塔里木油田高压气井井下节流防治水合物技术

Downhole Throttling Technology for Gas Hydrate Prevention in Deep Gas Wells of Tarim Oilfield

塔里木油田高压气井开采过程中水合物堵塞问题严重,影响了气井的正常生产,因而研究应用了合理的井下节流防治水合物技术。利用水合物生成预测模型与气井井筒压力温度预测模型,对高压气井的水合物生成温度和生成位置进行了预测;采用节点系统分析方法,以节流器为节点预测气井井下节流后的温度压力分布,对比节流前后的井筒压力和温度分布,分析高压气井井下节流防治水合物效果。根据高压气井LN422井的水合物相态曲线和井筒内温度压力场,认为水合物形成风险区为500m以浅井段。应用井下节流技术后,LN422井的井口压力由29.2MPa降至12.0MPa,井口温度由21.0℃升至23.7℃,且井筒中各处的温度均高于该处的水合物生成临界温度。研究结果表明,井下节流技术可显著降低高压气井的井筒压力和水合物生成风险,延长生产免修期。

T he dow nhole throttling technique for gas hydrate prevention has been studied for preven-tion hydrate blockage in high pressure gas wells .Hydrate formation temperature-pressure was predicted by using hydrate formation prediction model for high-pressure gas well .Temperature and pressure of the fluid in the wellbore in production process was forecasted by gas well pipe flow model .And the section hydrate plugs likely to form was analyzed .Downhole throttling temperature and pressure predictive models were constructed based on throttle node .Comparison of the pressure and temperature distribution in the well-bore up and down the downhole throttling shows the section hydrate likely to form in Well LN 422 is in the section above 500 m in depth .Wellhead pressure of Well LN422 reduced from 29.2 MPa to 12.0 MPa after throttling ,and the wellhead temperature rose from 21.0 ℃ to 23.7 ℃ .The temperature throughout the wellbore is higher than the critical hydrate formation temperature .The results show that downhole thrott-ling technique can significantly reduce wellbore pressure of high-pressure gas wells ,reduce the risk of hy-drate plugs formation ,and effectively extend the repair free period .