Abstract
The diameter of the exploration borehole varies during drilling from largest to smallest. Diameter depends on the physical and mechanical properties of rocks along which the intersection of geological section of the field. There is measured the diameter of the borehole from the start to the end of the drilling using the caliper method and determine the state of the borehole walls. There rocks with different physical and mechanical properties in section of the wellbore. In the intervals of the well that had strong rocks its diameter changes slightly. A place that folded soft rock, broken up quickly and intensively. This requires the adoption of appropriate measures to prevent the accident. In this regard, the diameter wells estimate changes in the drilling process is an actual problem.