海底天然气水合物原位提纯分离器结构设计及优选

Structural design and optimization of in-situ purification separator for submarine gas hydrate

深水浅层非成岩天然气水合物储层胶结性差、含砂量大,在应用固态流化方法开采时原位提纯除砂回填具有可降低能耗、增加开采效率和防止储层坍塌等优势。基于固态流化开采方法提出了原位分离工艺,根据相关经验公式设计了原位分离器结构和初定参数,并采用CFD-Fluent结合单因素法与正交试验法对分离器溢流口直径、锥角、圆柱段长度以及底流口直径等结构参数进行了优选分析。分析结果表明,随着溢流口直径、锥角、圆柱段长度和底流口直径的增大,分离效率先增大后减小;采用单因素法优选结构参数后分离器除砂效率高达98.7%、天然气水合物回收效率高达97.8%,采用正交试验法优选结构参数后分离器除砂效率高达93.8%、水合物回收效率高达98.5%;从最大程度回收天然气水合物考虑,正交试验法对提纯分离器结构参数进行优选效果更好,且应着重考虑底流口直径。本文研究成果可为天然气水合物混合浆体原位提纯分离器设计、制造提供参考。

The deep water shallow non-diagenetic natural gas hydrate reservoir exhibits poor cementation and large sand content.When the hydrate is produced with solid fluidization method,the in-situ purification and sand removal backfilling have the advantages of reducing energy consumption,enhancing mining efficiency,avoiding reservoir collapse,etc.Based on the solid fluidization mining method,the in-situ separation process was proposed,the structure and initial parameters of this separator were designed according to relevant empirical formulas,and the structural parameters such as the diameter of separator overflow port,taper angle,cylindrical section length and the diameter of the underflow port were optimally analyzed by CFD-Fluent combined with single factor method and orthogonal test method.The analysis results show that as the diameter of overflow port,taper angle,cylindrical section length and the diameter of underflow port increase,the separation efficiency increases initially and then decreases.After the structural parameters are optimized by the single-factor method,the sand removal efficiency of separator is as high as 98.7%,the recovery efficiency of natural gas hydrate is up to 97.8%.After the structural parameters are optimized by the orthogonal test method,the sand removal efficiency is as high as 93.8%and the hydrate recovery efficiency is as high as 98.5%.From the perspective of maximizing the recovery of hydrate,the orthogonal test method can more effectively optimize the structural parameters of the purification separator,and more attention shall be paid to the diameter of underflow port.The research results in this paper can provide reference for the design and manufacturing of natural gas hydrate mixed slurry in-situ purification separator.