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

The downhole throttling technique for gas hydrate prevention has been studied for prevention 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 wellbore up and down the downhole throttling shows the section hydrate likely to form in Well LN422 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 throttling technique can significantly reduce wellbore pressure of high-pressure gas wells,reduce the risk of hydrate plugs formation,and effectively extend the repair free period.