海上大斜度热采井氮气隔热注氮排量优化研究

Optimization of nitrogen injection rate for thermal insulation by nitrogen in highly deviated wells for thermal recovery in offshore fields

海上稠油热采多采用环空注氮气的隔热方式,注氮排量设计目前尚没有经济可行的优化方法。根据海上大斜度热采井的井身结构特点,利用流体力学和传热学基本原理建立了蒸汽和氮气参数的计算模型,然后通过两种流体在隔热管出口处混合后的特征分析推导出了注氮排量的优化方法,并通过实例计算对注氮排量进行了优化分析。该方法可为海上大斜度热采井现场注氮排量的调控提供理论依据,从而实现海上油田持久、高效的蒸汽吞吐热采。

Thermal insulation with annular nitrogen injection is commonly adopted for offshore heavy oil thermal recovery. There is no economically feasible optimization method for nitrogen injection rate design. The calculation model of steam and nitrogen parameters was established based on the principles of fluid mechanics and heat transfer according to the characteristics of well trajectory in offshore highly deviated wells. The optimization method of nitrogen injection rate was derived according to the analysis of mixing phenomenon of the two fluids at the outlet of the thermal insulation pipeline, and was verified with case study calculation. The method can realize the regulation of nitrogen injection rate for the highly deviated thermal recovery wells as the theoretical basis, achieving the sustainable and effective development of CSS for the offshore oilfield.