borehole, which consists in measuring the redox-potential of the drilling mud contained in the borehole, cleaning the walls of the well from the argillaceous incrustation and preparation of an additional portion of the drilling mud with its redox-potential being different from that of the drilling mud contained in the borehole. The thus prepared additional portion of the drilling mud is then injected into the borehole until the drilling mud is completely cast out, then the circulation of the additional portion of the drilling mud is stopped for a time needed for relaxation of ion-exchange processes between the chemically aggressive stratum and the additional portion of the drilling mud, after which the injecting of the additional portions of the drilling mud is resumed. The depth of occurrence of the chemically aggressive stratum is then determined mathematically depending on the time passed from the moment the injecting is resumed until the outcome to the surface of the beginning and the end of the column of the additional portion of the drilling mud which has been in contact with the chemically aggressive stratum and which is identified by the variation of its redox-potential. </p> |
