The Analyze Of Newton Fluid Flow Field Induced By The Drill String Rotation Revolution And Radial Motion

Currently, the drill string is the essential tools in the process of drilling. Its long-term immersion of the drilling hole which be full of drilling fluid, during driven by rotating plate, drill string will not only rotation with its own axis, but also may rotation with the borehole axis and may radial motion. Research the drilling fluid flow pattern induced by drill string rotation、revolution and radial movement is great importance, can effectively reduce the drilling accidents produced by vortex and bucking of the drill string, also can reduce the economic loss, has important application value.At present, scholars at home and abroad has conducted a lot of research on the eccentric annulus flow, and has achieved some results.This topic will be on the research achievements of predecessors, taking into account the radial motion of the drill string for the first time, set up the dring rotates, and the mathematic model of radial motion induced newton fluid flow, and to sove, in the hope to better study the drilling fluid flow law in the wellbore, provide the basis for the drill string stress analysis, so as to reduce the occurrence of drilling accidents.Firstly, this paper analyzing the existing problems and shortcoming on the study of eccentric annulus flow between the domestic and foreign scholars, and to solve these problems and the insufficiency, put forward the research contents and research methods in this paper. Through research and analysis, the control equations of the inertial coordinate is established from the continuity equation and momentum equation under the inertial coordinate system; Through the basic hypothesis, the newton mathmatical model of fluid flow is established by the drill string rotation、revolution and radical motion, at the same time, has also established the correspongding boundary condtions; Adopting double polar corrdinates, the eccentric annulus region into a rectangular area, using the better applicability, and has obvious advantages finite volume method to discrete the mathematical model which has be established, got the discrete mathematical equation; By MATLAB software, analyzing the flow field of newton fluid flow induced by the drill string rotation movement. Calculate the axial velocity distribution and tangential velocity distribution, and mapped the speed of flow chart under the conditions of different eccentricity. Analyzing the flow field under the same conditions by FLUENT, drawn the speed flow chart under the contions of different eccectricity, and compares the two methods to flow chart, after contrast find that two methods calculated results are similar, at the same time have found only eccentricity reaches a certain distance will occur secondary flow.