海上热采井氮气隔热注氮参数的优化

Optimisation of nitrogen injection parameters for nitrogen insulation in offshore thermal recovery wells

为研究海上热采井环空注氮参数对井筒隔热效果的影响,建立了环空注氮井筒传热系数计算模型,通过自主研发的井筒热力参数优化设计软件分析不同注氮排量、温度、压力参数对套管温度、井底蒸汽干度及进入地层热量的影响。结果表明:注氮排量在200~500 m~3/h之间,注氮温度在50~100℃之间,井筒热损失小,井底蒸汽干度高;在保障氮气能注入地层并能抑制蒸汽环空上返的条件下,降低注氮压力,可有效增加进入地层热量,提高井底蒸汽干度,降低套管温度,对套管起到良好的保护作用。该研究可为海上稠油热采井现场注氮参数的设计提供科学指导和依据。

This paper aims to study the influence of nitrogen injection parameters in the annulus of offshore thermal recovery wells on the thermal insulation effect.The study involves stablising a calculation model for heat transfer coefficient of the annulus nitrogen injection wellbore,and analyzing the influence of different nitrogen injection displacement,temperature and pressure parameters on casing temperature bottomhole steam dryness,and the heat entering the formation by means of the self-developed wellbore thermal parameter optimization design software.The results show that when the nitrogen injection rate is between 200-500 m~3/h and the nitrogen injection temperature is between 50-100 ℃,the wellbore heat loss is small,and the steam bottomhole dryness is high.Under the condition that nitrogen can be injected into the formation and the steam annulus can be suppressed,reducing nitrogen injection pressure can add more heat entering the formation,improve dryness at the bottom of the well,reduce casing temperature,as which protects the casing.This research can provide a basis and guidance for the design of nitrogen injection parameters in offshore heavy oil thermal recovery wells.