水射流破碎联合CO2置换开采天然气水合物新工艺及实验研究

New technology and experimental research on water jet crushing combined with CO2 replacement to exploit natural gas hydrate

摘要:

本文对目前开采天然气水合物的5种方法进行了归纳总结，重点分析了CO₂置换开采以及固体开采法，并通过分析这2种开采方法的优劣势，提出了水射流冲蚀、破碎海洋天然气水合物储层联合CO₂置换开采天然气水合物的新思路。水射流冲蚀、破坏水合物储层后形成的采空区能为CO₂提供更好的储藏空间并提高其与储层的作用面积，提高置换效率；封存的CO₂水合物也可以提高水合物储层的稳定性，具有良好的互补效应。实验结果表明，在整个置换过程中，含采空区储层CH₄置换率为24.3%，CO₂封存率为22.1%；完整储层CH₄置换率为15.3%，CO₂封存率为20.9%，置换率提升约59%，封存率提升约5.7%。采空区的作用主要体现在提升水合物置换介质的注入量上。

关键词:天然气水合物;水射流破碎;CO₂/N₂置换;联合开采工艺;CO₂封存

Abstract:

The five current methods of mining natural gas hydrates are summarized with focus on the analysis of CO₂ replacement mining and solid mining methods， and by analyzing the advantages and disadvantages of the two mining methods， a new approach， by which water jets erodes and breaks ocean gas hydrates in combination with CO₂ replacement， is proposed for the exploitation of natural gas hydrates， The mined-out area formed by erosion and breaking of water jets in the hydrate reservoir can provide better storage space for CO₂， increase its interaction area with the reservoir， and improve the replacement efficiency. The stored CO₂ hydrate can also increase the stability of the hydrate reservoir， providing good complementary effect. The experimental results show that during the entire replacement process， the CH₄ replacement rate in the reservoir containing the mined-out area is 24.3%， and the CO₂ storage rate is 22.1%； while the CH₄ replacement rate in the intact reservoir is 15.3%， and the CO₂ storage rate is 20.9%； indicating that the replacement rate increases about 59%， the storage rate increases about 5.7%. The function of the goaf is mainly reflected in increasing the injection volume of the hydrate replacement medium.

Key words:natural gas hydrate;water jet breaking;CO₂/N₂ replacement;combined mining technology;CO₂ storage