井下节流技术在低温分离工艺中的配套应用

MATCHING APPLICATION OF DOWNHOLE THROTTLING TECHNOLOGY IN LOW-TEMPERATURE SEPARATION PROCESS

长庆榆林气田集气站内采用多井加热、节流制冷、低温分离工艺流程,气井井口压力为18～22MPa,单井进站天然气直接节流制冷后温度将低于-20℃,这超过了集气站所采用设备普通20#钢适用温度范围,需要先经加热后再节流,才能达到低温分离工艺温度要求。针对集气站低温分离工艺运行实际,为解决多井集气站所辖低产气井井筒积液、采气管线水合物堵塞频繁等问题,引入井下节流技术,研究了井下节流技术和配套低温分离工艺应用基本原理和技术关键,现场共成功配套应用14井次,使单井采气管线运行压力降为10～12MPa,单井进站天然气直接节流制冷,停运了多井加热炉,不但满足了低温分离工艺温度-8～-18℃的要求,而且有效解决了低产气井水合物堵塞等问题,实现了正常生产和节能降耗,减少了甲醇注入量和燃气消耗,提高了气井采气时率,14口井每天可节能价值约1.07万元,经济效益显著。

The Multiwell heating,throttling refrigeration and low-temperature separation process have been applied in the gas gathering station of the Yulin gas field.Due to the higher wellhead pressure(18-22 MPa),the temperature of incoming gas in a single well directly through the throttling refrigeration would be lower than-20℃ which outreaches the applicable temperature range of normal steel No.20,therefore,it needs to be throttled after being heated so as to attain its temperature demand by low-temperature separation process.On the basis of operation practice of low-temperature separation process in gas gathering stations,in order to solve problems of liquid loading(well bore) and hydrate block(flow line) in multiwell gas gathering stations,the downhole throttling technology was introduced,fundamental principle and gordian technique of the bottom hole choke were studied.Through successful matching application of low-temperature separation process in 14 gas wells,the flow line for a single well was operated under the pressure about 10 to 12 MPa,the incoming gas from a single well was choked directly without heating,the heating furnace was blocked up,not only could the temperature demand of-8 to-18 ℃ be satisfied for the low-temperature separation process,but also the hydrate block of low-productivity gas wells could be removed effectively as well.By means of the matching application,the normal production of low-productivity gas wells and energy saving & declining consumption could be all achieved,methanol rate of injection and gas firing consumption could be reduced,gas production time per year had been raised,and 14 gas wells could save up to 10.7 thousand Yuan per day with obvious economic benefit.