速度管采气工艺在大牛地气田水平井的应用

Application of Gas Recovery Technology through Velocity String in Horizontal Wells of Daniudi Gas Field

大牛地气田水平井普遍具有低压、低产、携液能力差及井筒压力损失大的特点,严重制约着气井后期的稳定生产。速度管采气工艺是目前水平井应用的主要排水采气工艺之一,其工作原理是利用小直径连续油管充当速度管柱,下入深度至气井造斜点以上50m,减小流体的流动面积,提高气体的流速,从而有效预防井筒积液。阐述了速度管采气工艺的工艺原理、作业过程,并根据气井临界携液理论和管流压降模型,优选出■38.1mm速度管,可经济有效地满足气田中后期生产要求。综合分析速度管下入前后气井产量、压力、生产时率、助排措施等变化情况,建立速度管现场应用效果评价准则。通过对10口速度管水平井下入前后的生产情况进行对比分析表明,水平井下入速度管后总体排水采气效果较好。此外,速度管可实现连续冲砂,且冲砂深度可到水平段,恢复气井生产后增产效果明显。

The horizontal wells in the Daniudi gas field have the characteristics of low pressure ,low produc- tivity,poor liquid carrying capacity and high pressure loss in the wellbore,which seriously restrict the stable production of the late stage of gas well.Gas recovery technology through velocity string is one of the main drainage gas recovery technologies for the horizontal wells.Its working principle is to use small-diameter coiled tubing as the velocity string with above 50m of the kick-off point of running depth in gas wells ,and the fluid flow area may be reduced,gas flow velocity will be improved and liquid loading in the wellbore may be prevented effectively.The process principle and operation process of the gas recovery through velocity string were described.According to the theory of critical fluid carrying in gas wells and pressure drop model of pipe flow,~b38.1mm velocity string was optimized that may effectively meet the requirements of production of the gas field in middle-late stage.After the variation of gas well output,pressure,production rate,and drainage measures before and after velocity string running was analyzed,the evaluation criterion for the field application effect of the velocity string was established.The comparison and analysis on the production situa- tion before and after velocity string running in 10 horizontal wells show that the total drainage and gas re- covery is better after the velocity string running in the horizontal wells.In addition,the velocity string can re- alize continuous sand flushing,and the sand flushing depth can reach the horizontal section,and the stimula- tion effect is obvious after the recovery of gas well production.