深水测试管柱与隔水管的横向承载特性

在海上深水油气井测试过程中，隔水管、测试管柱与海水、环空流体、管内流体相互作用，并组成海上测试的“管中管”结构体系，目前对于由隔水管—测试管柱组成体系产生的复杂横向承载特性的认识不足。为了给海上安全测试作业的控制提供理论支撑，针对我国南海测试使用“管中管”体系结构及作业水深超过900 m的特点，建立了海水段测试管柱的井筒温度场、压力场及轴向力计算模型；考虑内外流体与管柱相互作用，建立了隔水管和测试管柱横向动态受力模型；基于数值求解方法，进行了不同顶张力、悬挂力、海流流速及平台漂移下的“管中管”结构体系横向承载特性分析。研究结果表明：①增大顶张力、悬挂力均能减小管柱体系的横向最大承载参数，同等幅度下的顶张力对管柱横向承载参数的影响更明显；②随着海流流速的增加，管柱体系的最大横向位移、转角、弯矩增大明显；③随着平台漂移量的增加，管柱体系的最大转角和弯矩先减小后增大，即顺着海流方向使平台产生适当的漂移有助于减小管柱体系横向的最大承载参数。结论认为，该研究成果可对海上测试作业的安全控制提供理论支撑。

Transverse bearing behaviors of strings and risers in deepwater tests

Risers and test strings interact with seawater, annulus fluid and internal fluid in the process of offshore deepwater oil and gas testing, thus a "pipe-in-pipe" structure system is formed, however, the complex transverse bearing behaviors generated by the riser-test string system are not understood sufficiently. In order to provide theoretical support for the control of offshore safety testing operation, this paper established a model for calculating the wellbore temperature field, pressure field and axial force of test string in seawater section in view of the characteristics of the "pipe-in-pipe" structure system applied in the testing operation and the operating water depth over 900 m in the South China Sea. Then, considering the interaction between internal and external fluid and string, a transverse dynamic force model of risers and test strings was established. Finally, the transverse bearing behaviors of the "pipe-in-pipe" structure system under different top tensions, hanging forces, current velocities and platform drifts were analyzed using the numerical method. And the following research results were obtained. First, increasing top tension and hanging force can reduce the transverse bearing parameters of the string system, and the influence of top tension on the transverse bearing parameters of the string system is more obvious under the same amplitude. Second, with the increase of current velocity, the maximum transverse displacement, rotation angle and bending moment of the string system increase obviously. Third, with the increase of platform drift, the maximum rotation angle and bending moment of the string system decrease first and then increase. That is to say, appropriate platform drift along the current direction is conducive to reducing the maximum transverse bearing parameters of the string system. In conclusion, the research results provide theoretical support for the safety control of offshore testing operations.