Analysis On The Lateral Vibration Of The Solid-liquid Coupling Drilling String Of The Horizontal Well

With the rapid development of drilling technology, the drilling technology of thehorizontal well has been rapidly developed and widely used. The drainage area of thehorizontal well is large and the production per well is high, but borehole curvature is big, thebias of drilling string in the horizontal section is severe, and the lateral vibration of drillingstring is easily caused, which will cause local stress concentration of the drill string and drillstring fatigue failures or fracture, thus drilling accidents occurs. So a model is built up tostudy the lateral vibration on the solid-liquid coupling drilling string of the horizontal well inthis paper. The lateral vibration on the solid-liquid coupling drilling string of the horizontalwell is studied by the principle of least action and finite element method. Some results areachieved as follows:Firstly, considering the effects of the drilling fluid inside the drilling string, a lateralvibration mathematical model of the solid-liquid coupling drilling string in vertical section ofthe horizontal well is established by adopting the principle of least action and Euler method..The frequency model of the lateral vibration on the solid-liquid coupling drilling string is setup The influence of drilling fluid inside the drilling string on lateral vibration is analyzed.Besides，a lateral vibration mathematical model of solid-liquid coupling drilling string is builtup based on mechanics balance principle, the influence of drilling fluid inside and outside thedrilling string to the vibration frequency of drill string is studied; The rules of solid-liquidcoupling lateral vibration of drilling string in vertical section of horizontal well is obtained.Secondly, the lateral vibration model of solid-liquid coupling drilling string in thehorizontal section of horizontal well is built by applying the finite element method and theprinciple of fluid dynamics, and the lateral vibration rules of considering bias and bending ofdrilling string and the coupling effect between the drill string and drilling fluid is analyzed.Once more, the drill string vibration model is established by ANSYS software, themodal analysis and harmonic response analysis is made. Lateral vibration frequency andvibration modes of drill string in horizontal well and the dynamic response of differentfrequency is obtained. The influence rules of the length of the drill string, density of drillingfluid, and weight-on-bit on lateral vibration frequency are analyzed.Finally, the calculation procedure of the frequency model is compiled. The vibrationfrequency of drilling string is calculated according to the data of one oilfield, and theinfluence rules of the length of the drill string, density and flow velocity of drilling fluid, and weight-on-bit on lateral vibration frequency are summarized. The measures of preventingdrilling vibration have been put forward.which provides theoretical evidence to the drillingconstruction.The lateral vibration of solid-liquid coupling drilling string in the horizontal well isanalyzed in this paper, and the contents of the research is highly targeted and practical, whichcan provide some reliable evidence for drilling construction. It is realistic significance forpreventing severe resonance of drill string and reducing drilling tool fatigue failure andimproving the economic benefits of the oilfield...