ABSTRACT
The solution to the problem of determining the eccentric location of the drill string in the borehole using analytical studies and modern systems of mathematical computer modeling was analyzed. The practical implementation of technological problem solving was parameters calculation of the formation and changes in the area of stagnant zone in the cross section of the wellbore annulus in set out put characteristics of its washing. As a result of studies it has been found that at lower eccentric placement of both straight and deformed drill strings in the well drilling mud moves by crescent-shaped core flow. The maximum velocity of mud is inside the core, and the minimum one-in the contact zones of a flexible pipe with the borehole wall. Thus, the dependences in changes of hydraulic pressure loss in pumping by the mud pump and the core flow rate distribution along the axis of the drill string at its eccentric location in the wellbore were determined. The conditions of drilling mud stagnant zones formation in the annular space were defined and the solutions to eliminate them were proposed.
