中文摘要：

通常采用的水合物预防方法有注入抑制剂、井下节流、采用重力热管或注入热流体等。为分析其应用于深水气井井筒时的适用性和高效性等，开展了深水气井井筒天然气水合物预防方法的比较研究，比较分析了注抑制剂、采用重力热管和井下节流等方法抑制水合物生成的机理。抑制剂直接阻碍水合物的成核和生长，重力热管法与井下节流法则是通过调节井筒温度和压力分布，使其不具备水合物生成条件。利用改进的双流体模型计算井筒内温度和压力分布，以南海东部某深水气井设计资料为基础，比较分析了此3种方法对天然气水合物生成区域的影响规律。分析结果表明：注入抑制剂后，在低浓度范围内，随浓度增加初始生成位置呈小幅上升趋势；在高浓度范围内，随浓度增加初始生成位置大幅度上升；在热流体注入口附近，井筒流体温度出现突变，并随注入量增加与注入温度升高而升高；高产量下，井下节流使水合物生成区域增大；低产量下，节流后水合物生成区域减小。研究结果可为深水气井井筒流动安全保障设计提供参考。

英文摘要：

Commonly used hydrate prevention methods include inhibitor injection, downhole throttling, gravity assisted heat pipe application, thermal fluid injection, etc.In order to analyze applicability and effectiveness of the above methods in the deepwater gas well borehole, a comparative study is conducted on prevention methods of natural gas hydrate in the deepwater gas well borehole,and the hydrate generation inhibiting principle of inhibitor injection, downhole throttling, gravity assisted heat pipe application is comparatively analyzed.The inhibitor can directly hinder nucleation and growth of hydrates; the gravity assisted heat pipe and downhole throttling can adjust borehole temperature and pressure distribution to eliminate hydrate generating conditions.An improved two-fluid model is used for calculating borehole temperature and pressure distribution, and a comparative analysis is conducted on influencing pattern of these three methods on natural hydrate generating area based on design data of some deepwater well in the eastern South China Sea.Analysis results show that, within the range of low concentration, initial generating location has a small rise with increase of the concentration after injection of inhibitors; within range of high concentration, the initial generating location has a large rise with increase of concentration; near the thermal fluid injection inlet, borehole fluid temperature has a sudden change and rises with increase of injection amount and injection temperature; under high yield, the downhole throttling can increase the hydrate generating area; under low yield, the hydrate generating area is reduced after throttling.The results can provide references for flow safety guarantee design of deepwater gas well borehole.