SAGD系统输送过热蒸汽热力适应性分析

Thermodynamic adaptability analysis of SAGD Superheat Steam Transportation

根据SAGD原理,注入蒸汽干度的高低直接影响开发效果和经济效益,因此将过热蒸汽应用于SAGD开发会带来显著经济效益。与高干度湿蒸汽相比,过热蒸汽携带热焓多、温度高,对地面管线、井筒管柱热应力、蒸汽腔发育等方面产生的影响也不同。通过输汽管线应力分析和保温设计校核,发现现有的地面注汽管线输送过热蒸汽后,虽然管线热损失增大了,但仍在国标许可范围内,因此无需更换保温层厚度。由于注过热蒸汽流动阻力大,部分工况下需更换管线,增大管径。开展过热蒸汽井筒流动传热规律研究及注入参数优化设计,建立井筒内过热蒸汽流动传热模型并模拟,得到井筒压力、温度、热损失分布规律,并对确保井底过热工况下井口所需的过热蒸汽过热度、压力等参数进行了优化计算,给出18组优化注汽参数组合,用以指导SAGD高效注汽生产。

Base on SAGD principle,the steam quality will directly influence the development performance and economic benefit,therefore application of superheat steam will get significant economic benefit during SAGD development.Superheat steam carries more enthalpy,possess higher temperature than high quality wet saturated steam.The impacts on surface pipeline,thermal stress of wellbore string and growth of steam chamber are different.After stress analysis and heat-up design check of steam transmission pipeline,the existing high quali- ty saturated steam pipelines were still suitable for superheat steam transportation,although the heat loss in-creases （within the range of national standard）,the thickness of insulation layer has no need to be changed. Due to the increase of flow resistance of superheat steam injection,the pipeline should be replaced under some working conditions to increase the diameter of it.Flow and heat transfer law of superheat steam wellbore was researched,and steam injection parameters were optimized and designed.Flow and heat transfer model of the superheat steam in wellbore was built and simulated,and then wellbore pressure,temperature and heat loss distribution rule were known.Superheat degree of the superheat steam,pressure and other parameters at wellhead under superheat condition were optimized and calculated.Eighteen groups of optimized steam injection parameters were given to guide SAGD high efficient steam injection.