Impact On The Mechanical Properties Of The Continuous Tube Vibration Reducing Friction Device

Coiled tubing technique is widely applied in oil and gas field for well repair, well drilling, well completion and stimulation etc. Coiled tubing technique plays an increasingly important role in oil and gas field’s exploration and development. However, during the process of the coiled tubing conveyance, the buckling will easily occur under the injection force and bottom friction, due to its big flexibility, which then results in the "Locking Up" of the coiled tubing and limits its application in extended reach wells and horizontal wells.Therefore, it is important and pratical to research how to put the coiled tubing into a well with larger horizontal displacement.The employment of Friction Drag Reducer reduces the average friction on the coiled tubing when during the process of the coiled tubing conveyance and thus increase the extended distance of the coiled tubing in the horizontal section. The working fluid properties are constant in this process and it is also not limited by the roughness of borehole while with a low maintenance cost. These advantages make this method a good application prospect. However, most of the related researches are focused on field experiment researches and there are no comprehensive theoretical studies at present. This paper analyzed the effect of Friction Drag Reducer on the average friction to the coiled tubing and provided an initial theoretical guidance for the future design and employment of Friction Drag Reducer.This paper established vertical vibration anti-friction model and parallel vibration antifriction model of particle, and discussed the relationship between the vibration antifriction model of particle and the vibration antifriction model of coiled tubing.According to the conditions analysis of coiled tubing conveyance along the well, reasonably simplified vibration antifriction problem of coiled tubing, established the finite element model to analyze the vibration of coiled tubing in the horizontal section, and provided the corresponding assumptions and boundary conditions.Programmed the finite element code used to analyze the vibration anti-friction model of coiled tubing; comparing the transient solution of programm and the use of Ansys software to vibration model of straight rod partly proves that the program is feasibility to study vibration antifriction of coiled tubing on the horizontal section; providing the method to judge the average friction reduction of coiled tubing.Antifriction process of axial vibration and torsional vibration to1000m long coiled tubing on the horizontal section was calculated respectively by the finite element program; antifriction effect of the axial vibration and torsional vibration of continuous tube was compared under the same conditions. Draw the conclusion that the antifriction effect of axial vibration is slightly better than torsional vibration, and further research and improvement of axial vibration antifriction is suggested from the simplicity of design and use safety perspective of Friction Drag Reducer.The influence vibration frequency, pipe length, the speed of coiled tubing conveyance on the effect of antifriction has been studied. According to the conclusion, come up with the way of optimizing the A hypothetical condition is analyzed by utilizing the above research results, and providing a method to get the optimal solution of descending pipe parameters.. Conducted the inherent frequency analysis of coiled tubing to a horizontal well, and limited the frequency range of the Friction Drag Reducer.A hypothetical condition is analyzed by utilizing the above research results, and providing a method to get the optimal solution of descending pipe parameters.