Examining the current of drilling mud in a power section of the screw down-hole motor

Abstract

By using the module Flow Simulation from the programming environment SolidWorks, we obtained parametric fields of turbulent flow of drilling mud in the subject of research – a power section of the screw down-hole motor (SDM). The subject of research is the characteristics of turbulence of the drilling mud flow. An analysis of the obtained model parametric fields of turbulent flow of drilling mud in the power section of SDM shows two distinctive regions that differ by the characteristics of turbulence in the drilling mud current. These sections are localized in the neighborhood of contact points "rotor-stator", and along the distance between these points. In the first section, the developed flow turbulence almost disappears; the dissipation of flow energy significantly decreases. In the second section, there is a developed turbulence of drilling mud, which causes increased dissipation of flow energy and a possible damage to the stator by a solid phase of drilling mud. Turbulent time scale in the second region reaches the minimum values of 0.001 s, and the metrical scale of pulsations is comparatively small – from 0.011 to 5.666 m, indicating the presence of small-scale turbulent vortices and the elevated dissipation of flow energy. Thus, the second section is the most vulnerable to a damage to the stator by a solid phase of drilling mud. An endoscopic examination of the surface of the SDM stator, which we conducted, revealed damage to its working surface, specifically deep scratches, guide scratches, cavities. Localization of damage is from the middle and to the tail part of the power section at a distance of 2.53−4.78 m from the beginning of the power section of SDM. The models obtained are recommended for using in hydraulic calculations of SDM, for choosing a rational mode of its operation.

Моделюванням FlowSimulation/SolidWorks отримані параметричні поля течії бурового розчину в об’єкті дослідження – силовій секції гвинтового вибійного двигуна (ГВД). Предмет дослідження – характеристики турбулентності потоку поблизу точок дотику "ротор-статор" та між ними. Друга ділянка характерна розвиненою турбулентністю, дисипацією енергії потоку, пошкодженнями статора твердою фазою розчину, що підтвердили ендоскопічні обстеження. Моделі доцільно використати при гідравлічних розрахунках ГВД.