The Effect Of Axial Vibration On Friction Of Drill String In Horizontal Well With Long Horizontal Section

In recent years,in order to reduce drilling cost and improve development efficiency,horizontal drilling technology in the long horizontal section has been widely applied.However,in the long horizontal section of the horizontal well,the frictional resistance increases because the drill string lay on the wall of the well,which makes it difficult to transfer the WOB effectively.This situation win a series of drilling problems.The field experiences show that the application effect of axial friction reduction tools on drilling string in horizontal wells is obvious.By applying axial vibration on the drill string,the friction resistance of horizontal wells can be effectively reduced,but the mechanisms of the effect of axial vibration on friction reduction are still not clear at present.Therefore,it is of great significance to study the influence of axial vibration on drill string friction in horizontal wells.By investigating the research status,the drilling problems of horizontal wells in long horizontal section are analyzed,and the principle of axial vibration friction reduction tool is studied.Based on the Hamilton's principle,a mathematical model of drill string friction with axial vibration is established under the condition of sliding drilling in horizontal wells.The Newmark-beta algorithm is selected to solve the model,and the software for solving the mathematical model is developed independently.In order to further verify the rationality of the model,a laboratory experiment was designed and carried out in the case of axial vibration on the simulated drill string,the model and the solving method were compared with the field data.According to the established axial vibration model and solving method,the influencing factors of axial vibration on drill string friction resistance were analyzed.The analysis results show that the friction reduction on the drill string is related to the axial vibration parameters,and the increase of the axial vibration excitation force can significantly increase the friction reduction efficiency.In the range of the equipment conditions,the axial vibration reduction tool with high excitation force should be selected as far as possible.On the optimal excitation frequency,the maximum reduction effect can be obtained,and the installation position of the axial vibration friction reduction tool has a optimized distance to the drill bit.In the field application,it is necessary to use the axial vibration friction reduction tool with high exciting force in the range of the equipment conditions,and with the optimal excitation frequency the better effect of the friction reduction tool can be obtained.