Formation prediction of hydrate in surface throttling process in Puguang Gasfield and its prevention measures

The natural gas in Puguang Gasfield has high content of sulfur and mediate content of carbon-dioxide dry gas.Therefore,hydrate is easily formed in surface throttling process,and it will plug gas transmission pipeline.For this reason,the formation of hydrate is predicted.Based on seepage theory,productivity equation and throttling principle,the wellhead temperature and pressure of Puguang 2 well under different gas production rates is calculated by using WELLFLO software,and the temperatures after throttling under different throttling orders and different throttling pressures are also calculated.According to the calculation results,it is predicted whether hydrate can be formed in the pipeline after throttling valves.The results show that,the hydrate is very easily formed in the throttling process,and therefore the first-order throttling parameters should reasonably be selected when two-order throttling is adopted.Some prevention measures from the formation of the hydrate are proposed.