连续管在内压和循环弯曲作用下的试验研究

An experimental study of the coiled tubing under the effect of internal pressure and cyclic bending

连续管在稳定内压和循环弯曲的复合载荷作用下会出现直径增长和壁厚减薄。阐述了连续管直径增长、壁厚减薄的机理,并在不同内压下对外径38.1mm的QT-80连续管进行了变形试验研究。研究结果表明,内压为0时,直径不增长,有内压时,直径出现增长;内压越高,连续管直径增长速率越大;有内压时,随着循环次数的增加,椭圆度逐渐变大、壁厚减薄、直径增长。在40 MPa内压下,最大的直径增长率高达8%,壁厚减薄率高达19%,椭圆度超过8%。

The diameter of coiled tubing would increase and its wall thickness would become thinner when it was subject to the effect of the complex loading of stable internal pressure and cyclic bending. The mechanism of the coiled tubing’s diameter increase and wall thickness thinning were expounded in this paper and a deformation experimental study of the QT-80 coiled tubing with an outer diameter of 38.1 mm was made in different internal pressures. The research result showed that, when the internal pressure was zero, the diameter would not increase; when there was an internal pressure, the diameter would increase. The higher the internal pressure got, the greater the growth rate of the tubing diameter would be. When there was an internal pressure, the ellipticity would get greater, the wall thickness would get thinner and the diameter would increase with the increase of circulation. When the internal pressure was 40 MPa, the maximum diameter growth rate would reach 8%, the wall thickness thinning rate would be 19% and the ellipticity would be over 8%.